The next innovation was in the same vein as the Conaphore: a way to better direct light down to the road and away from other drivers eyes. The solution this time was a dipping light a headlight that was physically moved to change the angle of the beam downwards. This reduced the range but also lowered the beam enough to not blind oncoming traffic. The first system, developed by the Guide Lamp Company in 1915, required the driver to physically get out of the car to set the lights to low beam. Cadillac improved on the system in 1917 with a lever in the car that did the same thing.
Dude, the new BMW headlights totally ROCK!
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As noted above, headlight options were limited for US-market cars, but in Europe there was all sorts of strangeness abounding. Glass-covered headlights, such as on the Jaguar E-type and the Citroen DS were common across the pond but taboo in the states. Then in 1983, Standard 108 was amended to allow what were called composite headlights. Instead of replacing the whole unit, all you had to do with a composite system was remove the bulb the housing, lens, and reflectors were all permanent. The first US market car to sport such a headlight assembly was the 1984 Lincoln Continental Mark VII, recently restyled as part of the first wave of aero- or jellybean-designed cars that you probably can best visualize in the first-generation Ford Taurus. This allowed all sorts of unique front end designs to promulgate, and became the standard headlight type that youre probably most familiar with.
The famous Taurus composite headlights.
You left out an important though short-lived development: About 1905 or so, the Prest-O-Lite company began making refillable acetylene cylinders which could be mounted to the automobiles running boards. These tanks provided a large refillable reservoir of acetylene for the headlights, eliminating the caustic sludge problem and the need for frequent refilling of the carbide and water. These systems quickly replaced the carbide lamps and remained the standard for ten to fifteen years until electric lamps became reliable enough to replace them in the late teens.
Mazda Miata showing pop-ups (with 7 inch sealed beam lights)
@Aaron Andrusko Im having trouble understanding your statement.
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Finally, my personal preference is against LEDs. From the drivers seat, I dislike the color robbing effect of LED light. From the oncoming or following car, I find their light to be brutal to look at and LED tail lights have an extremely annoying and distracting flicker on top of being too bright.
This system represented the hi/low beam setup we know today: two filaments in the same lamp, where the lamp stays in the same position physically and the switch merely affects the lights output (wattage). This lead to the dimmer switch, initially a foot-operated one, but eventually the stalk-actuated dimmer that were most familiar with today. folks over at m have an excellent read on the history of headlights, worth a visit! Share this on FacebookPost this to MySpaceTweet This!Digg this!Share this on Stumble 
Also known as polyellipsoidal lamps, these lights first use as the main standard headlight was on the 1986 BMW 7-Series. It places the bulb in the middle of a wine-glass shaped reflector. The light is focused into a convex lens, which then projects the light out into a very specifically defined pattern. A very sharp cutoff is achieved by blocking part of the light with an opaque shield, focusing more of the light down than in traditional lens lights. Some projector headlights switch between low and high beam by moving the shield, allowing for a higher cutoff. These are generally used in higher-end cars, notably BMW, Acura, and Mercedes-Benz.
Im about thisfar from installing a bank of KC lights on the top of my car so I can return the blindness factor at every HID user who doesnt properly maintain clean, glarefree headlights.
Also, contrary to your statement, old eyes are not more sensitive to certain spectrums of light. Old eyes typically become less sensitive to any particular spectrum.
Today were going to take a look at a piece of automotive equipment that most people dont give much thought to unless youre blinded by them or forget to turn them on and get a freakin ticket. Headlights have been around for longer than automobiles (carriages used lights that were basically lanterns), but the vast increase in speed afforded by the auto meant that old technologies just wouldnt cut it in the new order of things. Join us to explore how the headlight evolved into the high-tech device we know today.
Starting with the 36 Cord and ending only in 2004, when the Corvette was last produced with pop-up lights, this feature allowed for smooth, aerodynamic front ends and kept the lights clean when retracted. Of course, it added complexity and weight, needing motors or linkages to raise and lower the lights. In the 1960s, some cars were required to have them in order to meet US minimum-height laws for headlights. A majority of the reason that these lights have become less common is that European pedestrian safety regulations have rightly pegged a popped-up headlight as a hazard, and thus manufacturers have shied away from using them.
