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LAMP
Autofocus – Assist lamp
Many cameras that do not have a dedicated autofocus assist lamp instead use their built-in flash, illuminating the subject with stroboscopic bursts of light
Autofocus – Assist lamp
In some cases, external flash guns have integrated autofocus assist lamps that replace the stroboscopic on-camera flash. Another way to assist contrast based AF systems in low light is to beam a laser pattern on to the subject. The laser method is commercially called Hologram AF Laser and was used in Sony Cybershot cameras around the year 2003, including Sony’s F707, F717 and F828 models.
LAMP (software bundle)
The acronym LAMP refers to first letters of the components of the solution stack composed entirely of free and open-source software, suitable for building high-availability heavy-duty dynamic web sites, and capable of serving tens of thousands of requests simultaneously.
LAMP (software bundle)
Meaning of the LAMP acronym depends on specific components used as part of the actual bundle:
LAMP (software bundle)
Linux, the Operating System (i.e. not just the Linux kernel, but also glibc and some other essential components of an Operating System);
LAMP (software bundle)
P for PHP, Perl, or Python, the scripting languages (respectively programming languages) used for dynamic web pages and web development.
LAMP (software bundle)
Though the original authors of these programs did not design them all to work as a component of a LAMP stack, the development philosophy and tool sets are shared and were developed in close conjunction, so they work and scale very well together
LAMP (software bundle)
Due to the nature of free and open-source software and the ubiquity of its components, each and every component of the LAMP stack is very well tested regarding performance and security. At the same time, there is an abundance of experienced contractors to do the tailoring required for various customizations, or for complex setups. There is also constant development going on.
LAMP (software bundle)
The components of the LAMP stack are present in the software repositories of most (if not all) Linux distributions, giving any end-user a simple way to install, set up and operate an initial LAMP stack out of the box. The web presence of a small company which does not have a high hit count and is not prone to frequent attacks, can therefore be administered by another small company, by a one man company or even by a student.
LAMP (software bundle)
The LAMP stack, because of the general advantages and benefits of free and open-source software, may be one of the reasons for the very high Linux adoption rate among web servers.
LAMP (software bundle)
The LAMP bundle can be and is combined with many other free and open-source software packages such as e.g. netsniff-ng for security testing and hardening, Snort, an intrusion detection (IDS) and intrusion prevention system (IPS), RRDtool for diagrams, or nagios, Collectd, or Cacti, for monitoring. The Django (web framework) for development.
LAMP (software bundle) – Linux
Linux is a Unix-like and POSIX-compliant computer Operating System assembled under the model of free and open source software development and distribution. The main form of distribution are Linux distributions, usually providing complete LAMP setups out of the box through their package management systems. Of the most widespread Linux distributions, as of 1 October 2013, Debian and Ubuntu are together at the web servers market share of 58.5%, while RHEL, Fedora and CentOS are at 37.3%.
LAMP (software bundle) – Linux
Many options are available for customizing and securing Linux installations, for example by using SELinux, or by employing chroot environments.
LAMP (software bundle) – Apache
Apache is a web server, the most popular in use.
LAMP (software bundle) – MySQL
MySQL is a multithreaded, multi-user, SQL database management system (DBMS) now owned by Oracle Corporation. Alternatives at this level of the stack do also exist, primarily the MySQL fork . Other RDBM Systems such as PostgreSQL (LAPP) are also viable.
LAMP (software bundle) – MySQL
MySQL has been owned by Oracle Corporation since January 27, 2010 through the purchase of Sun Microsystems. Sun had originally acquired MySQL on February 26, 2008.
LAMP (software bundle) – Variants and equivalents on other platforms
With the growing use of LAMP, variations and retronyms appeared for other combinations of operating system, web server, database, and software language
LAMP (software bundle) – Variants and equivalents on other platforms
A server running LAMP may be colloquially known as a lamp box, punning on the type of post box. The GNU project is advocating people to use the term “GLAMP” since what is known as “Linux” includes the GNU tools as well as the Linux kernel.
Tilley lamp
Tilley storm lantern X246B May 1978: this model has been in production since 1964.
Tilley lamp
The Tilley lamp derives from John Tilley’s invention of the hydro-pneumatic blowpipe in 1813 in England. W.H.Tilley were manufacturing pressure lamps at their works in Stoke Newington in 1818, and Shoreditch, in the 1830s. The company moved to Brent Street in Hendon in 1915 during World War I, and started work with paraffin (kerosene) as a fuel for the lamps.
Tilley lamp
During the 1920s the company had diversified into domestic lamps, and had expanded rapidly after orders from railway companies
Automotive lighting – Motorsport and off-road lamps
Vehicles used in rallying, off-roading, or auto races often have powerful lamps to broaden and extend the field of illumination in front of the vehicle. On off-road vehicles in particular, these additional lamps are sometimes mounted along with forward-facing lights on a bar above the roof, which protects them from road hazards and raises the beams allowing for a greater projection of light forward.
Automotive lighting – Front fog lamps
They are sometimes used in place of dipped-beam headlamps, reducing the glareback from fog or falling snow, although the legality varies by jurisdiction of using front fog lamps without low beam headlamps.
Automotive lighting – Front fog lamps
Use of the fog lamps when visibility is not seriously reduced is often prohibited;for example, in New South Wales, Australia: “The driver of a vehicle must not: (a) use any fog light fitted to the vehicle unless the driver is driving in fog, mist or under other atmospheric conditions that restrict visibility”.
Automotive lighting – Front fog lamps
A study has shown that in the United States more people inappropriately use their fog lamps in dry weather than use them properly in poor weather.
Automotive lighting – Cornering lamps
Cornering lamps have traditionally been prohibited under international UN Regulations, though provisions have recently been made to allow them as long as they are only operable when the vehicle is travelling at less than 40 kilometres per hour (about 25 mph).
Automotive lighting – Front position lamps (parking lamps, standing lamps)
Colloquial city light terminology for front position lamps derives from the practice, formerly adhered to in cities like Moscow, London and Paris, of driving at night in built-up areas using these low-intensity lights rather than headlamps.
Automotive lighting – Front position lamps (parking lamps, standing lamps)
Since the late 1960s, front position lamps have been required to remain illuminated even when the headlamps are on, to maintain the visual signature of a dual-track vehicle to oncoming drivers in the event of headlamp burnout. Front position lamps worldwide produce between 4 and 125 candelas.
Automotive lighting – Front position lamps (parking lamps, standing lamps)
In Germany, the StVZO (Road Traffic Licensing Regulations) calls for a different function also known as parking lamps: With the vehicle’s ignition switched off, the operator may activate a low-intensity light at the front (white) and rear (red) on either the left or the right side of the car
Automotive lighting – Dim-dip lamps
In practice, most vehicles were equipped with the dim-dip option rather than the running lamps.
Automotive lighting – Dim-dip lamps
Dim-dip was intended to provide a nighttime “town beam” with intensity between that of the parking lamps commonly used at the time by British drivers in city traffic after dark, and dipped (low) beams; the former were considered insufficiently intense to provide improved conspicuity in conditions requiring it, while the latter were considered too glaring for safe use in built-up areas
Automotive lighting – Dim-dip lamps
In 1988, the European Commission successfully prosecuted the UK government in the European Court of Justice, arguing that the UK requirement for dim-dip was illegal under EC directives prohibiting member states from enacting vehicle lighting requirements not contained in pan-European EC directives
Automotive lighting – Rear position lamps (tail lamps)
The tail and stop light functions may be produced separately or by a dual-intensity lamp.
Automotive lighting – Rear position lamps (tail lamps)
Regulations worldwide stipulate minimum intensity ratios between the bright (stop) and dim (tail) modes, so that a vehicle displaying rear position lamps will not be mistakenly interpreted as showing stop lamps, and vice versa.
Automotive lighting – Rear position lamps (tail lamps)
Many modern designs use LED lighting sources beginning in 1999 with the 2000 Cadillac Deville.
Automotive lighting – Stop lamps (brake lights)
In Northern America, the acceptable range for a single-compartment stop lamp is 80 to 300 candela.
Automotive lighting – Centre High Mount Stop Lamp (CHMSL)
The CHMSL (pronounced /?t??mz?l/) is also sometimes referred to as the “centre brake lamp”, the “third brake light”, the “eye-level brake lamp”, the “safety brake lamp”, or the “high-level brake lamp”
Automotive lighting – Centre High Mount Stop Lamp (CHMSL)
The CHMSL is intended to provide a deceleration warning to following drivers whose view of the vehicle’s left and right stop lamps is blocked by interceding vehicles. It also helps to disambiguate brake vs. turn signal messages in Northern America, where red rear turn signals identical in appearance to stop lamps are permitted, and also can provide a redundant stop light signal in the event of a stop lamp malfunction.
Automotive lighting – Centre High Mount Stop Lamp (CHMSL)
The CHMSL is generally required to illuminate steadily and not permitted to flash, though U.S. regulators granted Mercedes-Benz a temporary, limited exemption to the steady-light requirement so as to evaluate whether a flashing CHMSL provides an emergency stop signal that effectively reduces the likelihood of a crash.
Automotive lighting – Centre High Mount Stop Lamp (CHMSL)
Depending on the left and right lamps’ height, the lower edge of the CHMSL may be just above the left and right lamps’ upper edge.
Automotive lighting – Centre High Mount Stop Lamp (CHMSL)
Auto and lamp manufacturers in Germany experimented with dual high-mount supplemental stop lamps in the early 1980s, but this effort, too, failed to gain wide popular or regulatory support.
Automotive lighting – Centre High Mount Stop Lamp (CHMSL)
Once the novelty effect wore off as most vehicles on the road came to be equipped with the central third stop lamp, the crash-avoidance benefit declined
Automotive lighting – Rear fog lamps
Further, rear fog lamps are not required equipment in the U.S., however, they are permitted, and are found almost exclusively on European-brand vehicles in North America — Audi, Jaguar, Mercedes, MINI, Land Rover, Porsche, Saab and Volvo provide functional rear fog lights on their North American models
Automotive lighting – Rear fog lamps
To provide some safeguard against rear fog lamps being confused with stop lamps, UN Regulation 48 requires a separation of at least 10 cm between the closest illuminated edges of any stop lamp and any rear fog lamp.
Automotive lighting – Reversing lamps
state of Washington presently permits reversing lamps to emit white or amber light.
Automotive lighting – Rear registration plate lamp
The rear registration plate is illuminated by a white lamp designed to light the surface of the plate without creating white light directly visible to the rear of the vehicle; it must be illuminated whenever the position lamps are lit.
Automotive lighting – Identification lamps
In the US, vehicles over 2,032 mm (80 inches) wide must be equipped with three amber front and three red rear identification lamps spaced between 6 and 12 inches apart at the center of the front and rear of the vehicle, as high as practicable. The front identification lamps are typically mounted atop the cab of vehicles. This type of identification lamp can also be found on road trains in Australia.
Automotive lighting – Clearance lamps
In the US, vehicles over 2,032 mm (80 inches) wide must be equipped with left and right amber front and red rear clearance lights to indicate the overall width of the vehicle. These must be amber at the front, red at the rear, and mounted as high as practicable.
Automotive lighting – End outline marker lamps
UN Regulations require large vehicles to be equipped with left and right white front and red rear end outline marker lamps, which serve a purpose similar to that of the American clearance lamp.
Automotive lighting – Intermediate side marker lamps and reflectors
US regulations require large North American vehicles to be equipped with left and right amber side marker lights and reflectors mounted midway between the front and rear side markers.
Automotive lighting – Incandescent lamps
Signal lamps with internal or external coloured lenses use colourless bulbs; conversely, lamps with colourless lenses may use red or amber bulbs to provide light of the required colours for the various functions.
Automotive lighting – Incandescent lamps
Typically, bulbs of 21 to 27 watts, producing 280 to 570 lumens (22 to 45 mean spherical candlepower) are used for stop, turn, reversing and rear fog lamps, while bulbs of 4 to 10 W, producing 40 to 130 lm (3 to 10 mscp) are used for tail lamps, parking lamps, side marker lamps and side turn signal repeaters.
Automotive lighting – Incandescent lamps
Tungsten-halogen lamps are a very common light source for headlamps and other forward illumination functions. Some recent-model vehicles use small halogen bulbs for exterior signalling and marking functions, as well. The first halogen lamp approved for automotive use was the H1, which was introduced in Europe in 1962, 55 W producing 1500 lm.
Automotive lighting – Variable-intensity signal lamps
International UN Regulations[which?] explicitly permit vehicle signal lamps with intensity automatically increased during bright daylight hours when sunlight reduces the effectiveness of the stop lamps, and automatically decreased during hours of darkness when glare could be a concern. Both US and UN regulations contain provisions for determining the minimum and maximum acceptable intensity for lamps that contain more than a single light source.
Ceramic discharge metal-halide lamp
The discharge is contained in a ceramic tube, usually made of sintered alumina, similar to what has been used in the high pressure sodium lamp
Ceramic discharge metal-halide lamp
There are also warm-white CDM lamps, with somewhat lower CRI (78-82) which still give a more clear and natural-looking light than the old mercury-vapour and sodium-vapour lamps when used as street lights, besides being more economical to use.
Ceramic discharge metal-halide lamp
The ceramic tube is an advantage in comparison to earlier fused quartz. During operation, at high temperature and radiant flux, metal ions tend to penetrate the silica, depleting the inside of the tube. Alumina is not prone to this effect.
Ceramic discharge metal-halide lamp
CDM lamps use one fifth of the power of comparable tungsten incandescent light bulbs for the same light output (80–117 lm/W) and retain colour stability better than most other gas discharge lamps. Like other high-intensity discharge lamps, they require a correctly rated electrical ballast in order to operate.
Ceramic discharge metal-halide lamp
Applications for these lamps include television and film making as well as shop lighting, digital photography, street and architectural lighting.
Hydrargyrum medium-arc iodide lamp
Hydrargyrum medium-arc iodide lamp
Hydrargyrum medium-arc iodide lamp
Hydrargyrum medium-arc iodide, or HMI, is the brand name of Osram brand for a metal-halide gas discharge medium arc-length lamp manufactured for film and entertainment applications. Hydrargyrum is Latin for mercury (Hg).
Hydrargyrum medium-arc iodide lamp
The high CRI and color temperature are due to the specific lamp chemistries.
Hydrargyrum medium-arc iodide lamp – History
In the late 1960s German television producers sought out lamp developer OSRAM to create a less expensive replacement for incandescent lights for the film industry. Osram developed and began producing HMI bulbs at their request.
Hydrargyrum medium-arc iodide lamp – History
It uses a standard two-prong lampbase
Hydrargyrum medium-arc iodide lamp – History
Within the last ten years, a lot of research has gone into making HMI lamps smaller because of their use in moving light fixtures such as those manufactured by Vari-Lite, Martin, Robe, and Highend. Philips’ main contribution after this was the invention of a phosphor coating on the weld of the filament to the molybdenum foil that reduces oxidization and early failures at that point, making that area capable of withstanding extreme heat.
Hydrargyrum medium-arc iodide lamp – History
Multi-kilowatt HMI lights are used in the film industry and for large-screen slide projection because of their daylight-balanced light output, as well as their efficiency.
Hydrargyrum medium-arc iodide lamp – Flicker and color temperature
Unlike incandescent-lighting units, which are blackbody radiators limited to a theoretical maximum of 3680 K (the melting point of tungsten), HMI lamps, like all gas discharge lighting, emit the emission spectral lines of its constituent elements, specifically chosen so that combined, they resemble the blackbody spectrum of a 6000 K source
Hydrargyrum medium-arc iodide lamp – Flicker and color temperature
With HMI bulbs, color temperature varies significantly with lamp age
Hydrargyrum medium-arc iodide lamp – Flicker and color temperature
For HMI lamps, flicker can be avoided by the use of electronic ballasts that cycle at frequencies thousands of times faster than the mains frequency.
Hydrargyrum medium-arc iodide lamp – Ballast operation
Input power is routed to a choke coil connected between the main input and the lamp
Hydrargyrum medium-arc iodide lamp – Ballast operation
This control board carefully adjusts the high frequency duty cycle of its transistors to maintain optimum color and light output as the lamp ages
Hydrargyrum medium-arc iodide lamp – Ballast operation
The square wave nature of the output results in a straight-line power output from the lamp
Hydrargyrum medium-arc iodide lamp – Ballast operation
The lamp housing does not help this, acting as a resonating chamber that amplifies the noise and presents a problem for sync-sound recording for film and video
Hydrargyrum medium-arc iodide lamp – Ballast operation
Most modern ballasts are now also equipped with a dimmer, which uses pulse-width modulation to dim the lamp up to 50%, or as much as one stop of light
Hydrargyrum medium-arc iodide lamp – Safety
HMI lamps are approximately the same color temperature as the sun, and as with most other mercury-based high intensity discharge lamps, generate ultra-violet light. Each HMI light has a UV safety glass cover that should be used to protect persons who may be in front of the light. Exposure to an unprotected lamp can cause retinal damage and severe skin burns.
Hydrargyrum medium-arc iodide lamp – Safety
It is good practice to strike the light from the ballast and not the head, in the event that there is a short circuit in the lamp head
Hydrargyrum medium-arc iodide lamp – Safety
There is the possibility of the front lens element on the lamp head cracking from thermal shock (though not completely blowing out or shattering)
L Prize – 21st Century Lamp
On August 1, 2011, Cree announced that they had created a bulb that would exceed the DOE specifications for a 21st-century lamp. It emitted 1,300 lumens at 152 lumens per watt with a CRI of 91.2 and a color temperature of 2800 K. They also stated at the time that they would not be bringing the bulb to market. As of March, 2013 they had not brought the bulb or any bulb like it to market.
