Really? I've owned numerous vehicles with steerable headlamps, now more often called "curve-adaptive" headlights. Clearly the law didn't hold?
Our 2010 Volvo V50 had Xenon HID's that were literally better than daylight. Never seen anything like the headlights that came with that car, before or since. If someone were going to outlaw a headlight, I'd suspect they'd be a target, I can't even imagine driving toward that thing if someone failed to dim the high beams.
Yes, really.
U.S. Car, Truck, and SUV Headlight Standards to Get Major Update Thanks to Infrastructure Law
Also I believe the Cords and some of the Duesenbergs also used steerable head lamps.
These were a tad bit before my time but I do recall reading about them in my younger years.
Headlight
From Academic Kids
(Redirected from
Headlamp)
A
headlight or
headlamp is a
light, usually attached to the front of a
vehicle such as a
car, with the purpose of illuminating the
road ahead during periods of low
visibility, such as
night or
precipitation.
A headlight can also be mounted on a
bicycle (with a
battery or small
generator), and most other moving vehicles from
airplanes to
trains tend to have headlights of their own. Single small headlights may also be mounted on a
helmet designed to be worn in situations where light is required but both hands are needed, for example in subterranean
mines or for
spelunking in
caves.
Automotive headlights
Modern headlights are electric
floodlights, positioned in pairs, one on each side of a moving vehicle. Headlights are usually combinations of multiple lamps and
reflectors and can be switched between two modes or configurations: low beams and high beams. High beams cast more light at a higher angle, allowing the driver to see further away, but at the cost of potentially blinding drivers of oncoming vehicles. High beams also increase
reflection from
fog, due to the
refraction of the
water droplets.
In the USA, many headlights are of the
sealed beam type, meaning that the reflector, lens array on the front, as well as bulb, are all one unit that must be replaced together. In most
European countries sealed beam headlights are not allowed on automobiles. 'H4' halogen
incandescent light bulbs are used instead.
Several countries, including
Canada and the
Scandinavian countries, require
daytime running lights (
DRLs) or the use of low-beam headlights during daytime driving as well. Most often, this is the high beams running at half
power. Many models of automobiles sold elsewhere are also equipped with daytime running lights, which are
automatic when the car is running. This is entirely for the visibility of the car itself by other drivers, especially when there are low-light conditions which a driver may forget to turn on his or her regular headlights. A slight disadvantage of the DRL is that it wastes a small amount of
gasoline or
petrol, especially with incandescent light bulbs.
Most headlights use incandescent light bulbs (usually halogen-type), either with separate high and low beam bulbs, or a single bulb on each side with dual
filaments. More and more are using
high-intensity discharge (HID) lamps, similar to the
Mercury-vapor lamps used in white
street lights. These have a distinct purplish or bluish cast to them, which also causes
fluorescence in certain materials. HID bulbs are also extremely
energy-
efficient, using over 80% less power, and drawing less
electrical current from the
alternator and improving
fuel efficiency.
Headlights usually have a distinctive shape with a light bulb positioned in the
focus of a
parabolic reflector cone. The glass
lens usually has additional patterns to direct the lightbeam in a certain direction. These patterns are different (
mirrored) for left- or right hand traffic.
Headlights must be adjusted, aimed to an
ISO-
regulated inclination and
center. This applies most of all to low beams (US name) or dipped beams (UK name), where the aiming results in a specific position of the cut-off line in the beam when projected on a
wall at a minimum 10-
metre (33-
foot)
distance from the car. The cut-off line is the
transition between the illuminated and dark section of the beam. Headlights are checked for alignment prior to leaving the
production line, and may need realignment periodically throughout the car's lifetime, or after repairing body damage.
History of automotive headlights
The earliest headlights were fueled by
acetyline or
oil and were introduced by drivers in the late
1880s. Acetyline was popular because the flame was resistant to wind and rain. The first electric headlights were introduced in
1898 on the
Columbia Electric Car from the
Electric Vehicle Company of
Hartford, Connecticut, but they were optional. "Prest-O-Lite" acetylene lights were offered by a number of manufacturers as standard equipment for
1904, and
Peerless made electrical headlights standard in
1908. In
1912,
Cadillac integrated their vehicle's
Delco electrical ignition and lighting system, creating the modern vehicle electronics system.
"Dipping" (low beam) headlights were introduced in
1915 by the
Guide Lamp Company, but the
1917 Cadillac system was much more useful as it allowed the light to be dipped with a lever inside the car rather than requiring the driver to stop and get out. The
1924 Bilux bulb was the first modern unit, having both low- and high-beams in a single bulb. A similar design was introduced the next year by Guide Lamp called the "Duplo". In
1927, the foot-operated dimmer was introduced and would become standard for much of the century. The last vehicle with a foot-operated dimmer was the
1991 Ford F-Series.
Fog lights were new for
1938 Cadillacs, and that company's
1954 "Autronic Eye" system automated the switch between high and low beams.
The standardized 7 inch
sealed beam headlight was introduced in
1940, and was soon required for all vehicles sold in the
United States. Sealed beams were never accepted in other countries, however, leading to different front-end designs for each side of the Atlantic for decades. The
U.S. DOT also outlawed transparent covered headlights (as famously used on the
Jaguar E-Type and
Ferrari Daytona) in
1968, further altering the look of European models sold in the United States. In
1984, these regulations were finally reversed. The first U.S.-market car with composite headlights was the
Lincoln Mark VII of that year, but it would be another dozen years before sealed beam lights vanished from new cars altogether.
