LEDs are taking over a growing percentage of the automotive marketplace, helping conserve power and improve reliability. Though interior lighting and rear exterior lighting are slowly shifting to LEDs, headlights aren't expected to move into high volume production this decade.
Auto designers have many reasons for shifting to LEDs. Warranty providers like the low power consumption and long lifetimes, while stylists like the small size. Designers have still more reasons for using solid-state technology in applications such as brake lights. "LEDs have higher output; we can come up with simpler electronics and provide an extremely well functioning lamp that gives increased safety, responding 200 msec faster than a bulb," says Mahendra Dassanayake, staff technical specialist at Ford Motor Co. (www.ford.com).
Such response is why high center-mounted brake lights are the leading exterior application for LEDs, with taillights being used in a growing number of vehicles. LEDs have taken over the colored portion of interior lighting, leading some vendors to predict that bulbs used in colored roles like display panels will disappear before the end of the decade.
The change is being fueled by manufacturers who continue to come up with new materials that improve brightness and broaden the available color spectrum. "Indium gallium nitride increases light output by five to 10 times, and if you etch in phosphorous you can get white light," says P.C. Yong, product director at San Jose, CA-based Fairchild Semiconductor (www.fairchildsemi.com).
|
Bright Smile: Ford's Model U concept car
uses white LEDs, which are expected on 2010 vehicles.
|
White light has been the holy grail for LEDs ever since the early 1960s, according to Nick Holonyak, who invented the LED in 1962. "In 1963, I told a Reader's Digest reporter that LEDs would eventually replace light bulbs," says Holonyak, now a professor at the University of Illinois at Champaign (www.ece.uiuc.edu).
Though many concept cars have LED headlights, most observers don't expect to see them on a production vehicle until around 2010. "They're several times more expensive than bulbs," says Ken Hall, director of advanced technologies at Johnson Controls (www.jci.com).
That obstacle is particularly acute in white lights. White LEDs are quite new and often cost hundreds of times more than an incandescent bulb. Light output isn't bright enough for headlights, and a bluish hue isn't suitable for many interior applications, where warmer, more natural yellow tones are more desirable.
|
Backlit: indirect reflecting LED
tail-lights are the Ford GT supercar.
|
But there are applications such as backlit gauges that use white LEDs. "There are customers willing to pay a premium for white LEDs," says Mark Brainard, business development manager at Siemens VDO Automotive Corp. (www.siemensvdo.com).
LEDs will also make it simpler to implement the newest thing in headlights—adaptive forward lighting. Luxury cars are now offering what's also called bend lighting, turning headlights in response to steering wheel movements, casting light to the area the car is headed. That can be done inexpensively by lighting different banks of LEDs.
Tweet This
0 