Neon lighting – Neon glow lamps and plasma displays
In neon glow lamps, the luminous region of the gas is a thin, “negative glow” region immediately adjacent to a negatively charged electrode (or “cathode”); the positively charged electrode (“anode”) is quite close to the cathode. These features distinguish glow lamps from the much longer and brighter “positive column” luminous regions in neon tube lighting. The energy dissipation in the lamps when they are glowing is very low (about 0.1 W), hence the distinguishing term cold-cathode lighting.
Neon lighting – Neon glow lamps and plasma displays
Some of the applications of neon lamps include:
Neon lighting – Neon glow lamps and plasma displays
Pilot lamps that indicate the presence of electrical power in an appliance or instrument (e.g. an electric coffee pot or power supply).
Neon lighting – Neon glow lamps and plasma displays
Decorative (or “figural”) lamps in which the cathode is shaped as a flower, animal, etc.. The figures inside these lamps were typically painted with phosphorescent paints to achieve a variety of colors.
Neon lighting – Neon glow lamps and plasma displays
Active electronic circuits such as electronic oscillators, timers, memory elements, etc..
Neon lighting – Neon glow lamps and plasma displays
Intricate electronic displays such as the Nixie tube (see photograph).
Neon lighting – Neon glow lamps and plasma displays
These features include alternating sustain voltage, dielectric layer, wall charge, and a neon-based gas mixture.” As in colored neon lamps, plasma displays use a gas mixture that emits ultraviolet light
Heat sink – Light-emitting diode lamps
Light-emitting diode (LED) performance and lifetime are strong functions of their temperature
LED lamp
A LED lamp is a light-emitting diode (LED) product that is assembled into a lamp (or light bulb) for use in lighting fixtures. LED lamps have a lifespan and electrical efficiency that is several times better than incandescent lamps, and significantly better than most fluorescent lamps, with some chips able to emit more than 100 lumens per watt.
LED lamp
Like incandescent lamps and unlike most fluorescent lamps (e.g. tubes and CFL), LED lights come to full brightness without need for a warm-up time; the life of fluorescent lighting is also reduced by frequent switching on and off. Initial cost of LED is usually higher. Degradation of LED die and packaging materials reduces light output to some extent over time.
LED lamp
With research into organic LEDs (OLED) and polymer LEDs (PLED), cost per lumen and output per device have been improving so rapidly according to what has been called Haitz’s law, analogous to Moore’s law for semiconductor devices.
LED lamp
Some LED lamps are made to be a directly compatible drop-in replacement for incandescent or fluorescent lamps. An LED lamp packaging may show the lumen output, power consumption in watts, color temperature or description (“warm white”) and sometimes the equivalent wattage of an incandescent lamp of similar luminous output.
LED lamp
LEDs do not emit light in all directions, and their directional characteristics affect the design of lamps. The light output of single LEDs is less that that of incandescent and compact fluorescent lamps; in most applications multiple LEDs are used to form a lamp, although high-power versions are becoming available.
LED lamp
LED chips need controlled direct current (DC) electrical power; an appropriate power supply is needed. LEDs are adversely affected by high temperature, so LED lamps typically include heat dissipation elements such as heat sinks and cooling fins.
LED lamp – Technology overview
General-purpose lighting needs white light. LEDs emit light in a very narrow band of wavelengths, emitting light of a color characteristic of the energy bandgap of the semiconductor material used to make the LED. To emit white light from LEDs requires either mixing light from red, green, and blue LEDs, or using a phosphor to convert some of the light to other colors.
LED lamp – Technology overview
One method (RGB or trichromatic white LEDs) uses multiple LED chips, each emitting a different wavelength, in close proximity to generate white light. This allows the intensity of each LED to be adjusted to change the overall color.
LED lamp – Technology overview
The second method uses LEDs in conjunction with a phosphor. The CRI (color rendering index) value can range from less than 70 to over 90, and color temperatures in the range of 2700 K (matching incandescent lamps) up to 7000 K are available.
LED lamp – Application
A significant difference from other light sources is that the light is more directional, i.e., emitted as a narrower beam. LED lamps are used for both general and special-purpose lighting. Where colored light is needed, LEDs that inherently emit light of a single color require no energy-absorbing filters.
LED lamp – Application
White-light LED lamps have longer life expectancy and higher efficiency (more light for the same electricity) than most other lighting
LED lamp – Application
This allows full color mixing in lamps with LEDs of different colors
LED lamp – Lamp sizes and bases
LED lamps are made that replace screw-in incandescent or compact fluorescent light bulbs, mostly replacing incandescent bulbs rated from 5 to 60 watts. Such lamps are made with standard light bulb connections and shapes, such as an Edison screw base, an MR16 shape with a bi-pin base, or a GU5.3 (Bipin cap) or GU10 (bayonet fitting) and are made compatible with the voltage supplied to the sockets. They include circuitry to rectify the AC power and convert the voltage to an appropriate value.
LED lamp – Lamp sizes and bases
As of 2010 some LED lamps replaced higher wattage bulbs; for example, one manufacturer claimed a 16-watt LED bulb was as bright as a 150 W halogen lamp. A standard general-purpose incandescent bulb emits light at an efficiency of about 14 to 17 lumens/W depending on its size and voltage. According to the European Union standard, an energy-efficient bulb that claims to be the equivalent of a 60 W tungsten bulb must have a minimum light output of 806 lumens.
LED lamp – Lamp sizes and bases
LED lamps are available with a variety of color properties
LED lamp – Lamp sizes and bases
Several companies offer LED lamps for general lighting purposes. The technology is improving rapidly and new energy-efficient consumer LED lamps are available.
LED lamp – LED tube lamps
LED tube lights are designed to physically fit in fixtures intended for fluorescent tubes. Some LED tube lamps are intended to be a drop-in replacement into existing fixtures. Others require rewiring of the fixtures to remove the ballast. An LED tube lamp generally uses many individual LEDs and may be directional. Fluorescent lamps emit light all the way around the lamp. Most LED tube lights available can be used in place of T8, T10, or T12 tube designations, in lengths of 2, 4, and 8 feet.
LED lamp – Lighting designed for LEDs
Newer light fittings designed for LED lamps, or indeed with long-lived LEDs built-in, have been coming into use as the need for compatibility with existing fittings diminishes. Such lighting does not require each bulb to contain circuitry to operate from mains voltage.
LED lamp – Specialty uses
White LED lamps have achieved market dominance in applications where high efficiency is important at low power levels. Some of these applications include flashlights, solar-powered garden or walkway lights, and bicycle lights. Monochromatic (colored) LED lamps are now commercially used for traffic signal lamps, where the ability to emit bright monochromatic light is a desired feature, and in strings of holiday lights.
LED lamp – Specialty uses
The wavelengths of light emitted from LED lamps have been specifically tailored to supply light in the spectral range needed for chlorophyll absorption in plants, promoting growth while reducing wastage of energy by emitting minimal light at wavelengths that plants do not require
LED lamp – Commercial and industrial use
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LED lamp – Commercial and industrial use
Initial cost was three times more than a traditional mix of incandescent and fluorescent lamps, but the extra cost was recovered within two years via electricity savings, and the lamps should not need replacing for 20 years
LED lamp – Commercial and industrial use
In 2009 the exceptionally large Christmas tree standing in front of the Turku Cathedral in Finland was hung with 710 LED bulbs, each using 2 watts. It has been calculated that these LED lamps paid for themselves in three and a half years, even though the lights run for only 48 days per year.
LED lamp – Commercial and industrial use
In 2009 a new highway (A29) was inaugurated in Aveiro, Portugal, it included the first European public LED-based lighting highway.
LED lamp – Commercial and industrial use
By 2010 mass installations of LED lighting for commercial and public uses were becoming common. LED lamps have also been used for a number of demonstration projects for outdoor lighting and LED street lights. The United States Department of Energy has available several reports on the results of many pilot projects for municipal outdoor lighting. Many additional streetlight and municipal outdoor lighting projects have been announced.
LED lamp – Comparison to other lighting technologies
See luminous efficacy for an efficiency chart comparing various technologies.
LED lamp – Comparison to other lighting technologies
The typical lifespan of an AC incandescent lamp is 750 to 1,000 hours
LED lamp – Comparison to other lighting technologies
Compact fluorescent lamps’ specified lifespan typically ranges from 6,000 hours to 15,000 hours.
LED lamp – Comparison to other lighting technologies
The ballast-lamp combined system efficacy for then current linear fluorescent systems in 1998 as tested by NLPIP ranged from 80 to 90 lm/W
LED lamp – Comparison to other lighting technologies
Cost Comparison (U.S. electricity prices)
LED lamp – Comparison to other lighting technologies
Color Temperature Kelvin 2700 2900 2700 2700 2700 2700
LED lamp – Comparison to other lighting technologies
Lifespan (hours) 1,000 1,000 8,000 25,000 15,000 30,000
LED lamp – Comparison to other lighting technologies
Bulb lifetime in years @ 6 hours/day 0.5 0.5 3.7 >11.4 6.8 >13.7
LED lamp – Comparison to other lighting technologies
Comparison based on 6 hours use per day (21,900 hours over 10 yrs)
LED lamp – Comparison to other lighting technologies
†LED prices adjusted for life in this row
LED lamp – Comparison to other lighting technologies
In keeping with the long life claimed for LED lamps, long warranties are offered. One manufacturer warrants lamps for professional use, depending upon type, for periods of (defined) “normal use” ranging from 1 year or 2,000 hours (whichever comes first) to 5 years or 20,000 hours. A typical domestic lamp is stated to have an “average life” of 15,000 hours (15 years at 3 hours/day), and to support 50,000 switch cycles.
LED lamp – US Department of Energy
The Energy Independence and Security Act (EISA) of 2007 authorized the Department of Energy (DOE) to establish the Bright Tomorrow Lighting Prize competition, known as the “L Prize”, the first government-sponsored technology competition designed to challenge industry to develop replacement for the most commonly used and inefficient products, the 60 W incandescent lamps and PAR 38 halogen lamps.
LED lamp – US Department of Energy
The EISA legislation establishes basic requirements and prize amounts for each of the two competition categories, and authorizes up to $20 million in cash prizes. The competition may also lead to opportunities for federal purchasing agreements, utility programs, and other incentives for winning products.
LED lamp – US Department of Energy
In May 2008, DOE announced details of the competition and technical requirements for each category. Lighting products meeting the competition requirements would use just 17% of the energy used by most incandescent lamps in use today. A future L Prize program announcement will call for developing a new “21st Century Lamp”, as authorized in the legislation.
LED lamp – US Department of Energy
On September 24, 2009 the DOE announced that Philips Lighting North America was the first to submit lamps in the category to replace the standard 60 W A-19 “Edison screw fixture” light bulb, with a design based on their earlier “AmbientLED” consumer product. On August 3, 2011, DOE awarded the prize in the 60 W replacement category to Philips’ bulb after 18 months of extensive testing.
LED lamp – National Institute of Standards and Technology
In June 2008, NIST announced the first two standards for solid-state lighting in the United States. These standards detail performance specifications for LED light sources and prescribe test methods for solid-state lighting products.
LED lamp – National Institute of Standards and Technology
The Illuminating Engineering Society of North America (IESNA) published a documentary standard LM-79, which describes the methods for testing solid-state lighting products for their light output (lumens), efficacy (lumens per watt) and chromaticity.
LED lamp – National Institute of Standards and Technology
The solid-state lights being studied are intended for general illumination, but white lights used today vary greatly in chromaticity. ANSI C78.377-2008 specifies the recommended color ranges for solid-state lighting products using cool to warm white LEDs with various correlated color temperatures.
LED lamp – National Institute of Standards and Technology
DOE launched the Energy Star program for solid-state lighting products in 2008.
LED lamp – Environmental Protection Agency
In the United States and Canada, the Energy Star program since 2008 labels lamps that meet a set of standards for starting time, life expectancy, color, and consistency of performance. The intent of the program is to reduce consumer concerns due to variable quality of products, by providing transparency and standards for the labeling and usability of products available in the market. Energy Star Light Bulbs for Consumers is a resource for finding and comparing Energy Star qualified lamps.
LED lamp – Other venues
In the United Kingdom a program is run by the Energy Saving Trust to identify lighting products that meet energy conservation and performance guidelines.
LED lamp – Other venues
Philips Lighting has ceased research on compact fluorescents, and is devoting the bulk of its research and development budget, 5 percent of the company’s global lighting revenue, to solid-state lighting.
LED lamp – Other venues
In January 2009, it was reported that researchers at Cambridge University had developed an LED bulb that costs £2 (about $3 U.S.), is 12 times as energy efficient as a tungsten bulb, and lasts for 100,000 hours. Honeywell Electrical Devices and Systems (ED&S) recommend world wide usage of LED lighting as it is energy efficient and can help save the climate.
LED lamp – Limitations
Color rendition is not identical to incandescent lamps. A measurement unit called CRI is used to express how the light source’s ability to render the eight color sample chips compare to a reference on a scale from 0 to 100. LEDs with CRI below 75 are not recommended for use in indoor lighting.
LED lamp – Limitations
LED efficiency and life span drop at higher temperatures, which limits the power that can be used in lamps that physically replace existing filament and compact fluorescent types. Thermal management of high-power LEDs is a significant factor in design of solid state lighting equipment.
LED lamp – Limitations
The long life of LEDs, expected to be about 50 times that of the most common incandescent bulbs and significantly longer than fluorescent types, is advantageous for users but will affect manufacturers as it reduces the market for replacements.
LED lamp – Possible hazard to vision
Tests performed at the Complutense University of Madrid indicate that prolonged exposure to the shorter blue band spectrum LED lights may permanently damage the pigment epithelial cells of the retina. The test conditions were the equivalent of staring at a 100 watt blue incandescent source from 20 cm for 12 hours; researchers say additional testing is required to ascertain what intensities, wavelengths, and exposure times of LED lighting devices are lethal and non-lethal for retinal tissue.
LED lamp – Further reading
Light Emitting Diodes, Second edition by E. F. Schubert (Cambridge University Press, 2006) ISBN 0-521-86538-7
Fourteen-segment display – Incandescent lamp version
The scheme would have been used for “talking” signs to spell out messages, but a complete set of commutator switches, drums and lamps would have been required for each letter of a message, making the resulting sign quite expensive.
Lamp (electrical component)
“Electric lamp” redirects here. For the item of furniture, see light fixture.
Lamp (electrical component)
Various compact fluorescent (CFL) lightbulbs
Lamp (electrical component)
A clear glass 60 W Neolux light bulb
Lamp (electrical component)
A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. Re-lamping is the replacement of only the removable lamp in a light fixture.
Lamp (electrical component) – Types
Incandescent light bulb, a heated filament inside a glass envelope
Lamp (electrical component) – Types
Halogen light bulbs use a fused quartz envelope, filled with halogen gas
Lamp (electrical component) – Types
LED lamp, a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light
Lamp (electrical component) – Types
Ultra-high-performance lamp, an ultra-high-pressure mercury-vapor arc lamp for use in projectors
Lamp (electrical component) – Types
Gas-discharge lamp, a light source that generates light by sending an electrical discharge through an ionized gas
Lamp (electrical component) – Types
Compact fluorescent lamp, a fluorescent lamp designed to replace an incandescent light bulb
Lamp (electrical component) – Types
Electrodeless lamp, a gas discharge lamp in which the power is transferred from outside the bulb to inside via electromagnetic fields
Lamp (electrical component) – Uses other than illumination
Lamps can be used as heat sources, for example in incubators and toys such as the Easy-Bake Oven.
Lamp (electrical component) – Uses other than illumination
Filament lamps have long been used as fast acting thermistors in electronic circuits. The filaments are most likely made out of tungston. Popular uses have included:
Lamp (electrical component) – Uses other than illumination
Automatic volume control in telephones
Oil lamp
An oil lamp is an object used to produce light continuously for a period of time using an oil-based fuel source. The use of oil lamps began thousands of years ago and is continued to this day, although not commonly anymore. Often associated with stories about genies, fictional creatures who live in oil lamps.
Oil lamp
Oil lamps are a form of lighting, and were used as an alternative to candles before the use of electric lights. Starting in 1780 the Argand lamp quickly replaced other oil lamps still in their basic ancient form. These were, in turn, replaced by the kerosene lamp in about 1850. In small towns and rural areas these continued in use well into the 20th century, until such areas were finally electrified, and light bulbs could be used for lighting.
Oil lamp
Most modern lamps (such as fueled lanterns) have been replaced with gas-based or petroleum-based fuels to operate when emergency non-electric light is required. As such, oil lamps of today are primarily used for the particular ambience they produce, or in rituals and religious ceremonies.
Oil lamp – Components
The hole through which fuel is put inside the fuel chamber. The width ranges from 0.5-5 cm in general. There may be single or multiple holes.
Oil lamp – Components
It may be just an opening in the body of the lamp, or an elongated nozzle. In some specific types of lamps there is a groove on the superior aspect of the nozzle that runs to the pouring hole to collect back the oozing oil from the wick.
Oil lamp – Components
Others think that the pierced lugs were used to hang the lamp with a metal hook when not in use.
Oil lamp – Components
The fuel reservoir. The mean volume in a typical terra-cotta lamp is 20 cc.
Oil lamp – Lamp typology
Lamps can be categorized based on different criteria, including material (Clay, Silver, Bronze, Gold, Stone, slip), shape, structure, design, and imagery (e.g. symbolic, religious, mythological, erotic, battles, hunting).
