Halogen was a breakthrough. Because the greatest effort in the field of electric vehicle lighting (up to 1970) has always been invested in an increase in reliability and an extension of the service life. And once 45 Watt light bulbs were already quite a few…
Halogen was revolutionary
Until the introduction of the halogen lamp, the light efficiency had not increased spectacularly; the halogen lamp increased the efficiency considerably, often halogen 100 delivered more light than conventional incandescent lamps.
General Electric had invested heavily in halogen gas lighting in the early years of 40. The resulting high temperatures were a difficult point to overcome. GE did its search in the field of headlight technology based on the then incandescent lamp technology.
Those investments started to generate a lot of money in the 50 years. But the "US Department of Transportation" did not allow this lamp on the US market due to the risk of blinding. After all, more and more cars were coming onto the road, so all that light was found to be dangerous. Despite the fact that American car manufacturers had already devised very smart light sensors that dim their own light when approaching another vehicle with lighting.
Success through European legislation
In 1957, Europe switched to standardizing the asymmetrical low beam. This made it possible to increase the power of the headlight illumination without increasing the glare of the oncoming car. When the series production of high-quality halogen lamps got off to a good start, no complete headlights were produced yet. Only bright lights and fog lights were made. Hella pioneered with fog lamps that were mounted on the front bumper. Those lamps became real status symbols.
One of the problems that initially prevented the development of a headlamp with integrated low beam and high beam in the 1960s was that it was difficult to make the halogen equivalent of the conventional duplicate lamp. The biggest problem was the halogen cycle process of the double-filament lamp that was not stable due to the 2 filaments. Philips has solved this problem in 1965. Then the road was clear for the further development of halogen headlights.
The start of the success
After a somewhat slow start, the success of the halogen lamp in the 70 years became ever greater. For example, the H4 lamp had a light output that was higher for high and low beam 100 than that of the conventional double lamp. In 1978 in Germany, 50% of the new cars were already equipped with H4 lamps. This was often standard for the luxury cars, while halogen lighting was often optional for the somewhat cheaper cars. After the introduction of the H4 lamp, virtually no new lamp types have been developed, the main focus was on improving the existing lamp types. Only when the H7 lamp was introduced, in 1993, it seems that the development of new H lamps got a boost again and soon afterwards the H8, H9 and H11 entered the market. These are all lamps with a single filament.
And dated again
And in the meantime, those once revolutionary halogen lamps have once again passed. Current body types require smaller lighting units. In order to get sufficient light from those units, the possibilities of the halogen lamps must be stretched so far that the operating temperature becomes approximately the melting temperature of the tungsten filaments.