The history of automotive headlights is pretty interesting. Considering that automobiles have been in existence for well over 100 years, its not surprising that some amazing change has occurred in illumination technology. Join me while I explore how the automotive headlight evolved all the way from primitive gas lanterns into the high-tech illumination devices we have today.
Acetylene Lamps - 1880s
The earliest headlight technology was a gas lantern with a reflecting mirror. The light beam was fairly unfocused and this combined with the low-candlepower light sources of the time meant that they were a poor means of illumination. The fuel was usually oil or acetylene gas. Acetylene lamps were also known as carbide lamps which had been originally developed for mining many years before.
Early Electric Lights – 1890s
The first electric headlights debuted on an electrically-powered car, an 1898 Columbia. Unfortunately, they weren't immediately an improvement. They had weak tungsten filaments that often broke on rough roads. Plus, the gasoline-powered vehicles in the early part of the century used dynamos which produced a lot less electricity than alternators do today. The bottom line is that these headlights were dim, and broke easily.
Lens-Focused Headlights - 1910s
The Corning glass company of Corning, NY, debuted their revolutionary Conaphore headlight in the 1910s. The Conaphore was the first modern headlamp because it used a Conaphore lens to direct electric light bulb into a projecting "cone". It was billed as a major safety innovation at the time.
Hi/Low Beams: late 1910s
The next innovation was a "dipping light" – a headlight that was physically moved to point the angle of the beam downwards. The first system, developed by the Guide Lamp Company in 1915, required the driver to 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.
Two-Filament Hi/Low Beams: 1920s
The two-filament system represented the hi/low beam setup that we know today: two filaments in the same lamp. This lead to the foot-operated highbeam switch but eventually the stalk-actuated switch that we're most familiar with today.
Sealed Beam: 1940s to 1980s
Anyone who's worked on an American-market car from 1940 until the early 1990s knows these guys. Much like a household flood light, these one-piece lights combined the filament, reflector, housing, and lens all into one unit. It was a brilliant idea, meaning that when it burned out, the whole thing needed replacement. This allowed the government to get involved also. 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 be used.
Composite Headlights: 1983-Present
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 replace the bulb – the housing, lens, and reflectors were all permanent. This allowed all sorts of unique front end designs to promulgate, and became the standard headlight type that you're probably most familiar with.
Halogen Bulbs – 1990s
These could be more accurately called tungsten-halogen bulbs. Halogen is technically not a gas, it's 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. Most modern headlights use halogen bulbs.
High-Intensity Discharge (HID) Lights
The most recent revolution in headlight technology is the HID, 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 produces a plasma that emits a very intense light. HID lights tend to have a unique color based on the different spectrum of light emitted by this different process; usually, it's tinged blue.
Light-emitting diodes (LEDS) are the big thing in automotive lighting now. Today they are commonly used on parking lights, taillights, and turn signals however they are starting to be put into headlights. One of the most important advantages that LEDS offer is that they are low-heat producing and are thus very efficient. However in cold weather, you can't count on an LED headlight to thaw ice or snow off of the headlight like you can with typical halogen or HID setups. Will they become the premium headlight technology of the future? Only time will tell.
Source: Akins Ford