Oil lamp – Lamp typological categories
Wheel made: This category includes Greek and Egyptian lamps that date before the 3rd century BCE. They are characterized by simple, little or no decoration, and a wide pour hole, a lack of handles, and a pierced or unpierced lug. Pierced lugs occurred briefly between 4th and 3rd century BCE. Unpierced lugs continued until 1st century BCE.
Oil lamp – Lamp typological categories
Volute, Early Imperial: With volutes extending from their nozzles, these lamps were predominately produced in Italy during the Early Roman period. They have a wide discus, a narrow shoulder and no handle, elaborate imagery and artistic finishing, and a wide range of patterns of decoration.
Oil lamp – Lamp typological categories
High Imperial: These are late Roman. The shoulder is wider and the discus is smaller with fewer decorations. These lamps have handles and short plain nozzles, and less artistic finishing.
Oil lamp – Lamp typological categories
Frog: This is a regional style lamp exclusively produced in Egypt and found in the regions around it, between c. 100 and 300 CE. The frog, (Heqet), is an Egyptian fertility symbol.
Oil lamp – Lamp typological categories
African Red Slip lamps were made in North Africa, but widely exported, and decorated in a red slip. They date from the 2nd to the 7th century CE and comprise a wide variety of shapes including a flat, heavily decorated shoulder with a small and relatively shallow discus. Their decoration is either non-religious, Christian or Jewish. Grooves run from the nozzle back to the pouring hole and it is hypothesized that this is to take back spilled oil. These lamps often have more than one pour-hole.
Oil lamp – Lamp typological categories
Slipper lamps are oval shaped and found mainly in the Levant. They were produced between the 3rd to 9th centuries CE. Decorations include vine scrolls, palm wreaths, and Greek letters.
Oil lamp – Lamp typological categories
Factory lamps: Also called Firmalampen (from German), these are universal in distribution and simple in appearance. They have a channeled nozzle, plain discus, and 2 or 3 bumps on the shoulder. Initially made in factories in Northern Italy and Southern Gaul between the 1st and 3rd centuries CE, they were exported to all Roman provinces. The vast majority have been stamped on the bottom to identify the manufacturer.
Oil lamp – Judaism
The oil lamp and its light also became important ritualistic articles with the further development of Jewish culture and its religion.
Oil lamp – Judaism
“And you shall command the people of Israel that they bring to you pure beaten olive-oil for the light, that a lamp may be set to burn continually”. Exodus 27:20
Oil lamp – Judaism
“When you set the lamps, the seven lamps shall give light in front of the lamp stand (menorah).” Numbers 8: 1 -4
Oil lamp – Judaism
“There I shall cause pride to sprout for David; I have prepared a lamp for my anointed.” (Psalms 132:16);
Oil lamp – Judaism
“A man’s soul is the lamp of God, which searches the chambers of one’s innards.” (Proverbs 20:27).
Oil lamp – Judaism
“A lamp is called a lamp, and the soul of man is called a lamp.” (Babylonian Talmud, Shabbat 30B)
Oil lamp – Chanukah
The Temple Menorah, a ritual seven branched oil lamp used in the Second Temple, forms the centre of the Chanukah story and centers on the miracle that during the cleansing of the Jewish temple in Jerusalem after its looting, the lamp was supposed to burn continuously, forever, but there was only oil enough for one day, and no more oil would be available for 8 days; miraculously the oil expected to last for only one day instead burnt for 8 full days.
Oil lamp – Christianity
“Your eye is the lamp of your body; when your eye is sound, your whole body is sound, your whole body is full of light; but when it is not sound, your body is full of darkness.” (Luke 11:34);
Oil lamp – Christianity
“He was a burning and shining lamp, and you were willing to rejoice for a while in his light.” (John 5:35);
Oil lamp – Christianity
“And night shall be no more; they need no light of lamp or sun, for the Lord God will be their light, and they shall reign for ever and ever.” (Rev 22:5).
Oil lamp – Christianity
In the Orthodox Church and many Eastern Catholic Churches oil lamps (Greek: kandili, Slavonic: lampada) are still used both on the Holy Table (altar) and to illuminate icons on the iconostasis and around the temple (church building). Orthodox Christians will also use oil lamps in their homes to illuminate their icon corner.
Oil lamp – Christianity
Traditionally, the sanctuary lamp in an Orthodox church is an oil lamp. It is lit by the bishop when the church is consecrated, and ideally it should burn perpetually thereafter. The oil burned in all of these lamps is traditionally olive oil.
Oil lamp – Christianity
The sign of the cross is often made with soot from this flame on the lintel above the home’s main door, and the flame is transferred to the icon corner oil lamp; only then can the lampáda be extinguished
Oil lamp – Islam
The parable of His light is, as it were, that of a niche containing a lamp; the lamp is [enclosed] in glass, the glass [shining] like a radiant star: [a lamp] lit from a blessed tree – an olive-tree that is neither of the east nor of the west the oil whereof [is so bright that it] would well-nigh give light [of itself] even though fire had not touched it: light upon light! God guides unto His light him that wills [to be guided]; and [to this end] God propounds parables unto men, since God [alone] has full knowledge of all things”
Oil lamp – Hinduism
By folly, darkening knowledge. But, for whom
Oil lamp – Hinduism
That darkness of the soul is chased by Light (of the Lord),
Oil lamp – Hinduism
As if a Sun of Wisdom sprang to shed
Oil lamp – Hinduism
The souls illuminated take that road
Oil lamp – Hinduism
Which hath no turning back—their sins flung off
Oil lamp – Hinduism
Oil lamps are commonly used in Hindu temples as well as in home shrines. Generally the lamps used in temples are circular with places for five wicks. They are made of metal and either suspended on a chain or screwed onto a pedestal. There will usually be at least one lamp in each shrine, and the main shrine may contain several. Usually only one wick is lit, with all five burning only on festive occasions. The oil lamp is used in the Hindu ritual of Aarti.
Oil lamp – Hinduism
In the home shrine, the style of lamp is usually different, containing only one wick. There is usually a piece of metal that forms the back of the lamp, which has a picture of a Hindu deity embossed on it. In many houses, the lamp burns all day, but in other homes, it is lit at sundown. The lamp in the home shrine is supposed to be lit before any other lights are turned on at night.
Oil lamp – Hinduism
A hand-held oil lamp or incense sticks (lit from the lamp) are also used during the Hindu puja ceremony. In the North of India, a five-wick lamp is used, usually fueled with ghee. On special occasions, various other lamps may be used for puja, the most elaborate having several tiers of wicks.
Oil lamp – Hinduism
In South India, there are a few types of oil lamps that are common in temples and traditional rituals, some of the smaller ones are used for offerings as well:
Oil lamp – Hinduism
Deepalakshmi, a brass lamp with a depiction of goddess Sri Lakshmi over the back piece. they are usually small-size and have only one wick.
Oil lamp – Hinduism
Nilavilakku, a tall brass or bronze lamp on a stand where the wicks are placed at a certain height.
Oil lamp – Hinduism
Paavai vilakku, a brass or bronze lamp in the form of a lady holding a vessel with her hands. This type of lamp comes in different sizes, from very small to almost life-size. There are also large stone versions of this lamp in Hindu temples and shrines of Karnataka, Tamil Nadu and Kerala, especially at the base of columns and flanking the entrance of temples. They have only one wick.
Oil lamp – Hinduism
Thooku vilakku, a brass or bronze lamp hanging from a chain, often with multiple wicks.
Oil lamp – Chinese folk religion
Oil lamps are lit at traditional Chinese shrines before either an image of a deity or a plaque with Classical Chinese characters giving the name of the deity. Such lamps are usually made from clear glass (they look similar to normal drinking glasses) and are filled with oil, sometimes with water underneath. A cork or plastic floater containing a wick is placed on top of the oil with the bottom of the wick submerged in the oil.
Oil lamp – Chinese folk religion
Such lamps are kept burning in shrines, whether private or public, and incense sticks or joss sticks are lit from the lamp.
Oil lamp – History
(Mesolithic, Middle Stone Age Period, circa 10,300 – 8000 BC) The oldest stone-oil lamp was found in Lascaux in 1940 in a cave that was inhabited 10,000 to 15,000 years ago.
Oil lamp – History
Some archaeologists claim that the first shell-lamps were in existence more than 6,000 years ago. (Neolithic, Later Stone Age, c. 8500 – 4500 BC). They believe that the alabaster shell-shaped lamps dug up in Sumerian sites dating 2,600 BC were imitations of real shell-lamps that were used for a long time. (Early Bronze, Canaanite / Bronze I-IV, c. 3300 – 2000 BC)
Oil lamp – History
It is generally agreed that the evolution of handmade lamps moved from bowl-shaped to saucer-shaped, then from saucer with a nozzle, to a closed bowl with a spout.
Oil lamp – Chalcolithic Age, c. 4500 – 3300 BC
The first manufactured red pottery oil lamps appeared. These were of the round bowl type.
Oil lamp – The Bronze Ages (3200-1200 BC)
Lamps were simple wheel-made bowls with a slight pinch on four sides for the wick. Later lamps had only one pinch. These lamps vary in the shape of the rim, the general shape of the bowl and the shape of the base.
Oil lamp – The Bronze Ages (3200-1200 BC)
The earliest lamps known from Intermediate Bronze Age lamps (EBIV/MBI) With the four wick lamps. These lamps are made from large bowls with four shallow pinches for wicks.
Oil lamp – The Bronze Ages (3200-1200 BC)
The four-wick oil lamps persist into this period, most of the lamps now have one wick. Early in this period the pinch is shallow, while later on it becomes more prominent and the mouth protrudes from the lamp’s body. The bases are simple and flat. The crude potter’s wheel is introduced, transforming the handmade bowls to a more uniform container. The saucer style evolves into a single spout shape.
Oil lamp – The Bronze Ages (3200-1200 BC)
A more pronounced, deeper single spout is developed, and it is almost closed on the sides. The shape is evolving to be more triangular, deeper and larger. All lamps are now wheel-made. The base is simple, usually flat.
Oil lamp – The Iron Age (1200-560 BC)
The rim becomes wider and flatter with a deeper and higher spout. The tip of the spout is more upright in contrast to the rest of the rim.
Oil lamp – The Iron Age (1200-560 BC)
The lamps are becoming variable in shape and distribution. We still find lamps similar to the Late Bronze period. In addition, other forms evolve, such as small lamps with a flat base and larger lamps with a round base. The later form continues into the Iron Age II.
Oil lamp – The Iron Age (1200-560 BC)
In the later Iron Age, we encounter variant forms. One common type is small, with a wide rim and a wide base. Another type is a small, shallow bowl with a thick and high discus base.
Oil lamp – Persian
These large lamps have thin sides and a deep pinch, which flattens the mouth and makes it protrude outward.
Oil lamp – Greek
Lamps are more closed to avoid spilling. They are smaller and more refined. Most are handleless. Some are with a lug, pierced and not pierced. The nozzle is elongated. The rim is folded over to make the nozzle, so it overlaps and is then pinched to make the wick hole.
Oil lamp – Greek
They are round in shape, wheel-made.
Oil lamp – Chinese
The earliest Chinese oil lamps are dated from the Warring States period (481-221 BC). Lamps were constructed from jade, bronze, ceramic, wood, stone, and other materials. The largest oil lamp excavated so far is one discovered in a 4th-century tomb located in modern Pingshan, Hebei.
Oil lamp – Early Roman
Production of oil-lamps shifted to Italy as the main source of supply. Molds used. All lamps are closed in type. Lamps produced in large scale in factories. The lamp is produced in two parts, the upper part with the spout and the lower part with the fuel chamber. Most are of the characteristic Imperial Type. It was round with nozzles of different forms (volute, semi-volute, U shaped), with a closed body and with a central disk decorated with reliefs and its filling hole.
Oil lamp – Late Roman
The High Imperial Type. More decorations. Produced locally or imported in large scale. The multiple-nozzled lamps appear. Different varieties.
Oil lamp – Late Roman
In this period we find the frog type lamps. These are kidney or heart shaped or oval. With the motif of a frog or its abstraction, and sometimes with geometrical motifs. They were produced around 100 AD. They are so variant that it is seldom that two identical ones are found.
Oil lamp – Byzantine
Slipper shaped. Very decorative. The multiple nozzles continue. Most with handles. Some are complex in external anatomy.
Oil lamp – Early Islamic
There is a transition period from Byzantine to Islamic lamps. Lamps of this transition period changed from being decorated with crosses, animals, human likenesses, birds, fish, etc., to being decorated with plain linear, geometric, and raised dot patterns.
Oil lamp – Early Islamic
The early Islamic lamps are a continuation of Byzantine lamps. Decorations were initially a stylized form of bird, grain, tree, plant or flower. Then they became entirely geometric or linear with raised dots.
Oil lamp – Early Islamic
The first kerosene lamp was described by al-Razi (Rhazes) in 9th-century Baghdad, who referred to it as the “naffatah” in his Kitab al-Asrar (Book of Secrets).
Oil lamp – Early Islamic
In the transition period some lamps had Arabic writing. Then, writing disappears until the Mamluk period (13th – 15th centuries CE).
Oil lamp – Palestine
Jerusalem oil lamp: Characteristic black color of the clay because the clay was burned without oxygen. Usually of high quality.
Oil lamp – Palestine
Herodian oil lamp: Considered to be used mainly by Jews. Wheel made, rounded. Nozzle with concave sides. The lamps are usually not decorated. If there is decoration, it tends to be simple. Very common throughout all of Israel, and some lamps have also been found in Jordan. Date from 1st century BCE to the end of the 1st century CE.
Oil lamp – Palestine
Menorah oil lamp, seven nozzles: Rare and are associated with Judaism because of the numerical connection with the seven branches or arms of the Menorah.
Oil lamp – Palestine
Samaritan oil lamp: Characterized by a sealed filling hole, which was to be broken by the buyer. This was probably done to ensure ritual purity. A wider spout, and the concavities flanking the nozzle are almost always emphasized with a ladder pattern band. In general the lamps are uncoated. The decorations are linear and/or geometric.
Oil lamp – Palestine
Type I: A distinct channel running from the pouring-hole to the nozzle, a small knob handle, a ladder pattern around the nozzle and shows no ornamentation on the bottom of the base.
Oil lamp – Palestine
Type II: Pear-shaped and elongated, lined channel that extends from the filling-hole to the nozzle, continued to be used through to the early Muslim period.
Oil lamp – Palestine
Candle Stick oil lamp: Menorah design on the nozzle and bunch of grapes on the shoulders.
Oil lamp – Palestine
Byzantine oil lamp: The upper parts are covered with braided patterns and their handles. All are made of a dark orange-red clay. A rounded bottom with a distinct X or cross appears inside the circled base.
Oil lamp – Palestine
Early Islamic oil lamp: Large knob handle and the channel above the nozzle are dominant elements. The handle is tongue-shaped. Decoration is rich and elegant. The lower parts are extremely broad and the nozzles are pointed.
Oil lamp – Importance of oil lamps in India
In vedic times, fire was kept alive in every household in some form and carried with oneself while migrating to new locations. Later the presence of fire in the household or a religious building was ensured by an oil lamp. Over the years various rituals and customs were woven around an oil lamp.
Oil lamp – Importance of oil lamps in India
Moreover, a day is kept aside for the worship of the lamp in the busy festival calendar, on one amavasya (no moon) day in the month of Shravan
Oil lamp – Importance of oil lamps in India
For lighting multiple lamps, wooden and stone deepastambhas (towers of light) were created.
Oil lamp – Importance of oil lamps in India
Kuthuvilakku is another typical lamp traditionally used for house hold purposes in South India.
Oil lamp – Importance of oil lamps in India
Oil lamps also became proverbial. For example, a Bradj (pre-Hindi) proverb says, “Chiraag tale andhera”, “the [utmost] darkness is under the oil-lamp (chiraag)”, meaning that what you seek could be close but unnoticed, in various senses (and indeed, a lamp’s container casts shadow)
Oil lamp – General
Bailey, D.M. (1975-96). A Catalogue of Lamps in the British Museum. British Museum. ISBN 0-7141-2206-8. Huge catalogue in four quarto volumes, THE lamp bible but extremely expensive even second-hand. Referred to as BMC.
Oil lamp – General
Walters, H.B. (1914). Catalogue of the Greek and Roman Lamps in the British Museum. British Museum. Superseded by Bailey but still worthwhile and much cheaper if you can find an old copy.
Oil lamp – General
Hayes, J.W. (1980.). Ancient Lamps in the Royal Ontario Museum – I: Greek and Roman Clay Lamps. ROM. ISBN 0-88854-253-4. Another superb catalogue and excellent reference, perhaps second only to Bailey
Oil lamp – General
Djuric, Srdjan (1995). The Anawati Collection Catalog I – Ancient Lamps from the Mediterranean. Eika. ISBN 1-896463-02-9. Less academic than the museum catalogues and short on dating but fairly comprehensive (within its specified area, i.e. not Northern Europe) and extensively illustrated.
Oil lamp – General
Lyon-Caen; Hoff (1986). Catalogue des Lampes en terre cuite Grecques et Chretiennes. Louvre. ISBN 2-7118-2014-9. In French, good coverage of earlier and later lamps in the Louvre, well illustrated.
Oil lamp – General
Mlasowsky, Alexander (1993). Die antiken Tonlampen im Kestner-Museum Hannover. Kestner-Museum. ISBN 3-924029-13-X. In German, superb catalogue, profusely illustrated and captioned.
Oil lamp – General
Robins, F.W. (1970 (reprint of 1939 edition)). The Story of the Lamp. Kingsmead. ISBN 0-901571-33-4. Useful introduction but illustrations are very poor and beware as several of the items shown have since been exposed as fakes.