Directional headlights were a notable feature of the
1948 Tucker, but the technology went back to the
1937 Tatra T77A. The first real production car with steerable headlights was the
1967 Citroën DS. The technology was slow to gain acceptance, but is today offered on a number of luxury vehicles, including those from
Lexus,
Infiniti, and the
Porsche Cayenne.
In
1954,
Cibie introduced an automatic headlight leveling system. First used in the
Panhard Dyna, it would spread slowly. Although automatic headlight leveling never became a standard feature on all cars, it is still used on some today.
Cadillac introduced quad headlights (using 5¾ inch sealed lamps) in
1957. Chrysler soon followed suit, and by
1958, every new car would have four round headlights, instead of two. The vastly superior illumination afforded by this system makes it common in the next decade, changing the look of many cars for the
1960s.
Rectangular lamps were first used in
1961. Developed by
Cibie for the
Citroën Ami 6, they would not be allowed in the United States until
1975, on the
Cadillac Eldorado. By
1979, the majority of new cars now had the square headlights.
Pop-up headlights were introduced in
1963, on the
Chevrolet Corvette. When the lights were turned on, they would appear from inside the car's front bumper. Many famous cars to use this feature include the
Ferrari Testarossa,
Mazda RX-7,
RX-8 and
Miata,
Dodge Daytona,
Pontiac Firebird,
Nissan 300ZX,
Toyota Celica and
Supra,
Honda Accord and
Prelude, and
Buick Reatta. The Corvette itself continued to use pop-up headlights until it was redesigned for
2004.
The first
halogen bulbs for vehicle use were introduced in
1962 by
Hella. First used only for
auxiliary lights, they spread to headlight use in
1965. The modern dual-filament
H4 bulb was patented in
1971.
General Motors introduced halogen headlights in the U.S. in
1978.
Daytime running lights were mandatory in
Finland for
1972. The technology spread around Scandanavia, with
Sweden following in
1977,
Norway in
1986,
Iceland in
1988, and
Denmark in
1990.
Canada was the first large DRL market, requiring them as of
1990. General Motors,
Saab, and
Volkswagen introduce daytime running lights in the U.S. market in
1995, though they would not be mandated.
Projector beam lamps first appeared in
1983. Developed by
Hella, the "DE" lights are much brighter than previous systems. The
1986 BMW 7 Series was the first to use projectors for low beams. Projector and
CAD technology allowed the development of so-called "free form" headlights. First used by the
1989 Citroën XM, free form headlights would revolutionize automobile design, and lead to the downfall of the United States' decades-long sealed beam standard. The
1990 Honda Accord was the first U.S.-market car with free form lights.
High-intensity discharge systems were introduced in
1991's
BMW 7-series as an even-brighter system than projectors. The technology spread to the United States for
1997's
Lincoln Mark VIII, which was also the first car with
DC HIDs.
Directional headlights
These provide improved lighting for
cornering. Some automobiles have their headlights connected to the
steering mechanism so the lights will follow the movement of the front wheels. The
Citroën DS was one car equipped with such a system. Also, some automobiles have vertically adjustable lights, to compensate for dipping when carrying heavy loads.
Dual-beam headlights
Night driving has long been dangerous due to the glare of headlights that blind drivers approaching from the opposite direction. Therefore, headlights that satisfactorily illuminate the highway ahead of the automobile for night driving without temporarily blinding approaching drivers have long been sought. To correct this problem resistance-type dimming circuits, which decreased the brightness of the headlights when meeting another car, were first introduced. This gave way to mechanical tilting reflectors and later to double-filament bulbs with a high and a low beam, called sealed-beam units.
There was only one filament at the focal point of the reflector in the double-filament headlight unit of necessity. Greater illumination required for high-speed driving with the high beam, consequently, the lower beam filament was placed off center, with a resulting decrease in lighting effectiveness. From the
1950s, manufacturers equipped their models with four headlights to improve illumination.
In some cars, dimming is automatically achieved. This happens by means of a photocell-controlled switch in the lamp circuit that is triggered by the lights of an oncoming car. Larger double-filament lamps and halogen-filled lamp bulbs with improved photometrics permitted a return to two-headlight systems on some cars. At many places the law limits the total intensity of forward lighting systems to 75,000
candlepower (800,000
lux).
In most new automobiles, lowering front hood heights for improved aerodynamic drag and driver visibility reduces the vertical height available for headlights. Due to this, lower-profile rectangular sealed-beam units and higher-intensity bulbs, in conjunction with partial parabolic reflectors with reduced vertical axis, were adopted in the
1970s. In some cases, models featured full-size concealed headlights that were not visible until turned on. An electric motor linkage was used to rotate the lamp housing or a housing cover into proper position to supply lighting. Aerodynamic benefits were provided by this system only when the headlights were concealed.
In the
1960s, signal lamps and other special-purpose lights were increased in usage. Amber-colored front and red rear signal lights are flashed as a turn indication; all these lights are flashed simultaneously in the "flasher" system for use when a car is parked along a roadway or is traveling at a low speed on a high-speed highway. The law requires that marker lights that are visible from the front, side, and rear be also present. Red-colored rear signals are used to denote braking, and, on some models, cornering lamps to provide extra illumination in the direction of an intended turn are available. These are actuated in conjunction with the turn signals. To provide illumination to the rear when backing up, backup lights are required