Two years ago,LED headlamps were in demand at motor shows,but xenon high-intensity discharge(HID)lights were brighter,and 99.9%of car buyers still got good old-fashioned halogen bulbs.
Now LED headlamp technology has matured and caught up,although,thanks to banking crisis,almost everyone still gets halogen bulbs.
"There is not a big difference on the street between xenon and LED.LEDs have the same performance as a good xenon system,not just a low-end xenon system,"Dr Wolfgang Pohlmann of German automotive lighting firm Hella told Electronics Weekly.
See also:LED headlights beam beyond premium cars
So why are car makers still using HID in their top models,despite their limited lifespan and the need for high-voltage inverters?
"It is a question of time,LED technology is very new,"he said."Maybe in four to five years we will see more LED headlamps than xenon headlamps."
Halogen and HID lamps are both essentially omni-directional infra-red-cooled point light sources so they can share similar optical designs.LEDs emit light in less than a hemisphere and need cooling from the back,so they needed a complete re-think to fit into even outwardly similar designs.However,the work has been done and car lighting firms have a portfolio to pick from when they get a design brief.
"There are options:to keep the classical system used for bulbs and HID with one light source with a reflector,projector or a lens;or the new option is to have more than one light source:for example the Audi A8 has a couple of projectors and also reflectors,"said Pohlmann:"You don't need one big reflector,you can spread it over several small reflectors."And even though the light comes from LEDs,the laws of physics bring limitations that even the all-powerful automotive stylists have to obey.