Oil lamp – General
Bailey, D.M. (1972). Greek and Roman Pottery Lamps. British Museum. ISBN 0-7141-1237-2. Excellent introductory booklet, well illustrated.
Oil lamp – General
Wetzel, Henning (1997). Antike Tonlampen. Leipzig University. ISBN 3-931922-65-0. In German, small booklet but excellent illustrations in color.
Oil lamp – General
Skinkel-Taupin, Claire (1980). Lampes en Terre Cuite de la Méditerranée Grecque et Romaine. Brussels. In French, brief guide to a few lamps in the Brussels Museum.
Oil lamp – General
Clephan, R. Coltman (1907). On Terra-cotta Lamps. Edinburgh. Edwardian illustrated article for the Society of Antiquaries of Scotland, interesting insight into the general knowledge of that time.
Oil lamp – Western Europe
Goethert, Karin (1997). Römische Lampen und Leuchter. Trier: Auswahlkatalog des Rheinischen Landesmuseums Trier. ISBN 3-923319-38-X. In German, emphasis on local lamps found in Trier but excellent coverage of all Roman types of the Rhineland.
Oil lamp – Western Europe
Eckardt, Hella (2002). Illuminating Roman Britain. Montagnac: Editions Monique Mergoil. ISBN 2-907303-70-8. Paperback, frustratingly unindexed but a refreshing approach and well worth plowing through.
Oil lamp – Western Europe
Loeschcke, Siegfried (1919). Lampen aus Vindonissa. Zurich. In German, long out-of-print classic but a superb reference if you can find a copy
Oil lamp – Western Europe
Kirsch, Annette (2002). Antike Lampen im Landesmuseum Mainz. Mainz. ISBN 3-8053-2864-8. In German, catalogue of lamps.
Oil lamp – Western Europe
Chrzanovski, Laurent (2000). Lumieres Antiques: Les lampes à huile du musée romain de Nyon. Edizioni ET. ISBN 88-86752-15-6. Paperback. In French with short summaries in English, Italian and German. Excellent general survey of lamps, detailed study and catalogue of the small collection of Roman oil lamps at Nyon.
Oil lamp – Middle (Near) East
Rosenthal, Renate; Sivan, Renée (1978). Qedem 8, Monographs of the Institute of Archaeology, Vol. 8: Ancient Lamps in the Schloessinger Collection. The Hebrew University of Jerusalem. Standard reference.
Oil lamp – Aegean
Broneer, Oscar (1977). Isthmia Volume III: Terracotta Lamps. American School at Athens. Good coverage of local lamps.
Oil lamp – Aegean
Perlzweig, Judith (1963). Lamps from the Athenian Agora. American School at Athens. Excellent booklet, profusely illustrated and a recommended reference, very cheap used copies.
Oil lamp – North Africa
Herrman, J.L.; van der Hoek, A. (2002). Light from the Age of Augustine. Harvard. Paperback, lavishly color-illustrated guide to North African red slipware including many lamps.
Oil lamp – North Africa
Fabbricotti, E. (2001). Catalogo delle lucerne di Tolemaide (Cirenaica), BAR International Series 962. Oxford. ISBN 1-84171-182-9. In Italian, detailed catalogue of locally found lamps.
Oil lamp – Further reading
Amiran Amiran R. Ancient Pottery of the Holy Land, Jerusalem 1969.
Oil lamp – Further reading
Appolonia-Arsuf 1983 Sussman V. “The Samaritan Oil Lamps from Apolonia-*Arsuf”, TA 10, pp. 71–96.1996 Wexler L. & Gilboa G. “Oil Lamps of the Roman Period from Apollonia-Arsuf”, TA 23, pp. 115–131.
Oil lamp – Further reading
Bailey Bailey D.M. A Catalogue of the Lamps in the British Museum, III: Roman provincial lamps, London 1988.
Oil lamp – Further reading
Ran N., 1987. Journeys to the Promised Land, Terra Sancta Arts
Oil lamp – Further reading
Roth C., 1996. Encyclopaedia Judaica, Keter Publishing
Oil lamp – Further reading
Runes D., 1959. Dictionary of Judaism, Citadel Press
Oil lamp – Further reading
Ryan W., Pitman W., 1998. Noha’s Flood, Simon and Schuster
Oil lamp – Further reading
Scheindlin R. P., 1996. The Chronicles of the Jewish People, Michael Friedman Pub.
Oil lamp – Further reading
Sussman V., 1972. Ornamented Jewish Oil-lamps, Israel Inst. and Exploration Society
Oil lamp – Further reading
The Tanakh, 1985 The Holy Scriptures, Jewish Publication Society
Oil lamp – Further reading
Uris L., 1998. Jerusalem, Doubleday and Company
Oil lamp – Further reading
Von Soden W., 1994. The Ancient Orient, William B.Eerdman Publishing.
Bicycle lighting – Filament lamps
The only real advantage to these is that they are often omnidirectional, a quality useful in running lights which must be visible through a very wide arc. Newer LED lights have this feature, removing even this final advantage. Energizer once made a 2.4W halogen rear lamp, which was essentially a headlamp with a red lens, but most rear lights only need to be around 0.5W.
Optical communication – Signal lamps
Signal lamps (such as Aldis lamps), are visual signaling devices for optical communication (typically using Morse code). Modern signal lamps are a focused lamp which can produce a pulse of light. In large versions this pulse is achieved by opening and closing shutters mounted in front of the lamp, either via a manually operated pressure switch or, in later versions, automatically.
Optical communication – Signal lamps
With hand held lamps, a concave mirror is tilted by a trigger to focus the light into pulses. The lamps are usually equipped with some form of optical sight, and are most commonly deployed on naval vessels and also used in airport control towers with coded aviation light signals.
Optical communication – Signal lamps
The light gun’s lamp has a focused bright beam capable of emitting three different colors: red, white and green
Lava lamp
A lava lamp (or Astro lamp) is a decorative novelty item, invented by British accountant Edward Craven-Walker in 1963. The lamp contains blobs of coloured wax inside a glass vessel filled with clear liquid; the wax rises and falls as its density changes due to heating from an incandescent light bulb underneath the vessel. The appearance of the wax is suggestive of p?hoehoe lava, hence the name. The lamps are designed in a variety of styles and colours.
Lava lamp – Operation
A classic lamp contains a standard incandescent bulb or halogen lamp which heats a tall (often tapered) glass bottle. A formula from 1968 US patent consisted of water and a transparent, translucent or opaque mix of mineral oil, paraffin wax and carbon tetrachloride.p 2 line 30 The clear water and/or mineral oil can optionally be coloured with transparent dyes.
Lava lamp – Operation
Common wax has a density much lower than that of water, and would float on top under any temperature
Lava lamp – Operation
However, lava lamps made for the US market since 1970 do not use carbon tetrachloride, because its use was banned that year due to toxicity. The manufacturer (Haggerty) states that their current formulation is a trade secret.
Lava lamp – Operation
The underlying fluid mechanics phenomenon is a form of Rayleigh–Taylor instability.
Lava lamp – Operation
The bulb is normally 25 to 40 watts. Generally it will take 45–60 minutes for the wax to warm up enough to freely form rising blobs, when operating the lamp at standard room temperature. It may take as long as 2 to 3 hours if the room is below standard room temperature.
Lava lamp – Operation
Once the wax is molten, the lamp should not be shaken or knocked over or the two fluids may emulsify, and the fluid surrounding the wax blobs will remain cloudy rather than clear. Some recombination will occur as part of the normal cycle of the wax in the container, but the only means to recombine all of wax is to turn off the lamp and wait a few hours. The wax will settle back down at the bottom, forming one blob once again. Severe cases can require many heat-cool cycles to clear.
Lava lamp – History
A British accountant Edward Craven-Walker invented the lava lamp in 1963, after watching a homemade egg timer made out of a cocktail shaker filled with liquids bubbling on a stove top at a pub. His U.S. Patent 3,387,396 for “Display Device” was filed in 1965 and issued in 1968. Craven-Walker’s company was named Crestworth and was based in Poole, Dorset, in the United Kingdom. Craven-Walker named the lamp “Astro”, and had variations such as the “Astro Mini” and the “Astro Coach” lantern.
Lava lamp – History
Craven-Walker presented it at a Brussels trade show in 1965, where the entrepreneur Adolph Wertheimer noticed it
Lava lamp – History
The lamps were a success throughout the 1960s and early 1970s. Lava Corporation’s name changed to Lava-Simplex-Scribe International in the early 1970s, and they also made instant-loading camera-film cartridges, as well as postage-stamp vending machines. In the late 1970s Spector sold Lava Simplex International to Michael Eddie and Lawrence Haggerty of Haggerty Enterprises. Haggerty Enterprises continues to sell their lava lamp in the US.
Lava lamp – History
In the 1990s, Craven-Walker, who had retained the rights for the rest of the world, took on a business partner called Cressida Granger. They changed the company name to Mathmos in 1992. Mathmos continues to make Lava Lamps and related products. Astro lavalamp was launched in 1963 and celebrates its 50th anniversary in 2013. Mathmos lava lamps are still made in the original factory in Poole, Dorset, UK.
Lava lamp – Hazards
In 2004, a man from Kent, Washington was killed while attempting to heat up a lava lamp on a kitchen stove while closely observing it from only a few feet away. The heat from the stove built up pressure in the lamp until it exploded and a shard pierced his heart causing fatal injuries.
Lava lamp – Hazards
The show also noted that the safety instructions clearly state that lava lamps should not be heated by any source other than the specifically rated bulbs and purpose-designed bases that are provided.
Argand lamp
The Argand lamp is a home lighting oil lamp producing a light output of 6 to 10 candela which was invented and patented in 1780 by Aimé Argand. Aside from the improvement in brightness, the more complete combustion of the wick and oil required much less frequent trimming of the wick.
Argand lamp
In France, they are known as “Quinquets” after Antoine-Arnoult Quinquet, a pharmacist in Paris, who used the idea originated by Argand and popularized it in France. He is sometimes credited with the addition of the glass chimney to the lamp.
Argand lamp – Design
The Argand lamp had a sleeve-shaped candle wick mounted so that air can pass both through the center of the wick and also around the outside of the wick before being drawn into cylindrical chimney which steadies the flame and improves the flow of air. Early models used ground glass which was sometimes tinted around the wick. Later models used a mantle of thorium dioxide suspended over the flame, creating a bright, steady light.
Argand lamp – Design
An Argand lamp used whale oil, colza, olive oil or other vegetable oil as fuel which was supplied by a gravity feed from a reservoir mounted above the burner.
Argand lamp – Design
A disadvantage of the original Argand arrangement was that the oil reservoir needed to be above the level of the burner because the heavy, sticky vegetable oil would not rise far up the wick. This made the lamps top heavy and cast a shadow in one direction away from the lamp’s flame. The Carcel lamp of 1800 and Franchot’s moderator lamp of 1836 avoided these problems.
Argand lamp – Design
The same principle was also used for cooking and boiling water due to its ‘affording much the strongest heat without smoke’.
Argand lamp – History
The Argand lamp was new to Thomas Jefferson in Paris in 1784, according to him gave off “a light equal to six or eight candles.”
Argand lamp – History
These new lamps, much more complex and costly than the previous primitive oil lamps were first adopted by the well-to-do, but soon spread to the middle classes and eventually the less well-off as well. Argand lamps were manufactured in a great variety of decorative forms and quickly became popular in America.
Argand lamp – History
It was the lamp of choice until about 1850 when kerosene lamps were introduced. Kerosene was cheaper than vegetable oil, it produced a whiter flame, and as a liquid of low viscosity it could easily travel up a wick eliminating the need for complicated mechanisms to feed the fuel to the burner.
Argand lamp – Notes
Jump up ^ “Lamp.” Columbia Electronic Encyclopedia, 6Th Edition (2011): 1. Academic Search Premier. Web. 5 Dec. 2011.
Argand lamp – Notes
Jump up ^ www.johnmoncrieff.co.uk/shop-2/products.php?cat=32
Argand lamp – Notes
Jump up ^ “Lamp.” Encyclopaedia Britannica: or, a dictionary of Arts, Science, and Miscellaneous Literature. 6th ed. 1823 Web. 5 Dec. 2011
Argand lamp – Notes
Jump up ^ An Encyclop?dia of Domestic Economy:Comprising Such Subjects As Are Most Immediately Connected with Housekeeping. 1844. p. 841.
Argand lamp – Notes
Jump up ^ Crowley, John E. The Invention of Comfort: Sensibilities & Design in Early Modern Britain & Early America. Baltimore, MD: Johns Hopkins UP, 2000. Web. 5 Dec. 2011
Argand lamp – Notes
Jump up ^ McCullough, Hollis Koons. Telfair Museum of Art: Collection Highlights. McCullough, Hollis Koons. Telfair Museum of Art: Collection Highlights. Savannah, GA: Telfair Museum of Art, 2005.Web. 5 Dec. 2011
Electrodeless lamp
The internal electrodeless lamp or induction light is a gas discharge lamp in which the power required to generate light is transferred from outside the lamp envelope to the gas inside via an electric or magnetic field, in contrast with a typical gas discharge lamp that uses internal electrodes connected to the power supply by conductors that pass through the lamp envelope. There are three advantages to elimination of the internal electrodes:
Electrodeless lamp
Extended lamp life, because the internal electrodes are usually the limiting factor in lamp life.
Electrodeless lamp
The ability to use light-generating substances of higher efficiency that would react with internal metal electrodes in normal lamps.
Electrodeless lamp
Improved collection efficiency because the source can be made very small without shortening life, a problem in internal electroded lamps.
Electrodeless lamp
Two systems are described below – plasma lamps, which use electrostatic induction to energize a bulb filled with sulfur vapor or metal halides, and fluorescent induction lamps, based upon a conventional fluorescent lamp bulb in which current is induced by an external coil of wire via electrodynamic induction.
Electrodeless lamp – History
Noting the diagrams in Tesla’s lectures and patents, a striking similarity of construction to electrodeless lamps that are available on the market currently is readily apparent
Electrodeless lamp – History
In my opinion, it will soon be superseded by the electrodeless vacuum tube which I brought out thirty-eight years ago, a lamp much more economical and yielding a light of indescribable beauty and softness.
Electrodeless lamp – History
Intersource Technologies also announced one in 1992, called the E-lamp
Electrodeless lamp – History
In 1990, Michael Ury, Charles Wood and colleagues, formulated the concept of the sulphur lamp. With support from the United States Department of Energy, it was further developed in 1994 by Fusion Lighting of Rockville, Maryland, a spinoff of the Fusion UV division of Fusion Systems Corporation. Its origins are in microwave discharge light sources used for ultraviolet curing in the semiconductor and printing industries.
Electrodeless lamp – History
Since 1994, General Electric has produced its induction lamp Genura with an integrated ballast, operating at 2.65 MHz. In 1996, Osram started selling their Endura induction light system, operating at 250 kHz. It is available in the US as the Sylvania Icetron. In 1997 PQL Lighting Introduced in the US the Superior Life Brand Induction Lighting Systems. Most induction lighting systems are rated for 100,000 hours of use before requiring absolute component replacements.
Electrodeless lamp – History
Since 2005, Amko Solara in Taiwan introduced induction lamps that can dim and use IP based controls. Their lamps have a range from 12 to 400 watts and operate at 250 kHz.
Electrodeless lamp – History
From 1995, the former distributors of Fusion, Jenton / Jenact, expanded on the fact that energised UV-emitting plasmas act as lossy conductors to create a number of patents regarding electrodeless UV lamps for sterilising and germicidal uses.
Electrodeless lamp – History
This system, for the first time, permitted an extremely bright and compact electrodeless lamps
Electrodeless lamp – History
In 2006 Luxim introduced a projector lamp product trade-named LIFI. The company further extended the technology with light source products in instrument, entertainment, street, area and architectural lighting applications among others throughout 2007 and 2008.
Electrodeless lamp – History
In 2009 Ceravision Limited introduced the first High Efficiency Plasma (HEP) lamp under the trade name Alvara. This lamp replaces the opaque ceramic waveguide used in earlier lamps with an optically clear quartz waveguide giving greatly increased efficiency. In previous lamps, though the burner, or bulb, was very efficient, the opaque ceramic waveguide severely obstructed the collection of light. A quartz waveguide allows all of the light from the plasma to be collected.
Electrodeless lamp – History
In 2012 Topanga Technologies introduced a line of advanced plasma lamps (APL), driven by a solid state RF driver, thereby circumventing the limited life of magnetron based drivers, with system power of 127 and 230 Watts and system efficacies of 96 and 87 lumen/Watt, with a CRI of about 70.
Electrodeless lamp – Plasma lamps
Typically, such lamps use a noble gas or a mixture of these gases and additional materials such as metal halides, sodium, mercury or sulfur
Electrodeless lamp – Plasma lamps
The first plasma lamp was an ultraviolet curing lamp with a bulb filled with argon and mercury vapor developed by Fusion UV. That lamp led Fusion Systems to the development of the sulfur lamp, a bulb filled with argon and sulfur which is bombarded with microwaves through a hollow waveguide.
Electrodeless lamp – Plasma lamps
Plasma lamps are currently produced by Ceravision and Luxim and in development by Topanga Technologies.
Electrodeless lamp – Plasma lamps
Ceravision claims the highest Luminaire Efficacy Rating (LER) of any light fitting on the market and to have created the first High Efficiency Plasma (HEP) lamp
Electrodeless lamp – Plasma lamps
Luxim’s LIFI, or light fidelity lamp, claims 120 lumens per RF watt (i.e. before taking into account electrical losses). The lamp has been used in Robe lighting’s ROBIN 300 Plasma Spot moving headlight. It was also used in a line of, now discontinued, Panasonic rear projection TVs.