Posted inCar TechHistoryOld CarsSafetyScienceby Alex Kierstein July 13th, 2009 19 Responses
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@John Doe Please enjoy the ignorance of your youth. Sadly, hopefully, it wont last.
The most recent revolution in headlight design is the high-intensity discharge, or xenon, lights. These are actually metal halide arc lights, which use two tungsten electrodes to arc a powerful electric charge. This charge interacts with the gases inside and vaporizes metal salts present in the bulb, producing a plasma that emits a very intense light. This is in contrast to a normal halogen bulb, which simply uses electricity to heat the filament until it is incandescent, emitting light. Temperatures inside a HID bulb can reach 2000 degrees F. Xenon gas is used the help the lamp warm up quickly and produce light, unlike argon-based arc lamps commonly used as streetlights, which would take far too long to work in an automotive setting. HID lights tend to have a unique color based on the different spectrum of light emitted by this different process; usually, its tinged blue. They are used in combination with projector lens headlamp assemblies to produce a very effective light at less power consumption than a normal halogen bulb. However, any contamination like dirt or dead bugs on the lens can cause a great deal of glare to be directed up and towards other motorists, and so care should be taken to keep HID lights clean to avoid blinding other drivers.
Carbide lamp showing flame and reflector.
In the early days, when gasoline-powered cars were loud, dirty, and dangerous to start (before electric starters, the starter crank definitely could break your arm if you did it wrong), electric cars actually outsold them. So its probably no surprise that the first electric headlights debuted on an electric car, a Columbia. They werent necessarily an improvement right off the bat: they had weak tungsten filaments that often broke on the rough roads of the time. Soon they were adopted by gas vehicles, but at that point all gasoline-powered vehicles used dynamos rather than the alternators we know of today, and basically they produced a lot less electricity. The bottom line is that these headlights were dim and broke easily, and probably most importantly, still didnt have a lens to focus their light. That innovation would come soon after. Ridelust has an interesting post on the history of the car headlamp. 
I hate the HID lights. They are blinding and Ive nearly smashed my car, along with other people smashing into me, from being blinded by those lights. They are dangerous and there is no reason we should be using them.
Incandescent bulbs are, by far, the most successful bulbs to date. Even today with the advent of LED and HID, incandescents still produce as much light as the competition at a greatly reduced cost. predicting the energy saving red herring argument, automobiles do not lack for electricity to run lights, even incandescent ones, and there is no measurable energy/fuel savings by shaving a few amps off an alternator.
You imply that there is some form of governmental conspiracy in favor of incandescents. How exactly do governmental departments make money form the use of incandescents? In my opinion, if there was a conspiracy, I would say that it was against incandescents. Already we have government mandates requiring the switch from incandescents to CFLs for home use. Cars seem like the likely next target for no legitimate reason. refinements have certainly been made, but the system as a whole is basically exactly the same. The history of the headlight is analogous in some ways. Originating with horse drawn carriages and gradually evolving into the 
Contrary to your statement, the majority of drivers are in fact what you call old farts. to get a clue, do the math on populations and aging. They will always be the majority.
For those who dont like HIDs are old farts who cant really use their eyes anymore. Their old eyes are more sensitive to certain spectrum of light, thus, not looking the blue effect of HIDs. But if they sit in one, they will appreciate the benefits of HIDs. HIDs got in trouble with DOT a few years ago from complaints by old farts only, while the majority of drivers have no problem. I believe LED headlights need much improvement to be marketed worldwide, as the LS600h triple LED headlight is weak and has an undefined beam pattern compared to HID projectors.
