Halogen lamp
A halogen lamp (also called tungsten halogen, quartz-halogen, and quartz iodine lamp) is an
Standard and halogen incandescent bulbs are much less efficient than LED and compact fluorescent lamps, and therefore have been or are being phased out in many places.
History
A carbon filament lamp using chlorine to prevent darkening of the envelope was patented[2] in 1882, and chlorine-filled "NoVak" lamps were marketed in 1892.[3]
The use of iodine was proposed in a 1933 patent,[4] which also described the cyclic redeposition of tungsten back onto the filament. In 1959, General Electric patented[4] a practical lamp using iodine.[5]
Phase-out
In 2009, the
Halogen cycle
In ordinary incandescent lamps, evaporated tungsten mostly deposits onto the inner surface of the bulb, causing the bulb to blacken and the filament to grow increasingly weak until it eventually breaks. The presence of the halogen, however, sets up a reversible chemical reaction cycle with this evaporated tungsten. The halogen cycle keeps the bulb clean and causes the light output to remain almost constant throughout the bulb's life. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling. At some point, however, it will reach higher temperature regions within the bulb where it then dissociates, releasing tungsten back onto the filament and freeing the halogen to repeat the process. However, the overall bulb envelope temperature must be significantly higher than in conventional incandescent lamps for this reaction to succeed: it is only at temperatures of above 250 °C (482 °F)[11] on the inside of the glass envelope that the halogen vapor can combine with the tungsten and return it to the filament rather than the tungsten becoming deposited on the glass.[12] A 300 watt tubular halogen bulb operated at full power quickly reaches a temperature of about 540 °C (1,004 °F), while a 500 watt regular incandescent bulb operates at only 180 °C (356 °F) and a 75 watt regular incandescent at only 130 °C (266 °F).[13]
The bulb must be made of
Quartz iodine lamps, using elemental iodine, were the first commercial halogen lamps launched by GE in 1959.
For a fixed power and life, the luminous efficacy of all incandescent lamps is greatest at a particular design voltage. Halogen lamps made for 12 to 24 volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture). The ranges of multifaceted reflector "MR" lamps of 20–50 watts were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home. More recently, wider beam versions have become available designed for direct use on supply voltages of 120 or 230 V.
Effect of voltage on performance
Tungsten halogen lamps behave in a similar manner to other incandescent lamps when run on a different voltage. However the light output is reported as proportional to , and the luminous efficacy proportional to .[21] The normal relationship regarding the lifetime is that it is proportional to . For example, a bulb operated at 5% higher than its design voltage would produce about 15% more light, and the luminous efficacy would be about 6.5% higher, but would be expected to have only half the rated life.
Halogen lamps are manufactured with enough halogen to match the rate of tungsten evaporation at their design voltage. Increasing the applied voltage increases the rate of evaporation, so at some point, there may be insufficient halogen and the lamp goes black. Over-voltage operation is not generally recommended. With a reduced voltage, the evaporation is lower and there may be too much halogen, which can lead to abnormal failure. At much lower voltages, the bulb temperature may be too low to support the halogen cycle, but by this time the evaporation rate is too low for the bulb to blacken significantly. If the bulbs do blacken, it is recommended to run the lamps at the rated voltage to restart the cycle.[22] There are many situations where halogen lamps are dimmed successfully. However, lamp life may not be extended as much as predicted. The life span on dimming depends on lamp construction, the halogen additive used, and whether dimming is normally expected for this type.
Spectrum
Like all incandescent light bulbs, a halogen lamp produces a continuous spectrum of light, from near ultraviolet to deep into the infrared.[23] 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 and higher power efficiency.
High-temperature filaments emit some energy in the UV region. Small amounts of other elements can be mixed into the quartz, so that the doped quartz (or selective optical coating) blocks harmful UV radiation. Hard glass blocks UV and has been used extensively for the bulbs of car headlights.[24] Alternatively, the halogen lamp can be mounted inside an outer bulb, similar to an ordinary incandescent lamp, which also reduces the risks from the high bulb temperature. Undoped quartz halogen lamps are used in some scientific, medical, and dental instruments as a UV-B source.