Electrodeless lamp – Magnetic induction lamps
Unlike an incandescent lamp or conventional fluorescent lamps, there is no electrical connection going inside the glass bulb; the energy is transferred through the glass envelope solely by electromagnetic induction.
Electrodeless lamp – Magnetic induction lamps
There are two main types of magnetic induction lamp: external inductor lamps and internal inductor lamps. The original, and still widely used form of induction lamps are the internal inductor types. A more recent development is the external inductor types which have a wider range of applications and which are available in round, rectangular and “olive” shaped form factors.
Electrodeless lamp – Magnetic induction lamps
The glass walls of the lamp prevent the emission of the UV light as ordinary glass blocks UV radiation at the 253.7 nm and 185 nm range.
Electrodeless lamp – Magnetic induction lamps
In the internal inductor form (see diagram), a glass tube (B) protrudes bulb-wards from the bottom of the discharge vessel (A), forming a re-entrant cavity. This tube contains an antenna called a power coupler, which consists of a coil wound over a tubular ferrite core. The coil and ferrite forms the inductor which couples the energy into the lamp interior
Electrodeless lamp – Magnetic induction lamps
The antenna coils receive electric power from the electronic ballast (C) that generates a high frequency. The exact frequency varies with lamp design, but popular examples include 13.6 MHz, 2.65 MHz and 250 kHz. A special resonant circuit in the ballast produces an initial high voltage on the coil to start a gas discharge; thereafter the voltage is reduced to normal running level.
Electrodeless lamp – Magnetic induction lamps
The system can be seen as a type of transformer, with the power coupler (inductor) forming the primary coil and the gas discharge arc in the bulb forming the one-turn secondary coil and the load of the transformer
Electrodeless lamp – Magnetic induction lamps
Such lamps are typically used in commercial or industrial applications
Electrodeless lamp – Advantages
Long lifespan due to the lack of electrodes – Strictly speaking almost indefinite on the lamp itself but between 25,000 and 100,000 hours depending on lamp model and quality of electronics used;
Electrodeless lamp – Advantages
Very high energy conversion efficiency of between 62 and 90 Lumens/Watt [higher power lamps are more energy efficient];
Electrodeless lamp – Advantages
High power factor due to the low loss of the high frequency electronic ballasts which are typically between 95% and 98% efficient;
Electrodeless lamp – Advantages
Minimal Lumen depreciation (declining light output with age) compared to other lamp types as filament evaporation and depletion is absent;
Electrodeless lamp – Advantages
“Instant-on” and hot re-strike, unlike most HID lamps used in commercial-industrial lighting applications (such as mercury-vapor lamp, sodium-vapor lamp and metal halide lamp);
Electrodeless lamp – Advantages
Environmentally friendly as induction lamps use less energy, and use less mercury per hour of operation than conventional lighting due to their long lifespan. The mercury is in a solid form and can be easily recovered if the lamp is broken, or for recycling at end-of-life.
Electrodeless lamp – Advantages
These benefits offer considerable cost savings of between 35% and 55% in energy and maintenance costs for induction lamps compared to other types of commercial and industrial lamps which they replace.
Electrodeless lamp – Disadvantages
Some models of internal inductor lamps that use high frequency ballasts can produce radio frequency interference (RFI) which interferes with radio communications in the area. Newer, external inductor type lamps use low frequency ballasts that usually have FCC or other certification, thus complying with RFI regulations.
Electrodeless lamp – Disadvantages
External inductor lamps tend to be quite large, especially in higher wattage models, thus they are not always suitable for applications where a compact light source is required.
Electrodeless lamp – Disadvantages
Some types of inductor lamps contain mercury, which is highly toxic if released to the environment.
Halogen lamp
The small size of halogen lamps permits their use in compact optical systems for projectors and illumination.
Halogen lamp – History
A carbon filament lamp using chlorine to prevent darkening of the envelope was patented in 1882, and chlorine-filled “NoVak” lamps were marketed in 1892. The use of iodine was proposed in a 1933 patent, which also described the cyclic redeposition of tungsten back onto the filament. In 1959 General Electric patented a practical lamp using iodine.
Halogen lamp – Halogen cycle
The overall bulb envelope temperature must be higher than in conventional incandescent lamps for the reaction to work.
Halogen lamp – Halogen cycle
The bulb must be made of fused silica (quartz) or a high-melting-point glass (such as aluminosilicate glass). Since quartz is very strong, the gas pressure can be higher, which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so luminous efficacy) for the same average life.
Halogen lamp – Halogen cycle
The tungsten released in hotter regions does not generally redeposit where it came from, so the hotter parts of the filament eventually thin out and fail. Regeneration of the filament is also possible with fluorine, but its chemical reactivity is so great that other parts of the lamp are attacked.
Halogen lamp – Halogen cycle
Quartz iodine lamps, using elemental iodine, were the first commercial halogen lamps launched by GE in 1959. Quite soon, bromine was found to have advantages, but was not used in elemental form. Certain hydrocarbon bromine compounds gave good results. The first lamps used only tungsten for filament supports, but some designs use molybdenum — an example being the molybdenum shield in the H4 twin filament headlight for the European Asymmetric Passing Beam.
Halogen lamp – Halogen cycle
Undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source.
Halogen lamp – Halogen cycle
The range of MR-16 (50 mm diameter) reflector lamps of 20 W to 50 W were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home
Halogen lamp – Effect of voltage on performance
Tungsten halogen lamps behave in a similar manner to other incandescent lamps when run on a different voltage
Halogen lamp – Effect of voltage on performance
The life span on dimming depends on lamp construction, the halogen additive used and whether dimming is normally expected for this type.
Halogen lamp – Spectrum
Like all incandescent light bulbs, a halogen lamp produces a continuous spectrum of light, from near ultraviolet to deep into the infrared. Since the lamp filament can operate at a higher temperature than a non-halogen lamp, the spectrum is shifted toward blue, producing light with a higher effective color temperature.
Halogen lamp – Safety
Some safety codes now require halogen bulbs to be protected by a grid or grille, especially for high power (1–2 kW) bulbs used in theatre, or by the glass and metal housing of the fixture to prevent ignition of draperies or flammable objects in contact with the lamp.
Halogen lamp – Safety
To reduce unintentional ultraviolet (UV) exposure, and to contain hot bulb fragments in the event of explosive bulb failure, general-purpose lamps usually have a UV-absorbing glass filter over or around the bulb. Alternatively, lamp bulbs may be doped or coated to filter out the UV radiation. With adequate filtering, a halogen lamp exposes users to less UV than a standard incandescent lamp producing the same effective level of illumination without filtering.
Halogen lamp – Handling precautions
Consequently, manufacturers recommend that quartz lamps should be handled without touching the clear quartz, either by using a clean paper towel or carefully holding the porcelain base
Halogen lamp – Applications
Halogen headlamps are used in many automobiles. Halogen floodlights for outdoor lighting systems as well as for watercraft are also manufactured for commercial and recreational use. They are now also used in desktop lamps.
Halogen lamp – Applications
Tungsten-halogen lamps are frequently used as a near-infrared light source in Infrared spectroscopy.
Halogen lamp – Applications
Halogen lamps were used on the Times Square Ball from 1999 to 2006. However, from 2007 onwards, the halogen lamps were replaced with LED lights. The year numerals that light up when the ball reaches the bottom used halogen lighting for the last time for the 2009 ball drop. It was announced on the Times Square website that the year numerals for the 2010 ball drop would use LED lights.
Halogen lamp – Automotive
Tungsten-halogen lamps are commonly used as the light sources in automobile headlamps.
Halogen lamp – Architectural
Linear in various sizes and power
Halogen lamp – Architectural
R7S: linear halogen lamp measuring 118mm or 78mm. Also known as a double ended halogen lamp.
Halogen lamp – Architectural
Dichroic and plain reflector spots. Higher efficiency versions using infrared reflective coating (IRC) technology are 40% more efficient than standard low voltage halogen lamps
Halogen lamp – Home use
Higher efficiency LED versions of all of these lamps are now available, but these have widely varying light output and quality.
Halogen lamp – Home use
With the help of some companies such as Philips and Osram Sylvania, halogen bulbs have been made for standard household fittings, and can replace banned incandescent light bulbs of low luminous efficacy.
Halogen lamp – Home use
Tubular lamps with electrical contacts at each end are now being used in standalone lamps and household fixtures. These come in various lengths and wattages (50–300 W).
Halogen lamp – Stage lighting
Tungsten halogen lamps are used in the majority of theatrical and studio (film and television) fixtures, including Ellipsoidal Reflector Spotlights and Fresnels. PAR Cans are also predominately tungsten halogen.
Halogen lamp – Specialized
Projection lamps are used in motion-picture and slide projectors for homes and small office or school use. The compact size of the halogen lamp permits a reasonable size for portable projectors, although heat-absorbing filters must be placed between the lamp and the film to prevent melting. Halogen lamps are sometimes used for inspection lights and microscope stage illuminators. Halogen lamps were used for early flat-screen LCD backlighting, but other types of lamps are now used.
Halogen lamp – Disposal
Halogen lamps do not contain any mercury. General Electric claims that none of the materials making up their halogen lamps would cause the lamps to be classified as hazardous waste.[non-primary source needed]
Lightbulb socket – Lamp base styles
MS Miniature screw (with reference shoulder)
Lightbulb socket – Lamp base styles
Rect RSC rectangular recessed single contact
Lightbulb socket – Lamp base styles
SC Pf Single contact prefocus
Lightbulb socket – Lamp base styles
TB2P TruBeam two pin
Lightbulb socket – Lamp base styles
TLMS Tru-Loc miniature screw
Lightbulb socket – Lamp base styles
2PM Two pin miniature
Lightbulb socket – Lamp base styles
Some of the above base styles are now obsolete. The trend in recent years has been to design newer bases to reduce waste of raw materials and simplify the replacement process.
Lighting – Lamps
Rating and marketing emphasis is shifting away from wattage and towards lumen output, to give the purchaser a directly applicable basis upon which to select a lamp.
Lighting – Lamps
Ballast: A ballast is an auxiliary piece of equipment designed to start and properly control the flow of power to discharge light sources such as fluorescent and high intensity discharge (HID) lamps. Some lamps require the ballast to have thermal protection.
Lighting – Lamps
fluorescent light: A tube coated with phosphor containing low pressure mercury vapor that produces white light.
Lighting – Lamps
Halogen: Incandescent lamps containing halogen gases such as iodine or bromine, increasing the efficacy of the lamp versus a plain incandescent lamp.
Lighting – Lamps
Neon: A low pressure gas contained within a glass tube; the color emitted depends on the gas.
Lighting – Lamps
Light emitting diodes: Light emitting diodes (LED) are solid state devices that emit light by dint of the movement of electrons in a semiconductor material.
Lighting – Lamps
Compact fluorescent lamps: CFLs are designed to replace incandescent lamps in existing and new installations.
Digital Light Processing – Metal-halide lamps
The lamp’s end of life is typically indicated via an LED on the unit or an onscreen text warning, necessitating replacement of the lamp unit.
Digital Light Processing – Metal-halide lamps
However, practically all lamp housings contain heat-resistant barriers (in addition to those on the lamp unit itself) to prevent the red-hot quartz fragments from leaving the area.
Neon lamp
Neon glow lamps were very common in the displays of electronic instruments through the 1970s; the basic design of neon lamps is now incorporated in contemporary plasma displays.
Neon lamp – History
Neon was discovered in 1898 by William Ramsay and Morris W. Travers. The characteristic, brilliant red color that is emitted by gaseous neon when excited electrically was noted immediately; Travers later wrote, “the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget.”
Neon lamp – History
Neon’s scarcity precluded its prompt application for electrical lighting along the lines of Moore tubes, which used electric discharges in nitrogen
Neon lamp – History
Glow lamps found practical use as indicators in instrument panels and in many home appliances until the widespread commercialisation of Light-Emitting Diodes (LEDs) in the 1970s.”
Neon lamp – Description
The ubiquitous high pressure sodium-vapor lamp uses a neon penning mixture for warm up and can be operated as a giant neon lamp if operated in a low power mode
Neon lamp – Description
Larger neon sign sized lamps often use a specially constructed high voltage transformer with high leakage inductance or other electrical ballast to limit the available current.
Neon lamp – Description
However, while too low a current causes flickering, too high a current increases the wear of the electrodes by stimulating sputtering, which coats the internal surface of the lamp with metal and causes it to darken.
Neon lamp – Description
The potential needed to strike the discharge is higher than what is needed to sustain the discharge. When there is not enough current, the glow forms around only part of the electrode surface. Convective currents make the glowing areas flow upwards, not unlike the discharge in a Jacob’s ladder. A photoionization effect can also be observed here, as the electrode area covered by the glow discharge can be increased by shining light at the lamp.
Neon lamp – Description
In comparison with incandescent light bulbs, neon lamps have much higher luminous efficacy
Neon lamp – Applications
A variant of the NE-2 type lamp, the NE-77, had three parallel wires (in a plane) instead of the usual two
Neon lamp – Applications
They were also used for a variety of other purposes; since a neon lamp can act as a relaxation oscillator with an added resistor and capacitor, it can be used as a simple flashing lamp or audio oscillator
Neon lamp – Applications
More recently it has been found that these lamps work well as detectors even at submillimeter (‘terahertz’) frequencies and they have been successfully used as pixels in several experimental imaging arrays at these wavelengths.
Neon lamp – Applications
In these applications the lamps are operated either in ‘starvation’ mode (to reduce lamp-current noise) or in normal glow discharge mode; some literature references their use as detectors of radiation up into the optical regime when operated in abnormal glow mode. Coupling of microwaves into the plasma may be in free space, in waveguide, by means of a parabolic concentrator (e.g., Winston cone), or via capacitive means via a loop or dipole antenna mounted directly to the lamp.
Neon lamp – Applications
Although most of these applications use ordinary off-the-shelf dual-electrode lamps, in one case it was found that special 3 (or more) electrode lamps, with the extra electrode acting as the coupling antenna, provided even better results (lower noise and higher sensitivity). This discovery received an application patent (Kopeika et al.)
Neon lamp – Applications
Neon lamps with several shaped electrodes were used as alphanumerical displays known as Nixie tubes. These have since been replaced by other display devices such as light emitting diodes, vacuum fluorescent displays, and liquid crystal displays. Novelty glow lamps with shaped electrodes (such as flowers and leaves), often coated with phosphors, have been made for artistic purposes. In some of these, the glow that surrounds an electrode is part of the design.
Neon lamp – Colour
Neon indicator lamps are normally orange, and are frequently used with a coloured filter over them to improve contrast and change their colour to red or a redder orange, or less often green.
Neon lamp – Colour
A mixture of neon and krypton can be used for green glow, but nevertheless “green neon” lamps are more commonly phosphor-based.
Neon lamp – Latching
Since at least the 1940s, argon, neon, and phosphored glow thyratron latching indicators (which would light up upon an impulse on their starter electrode and extinguish only after their anode voltage was cut) were available for example as self-displaying shift registers in large-format, crawling-text dot-matrix displays, or, combined in a 4×4, four-color phosphored-thyratron matrix, as a stackable 625-color RGBA pixel for large video graphics arrays
Cold cathode – Lamps
Cold-cathode lamps include cold-cathode fluorescent lamps (CCFLs) and neon lamps. Neon lamps primarily rely on excitation of gas molecules to emit light; CCFLs use a discharge in mercury vapor to develop ultraviolet light, which in turn causes a fluorescent coating on the inside of the lamp to emit visible light.
Cold cathode – Lamps
Cold-cathode lamps are used for backlighting of LCDs, for example computer monitors and television screens.
Cold cathode – Lamps
In the lighting industry, “cold cathode” historically refers to luminous tubing which is larger than 20mm in diameter and operates on a current of 120 to 240 milliamps. This larger diameter tubing is often used for interior alcove and general lighting. The term “neon lamp” refers to tubing that is smaller than 15 mm diameter and typically operates at approximately 40 milliamps. These lamps are commonly used for neon signs.
Sodium-vapor lamp
Low pressure sodium lamps only give monochromatic yellow light and so inhibit color vision at night.
Sodium-vapor lamp
Because sodium-vapor lamps cause less light pollution than mercury-vapor lamps, many cities that have large astronomical observatories employ them.
Sodium-vapor lamp – Low-pressure sodium
These lamps produce a virtually monochromatic light averaging a 589.3 nm wavelength (actually two dominant spectral lines very close together at 589.0 and 589.6 nm)
Sodium-vapor lamp – Low-pressure sodium
LPS lamps have an outer glass vacuum envelope around the inner discharge tube for thermal insulation, which improves their efficiency. Earlier types of LPS lamps had a detachable dewar jacket (SO lamps). Lamps with a permanent vacuum envelope (SOI lamps) were developed to improve thermal insulation. Further improvement was attained by coating the glass envelope with an infrared reflecting layer of indium tin oxide, resulting in SOX lamps.
Sodium-vapor lamp – Low-pressure sodium
LPS lamps are the most efficient electrically powered light source when measured for photopic lighting conditions—up to 200 lm/W, primarily because the output is light at a wavelength near the peak sensitivity of the human eye
Sodium-vapor lamp – Low-pressure sodium
LPS lamps are available with power ratings from 10 W up to 180 W; however, longer bulb lengths create design and engineering problems.
Sodium-vapor lamp – Low-pressure sodium
Another unique property of LPS lamps is that, unlike other lamp types, they do not decline in lumen output with age. As an example, mercury vapor HID lamps become very dull towards the end of their lives, to the point of being ineffective, while continuing to consume full rated electrical use. LPS lamps, however, do increase energy usage slightly (about 10%) towards their end of life, which is generally around 18,000 hours for modern lamps.
