DETROIT - Although excessive glare from high-intensity discharge (HID) headlamps remains a point of regulatory debate in the U.S., a new lighting technology soon will be in production that could prove equally controversial.
A number of production vehicles - mostly in the luxury sector - already feature light-emitting diode (LED) taillamps and center high-mounted taillights. But by 2008, the first primary forward-lighting applications should be in production, using LEDs as the light source.
Hella KGaA Hueck & Co., a leading German automotive lighting supplier, says its prototype LED headlamp achieves illumination levels of 1,000 lumens, comparable with the light output of an HID xenon headlamp.
Hella says the LED system should be in production by 2008, although the company admits it does not yet have a signed contract.
Visteon supplied LED headlamps and fog lamps for Cadillac STS Technology Integration Vehicle.
Will consumers react to LED headlamps by complaining they are too bright? “It could be an issue,” says Michael Hamm, who heads research and development at Automotive Lighting Reutlingen GmbH, a German lighting supplier.
Hamm says the mere presence of an unusual light source on a new car or truck is bound to excite certain motorists, even if the light source, itself, is not offensive or excessively bright.
“If a light looks different, you tend to look to it,” Hamm tells Ward's following a lighting-technology session at this week's Society of Automotive Engineers World Congress here.
The heavily attended technology session lasted four hours and was dedicated entirely to the subject of LED lighting for automotive applications.
The session included presentations from major lighting suppliers, including Automotive Lighting, North American Lighting Inc., Hella, Osram Sylvania Automotive Lighting and Philips Electronics.
Based on the presentations, LEDs likely will appear in a growing number of new cars and trucks. First, however, government regulations allowing them for forward lighting need to be adopted.
The SAE next week will host a meeting in Arizona at which standards for LED lighting (and other automotive components) will be discussed, Mike Tucker, engineering manager-applications for Osram Sylvania, says.
Tucker doubts the SAE leadership will adopt an LED performance standard at the meeting, but he expects several significant issues to be discussed, including ownership of the technology for automotive applications.
There are three parties in the supply chain, and all claim a degree of ownership: the producer of the LED light source, the assembler of the headlight module and the auto maker.
Osram Sylvania officials say the U.S. National Highway Traffic Safety Admin. likely will adopt a standard for forward LED lighting before European authorities do so.
Hella hosted a media event earlier this year near its Lippstadt, Germany, headquarters, at which journalists participated in an evening drive in an Audi A8 equipped with prototype LED headlamps.
Each lamp contained four LEDs and consumed 5 watts of power. Hella officials say by 2008, its headlamps could function with as few as two LEDs and consume as little as 3 watts of power.
The lighting in the A8 prototype was crisp and white on the wet, snowy night, and the range of illumination was far superior to conventional halogen lamps and competitive with HID xenon lamps.
Lane markers and reflective signs appeared surprisingly bright - as if they were plugged in - when illuminated with the LED lamps, even from a distance of 100 yds. (91 m).
Hella already produces LED daytime running lamps for the Audi A8 W12, as well as LED rear-combination lamps for the VW Golf Plus.
The company's first production LED headlamp likely will use seven diodes - four for the low beam and three for the high beam, plus several more diodes for the symmetrical and asymmetrical portions of the low beam, Karsten Eichhorn, Hella's head of Corporate Research Optics, says.
Osram Sylvania urges auto industry to adopt standardized design for automotive LEDs, like this one above.
LEDs are finding favor in the auto industry for several reasons: They are extremely bright and robust and should work throughout the life of the vehicle. An LED's operational lifecycle is estimated at some 10,000 hours, compared with 500-1,000 hours for a conventional halogen bulb and 3,000 hours for an HID headlamp, Hamm says.
They are extremely small and lightweight and easily packaged when compared with a bulky halogen lamp. Because they are so robust, access would not be necessary from the backside of the light housing. With today's lamps, a hole in the rear of the housing allows the larger halogen bulbs to be replaced.
Plus, adaptive front-lighting systems that “bend” as a vehicle turns are even easier with LEDs than with halogen or xenon lamps.
With LEDs, the bending sensation can be achieved by merely illuminating certain diodes in the array, based on steering inputs. The bending is done electrically, eliminating the need for mechanical components to move the headlight housing.
Because of their size, designers also could be creative in shaping the diodes for stylistic or dramatic effect. A Hella prototype on a VW Golf has the diodes arrayed like a honeycomb, or the cylinder of a revolver without the bullets.
Visteon Corp. supplied the LED headlamps and foglamps that are drawing significant interest on the Cadillac STS Technology Integration Vehicle on display at SAE this week.
General Motors Corp. produced the car, which sports 50 innovative technologies developed in-house and with suppliers, to celebrate SAE's 100th birthday. (See related story: GM Celebrates SAE Anniversary with Tech Car)
LED headlamps will be expensive, at least in their initial applications. Hamm and other sources estimate they will be nearly twice as costly as HID headlamps and several times more expensive than halogen headlamps at first. However, prices should come down when higher volumes are achieved.
Hamm says the rollout for LED in forward lighting will take several years. Daytime running lamps, position lamps and side markers already use LEDs in a limited number of applications.
In 2006 or 2007, LED turn signals likely will debut, and headlamps and foglamps should arrive the following year, Hamm says.
There are industry drawbacks. LED headlamps will significantly cut into aftermarket sales for lighting suppliers because they need not be replaced, except in accidents.
Plus, LEDs emit no thermal radiation, which means they do not project heat forward onto the lens. Snow and ice, which do not accumulate on halogen lights because of their high temperatures, could be a significant problem for LED headlamps.
In its presentation, Osram Sylvania urges the industry to adopt a standardized design for automotive LEDs. With defined interfaces, the light source could be flexible enough to be interchangeable, regardless of the manufacturer, the supplier says.
Meanwhile, Osram Sylvania in June will begin producing in the U.S. a standardized LED for a taillamp for a new vehicle, Tucker says. The module uses eight red LEDs that provide braking, turn signal and taillamp functions.