The earliest headlight technology was essentially a lantern with a reflecting mirror. This focused the light source though an opening in the lantern, but because there were no effective headlight lenses at this time, the beam was fairly unfocused and there was significant scattering of the light upwards as glare. This, combined with the low-candlepower light sources of the time, meant that they were a weak, low-speed-only means of illumination unfocused and with poor range. Plus, a good gust of wind or a wayward splash of water could snuff the flame. The fuel was usually oil, or the more weather-resistant acetylene. Acetylene lamps were also known as carbide lamps, and had been developed for mining. Gas was produced by dripping water on calcium carbide, which produced the acetylene gas, which was then burnt in the lamp. However, the flame was sooty and the byproduct was caustic lime, a toxic substance that had to be disposed of. An improvement was badly needed
Light-emitting diodes are the next big thing in automotive lighting. While currently expensive, LEDs offer several advantages. One of the most important is that they are low-heat producing, as they dont heat up an element in order to produce light. However, there is heat produced from the back of the lamp, requiring complex and expensive heat sinks. That also means that in cold weather, you cant count on an LED headlight to thaw ice or snow off of the headlight like you can with typical halogen or HID setups. Theyre also temperature sensitive, giving different light levels at different ambient temperatures. Despite these engineering challenges, they give reasonable performance with lower energy consumption. The Lexus LS was the first auto to employ LED headlights beginning in 2008, although theyve been used as parking lights, taillights, and turn signals for a while. Will they become the premium headlight technology of the future? Only time will tell. warming up a mazda miata ridelust.com 
Illuminating! A Brief History of the Headlight
For those who dont like HIDs are old farts who cant really use their eyes anymore.
How old is old fart in your book? 30? The HIDs do a great job of illuminating the road for the driver but if that driver doesnt keep the headlights clean, the glare blinds other drivers.
Wonderful write up. It lighted my spirit.
Acetylene lamps were also known as carbide lamps, and had been developed for mining. Gas was produced by dripping water on calcium carbide, which produced the acetylene gas, which was then burnt in the lamp. However, the flame was sooty and the byproduct was caustic lime, a toxic substance that had to be disposed of. An improvement was badly needed
Chevrolet Impala showing quad sealed beam setup.
Thats it! Hope youve enjoyed this quick look into something that most people dont pay much attention to unless theyre burned out, that is.
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Anyone whos worked on an American-market car from 1940 until the early 1990s knows about these guys. Much like a household flood light bulb, these one-piece lights combined the filament, reflector, housing, and lens, meaning that when it burned out, the whole thing needed replacement. They improved reliability somewhat because there was no way foreign matter could find its way into the lamp, possibly causing hot spots and early burnout, but mostly they were a method for the US government to ensure that all cars were using the same government-approved lights. Federal Motor Vehicle Safety Standard 108 required that all cars use a system of two 7 round sealed beam headlight until 1970, when the Feds allowed rectangular headlights to sprout from some lucky vehicle fascias mostly trucks. The big change happened in 1983, when composite headlights were allowed (but not required) to be utilized. It would be a few years before sealed beams would be phased out in almost all applications.
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These could be more accurately called tungsten-halogen bulbs. As mentioned above, early electric headlights used tungsten filaments in a vacuum, which due to the properties of tungsten left the inside of the bulb blackened with residue. It was also not very efficient, needing a lot of power for a small amount of light. Enter then halogen lamp. Halogen is not a gas, its actually a group of gasses like chlorine and iodine. By combining a bit of one of these gasses with an inert filler gas, you can get a tungsten element to burn brighter with less energy whats not to like? Most modern headlights use halogen bulbs.
Domed lens of a projector light visible on a Subaru Impreza.
The U.S. DOT will be pushed by many departments to delay 100% LED adoption so they can continue to use the failures of incan bulbs as a funding stream, methinks.
Very interesting! Thanks for sharing.
LEDs last tens, if not hundreds of times longer than standard bulbs. That is why you will have congress critters dragging their feet or blustering about the shortcomings of LED bulbs as they pocket GEs, Sylvanias, Philips, and others money.
The Corning glass company of Corning, NY, debuted their revolutionary Conaphore headlight in the 1910s. Borrowing a page from lighthouses and other lens-focused light apparatus, the Conaphore was the first modern headlamp (other than an early attempt by Hella to use a lens technology on an acetylene headlight) because it used the lens to direct light from an electric bulb down and out in front of the car, allowing more of the available candlepower to illuminate the road. It was billed as a major safety innovation, eliminating accident-causing glare and increasing headlight range. How effective was it? Its hard to say how it would compare to a modern headlight, but it was leaps and bounds above anything at the time. It was also the direct ancestor of all modern automotive lighting. The folks over at ridelust.com have an excellent read on the history of headlights, worth a visit! 
Lexus LS600, first LED headlight car.