Sodium-vapor lamp – Light pollution considerations
Such lamps emit light on just two dominant spectral lines (with other far weaker lines), and therefore is the easiest to filter out
Sodium-vapor lamp – Film special effects
A yellow light of a LPS lamp falls into region that typical color negative is not sensitive to, but can be captured on special black-and-white film
Sodium-vapor lamp – High-pressure sodium
HPS lamps are favored by indoor gardeners for general growing because of the wide color-temperature spectrum produced and the relatively efficient cost of running the lights.
Sodium-vapor lamp – High-pressure sodium
High pressure sodium lamps are quite efficient—about 100 lm/W—when measured for photopic lighting conditions. The higher powered versions of 600 W have an efficacy of even 150 lm/W. They have been widely used for outdoor area lighting such as streetlights and security. Understanding the change in human color vision sensitivity from photopic to mesopic and scotopic is essential for proper planning when designing lighting for roads.
Sodium-vapor lamp – High-pressure sodium
Because of the extremely high chemical activity of the high pressure sodium arc, the arc tube is typically made of translucent aluminum oxide. This construction led General Electric to use the tradename “Lucalox” for their line of high-pressure sodium lamps.
Sodium-vapor lamp – High-pressure sodium
The low thermal conductivity minimizes thermal losses in the lamp while in the operating state, and the low ionization potential causes the breakdown voltage of the gas to be relatively low in the cold state, which allows the lamp to be easily started.
Sodium-vapor lamp – “White” SON
A variation of the high pressure sodium, the White SON, introduced in 1986, has a higher pressure than the typical HPS/SON lamp, producing a color temperature of around 2700 K, with a CRI of 85, greatly resembling the color of an incandescent light. These are often used indoors in cafes and restaurants to create a particular atmosphere. However, these lamps suffer from higher purchase cost, shorter life, and lower light efficiency.
Sodium-vapor lamp – Theory of operation
The higher the temperature of the amalgam, the higher will be the mercury and sodium vapor pressures in the lamp and the higher will be the terminal voltage
Sodium-vapor lamp – Theory of operation
The lamp is extinguished and no current flows.
Sodium-vapor lamp – Theory of operation
The lamp is operating with liquid amalgam in the tube.
Sodium-vapor lamp – Theory of operation
The result is an average lamp life in excess of 20,000 hours.
Sodium-vapor lamp – Theory of operation
Because the lamp effectively extinguishes at each zero-current point in the AC cycle, the inductive ballast assists in the reignition by providing a voltage spike at the zero-current point.
Sodium-vapor lamp – Theory of operation
The light from the lamp consists of atomic emission lines of mercury and sodium, but is dominated by the sodium D-line emission. This line is extremely pressure (resonance) broadened and is also self-reversed because of absorption in the cooler outer layers of the arc, giving the lamp its improved color rendering characteristics. In addition, the red wing of the D-line emission is further pressure broadened by the Van der Waals forces from the mercury atoms in the arc.
Sodium-vapor lamp – End of life
At the end of life, high-pressure sodium lamps exhibit a phenomenon known as cycling, which is caused by a loss of sodium in the arc. Sodium is a highly reactive element and is easily lost by reacting with the arc tube, made of aluminum oxide. The products are sodium oxide and aluminum:
Sodium-vapor lamp – End of life
The effect of this is that the lamp glows for a while and then goes out, typically starting at a pure or bluish white then moving to a red-orange before going out.
Sodium-vapor lamp – End of life
More sophisticated ballast designs detect cycling and give up attempting to start the lamp after a few cycles, as the repeated high-voltage ignitions needed to restart the arc reduce the lifetime of the ballast. If power is removed and reapplied, the ballast will make a new series of startup attempts.
Sodium-vapor lamp – End of life
LPS lamp failure does not result in cycling; rather, the lamp will simply not strike or will maintain its dull red glow exhibited during the start-up phase. Another failure mode is caused by a tiny puncture of the arc tube wherebyand some of the sodium vapor is sucked out into the outer vacuum bulb where it condenses and creates a mirror on the outer glass, partially obscuring the arc tube which often continues operating normally, but much of the light generated no longer leaves the lamp.
Germicidal lamp
A germicidal lamp is a special type of lamp which produces ultraviolet light (UVC). This short-wave ultraviolet light disrupts DNA base pairing causing thymine-thymine dimers leading to death of bacteria on exposed surfaces. It can also be used to produce ozone for water disinfection.
Germicidal lamp – Low pressure lamps
Low-pressure lamps are very similar to a fluorescent lamp, with a wavelength of 253.7 nm.
Germicidal lamp – Low pressure lamps
Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.
Germicidal lamp – Low pressure lamps
An older design looks like an incandescent lamp but with the envelope containing a few droplets of mercury. In this design, the incandescent filament heats the mercury, producing a vapor which eventually allows an arc to be struck, short circuiting the incandescent filament.
Germicidal lamp – Low pressure lamps
At the last two decades the rapid development is acquired so-called excimer lamps having a number of advantages over the other sources of ultraviolet and even vacuum ultraviolet radiation.
Germicidal lamp – Medium pressure lamps
Medium-pressure lamps are much more similar to HID lamps than fluorescent lamps.
Germicidal lamp – Medium pressure lamps
These lamps radiate a broad-band UV-C radiation, rather than a single line. They are widely used in industrial water treatment, because they are very intense radiation sources. They are as efficient as low-pressure lamps. Medium-pressure lamps produce very bright bluish white light.
Germicidal lamp – Auxiliary equipment
As with all gas discharge lamps, all of the styles of germicidal lamps exhibit negative resistance and require the use of an external ballast to regulate the current flow through them. The older lamps that resembled an incandescent lamp were often operated in series with an ordinary 40 W incandescent “appliance” lamp; the incandescent lamp acted as the ballast for the germicidal lamp.
Germicidal lamp – Uses
In this application, the light produced by the lamp is usually filtered to remove as much visible light as possible, leaving just the UV light.
Germicidal lamp – Uses
The light produced by germicidal lamps is also used to erase EPROMs; the ultraviolet photons are sufficiently energetic to allow the electrons trapped on the transistors’ floating gates to tunnel through the gate insulation, eventually removing the stored charge that represents binary ones and zeroes.
Germicidal lamp – Uses
Germicidal lamps are also used in waste water treatment in order to kill microorganisms.
Germicidal lamp – Ozone production
For most purposes, ozone production would be a detrimental side effect of lamp operation. To prevent this, most germicidal lamps are treated to absorb the 185 nm mercury emission line (which is the longest wavelength of mercury light which will ionize oxygen).
Germicidal lamp – Ozone production
In some cases (such as water sanitization), ozone production is precisely the point. This requires specialized lamps which do not have the surface treatment.
Germicidal lamp – Safety concerns
Short-wave UV light is harmful to humans. In addition to causing sunburn and (over time) skin cancer, this light can produce extremely painful inflammation of the cornea of the eye, which may lead to temporary or permanent vision impairment. It can also damage the retina of the eye. For this reason, the light produced by a germicidal lamp must be carefully shielded against both direct viewing and reflections and dispersed light that might be viewed.
Compact fluorescent lamp
A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent lamp; some types fit into light fixtures formerly used for incandescent lamps. The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp.
Compact fluorescent lamp
Like all fluorescent lamps, CFLs contain mercury, a neurotoxin especially dangerous to children and pregnant women, which complicates their disposal
Compact fluorescent lamp
CFLs radiate a spectral power distribution that is different from that of incandescent lamps. Improved phosphor formulations have improved the perceived color of the light emitted by CFLs, such that some sources rate the best “soft white” CFLs as subjectively similar in color to standard incandescent lamps.
Compact fluorescent lamp – History
The parent to the modern fluorescent lamp was invented in the late 1890s by Peter Cooper Hewitt. The Cooper Hewitt lamps were used for photographic studios and industries.
Compact fluorescent lamp – History
Edmund Germer, Friedrich Meyer, and Hans Spanner patented a high-pressure vapor lamp in 1927. George Inman later teamed with General Electric to create a practical fluorescent lamp, sold in 1938 and patented in 1941. Circular and U-shaped lamps were devised to reduce the length of fluorescent light fixtures. The first fluorescent bulb and fixture were displayed to the general public at the 1939 New York World’s Fair.
Compact fluorescent lamp – History
The spiral CFL was invented in 1976 by Edward E. Hammer, an engineer with General Electric, in response to the 1973 oil crisis. Although the design met its goals, it would have cost GE about $25 million to build new factories to produce the lamps, and thus the invention was shelved. The design eventually was copied by others. In 1995, helical CFLs, manufactured in China, became commercially available. Since that time, their sales have steadily increased.
Compact fluorescent lamp – History
In 1980, Philips introduced its model SL, which was a screw-in lamp with integral magnetic ballast. The lamp used a folded T4 tube, stable tri-color phosphors, and a mercury amalgam. This was the first successful screw-in replacement for an incandescent lamp. In 1985, Osram started selling its model EL lamp, which was the first CFL to include an electronic ballast.
Compact fluorescent lamp – History
Development of fluorescent lamps that could fit in the same volume as comparable incandescent lamps required the development of new, high-efficacy phosphors that could withstand more power per unit area than the phosphors used in older, larger fluorescent tubes.
Compact fluorescent lamp – Design
There are two types of CFLs: integrated and non-integrated lamps. Integrated lamps combine the tube and ballast in a single unit. These lamps allow consumers to replace incandescent lamps easily with CFLs. Integrated CFLs work well in many standard incandescent light fixtures, reducing the cost of converting to fluorescent. 3-way lamp bulbs and dimmable models with standard bases are available.
Compact fluorescent lamp – Design
Non-integrated CFLs have the ballast permanently installed in the luminaire, and only the lamp bulb is usually changed at its end of life
Compact fluorescent lamp – Design
CFLs have two main components: a magnetic or electronic ballast and a gas-filled tube (also called bulb or burner). Replacement of magnetic ballasts with electronic ballasts has removed most of the flickering and slow starting traditionally associated with fluorescent lighting, and has allowed the development of smaller lamps directly interchangeable with more sizes of incandescent bulb.
Compact fluorescent lamp – Design
Since the resonant converter tends to stabilize lamp current (and light produced) over a range of input voltages, standard CFLs do not respond well in dimming applications and special lamps are required for dimming service.
Compact fluorescent lamp – Design
Standard shapes of CFL tube are single-turn double helix, double-turn, triple-turn, quad-turn, circular, and butterfly.
Compact fluorescent lamp – Design
CFL light output is roughly proportional to phosphor surface area, and high output CFLs are often larger than their incandescent equivalents. This means that the CFL may not fit well in existing light fixtures.
Compact fluorescent lamp – Design
A CFL will thrive in areas that have good airflow, such as in a table lamp.
Compact fluorescent lamp – Spectrum of light
CFLs emit light from a mix of phosphors inside the bulb, each emitting one band of color
Compact fluorescent lamp – Spectrum of light
Color temperature can be indicated in kelvins or mireds (1 million divided by the color temperature in kelvins). The color temperature of a light source is the temperature of a black body that has the same chromaticity (i.e. color) of the light source. A notional temperature, the correlated color temperature, the temperature of a black body which emits light of a hue which to human color perception most closely matches the light from the lamp, is assigned.
Compact fluorescent lamp – Spectrum of light
A true color temperature is characteristic of black-body radiation; a fluorescent lamp may approximate the radiation of a black body at a given temperature, but will not have an identical spectrum. In particular, narrow bands of shorter-wavelength radiation are usually present even for lamps of low color temperature (“warm” light).
Compact fluorescent lamp – Spectrum of light
As color temperature increases, the shading of the white light changes from red to yellow to white to blue. Color names used for modern CFLs and other tri-phosphor lamps vary between manufacturers, unlike the standardized names used with older halophosphate fluorescent lamps. For example, Sylvania’s Daylight CFLs have a color temperature of 3,500 K, while most other lamps called daylight have color temperatures of at least 5,000 K.
Compact fluorescent lamp – Lifespan
CFLs typically have a rated service life of 6,000 to 15,000 hours, whereas standard incandescent lamps have a service life of 750 or 1,000 hours. However, the actual lifetime of any lamp depends on many factors, including operating voltage, manufacturing defects, exposure to voltage spikes, mechanical shock, frequency of cycling on and off, lamp orientation, and ambient operating temperature, among other factors.
Compact fluorescent lamp – Lifespan
So, presuming the illumination provided by the lamp was ample at the beginning of its life, such a difference will be compensated for by the eyes.
Compact fluorescent lamp – Lifespan
Fluorescent lamps get dimmer over their lifetime, so what starts out as an adequate luminosity may become inadequate. In one test by the U.S. Department of Energy of “Energy Star” products in 2003–04, one quarter of tested CFLs no longer met their rated output after 40% of their rated service life.
Compact fluorescent lamp – Energy efficiency
Compared to a theoretical 100%-efficient lamp (680 lm/W), these lamps have lighting efficiency ranges of 7–10% for CFLs and 1.5–2.5% for incandescents.
Compact fluorescent lamp – Energy efficiency
Since CFLs use much less energy than incandescent lamps (ILs), a phase-out of ILs would result in less carbon dioxide (CO2) being emitted into the atmosphere
Compact fluorescent lamp – Energy efficiency
Electrical power equivalents for differing lamps
Compact fluorescent lamp – Energy efficiency
Minimum light output (lumens) Electrical power consumption (Watts)
Compact fluorescent lamp – Energy efficiency
Incandescent Compact fluorescent LED
Compact fluorescent lamp – Energy efficiency
In warm climates or in office or industrial buildings where air conditioning is often required, CFLs reduce the load on the cooling system when compared to the use of incandescent lamps, resulting in savings in electricity in addition to the energy efficiency savings of the lamps themselves
Compact fluorescent lamp – Cost
While the purchase price of a CFL is typically 3–10 times greater than that of an equivalent incandescent lamp, a CFL lasts 8–15 times longer and uses two-thirds to three-quarters less energy. A U.S. article stated “A household that invested $90 in changing 30 fixtures to CFLs would save $440 to $1,500 over the five-year life of the bulbs, depending on your cost of electricity. Look at your utility bill and imagine a 12% discount to estimate the savings.”
Compact fluorescent lamp – Cost
commercial electricity and gas rates for 2006, a 2008 article found that replacing each 75 W incandescent lamp with a CFL resulted in yearly savings of $22 in energy usage, reduced HVAC cost, and reduced labour to change lamps
Compact fluorescent lamp – Cost
The current price of CFLs reflects the manufacturing of nearly all CFLs in China, where labour costs less
Compact fluorescent lamp – Cost
According to an August 2009 newspaper report, some manufacturers claimed that CFLs could be used to replace higher-power incandescent lamps than justified by their light output. Equivalent wattage claims can be replaced by comparison of actual light output produced by the lamp, which is measured in lumens and marked on the packaging.
Compact fluorescent lamp – Failure
New North American technical standards aim to eliminate smoke or excess heat at the end of lamp life.
Compact fluorescent lamp – Dimming
However, recent products have solved these problems so that they perform more like incandescent lamps
Compact fluorescent lamp – Dimming
Cold-cathode CFLs can be dimmed to low levels, making them popular replacements for incandescent bulbs on dimmer circuits.
Compact fluorescent lamp – Dimming
When a CFL is dimmed, its color temperature (warmth) stays the same. This is counter to most other light sources (such as the sun or incandescents) where color gets redder as the light source gets dimmer. The Kruithof curve from 1934 described an empirical relationship between intensity and color temperature of visually pleasing light sources.
Compact fluorescent lamp – Signal effects
The input stage of a CFL is a rectifier, which presents a non-linear load to the power supply and introduces harmonic distortion on the current drawn from the supply
Compact fluorescent lamp – Signal effects
Electronic devices operated by infrared remote control can interpret the infrared light emitted by CFLs as a signal; this may limit the use of CFLs near televisions, radios, remote controls, or mobile phones. Energy Star certified CFLs must meet FCC standards, and so are required to list all known incompatibilities on the package.
Compact fluorescent lamp – External use
CFLs are generally not designed for outdoor use and some will not start in cold weather. CFLs are available with cold-weather ballasts, which may be rated to as low as ?23 °C (?10 °F). Light output in the first few minutes drops at low temperatures. Cold-cathode CFLs will start and perform in a wide range of temperatures due to their different design.
Compact fluorescent lamp – Starting time
The halogen lamp lights immediately, and is switched off once the CFL has reached full brightness.
Compact fluorescent lamp – General
According to the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) in 2008, CFLs may pose an added health risk due to the ultraviolet and blue light emitted
Compact fluorescent lamp – General
A 2012 study comparing cellular health effects of CFL light and incandescent light found statistically significant cell damage in cultures exposed to CFL light
Compact fluorescent lamp – General
When the base of the bulb is not made to be flame-retardant, as required in the voluntary standard for CFLs, overheating of the electrical components in the bulb may create a fire hazard.
Compact fluorescent lamp – Mercury content
Because mercury is poisonous, even these small amounts are a concern for landfills and waste incinerators where the mercury from lamps may be released and contribute to air and water pollution
Compact fluorescent lamp – Mercury content
In areas with coal-fired power stations, the use of CFLs saves on mercury emissions when compared to the use of incandescent bulbs
Compact fluorescent lamp – Mercury content
In the United States, the U.S. Environmental Protection Agency estimated that if all 270 million CFLs sold in 2007 were sent to landfill sites, around 0.13 metric tons of mercury would be released, 0.1% of all U.S. emissions of mercury (around 104 metric tons that year).
