HEAD_LIGHTS

In addition to being a requirement of travelling in the dark, Crystal Clear, glittering headlights are the most prominent component of persona of a contemporary car today. They add looks and emotions to the ride as a headlight can easily make any car look happy, angry or gloomy. People even use to call certain popular models of Honda, Toyota, Mazda, Nissan and Chevrolet as snake, dolphin or cat all due to their facade. Since my childhood, I personally feel attracted most towards cars with the smartest headlights and I wonder how cars would look if they don’t have the headlights.

 Why do all classic cars have round headlights and why do modern cars have more architecturally designed headlines? These question creep to my mind when I was rubbing the wax out of my 2012 Corolla GLI headlights today. Was it style, choice or other techno limitations?

I then also remember my father’s saying, “They are the eyes of my car,” he once uttered these words to me when he was polishing his early Mazda 929 headlights. Indeed, they look like the eyes of a car! But it wasn’t just a styling choice or technological limitation rather it was the law.

The story trace its origin back to 1940 when the motor vehicle administrations of several states in USA came up with the idea of uniform standard of seven inches sealed-beam headlamps for all the vehicles throughout country. These one-piece lights combined the filament, reflector, housing, and lens. They were supposed to improve reliability as the chances of dirt and dead bugs finding its way into the lamp, possibly causing hot spots and early burnout were nearly impossible. The standard was adopted by the government and remained into effect for the next 40 years known as a Federal Motor Vehicle Safety Standard 108. USA being the large market for cars in those days compelled the Japanese and European manufacturers also to adopt the same standard for all their productions.  

  

Later in 1957 a substitute system of four 5¾ inches headlights with two high beams on the inside and two low beams on the outside was allowed for the cars to hit American highways, and in 1974 rectangular sealed beams were also alternated into the law by Vehicles administration authority. As earlier said the European and Japanese cars had to follow the costume this time also. It wasn’t until 1983 when a new era in automotive design began with the grant of architectural freedom to design housings of any shape for a car that could accept a light bulb. 

So far as their dynamics are concerned, it’s interesting to know that the oldest headlamps were fueled by acetylene or oil and were introduced in the late 1880s. Acetylene lamps were popular because the flame was resistant to wind and rain.

The earliest headlight 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 that 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. These 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 grimy and the byproduct was caustic lime, a toxic substance that had to be disposed of. To solve this problem, in 1905 or 1906, the Prest-O-Lite company began making refillable acetylene cylinders which could be mounted to the automobile’s 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 as a standard for another ten to fifteen years until electric lamps became reliable enough to replace them.

 Control and dip systems emerged but the next major changes in automotive headlight technology was not until the sealed beam headlight was introduced in the 1940s. The first electric headlights appeared on an electric car named Columbia. They weren’t inevitably development as they had the fragile tungsten filaments that often broke on the bumpy roads of the time. Soon they were adopted by the gas vehicles. All gasoline-powered vehicles were equipped with dynamos rather than the alternators which tend to produce a very limited amount of electric power. Therefore these headlights were dim and broke easily. They also lack a lens to focus their light. 

Conaphor headlight by The Corning Glass Company in the 1910 are said to be the first modern headlamp. These lamps were equipped with electric bulb and lens. To better utilize the available power, lens functions to direct the light from bulb ahead on the road. They provided better visibilities and increase in driving speed. The innovation was believed to be a major innovation in public safety. It’s probably wouldn’t be wrong here to say that the Canephor are the real ancestor of all modern automotive lighting.

The next innovation was the development of a headlight by Guide Lamp Company in 1915 called dipping light. The light physically moved to change the angle of the beam to direct light down to the road and away from other drivers’ eyes. This reduced the range but also lowered the beam enough to not blind upcoming traffic. The first system 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.

1924 resulted in a progress to dipping light with the innovation of Two-Filament Hi and Low Beams called Bilux System. This system offered the two filaments in the same lamp controlled through an electric switch. The switch that controlled the mechanism merely tends to affects the light’s output (wattage). Unlike earlier dipping light, the Bilux System made the lamp physically stable at same position while dipping the light and the driver hadn’t have to physically move the lamps through hand or liver. This innovation lead to the introduction of dimmer switch, initially a foot-operated one, but eventually the stalk-actuated dimmer that we’re most familiar with today.   

After 50 years of usage of this technology, the Incandescent bulbs also called tungsten-halogen bulbs made their way to the market and became the standard in the headlight technology. It was actually an innovation to the early electric headlights which used tungsten filaments in a vacuum, but the problem with those lamps were that they need lot of power for a small amount of light. Similarly the lamps also happen to turn blackened due to the residue like ordinary home bulbs. In these Incandescent bulbs the combination of group of gasses like chlorine and iodine got a tungsten element to burn brighter with less energy than all its previous ancestors. 

About another 50 years, we have the new Projectile HID and LED Headlight technology. The projector lamps first hit the market in 1986. Use of the first standard projector headlight was on the 1986 BMW 7-Series. In these lamps the bulb was placed in the middle of a reflector. The light is first focused into a convex lens which in turn projects the light out into a very specifically defined outline. In these lights normally very sharp cutoff is done through blocking of the light with an opaque shield. Through this blocking consequently more of the light is focused ahead than the traditional lens lights. Projector headlights can also switch between low and high beam by moving the shield.  Most of these lights are used in expensive rides like Mercedez, Audi and BMWs.

 In contrast to a normal halogen bulb, which simply uses electricity to heat the filament until it is glowing, the most recent revolution in headlight design is the high Intensity Discharge, (HID) or xenon 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 to produce plasma that results in a very intense light. HID lights tend to have a unique color based on the different spectrum of light usually a tingled 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. The worst part of these lights is that any contamination like dust can cause a great deal of glare to be directed up and towards other drivers.

 In 2008 The Lexus LS was the first automobile to show up with Light Emitting diode (LED) headlights.  LED, though expensive, offers numerous advantages. They are low heat producing, as they don’t heat up an element in order to produce light. Unlike HIDs, these lamps are cooler at the front and heat is usually produced at the back of the lamp therefore they need complex and expensive heat sinks at the back. These lights are also temperature sensitive, offering different levels at different ambient temperatures. With LED mounted as a tail, turning and parking lights even in economical cars, it apparently seems that due to their reasonable performance and lower energy consumption LED would be the premium headlight technology of future.

However on contrary to such expansion in technology, it’s surprising to know that Incandescent even today are the world most successful source of lightning the roads in front of automotives. Moreover cost, simplicity of production and after market replacement, as well as the growing intention to use of Hybrid technology for the cars to fight energy crises, makes the tungsten-halogen bulbs real competitor of LED and HID as it still produce the light at a greatly reduced electric cost. But, if the history repeats itself, I don’t think we will be around anything near when the next generation of headlight technology will be introduced.