Current European regulations banning mercury in automobiles excludes High Intensity Discharge (HID) headlamps whereas some state environmental laws in the US are moving to ban mercury completely. Manufacturers increasingly are becoming responsible for the disposition of their products at end of life. What does this mean for automotive HID headlamps?
We will review the role of mercury in automotive HIDs and the economic and performance effects on its removal. Performance shortcomings - lower voltage, lower lumens, shorter life and a more difficult arc to image - can be remedied to an extent and at a price. We will also examine the evolution of mercury free automotive HID lamps by the use of voltage enhancers to arc restricting chemistries and geometry variations. We will comment on the embodiments currently in the regulatory process and the potential for improvements in HID mercury free automotive headlamps.