Compact fluorescent lamp – Mercury content
The EPA updated their mercury comparison graph in November 2010. The graph assumes that CFLs last an average of 8,000 hours regardless of manufacturer and premature breakage. In areas where coal is not used to produce energy, the content emissions would be less than the power plant emissions for both types of bulb.
Compact fluorescent lamp – Recycling
Health and environmental concerns about mercury have prompted many jurisdictions to require spent lamps to be properly disposed of or recycled, rather than being included in the general waste stream sent to landfills. Safe disposal requires storing the bulbs unbroken until they can be processed.
Compact fluorescent lamp – Recycling
In the United States, most states have adopted and currently implement the federal Universal Waste Rule (UWR). Several states, including Vermont, New Hampshire, California, Minnesota, New York, Maine, Connecticut and Rhode Island, have regulations that are more stringent than the federal UWR. Home-supply chain stores make free CFL recycling widely available.
Compact fluorescent lamp – Recycling
In the European Union, CFLs are one of many products subject to the WEEE recycling scheme. The retail price includes an amount to pay for recycling, and manufacturers and importers have an obligation to collect and recycle CFLs.
Compact fluorescent lamp – Recycling
Special handling instructions for breakage are not printed on the packaging of household CFL bulbs in many countries
Compact fluorescent lamp – Recycling
The U.S
Compact fluorescent lamp – Recycling
They also note the EPA’s estimates for the percentage of fluorescent lamps’ total mercury released when they are disposed of in the following ways: municipal waste landfill 3.2%, recycling 3%, municipal waste incineration 17.55% and hazardous waste disposal 0.2%.
Compact fluorescent lamp – Recycling
The first step of processing CFLs involves crushing the bulbs in a machine that uses negative pressure ventilation and a mercury-absorbing filter or cold trap to contain mercury vapor. Many municipalities are purchasing such machines. The crushed glass and metal is stored in drums, ready for shipping to recycling factories.
Compact fluorescent lamp – Greenhouse gases
In some places, such as Quebec and British Columbia in 2007, central heating for homes was provided mostly by the burning of natural gas, whereas electricity was primarily provided by hydroelectric and nuclear power
Compact fluorescent lamp – Use and adoption
Phase-out of incandescent light bulbs
Compact fluorescent lamp – Use and adoption
CFLs are produced for both alternating current (AC) and direct current (DC) input. DC CFLs are popular for use in recreational vehicles and off-the-grid housing. There are various aid agency initiatives in developing countries to replace kerosene lamps, which have associated health and safety hazards, with CFLs powered by batteries, solar panels or wind generators.
Compact fluorescent lamp – Use and adoption
CFLs in solar powered street lights, use solar panels mounted on the pole.
Compact fluorescent lamp – Use and adoption
Due to the potential to reduce electric consumption and pollution, various organizations have encouraged the adoption of CFLs and other efficient lighting. Efforts range from publicity to encourage awareness, to direct handouts of CFLs to the public. Some electric utilities and local governments have subsidized CFLs or provided them free to customers as a means of reducing electric demand (and so delaying additional investments in generation).
Compact fluorescent lamp – Use and adoption
In 2008, the European Union approved regulations progressively phasing out incandescent bulbs starting in 2009 and finishing at the end of 2012. By switching to energy saving bulbs, EU citizens will save almost 40 TW·h (almost the electricity consumption of 11 million European households), leading to a reduction of about 15 million metric tons of CO2 emissions per year.
Compact fluorescent lamp – Use and adoption
Australia, Canada, and the United States have also announced plans for nationwide efficiency standards that would constitute an effective ban on most current incandescent bulbs.
Compact fluorescent lamp – Use and adoption
Venezuela and Cuba have launched massive incandescent light bulbs replacement programs in order to save energy
Compact fluorescent lamp – Use and adoption
The United States Department of Energy reports that sales of CFLs have dropped between 2007 and 2008, and estimated only 11% of suitable domestic light sockets use CFLs.
Compact fluorescent lamp – Use and adoption
In the United States, the Program for the Evaluation and Analysis of Residential Lighting (PEARL) was created to be a watchdog program. PEARL has evaluated the performance and ENERGY STAR compliance of more than 150 models of CFL bulbs.
Compact fluorescent lamp – Use and adoption
The UN Environment Programme (UNEP)/Global Environment Facility (GEF) en.lighten initiative has developed “The Global Efficient Partnership Program” which focuses on country-led policies and approaches to enable the implementation of energy-efficient lighting, including CFLs, quickly and cost-effectively in developing and emerging countries.
Compact fluorescent lamp – Use and adoption
“Energy Star Light Bulbs for Consumers” is a resource for finding and comparing Energy Star qualified lamps
Compact fluorescent lamp – Use and adoption
In the United Kingdom, a similar program is run by the Energy Saving Trust to identify lighting products that meet energy conservation and performance guidelines.
Compact fluorescent lamp – Use and adoption
The GU24 socket system was designed to replace the traditional screw base, in part to add a barrier to installing older bulbs. The GU24 is intended for energy efficient bulbs only.
Compact fluorescent lamp – Other CFL and lighting technologies
Another type of fluorescent lamp is the electrodeless lamp, known as magnetic induction lamp, radiofluorescent lamp or fluorescent induction lamp. These lamps have no wire conductors penetrating their envelopes, and instead excite mercury vapor using a radio-frequency oscillator.
Compact fluorescent lamp – Other CFL and lighting technologies
Their advantages are that they are instant-on, like incandescent lamps, and they have a long life of approximately 50,000 hours
Compact fluorescent lamp – Other CFL and lighting technologies
A few manufacturers make CFL bulbs with mogul Edison screw bases intended to replace 250- and 400-watt metal halide lamps, claiming a 50% energy reduction; these lamps require rewiring of the lamp fixtures to bypass the lamp ballast.
Compact fluorescent lamp – Other CFL and lighting technologies
Department of Energy (DOE) tests of commercial LED lamps designed to replace incandescent or CFLs showed that average efficacy was still about 30 lm/W in 2008 (tested performance ranged from 4 lm/W to 62 lm/W)
Compact fluorescent lamp – Other CFL and lighting technologies
General Electric discontinued a 2007 development project intended to develop a high-efficiency incandescent bulb with the same lumens per watt as fluorescent lamps. Meanwhile other companies have developed and are selling halogen incandescent bulbs that use 70% of the energy of standard incandescents.
Compact fluorescent lamp – Other CFL and lighting technologies
Incandescent Halogen Fluorescent LED (Generic) LED (Philips) LED (Philips L Prize)
Compact fluorescent lamp – Other CFL and lighting technologies
Lifespan (hours) 2,000 3,500 8,000 25,000 25,000 30,000
Solar lamp
Solar-powered household lighting may displace light sources such as kerosene lamps, saving money for the user, and reducing fire and pollution hazards.
Solar lamp
Solar lamps recharge during the day. Automatic outdoor lamps turn on at dusk and remain illuminated overnight, depending on how much sunlight they receive during the day.
Solar lamp
Solar garden lights are used for decoration, and come in a wide variety of designs. They are sometimes holiday-themed and may come in animal shapes. They are frequently used to mark footpaths or the areas around swimming pools. Some solar lights do not provide as much light as a line-powered lighting system, but they are easily installed and maintained, and provide a cheaper alternative to wired lamps.
Solar lamp
Solar street lights provide public lighting without use of an electrical grid; they may have individual panels for each lamp of a system, or may have a large central solar panel and battery bank to power multiple lamps.
Solar lamp
To reduce the overall cost of a solar lighting system, energy saving lamps of either the fluorescent or LED lamp type are used, since incandescent bulbs consume several times as much energy for a given quantity of light.
Solar lamp – Solar lantern
In rural India, solar lamps, commonly called solar lanterns, using either LEDs or CFLs, are being used to replace kerosene lamps.
Carbide lamp
Carbide lamps, or acetylene gas lamps, are simple lamps that produce and burn acetylene (C2H2) which is created by the reaction of calcium carbide (CaC2) with water.
Carbide lamp
Acetylene gas lamps were used to illuminate buildings, as lighthouse beacons, and as headlights on motor-cars and bicycles. Portable carbide lamps, worn on the hat or carried by hand, were widely used in mining in the early twentieth century. They are still employed by cavers, hunters, and cataphiles.
Carbide lamp – Mechanism
The conventional process of producing acetylene in a lamp involves putting the calcium carbide in the lower chamber (the generator)
Carbide lamp – Mechanism
This type of lamp generally has a reflector behind the flame to help project the light forward. An acetylene gas powered lamp produces a surprisingly bright, broad light. Many cavers prefer this type of unfocused light as it improves peripheral vision in the complete dark. The reaction of carbide with water produces a fair amount of heat independent of the flame. In cold caves, carbide lamp users can use this heat to help stave off hypothermia.
Carbide lamp – Mechanism
When all of the carbide in a lamp has been reacted, the carbide chamber contains a wet paste of slaked lime (calcium hydroxide). This is emptied into a waste bag and the chamber can be refilled.
Carbide lamp – Mechanism
Small carbide lamps called “carbide candles” are used for blackening rifle sights to reduce glare. These “candles” are used due to the sooty flame produced by acetylene.
Carbide lamp – History
In 1892, Thomas Willson discovered an economically efficient process for creating calcium carbide in an electric arc furnace from a mixture of lime and coke. The arc furnace provides the high temperature required to drive the reaction. Manufacture of calcium carbide was an important part of the industrial revolution in chemistry, and was made possible in the USA as a result of massive amounts of inexpensive hydroelectric power produced at Niagara Falls before the turn of the 20th century.
Carbide lamp – History
In 1895, Willson sold his patent to Union Carbide. Domestic lighting with acetylene gas was introduced circa 1894 and bicycle lamps from 1896.
Carbide lamp – History
On March 10, 1925 Andrew Prader of Spokane, Washington was granted a United States Patent, number 1,528,848 for certain new and useful improvements for Acetylene Lamps.
Carbide lamp – History
After carbide lamps were implicated in an Illinois coal-seam methane gas explosion that killed 54 miners, the 1932 Moweaqua Coal Mine disaster, carbide lamps were less used in United States coal mines. They continued in use in the coal pits of other countries, notably Russia and Ukraine.
Carbide lamp – History
In the birth of the cinema of Iquitos, a carbide lamp was used as light support to project the first film in the Casa de Fierro, in 1900.
Carbide lamp – Lighting systems
Carbide lighting was used in rural and urban areas of the United States which were not served by electrification
Carbide lamp – Lighting systems
Early models of the Ford Model T automobile used carbide lamps as headlamps.
Carbide lamp – Lighting systems
Acetylene lamps were also used on riverboats for night navigation. The National Museum of Australia has a lamp made in about 1910 that was used on board PS Enterprise, a paddle steamer which has been restored to working order and is also in the museum’s collection.
Carbide lamp – Lighting systems
They are also used for night hunting in some African countries.
Carbide lamp – Use in caving
Early caving enthusiasts, not yet having the advantage of light-weight electrical illumination, introduced the carbide lamp to their hobby. While increasingly replaced by more modern choices, a substantial percentage of cavers still use this method.
Carbide lamp – Use in caving
Especially favoured for this purpose are all-brass lamps or lamps made with no ferromagnetic metals, as these lamps do not deflect the needles of a magnetic compass, which is typically read while brightly illuminated from above using the caver’s lamp.
Carbide lamp – Use in caving
Apart from their use as cave surveying tools, many cavers favour carbide lamps for their durability and quality of illumination. They were once favoured for their relative illumination per mass of fuel compared to battery powered devices, but this advantage was largely negated with the advent of high-intensity LED illumination.
Carbide lamp – Use in caving
The acetylene producing reaction is exothermic, which means that the lamp’s reactor vessel will become quite warm to the touch; this can be used to warm the hands. The heat from the flame can also be used to warm the body by allowing the exhaust gases to flow under a shirt pulled out from the body: such a configuration is referred to as a “Palmer furnace”, after geologist Arthur Palmer.
Kerosene lamp
There are three types of kerosene lamp: flat wick, central draught (tubular round wick), and mantle lamp
Kerosene lamp
They produce more light per unit of fuel than wick-type lamps, but are more complex and expensive in construction, and more complex to operate
Kerosene lamp
The first description of a simple lamp using crude mineral oil was provided by al-Razi (Rhazes) in 9th century Baghdad, who referred to it as the “naffatah” in his Kitab al-Asrar (Book of Secrets). In 1846 Abraham Pineo Gesner invented a substitute for whale oil for lighting, distilled from coal. Later made from petroleum, kerosene became a popular lighting fuel. Modern versions of the kerosene lamp were later constructed by the Polish inventor Ignacy ?ukasiewicz in 1853 Lviv.
Kerosene lamp
Kerosene lamps are widely used for lighting in rural areas of Africa and Asia where electricity is not distributed, or is too costly. Kerosene lamps consume an estimated 77 billion litres of fuel per year, equivalent to 1.3 million barrels of oil per day, comparable to annual U.S. jet fuel consumption of 76 billion litres per year.
Kerosene lamp – Flat wick lamp
A flat-wick lamp has a fuel tank (fount), with the lamp burner attached
Kerosene lamp – Flat wick lamp
All kerosene flat wick lamps use the dead flame burner design, where the flame is fed cold air from below and hot air exits above.
Kerosene lamp – Central draft (tubular round wick) lamp
When the lamp is lit, the central draft tube supplies air to the flame spreader that spreads out the flame into a ring of fire and allows the lamp to burn cleanly.
Kerosene lamp – Mantle lamp
Mantle lamps typically use fuel faster than a flat wick lamp, but slower than a center-draugh round wick as they depend on a small flame heating a mantle, rather than having all the light coming from the flame itself.
Kerosene lamp – Mantle lamp
A lamp set too high will burn off its soot harmlessly if quickly turned down, but if not caught soon enough the soot itself can ignite and a “runaway lamp” condition can result.
Kerosene lamp – Mantle lamp
One popular model of mantle lamp uses only a wick and is unpressurized.
Kerosene lamp – Mantle lamp
Pressurized mantle lamps contain a gas generator and require preheating the generator before lighting. An air pump is used to deliver fuel under pressure to the gas generator.
Kerosene lamp – Mantle lamp
Large fixed pressurized kerosene mantle lamps were used in lighthouse beacons for navigation of ships, brighter and with lower fuel consumption than oil lamps used before.
Kerosene lamp – Kerosene lantern
Both hot blast and cold blast designs are called tubular lanterns and are safer than dead flame lamps as tipping over a tubular lantern cuts off the oxygen flow to the burner and will extinguish the flame within seconds.
Kerosene lamp – Dead flame
The earliest portable kerosene “glass globe” lanterns, of the 1850s and 60s, were of the dead-flame type meaning that it had an open wick, but the airflow to the flame was strictly controlled in an upward motion by a combination of vents at the bottom of the burner and an open topped chimney. This had the effect of removing side-to-side drafts and thus significantly reducing or even eliminating the flickering you get with an exposed flame.
Kerosene lamp – Dead flame
Later lanterns such as the Hot Blast and Cold Blast lanterns took this airflow control even further by partially enclosing the wick in a “deflector” or “burner cone” and channeling the airflow through that restricted area creating a brighter and even more stable flame.
Kerosene lamp – Hot blast
The hot-blast design, also known as a “tubular lantern” due to the metal tubes used in its construction, was invented by John Irwin and patented on January 12, 1868. The hot-blast design collected hot air from above the globe and fed it through metal side tubes to the burner, to make the flame burn brighter.
Kerosene lamp – Cold blast
The cold-blast design is similar to the hot-blast, except that cold fresh air is drawn in from around the top of the globe and is then fed though the metal side tubes to the flame, making it burn brighter. This design produces a brighter light than the hot blast design, because the fresh air that is fed to the flame has plenty of oxygen to support the combustion process.
Kerosene lamp – Operation and maintenance
Extinguishing the lamp is done by turning down the wick and blowing out the flame, or by turning the wick down below the top of the wick tube.
Kerosene lamp – Operation and maintenance
Mantle lamps, and other lamps that use the “central-draught” tubular wick burner are lit in a similar fashion. The wick on a mantle lamp or “central-draught” tubular wick lamp is trimmed only with a special wick cleaner to remove the carbon off the top of the wick and to leave a smooth surface on the top of it.
Kerosene lamp – Fuels
Citronella oil is a citronella-scented lamp oil; some brands also have lemongrass oil in them and they are used for their insect repellent properties
Kerosene lamp – Fuels
Kerosene wick lamps should only be operated with kerosene or lamp oil, but alternative fuels are used in an emergency. Such fuels may produce additional smoke and odor and may not be usable indoors. Tractor vaporizing oil is made from kerosene with some additive to make a motor fuel for tractors. No. 1 diesel fuel (also called winter diesel) is about the same as kerosene but with the additives to make it a motor fuel. Jet A jet-engine fuel is essentially kerosene with a few additives.
Kerosene lamp – Fuels
Any liquid with a low flash point presents a high risk of fire or explosion if used in a kerosene wick lamp. Such liquids are DANGEROUS and should NEVER be used in a Kerosene lamp or lantern. Examples include:
Kerosene lamp – Fuels
Charcoal lighter fluid
Kerosene lamp – Fuels
Naphtha, white gas or coleman fuel
Kerosene lamp – Fuels
other hydrocarbon solvents such as turpentine, benzene, xylene, toluene, acetone, camphene, lacquer thinner
Kerosene lamp – Fuels
Contamination of lamp fuel with even a small amount of gasoline results in a lower flash point and higher vapor pressure for the fuel, with potentially dangerous consequences. Vapors from spilled fuel may ignite; vapor trapped above liquid fuel may lead to excess pressure and fires. Kerosene lamps are still extensively used in areas without electrical lighting; the cost and dangers of combustion lighting are a continuing concern in many countries.
