Headlamp

The standardized 7-inch (178 mm) round sealed-beam headlamp, one per side, was required for all vehicles sold in the United States from 1940, virtually freezing usable lighting technology in place until the 1970s for Americans.

[7] Another early headlamp styling concept involved conventional round lamps faired into the car's bodywork with aerodynamic glass covers, such as those on the 1961 Jaguar E-Type, and on pre-1967 VW Beetles.

[34] Many tungsten (pre-halogen) European-code headlamps made in France by Cibié, Marchal, and Ducellier could be adjusted to produce either a left- or a right-traffic low beam by means of a two-position bulb holder.

[35][36] North American vehicle owners sometimes privately import and install Japanese-market (JDM) headlamps on their car in the mistaken belief that the beam performance will be better, when in fact such misapplication is quite hazardous and illegal.

[48] In addition to the EU and Canada, countries requiring DRL include Albania, Argentina,[49] Bosnia and Herzegovina, Czech republic, Colombia (no more from Aug/2011), Iceland, Israel, Macedonia, Norway, Moldova, Russia, Serbia, and Uruguay.

The 1983 Austin Maestro was the first vehicle equipped with Lucas-Carello's homofocal reflectors, which comprised parabolic sections of different focal length to improve the efficiency of light collection and distribution.

The first modern polyellipsoidal (projector) automotive lamp was the Super-Lite, an auxiliary headlamp produced in a joint venture between Chrysler Corporation and Sylvania and optionally installed in 1969 and 1970 full-size Dodge automobiles.

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,[95][96] and power consumption and light output expressed at the US test voltage of 12.8V.

[102] In Europe and the many non-European countries applying ECE Regulations, even HID headlamps designed as such must be equipped with lens cleaning and automatic self-leveling systems, except on motorcycles.

They have an opaque mask covering specific portions of the shield, which facilitates the optical creation of the light-dark boundary (cutoff) near the top of a low-beam light distribution.

In North America, ECE R48 does not apply and while lens cleaners and beam levelers are permitted, they are not required;[115] HID headlamps are markedly less prevalent in the US, where they have produced significant glare complaints.

Federal Motor Vehicle Safety Standard 108 has not been updated since the introduction of LEDs, and some manufacturers have reportedly engineered headlamps to have a dark spot where they are measured according to the regulation while being over-illuminated in the rest of the field.

With a daytime running lamp equipped and operated, the dipped beam headlamp should automatically turn on if the car is driving in less than 1,000 lux ambient conditions such as in a tunnel and in dark environments.

Such systems typically use stepper motors at the headlamp and a rotary switch on the dash marked "0", "1", "2", "3" for different beam heights, "0" being the "normal" (and highest) position for when the car is lightly loaded.

[9] The regulation stipulates a more stringent version of this anti-glare measure if the vehicle has headlamps with low beam light source(s) that produce more than 2,000 lumens – xenon bulbs and certain high-power halogens, for example.

[citation needed] Beginning in the 2000s, there was a resurgence in interest in the idea of moving or optimizing the headlight beam in response not only to vehicular steering and suspension dynamics, but also to ambient weather and visibility conditions, vehicle speed, and road curvature and contour.

A task force under the EUREKA organization, composed primarily of European automakers, lighting companies and regulators began working to develop design and performance specifications for what is known as Adaptive Front-Lighting Systems, commonly AFS.

General Motors introduced the first automatic headlight dimmer called the "Autronic Eye" in 1952 on their Cadillac, Buick, and Oldsmobile models; the feature was offered in other GM vehicles starting in 1953.

The GuideMatic had a more compact dashtop housing and a control knob that allowed the driver to adjust the system's sensitivity threshold to determine when the headlamps would be dipped from high to low beam in response to an oncoming vehicle.

The photosensor for this system used an amber lens, and the adoption of retro-reflective yellow road signs, such as for oncoming curves, caused them to dim prematurely - possibly leading to their discontinuation.

[citation needed] Though the systems based on photoresistors evolved, growing more compact and moving from the dashboard to a less conspicuous location behind the radiator grill, they were still unable to reliably distinguish headlamps from non-vehicular light sources such as streetlights.

American inventor Jacob Rabinow devised and refined a scanning automatic dimmer system impervious to streetlights and reflections,[151] but no automaker purchased the rights, and the problematic photoresistor type remained on the market through the late 1980s.

[153] Present systems based on imaging CMOS cameras can detect and respond appropriately to leading and oncoming vehicles while disregarding streetlights, road signs, and other spurious signals.

Intelligent Light System is a headlamp beam control system introduced in 2006 on the Mercedes-Benz E-Class (W211)[154] which offers five different bi-xenon light functions,[155] each of which is suited to typical driving or weather conditions: Adaptive Highbeam Assist is Mercedes-Benz's marketing name for a headlight control strategy that continuously automatically tailors the headlamp range so the beam just reaches other vehicles ahead, thus always ensuring maximum possible seeing range without glaring other road users.

An infrastructure bill enacted in November 2021 included language that directs the National Highway Traffic Safety Administration to amend FMVSS 108 to allow the use of this technology, and set a two-year deadline for implementing this change.

Sanding or aggressively polishing the lenses, or plastic headlight restoration, can buy some time, but doing so removes the protective coating from the lens, which when so stripped will deteriorate faster and more severely.

Kits for a quality repair are available that allow the lens to be polished with progressively finer abrasives, and then be sprayed with an aerosol of ultra violet resistant clear coating.

The reflector, made out of vaporized aluminum deposited in an extremely thin layer on a metal, glass, or plastic substrate, can become dirty, oxidised, or burnt, and lose its specularity.

Some cars with retractable headlamps, such as the original Mazda MX-5, have a squeegee at the front of the lamp recess which automatically wipes the lenses as they are raised or lowered, although it does not provide washer fluid.

[169] During World War II, civil and military authorities often enforced brownouts and blackouts, restricting the use of lights on passenger vehicles in order to hinder detection by aerial reconnaissance and bombers.