Safety
Halogen lamps must run at much higher temperatures than regular incandescent lamps for proper operation. Their small size helps to concentrate the heat on a smaller envelope surface, closer to the filament than a non-halogen incandescent. Because of the very high temperatures, halogen lamps can pose fire and burn hazards. In Australia, numerous house fires each year are attributed to ceiling-mounted halogen downlights.
Any surface contamination, notably the oil from human fingertips, can damage the quartz envelope when it is heated. Contaminants, because they absorb more light and heat than the glass does, will create a hot spot on the bulb surface when the lamp is turned on. This extreme, localized heat causes the quartz to change from its
The small glass envelope may be enclosed in a much larger outer glass bulb, which provides several advantages if small size is not required:[1]
- the outer jacket will be at a much lower, safer, temperature, protecting objects or people that might touch it
- the hot-running inner envelope is protected from contamination, and the bulb may be handled without damaging it
- surroundings are protected from possible shattering of the inner capsule
- the jacket may filter out UV radiation
- when a halogen bulb is used to replace a normal incandescent in a fitting, the larger jacket makes it mechanically similar to the bulb replaced
- the inner and outer envelope can be at different pressures, reducing heat dissipation by conduction or convection in order to optimize the trade-off between luminous efficacy and lifetime
Form factors
Halogen lamps are available in a series of different shapes and sizes, and are designated according to a coding system that specifies the diameter of the bulb as well as whether or not the bulb has a built-in infrared-transparent
An R7S is a double ended, Recessed Single Contact (RSC) linear halogen lamp, usually measuring a length of either 118 mm or 78 mm. Some less common lengths are 189 mm, 254 mm and 331 mm. These lamps have a T3 shape on an RSC/R7S base. These can also be known as J type and T type lamps.
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.
Tungsten-halogen lamps are frequently used as a near-infrared light source in Infrared spectroscopy.
Halogen lamps were used on the Times Square Ball from 1999 to 2006. However, from 2007 onward, the halogen lamps were replaced with LEDs, due to the much longer lifespan, about ten times longer for LED over incandescent.[32] The 'New Year' numerals that light up when the Times Square Ball reaches the base used halogen lighting for the last time for the 2009 ball drop.[33]
Heating
Halogen lamps are the heating-elements in halogen ovens, infrared heaters and ceramic cooktops.
Low wattage halogen lamp arrays are widely used by monitor lizard keepers. Two or three small halogen lamps can produce all the heat needed in an enclosure and are recognized by the animals as sources of heat preventing curious individuals from attempting to touch them. Halogen lamps' thick glass lenses are safe to use inside high humidity reptile enclosures.
Banks of powerful tubular halogen lamps were used to simulate the heat of
General lighting
Fixed-mount lamps are used in indoor and outdoor flood lighting, although improvements in LED systems are displacing halogen lamps. Round spotlights with built-in multifaceted reflector lamps are widely used in residential and commercial lighting. Tubular halogen lamps provide a large quantity of light from a small source and so can be used to produce powerful flood lamps for architectural lighting effects, or for lighting large areas outdoors.
Low voltage lamps use the GU5.3 and similar
Tubular lamps with electrical contacts at each end are now being used in standalone lamps and household fixtures. These come in various lengths and power ratings (50–300 W). More powerful lamps are used as portable work lights, with bulbs rated 250 or 500 watts.
Stage lighting
Tungsten halogen lamps are used in the majority of theatrical and studio (film and television) fixtures, including
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 such as CCFL and now LED are used.
Disposal
Halogen lamps do not contain any mercury. General Electric says that their quartz halogen lamps would not be classified as hazardous waste.[35]
See also
- Bi-pin connectorfor base designations GY6.35, G8, etc.
- FEL lamp
- Lightbulb socket for other bases
- List of light sources
Notes
- ^ However, a T-3, T hyphen 3, is a halogen "tube" lamp that is 3/8 of an inch in diameter with a single bi-pin base rather than a T3 cylindrical tube 3/8 of an inch in diameter with electrodes at opposite ends.
- ^ Thus, an MR11 is a multifaceted reflector bulb that is 11/8 or 1 3/8 inches in diameter
- ^ "G" stands for "glass"
References
- ^ a b "Tungsten Halogen - Double Jacket". Lamptech.co.uk. 14 September 2014. Retrieved 23 January 2019. Source has illustrations of various double-envelope halogen bulbs.
- ^ US 254780, Scribner, Edward A., "Electric incandescent lamp", published 1882-03-07, assigned to United States Electric Lighting Co.