Kerosene lamp – Performance
Wick-type lamps have the lowest light output, and pressurized lamps have higher output; the range is from 20 to 100 lumens. A kerosene lamp producing 37 lumens for 4 hours per day will consume about 3 litres of kerosene per month.
Electric light – Halogen lamp
Halogen lamps are usually much smaller than standard incandescents, because for successful operation a bulb temperature over 200 °C is generally necessary
Electric light – Halogen lamp
Those designed for 12 V or 24 V operation have compact filaments, useful for good optical control, also they have higher efficiencies (lumens per watt) and better lives than non halogen types. The light output remains almost constant throughout life.
Electric light – Fluorescent lamp
Fluorescent lamps have much higher efficiency than filament lamps. For the same amount of light generated, they typically use around one-quarter to one-third the power of an incandescent.
Electric light – Fluorescent lamp
Fluorescents were mostly limited to linear and a round ‘Circline’ lamp until the 1980s, with other shapes never gaining much popularity. The compact fluorescent lamp (CFL) was commercialized in the early 1980s.
Electric light – Fluorescent lamp
Most CFLs have a built-in electrical ballast and fit into a standard screw or bayonet base. Some make use of a separate ballast so that the ballast and tube can be replaced separately.
Electric light – Fluorescent lamp
Typical average lifetime ratings for linear fluorescent tubes are 10,000 and 20,000 hours, compared to 750 hours (110 V) and 1000 hours (240 V) for filament lamps.
Electric light – Fluorescent lamp
Some types of fluorescent lamp ballast have difficulty starting lamps in very cold conditions, so lights used outdoors in cold climates need to be designed for outdoor use to work reliably.
Electric light – Fluorescent lamp
Fluorescents come in a range of different color temperatures. In some countries cool white (CW) is most popular, while in some, warmer whites predominate.
Electric light – Fluorescent lamp
Compact fluorescent lamps are usually considered warm white, though many have a yellowish cast like an incandescent
Electric light – LED lamp
Solid state LEDs have been popular as indicator lights since the 1970s. In recent years, efficacy and output have risen to the point where LEDs are now being used in niche lighting applications.
Electric light – LED lamp
Indicator LEDs are known for their extremely long life, up to 100,000 hours, but lighting LEDs are operated much less conservatively (due to high LED cost per watt), and consequently have much shorter lives.
Electric light – LED lamp
Due to the relatively high cost per watt, LED lighting is most useful at very low powers, typically for lamp assemblies of under 10 W. LEDs are currently most useful and cost-effective in low power applications, such as nightlights and flashlights. Colored LEDs can also be used for accent lighting, such as for glass objects, and even in fake ice cubes for drinks at parties. They are also being increasingly used as holiday lighting.
Electric light – LED lamp
LED efficiencies vary over a very wide range. Some have lower efficiency than filament lamps, and some significantly higher. LED performance in this respect is prone to being misinterpreted, as the inherent directionality of LEDs gives them a much higher light intensity in one direction per given total light output.
Electric light – LED lamp
Single color LEDs are well developed technology, but white LEDs at time of writing still have some unresolved issues.
Electric light – LED lamp
CRI is not particularly good, resulting in less than accurate color rendition.
Electric light – LED lamp
The light distribution from the phosphor does not fully match the distribution of light from the LED die, so color temperature varies at differing angles.
Electric light – LED lamp
Phosphor performance degrades over time, resulting in change of color temperature and falling output. With some LEDs degradation can be quite fast.
Electric light – LED lamp
Limited heat tolerance means that the amount of power packable into a lamp assembly is a fraction of the power usable in a similarly sized incandescent lamp.
Electric light – LED lamp
LED technology is useful for lighting designers because of its low power consumption, low heat generation, instantaneous on/off control, and in the case of single color LEDs, continuity of color throughout the life of the diode and relatively low cost of manufacture.
Electric light – LED lamp
In the last few years, software has been developed to merge lighting and video by enabling lighting designers to stream video content to their LED fixtures, creating low resolution video walls.
Electric light – LED lamp
For general domestic lighting, total cost of ownership of LED lighting is still much higher than for other well established lighting types.
Electric light – Carbon arc lamp
The lamps produce significant ultra-violet output, they require ventilation when used indoors, and due to their intensity they need protecting from direct sight.
Electric light – Carbon arc lamp
Carbon arc lamps operate at high powers, and had high efficiency compared to other pre-1920s light sources. They also are a point source of light. These properties made them ideally suited to search lights, follow spots and film projector lights.
Electric light – Carbon arc lamp
Their need for ongoing attendance and adjustment, and frequent rod replacement made them ill suited to general lighting, though they were used for high power lighting in the years when nothing else with comparable output power existed. Carbon arcs fell out of use even for niche applications during and after World War 2.
Electric light – Discharge lamp
A discharge lamp has a glass or silica envelope containing 2 metal electrodes separated by a gas. Gases used include, neon, argon, xenon, sodium, metal halide, and mercury.
Electric light – Discharge lamp
The core operating principle is much the same as the carbon arc lamp, but the term ‘arc lamp’ is normally used to refer to carbon arc lamps, with more modern types of gas discharge lamp normally called ‘discha
Electric light – Discharge lamp
With some discharge lamps, very high voltage is used to strike the arc. This requires an electrical circuit called an igniter, which is part of the ballast circuitry. After the arc is struck, the internal resistance of the lamp drops to a low level, and the ballast limits the current to the operating current. Without a ballast, excess current would flow, causing rapid destruction of the lamp.
Electric light – Discharge lamp
Some lamp types contain a little neon, which permits striking at normal running voltage, with no external igniter circuitry. Low pressure sodium lamps operate this way.
Electric light – Discharge lamp
The simplest ballasts are just an inductor, and are chosen where cost is the deciding factor, such as street lighting. More advanced electronic ballasts may be designed to maintain constant light output over the life of the lamp, may drive the lamp with a square wave to maintain completely flicker-free output, and shut down in the event of certain faults.
Electric light – Lamp life expectancy
Life expectancy is defined as the number of hours of operation for a lamp until 50% of them fail. This means that it is possible for some lamps to fail after a short amount of time and for some to last significantly longer than the rated lamp life. This is an average (median) life expectancy. Production tolerances as low as 1% can create a variance of 25% in lamp life. For LEDs, lamp life is when 50% of lamps have lumen output drop to 70% or less.
Electric light – Lamp life expectancy
Rooms with frequent switching (bathroom, bedrooms, etc.) can expect much shorter lamp life than what is printed on the box.
Metal-halide lamp
Metal-halide lamp should not be confused with Halogen lamp
Metal-halide lamp
A metal-halide lamp is an electric light that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides (compounds of metals with bromine or iodine). It is a type of high-intensity discharge (HID) gas discharge lamp. Developed in the 1960s, they are similar to mercury vapor lamps, but contain additional metal halide compounds in the arc tube, which improve the efficacy and color rendition of the light.
Metal-halide lamp
They are used for wide area overhead lighting of commercial, industrial, and public spaces, such as parking lots, sports arenas, factories, and retail stores, as well as residential security lighting and automotive headlamps (xenon headlights).
Metal-halide lamp
The lamps consist of a small fused quartz or ceramic arc tube which contains the gases and the arc, enclosed inside a larger glass bulb which has a coating to filter out the ultraviolet light produced. They operate at a pressure between 4 to 20 atms, and require special fixtures to operate safely, as well as an electrical ballast. Metal atoms produce most of the light output. They require a warm-up period of several minutes to reach full light output.
Metal-halide lamp – Uses
Metal-halide lamps are used both for general lighting purposes both indoors and outdoors, automotive and specialty applications. Because of their wide spectrum, they are used for indoor growing applications, in athletic facilities and are quite popular with reef aquarists, who need a high intensity light source for their corals.
Metal-halide lamp – Uses
Metal-halide lamps are used in automobile headlights, where they are commonly known as “xenon headlamps” due to the use of xenon gas in the bulb instead of the argon typically used in other halide lamps. They produce a more intense light than incandescent headlights.
Metal-halide lamp – Uses
Another widespread use for such lamps is in photographic lighting and stage lighting fixtures, where they are commonly known as MSD lamps and are generally used in 150, 250, 400, 575 and 1,200 watt ratings, especially intelligent lighting.
Metal-halide lamp – Operation
The argon gas in the lamp is easily ionized, which facilitates striking the arc across the two electrodes when voltage is first applied to the lamp
Metal-halide lamp – Operation
About 24% of the energy used by metal-halide lamps produces light (an efficacy of 65–115 lm/W), making them substantially more efficient than incandescent bulbs, which typically have efficiencies in the range 2-4%.
Metal-halide lamp – Components
Metal-halide lamps consist of an arc tube with electrodes, an outer bulb, and a base.
Metal-halide lamp – Arc tube
Inside the fused quartz arc tube two tungsten electrodes doped with thorium, are sealed into each end and current is passed to them by molybdenum foil seals in the fused silica. It is within the arc tube that the light is actually created.
Metal-halide lamp – Arc tube
Argon filled lamps are typically quite slow to start up, taking several minutes to reach full light intensity; xenon fill as used in automotive headlamps has a much better start up time.
Metal-halide lamp – Arc tube
The ends of the arc tube are often externally coated with white infrared–reflective zirconium silicate or zirconium oxide to reflect heat back onto the electrodes to keep them hot and thermionically emitting. Some bulbs have a phosphor coating on the inner side of the outer bulb to improve the spectrum and diffuse the light.
Metal-halide lamp – Arc tube
These are usually referred as ceramic metal-halide lamps or CMH lamps.
Metal-halide lamp – Arc tube
Interestingly, the original concept of adding metallic iodides for spectral modification (specifically: sodium – yellow, lithium – red, indium – blue, potassium and rubidium – deep red, and thallium – green) of a mercury arc discharge to create the first metal-halide lamp can be traced to patent US1025932 in 1912 by Charles Proteus Steinmetz, the “Wizard of General Electric”.
Metal-halide lamp – Arc tube
Do not confuse metal halide lamps as requiring mercury. Mercury isn’t the only metal in the table of elements that vaporizes, i.e. see Sodium vapor lamp. However mercury is practical and used even in sodium metal lamps for coloring. The amount of mercury required for coloring is less than that of a lamp which is mercury driven. The amount of mercury used has lessened over years of progress.
Metal-halide lamp – Outer bulb
The cover glass of the luminaire can be used to block the UV, and can also protect people or equipment if the lamp should fail by exploding.
Metal-halide lamp – Base
Some types have an Edison screw metal base, for various power ratings between 10 to 18,000 watts. Other types are double-ended, as depicted above, with R7s-24 bases composed of ceramic, along with metal connections between the interior of the arc tube and the exterior. These are made of various alloys (such as iron-cobalt-nickel) that have a thermal coefficient of expansion that matches that of the arc tube.
Metal-halide lamp – Ballasts
The electric arc in metal-halide lamps, as in all gas discharge lamps has a negative resistance property; meaning that as the current through the bulb increases, the voltage across it decreases. If the bulb is powered from a constant voltage source such as directly from the AC wiring, the current will increase until the bulb destroys itself; therefore, halide bulbs require electrical ballasts to limit the arc’s current. There are two types:
Metal-halide lamp – Ballasts
Many fixtures use an inductive ballast similar to those used with fluorescent lamps. This consists of an iron-core inductor. The inductor presents an impedance to AC current. If the current through the lamp increases, the inductor reduces the voltage to keep the current limited.
Metal-halide lamp – Ballasts
Electronic ballasts are lighter and more compact. They consist of an electronic oscillator which generates a high frequency current to drive the lamp. Because they have lower resistive losses than an inductive ballast, they are more energy efficient. However, high-frequency operation does not increase lamp efficacy as for fluorescent lamps.
Metal-halide lamp – Ballasts
Pulse-start metal-halide bulbs don’t contain a starting electrode which strikes the arc, and require an ignitor to generate a high-voltage (1–5 kV on cold strike, over 30 kV on hot restrike) pulse to start the arc. Electronic ballasts include the igniter circuit in one package. American National Standards Institute (ANSI) lamp-ballast system standards establish parameters for all metal-halide components (with the exception of some newer products).
Metal-halide lamp – Self-ballasted lamps
In contrast to the former, these lamps usually have a clear outer bulb without a coating, making the arc tube and the halogen lamp tube clearly visible from the outside.
Metal-halide lamp – Colour temperature
Because the lamp’s color characteristics tend to change during lamp’s life, color is measured after the bulb has been burned for 100 hours (seasoned) according to ANSI standards
Metal-halide lamp – Colour temperature
The color temperature of a metal-halide lamp can also be affected by the electrical characteristics of the electrical system powering the bulb and manufacturing variances in the bulb itself
Metal-halide lamp – Starting and warm up
A “cold” (below operating temperature) metal-halide lamp cannot immediately begin producing its full light capacity because the temperature and pressure in the inner arc chamber require time to reach full operating levels. Starting the initial argon arc sometimes takes a few seconds, and the warm up period can be as long as five minutes (depending upon lamp type). During this time the lamp exhibits different colors as the various metal halides vaporize in the arc chamber.
Metal-halide lamp – Starting and warm up
A warm lamp also tends to take more time to reach its full brightness than a lamp that is started completely cold.
Metal-halide lamp – Starting and warm up
Most hanging ceiling lamps tend to be passively cooled, with a combined ballast and lamp fixture; immediately restoring power to a hot lamp before it has re-struck can make it take even longer to relight, because of power consumption and heating of the passively cooled lamp ballast that is attempting to relight the lamp.
Metal-halide lamp – End of life behaviour
In rare occurrences the lamp explodes at the end of its useful life.
Metal-halide lamp – End of life behaviour
Modern electronic ballast designs detect cycling and give up attempting to start the lamp after a few cycles. If power is removed and reapplied, the ballast will make a new series of startup attempts.
Metal-halide lamp – Risk of lamp explosion
All HID arc tubes deteriorate in strength over their lifetime because of various factors, such as chemical attack, thermal stress and mechanical vibration. As the lamp ages the arc tube becomes discoloured, absorbing light and getting hotter. The tube will continue to become weaker until it eventually fails, causing the breakup of the tube.
Metal-halide lamp – Risk of lamp explosion
Although such failure is associated with end of life, an arc tube can fail at any time even when new, because of unseen manufacturing faults such as microscopic cracks. However, this is quite rare. Manufacturers typically “season” new lamps to check for such defects before the lamps leave the manufacturer’s premises.
Metal-halide lamp – Risk of lamp explosion
Fragments of arc tube are launched, at high velocity, in all directions, striking the outer bulb of the lamp with enough force to cause it to break
Metal-halide lamp – Risk of lamp explosion
The risk of a “nonpassive failure” (explosion) of an arc tube is very small. According to information gathered by the National Electrical Manufacturers Association, there are approximately 40 million metal-halide systems in North America alone, and only a very few instances of nonpassive failures have occurred. Although it is impossible to predict or eliminate the risk of a metal-halide lamp exploding, there are several precautions that can reduce the risk:
Metal-halide lamp – Risk of lamp explosion
Using only well designed lamps from reputable manufacturers and avoiding lamps of unknown origin.
Metal-halide lamp – Risk of lamp explosion
Inspecting lamps before installing to check for any faults such as cracks in the tube or outer bulb.
Metal-halide lamp – Risk of lamp explosion
Replacing lamps before they reach their end of life (i.e. when they have been burning for the number of hours that the manufacturer has stated as the lamp’s rated life).
Metal-halide lamp – Risk of lamp explosion
For continuously operating lamps, allowing a 15-minute shutdown for every seven days of continuous operation.
Metal-halide lamp – Risk of lamp explosion
Relamping fixtures as a group. Spot relamping is not recommended.
Metal-halide lamp – Risk of lamp explosion
Also, there are measures that can be taken to reduce the damage caused by a lamp failure violently:
Metal-halide lamp – Risk of lamp explosion
Ensuring that the fixture includes a piece of strengthened glass or polymeric materials between the lamp and the area it is illuminating. This can be incorporated into the bowl or lens assembly of the fixture.
Metal-halide lamp – Risk of lamp explosion
Using lamps that have a reinforced glass shield around the arc tube to absorb the impact of flying arc tube debris, preventing it from shattering the outer bulb. Such lamps are safe to use in ‘open’ fixtures. These lamps carry an “O” designation on the packaging reflective of American National Standards Institute (ANSI) standards.
Metal-halide lamp – Risk of lamp explosion
Lamps that require an enclosed fixture are rated “/E”. Lamps that do not require an enclosed fixture are rated “/O” (for open). Sockets for “/O” rated fixtures are deeper. “/E” rated bulbs flare at the base, preventing them from fully screwing into a “/O” socket. “/O” bulbs are narrow at the base allowing them to fully screw in. “/O” bulbs will also fit in an “/E” fixture.
Metal-halide lamp – Eyes
Broken and unshielded high-intensity metal-halide bulbs are known to cause eye and skin injuries, particularly in school gymnasiums.
Mercury-vapor lamp
A mercury-vapor lamp is a gas discharge lamp that uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from the ultraviolet radiation the light produces, and a convenient mounting for the fused quartz arc tube.
Mercury-vapor lamp
They offer better color rendition than the more efficient high or low-pressure sodium vapor lamps.
Mercury-vapor lamp
They operate at an internal pressure of around one atmosphere and require special fixtures, as well as an electrical ballast. They also require a warm-up period of 4 – 7 minutes to reach full light output. Mercury vapor lamps are becoming obsolete due to the higher efficiency and better color balance of metal halide lamps.
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