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For headlamps whose low beam function is equipped with High Intensity Discharge (HID) technology, a high beam counterpart of equal lighting performance is presented which fits in the constructional space available in modern cars. The new Bifunction HID system allows the use of HID technology for both low and high beam in the same reflector, utilizing the same bulb and electronic control unit. Bifunction HID technology on the basis of reflection as well as projection type systems will be presented in this paper. An overview of the regulation guidelines for world wide application of this new technology is given. The main aspects of the switching mechanisms and their effects on the light distributions are discussed and compared.

For some years now the new HID technology has been used for headlamp systems to improve safety and comfort during night time driving. A new generation of projector type headlamps starts series production in 1997. The characteristics of the HID bulb and the specific requirements of the light distribution make it necessary to calculate special optical systems to control the high amount of light. There are different possible design strategies. On one hand, it is possible to improve the light pattern, e.g. increase the luminous flux and the range. On the other hand it is possible to build a system with extremely small dimensions. Such a system ensures an excellent light quality even in smallest headlamps and gives way to new styling possibilities. To match such different targets, some parameters of the reflector and the lens have to be optimized. Some examples of projection headlamps which are designed for different applications will be discussed.