The Bihalogen Projector – Chances and Challenges 2009-01-0338
For HID light sources bifunctional projectors for low and high beam are state of the art. In the last years the idea was carried over to halogen light sources and the first halogen projectors combining low and high beam are available now. The bihalogen projectors use just one single filament for both lighting functions.
Thus they offer lower power consumption and a spare of raw material, saving space in the headlamps for new lighting functions, for example DRL. Being compatible in construction volume and fixing points, the bihalogen projector is also interchangeable with other HID projectors.
But nevertheless, bihalogen has some challenges too: An efficient design of the system is needed, due to the limited available luminous flux of its halogen light source.
The performance of the projector, depending on the possibilities of the chosen halogen light source, has to offer satisfactory values, especially the maximum illuminance in the high beam and other critical minimum values.
Summing up all these points, it becomes clear that the optical design of an useable bihalogen projector is really sophisticated.