- .
- ^ General Electric Co.
- ISBN 9780881733785.
- ^ "The light bulb phase out schedule / Lighting Advice - Lyco". www.lyco.co.uk. Archived from the original on 27 October 2017. Retrieved 30 April 2018.
- ^ Crossley, David (February 2020). "HALOGEN LAMP (GLOBE) PHASE-OUT IN AUSTRALIA" (PDF). lightingcouncil.com.au. Lighting Council Australia. Retrieved 2 October 2023.
- ^ "Halogen Bulbs to be Banned in the EU Market from September - LEDinside". www.ledinside.com. Retrieved 26 August 2018.
- ^ Carabott, Mike (26 May 2020). "Halogen lamps phase-out in Australia pushed back to late 2021". Leading Edge Energy. Retrieved 9 March 2021.
- ^ "End of halogen light bulbs spells brighter and cleaner future". gov.uk. 9 June 2021. Retrieved 9 June 2021.
- ^ Sexton, J. Andrew (1 February 1991). "NASA Technical Reports Server (NTRS) - Vibration and thermal vacuum qualification test results for a low-voltage tungsten-halogen light". Https. Retrieved 19 January 2019.
- ISBN 978-0-307-56847-2.
- ^ Fire and Life-Safety Group. "Torchiere Halogen Lamps and Plastic Shades - Policies and Procedures" (PDF). University of Colorado Boulder.[permanent dead link]
- ^ Some lamps have as much as 15 times atmospheric pressure when cold, and some lamps increase pressure five-fold at operating temperature. Kane and Sell 2001, page 76–77
- ^ Zubler and Mosby Illuminating Engineering 1959 54.734
- ^ Covington, Edward J. "The Tungsten-Halogen Lamp". Archived from the original on 5 March 2016. Retrieved 4 March 2016.
- ^ a b Burgin and Edwards Lighting Research and Technology 1970 2.2. 95–108
- ^ T'Jampens and van der Weijer Philips Technical Review 1966 27.173
- ^ Schroder Philips Technical Review 1965 26.116
- ISBN 3527306730.
- ^ Neumann Lichtechnik 1969 21 6 63A
- ^ "Lutron Guide To Dimming Low Voltage Lighting | Lighting Services Inc". Lighting Services Inc. Archived from the original on 7 October 2018. Retrieved 12 October 2018. (Also available as a PDF from lutron.com)
- ^ Tungsten-halogen lamp information Archived 2011-03-03 at the Wayback Machine at Karl Zeiss Online Campus site (accessed Nov. 2 2010)
- ^ Burgin Lighting Research and Technology 1984 16. 2 71
- ^ Thousands at risk from halogen-light death traps Archived 2012-12-18 at the Wayback Machine at The Sunday Age site (accessed 22 Dec. 2012)
- ^ Halogen down light fire safety Archived 2013-04-09 at the Wayback Machine at Fire and Rescue NSW site (accessed 22 Dec. 2012)
- ^ Downlights Archived 2013-02-08 at the Wayback Machine at Western Australia Department of Fire and Emergency Services site (accessed 22 Dec. 2012)
- ^ "The Light Stuff". Popular Science: 41. October 1997.
- ISBN 0815628005.
The halogen lamp industry voluntarily undertook an initiative to repair about 40 million halogen torchère floor lamps. The CPSC is aware of 189 fires and eleven deaths that occurred because of these lamps.
- ^ Kremer, Jonathan Z."Types of Light Bulbs and Their Uses" Archived 2011-06-29 at the Wayback Machine Megavolt, section "Halogen", Accessed 26 May 2011.
- ISBN 978-3-319-04513-9.
- ^ "Lighting New Year's Eve". www.usa.philips.com. Philips. Archived from the original on 16 May 2016. Retrieved 21 September 2017.
- ^ "Times Square Alliance – New Year's Eve – 2010 Widgets". Archived from the original on 30 December 2009.
- ISBN 0-88173-351-2pp. 72-74
- ^ "MSDS — Lamp Material Information Sheet - Double-Ended or Pin-Based Quartz Halogen Lamps" (PDF). Current by GE. 2017. Archived from the original (PDF) on 23 January 2019. Retrieved 22 January 2019.
External links
- Media related to Halogen lamps at Wikimedia Commons