LED Headlights Find Their Way to High-End Automobiles ...

LED Headlights Find Their Way to High-End Automobiles

"Audi and Lexus get jiggy wit LEDs

While LED taillight technology has found its way into a wide range of sedans, wagons, sports cars and SUVs/crossovers, LED headlights are just now starting to find their way into the automotive sector. When used in taillights, LEDs provide better packaging efficiency, faster response times and longer life than traditional bulbs. More efficient packaging with LED technology also allows designers greater liberty in creating unique headlight designs for vehicles."
http://www.dailytech.com/article.aspx?newsid=4713

More information on issues with automotive LED headlights:

http://www.electronicsweekly.com/Articles/2005/03/22/34737/Full+beam+ahead+for+LED+headlights.htm

I guess I am a dinosaur, but I am not a fan of LED automotive lighting. My biggest concern up here in snow country is that LED lamps generate very little heat. Thus they do not melt falling snow that may accumulate on lenses as snow or ice during driving, nor do they melt snow that lazy drivers refuse to clean off. While I recognize that LED headlamps may generate heat, we all know that heat is detrimental to LED longevity, so there will be design changes to eliminate that heat. As someone who has been employed in the automotive field all of his life and who is also involved in public safety, the benefits of LED lighting (Quicker response time for example) do not outweigh this one huge negative factor. This is one "improvement" that I am not yet sold on.

GreySave: The incan concept contains the heat in the bulb to have a real white-glowing filament while the LED concept dissipates the heat so that the die stays as cool as possible. The LED solution is actually warmer on the outside.

I'm rather concerned abt the spectral quality of the LED light. Incan much better lights up dark objects like a fallen tree or an animal.

Incandescent and HID headlights both project most of their heat outward. This gives you the auto-defrosting effect and keeps the housing itself cooler as well. There are also two sides to the heat problem with LEDs: the accumulated heat is detrimental to efficiency and maintenance, and variations in climate would result in starkly different levels of output. Any present means of overcoming these challenges is going to mean increasing the complexity of the system (e.g., active temperature control), which isn't particularly desirable for the manufacturer unless significant gains can be had. Currently, HID is the most viable all around, with durability being the only real improvement current LED technology can boast (IMHO).

My main concern is that it seems from my experience led traffic lights arent as visible as regular bulb ones in fog and rain. I and a few other folks have noticed this on 460 where a few traffic lights are mixed, bulb and leds and the bulb ones show up a few seconds before the led ones when approaching so you have notice to let off the gas and let it roll down to a stop vs using the brakes. I just dont buy into racing to a stop light or using more brake than necessary if I have more notice.

I just hope they are more efficient. Seems to me, maybe I am wrong, but once you get leds hooked up, positions and sinked for heat dispursation, they draw about as much or more than the regular bulb they replaced. Sure more run time and lack for need to replace, but I dont think bulbs fail that often in most cars.

The thermal issues for LEDs can be handled easily enough. At highway speeds you have virtually unlimited forced-air cooling that can be deployed. At rest it would not be difficult to devise some additional forced-air or even liquid cooling.

As for defrosting windows, strip heaters can be deployed across the windows if necessary. The small size of individual LED headlamp elements will probably lend itself favorably to small glass windows, so no worries about melting plastic. You could also duct air from the LEDs' own heatsinks...

The automakers can devise near-immediate economies of scale when they feel the need and things that were previously expensive become surprisingly inexpensive.

I'm still not sure that the time is right for LED headlamps. Color rendition is a signifigant concern with blue die + yellow phosphor LEDs. I'd rather see wider adoption of HID headlights than LED, and even those have spectrum issues.

I believe there's a limit to the size (smallness) of a headlight. If the light exit area is too small, the beam is more vulnerable to dirt on the lens and the light is more disturbing to others. Consequently, very small headlights are not desireable.

All LED headlight conceps thus far use big arrays of LEDs - typically a few dozen per side. The combined surface area of the windows for the array is comparable to a conventional headlight.