Editing Headlamp (section)

=== Tungsten-halogen ===
[[Halogen lamp|Tungsten-halogen]] technology (also called "quartz-halogen", "quartz-iodine", "iodine cycle", etc.) increases the effective luminous [[efficacy]] of a [[tungsten]] filament: when operating at a higher filament temperature which results in more [[lumen (unit)|lumens]] output per watt input, a tungsten-halogen lamp has a much longer brightness lifetime than similar filaments operating without the halogen regeneration cycle. At equal luminosity, the halogen-cycle bulbs also have longer lifetimes. European-designed halogen headlamp light sources are generally configured to provide more light at the same power consumption as their lower-output plain tungsten counterparts. By contrast, many US-based designs are configured to reduce or minimize the power consumption while keeping light output above the legal minimum requirements; some US tungsten-halogen headlamp light sources produce less initial light than their non-halogen counterparts.<ref name="Dayton1">{{cite web |url=http://www.regulations.gov/search/Regs/contentStreamer?objectId=09000064802d582a&disposition=attachment&contentType=pdf |archive-url=https://web.archive.org/web/20210308151704/https://www.regulations.gov/search/Regs/contentStreamer?objectId=09000064802d582a&disposition=attachment&contentType=pdf |url-status=dead |archive-date=8 March 2021 |title=Dayton, David: Comments regarding NHTSA docket 8885, p. 5 |access-date=2010-12-29 }}</ref> A slight theoretical fuel economy benefit and reduced vehicle construction cost through lower wire and switch ratings were the claimed benefits when American industry first chose how to implement tungsten-halogen technology. There was an improvement in seeing distance with US halogen high beams, which were permitted for the first time to produce 150,000 [[candela]] (cd) per vehicle, double the non-halogen limit of 75,000&nbsp;cd but still well shy of the international European limit of 225,000&nbsp;cd. After replaceable halogen bulbs were permitted in US headlamps in 1983, the development of US bulbs continued to favor long bulb life and low power consumption, while European designs continued to prioritise optical precision and maximum output.<ref name=Dayton1/>

The [[H1 lamp]] was the first tungsten-halogen headlamp light source. It was introduced in 1962 by a consortium of European bulb and headlamp makers. This bulb has a single [[axis of rotation|axial]] filament that consumes 55 watts at 12.0 [[volt]]s, and produces 1550 lumens ±15% when operated at 13.2&nbsp;V. H2 (55&nbsp;W @ 12.0&nbsp;V, 1820&nbsp;lm @ 13.2&nbsp;V) followed in 1964, and the transverse-filament H3 (55&nbsp;W @ 12.0&nbsp;V, 1450&nbsp;lm ±15%) in 1966. H1 still sees wide use in low beams, high beams and auxiliary [[fog lamp|fog]] and [[driving lamp]]s, as does H3. The H2 is no longer a current type, since it requires an intricate bulb holder interface to the lamp, has a short life and is difficult to handle. For those reasons, H2 was withdrawn<ref>{{cite web|url=https://groups.google.com/group/rec.autos.driving/msg/de2d7f2f888fb298?hl=en& |title=Driving lights-was Re: headlight laws was re improving lightoutput - rec.autos.driving &#124; Google Groups |date=2003-12-06 |access-date=2012-01-31}}</ref> from [[World Forum for Harmonization of Vehicle Regulations|ECE Regulation 37]] for use in new lamp designs (though H2 bulbs are still manufactured for replacement purposes in existing lamps), but H1 and H3 remain current and these two bulbs were legalised in the United States in 1993.<ref name="NHTSA_8885">{{Cite web|url=https://www.regulations.gov/|title=Regulations.gov|website=www.regulations.gov}}</ref> More recent single-filament bulb designs include the H7 (55&nbsp;W @ 12.0&nbsp;V, 1500&nbsp;lm ±10% @ 13.2&nbsp;V), H8 (35&nbsp;W @ 12.0&nbsp;V, 800&nbsp;lm ±15% @ 13.2&nbsp;V), H9 (65&nbsp;W @ 12.0&nbsp;V, 2100&nbsp;lm ±10% @ 13.2&nbsp;V), and H11 (55&nbsp;W @ 12.0&nbsp;V, 1350&nbsp;lm ±10% @ 13.2&nbsp;V).<ref name=R37/> 24-volt versions of many bulb types are available for use in trucks, buses, and other commercial and military vehicles.
[[File:H4 IMG 1269.JPG|thumb|H4 bulb ([[Metre|cm]])]]
[[File:H7 IMG 1246.JPG|thumb|H7 bulb]]
The first dual-filament halogen bulb to produce both a low and a high beam, the H4 (60/55&nbsp;W @ 12&nbsp;V, 1650/1000&nbsp;lm ±15% @ 13.2&nbsp;V),<ref name=R37/> was released in 1971<ref name=100Hella/> and quickly became the predominant headlamp bulb throughout the world except in the United States, where the H4 is still not legal for automotive use. In 1989, the Americans created their own standard for a bulb called HB2: almost identical to H4 except with more stringent constraints on filament geometry and positional variance,<ref>{{Cite web|url=http://candlepowerinc.com/pdfs/H4_9003.pdf|title=H4, HB2, and 9003 bulbs}}</ref><ref>{{Cite book|title=Automotive Design Engineering|last=International|first=Grosvenor Press|year=1990|publisher=Century Press|pages=264}}</ref> and power consumption and light output expressed at the US test voltage of 12.8V.<ref>{{Cite web|url=https://www.regulations.gov/document/NHTSA-1998-3397-0011|title=Regulations.gov|website=www.regulations.gov}}</ref>

The first US halogen headlamp bulb, introduced in 1983, was the HB1/9004. It is a 12.8-volt, transverse dual-filament design that produces 700 lumens on low beam and 1200 lumens on high beam. The 9004 is rated for 65 watts (high beam) and 45 watts (low beam) at 12.8 volts. Other US approved [[halogen]] bulbs include the HB3 (65&nbsp;W, 12.8&nbsp;V), HB4 (55&nbsp;W, 12.8&nbsp;V), and HB5 (65/55 watts, 12.8&nbsp;V).<ref name="Docket3397">{{Cite web|url=https://www.regulations.gov/docketBrowser/NHTSA-1998-3397|title=Regulations.gov|website=www.regulations.gov}}</ref> All of the European-designed and internationally approved bulbs except H4 are presently approved for use in headlamps complying with US requirements.

==== Halogen infrared reflective (HIR) ====
A further development of the tungsten-halogen bulb has a [[dichroism|dichroic]] coating that passes [[visible spectrum|visible light]] and reflects [[Infrared#Heat|infrared radiation]]. The glass in such a bulb may be [[sphere|spherical]] or tubular. The reflected infrared radiation strikes the filament located at the center of the glass envelope, heating the filament to a greater degree than can be achieved through [[resistive heating]] alone. The superheated filament emits more light without an increase in power consumption.<ref>{{cite web |last1=Group |first1=Techbriefs Media |title=The Rebirth of the Incandescent Light Bulb |url= https://www.techbriefs.com/component/content/article/lighting-technology/lighting-technology/15641 |website=techbriefs.com |date=31 December 2012 |access-date=6 February 2019 }}</ref>