[opendtv] Re: A multifunction DTV tuner and LCD panels lit by LEDs

Jeroen Stessen wrote:

> I was just extrapolating the increase in efficiency
> that has happened over the last few years. We are
> now at a stage that the cost per Watt of electrical
> power is about equal to fluorescent tubes. But the
> lumen per Watt figure is still almost a factor 2
> lower. This figure has made good progress over the
> last years, so if it continues to do so then soon
> the break-even point with fluorescent tubes will be
> reached. The cost per LED (or per Watt) may not go
> down anymore, but we will need fewer LEDs to achieve
> the required light output.

This reminded me of an article I had read not long
ago. Here it is.

Also, in a Popular Photography column, I read where
LEDs are going to be used in photo flash
applications too.

Bert

---------------------------------------------
High beam hopes for LEDs
By Charles Murray , EE Times
August 20, 2004 (4:18 PM EDT)
URL: http://www.eet.com/article/showArticle.jhtml?articleId=3D29116700

Chicago - The venerable filament-type tail- and
headlight bulb - which succeeded candles and oil lamps
as the state of the art for automotive exterior lights
early last century - may finally be garaged in the
next decade, as a new breed of brighter LEDs is
designed in to vehicles.

Two LED suppliers said last week that they are working
on 100-lumen designs that would replace incandescent
bulbs in light assemblies on a one-for-one basis (as
opposed to the diode clusters now required to replace
a single incandescent bulb). And a tier-one supplier
said it is talking to several automakers about
employing LED-based headlights as soon as the 2008
model year.

The bright new LED technology is seen as an alternative
not only to incandescent bulbs but also to the current
crop of tiny LEDs, which must be employed in groups of
as many as 60 to provide sufficient brightness for
rear exterior lights. By offering a higher output, the
new LEDs could migrate from center high-mount stop
lamps to lights, brake lights and turn signals on the
rear of vehicles. LEDs could also, for the first time
ever, begin to serve in headlight assemblies.

"This is a monumental change for the auto industry,"
said Jeff Erion, R&D manager for exterior systems at
Visteon Corp. (Dearborn, Mich.), which recently
demonstrated a working LED-based headlight assembly.

"Since 1914," he said, "there has been only one way to
create light on a car. Now we're looking at a
technology that can replace every filament bulb on the
exterior of every vehicle."

Proponents of the technology say that LEDs are superior
to incandescent bulbs because they respond far faster
(thereby giving neighboring drivers more time and
distance to react to the flash of a brake light or
directional signal), last the life of a vehicle, are
more energy-efficient and better resist vibration.

Suppliers of automotive lighting assemblies, however,
say LEDs must clear some hurdles before achieving
widespread use. "In terms of cost, LEDs and bulbs are
not at all comparable," said Jianz-hong Jiao, general
manager for engineering technology at North American
Lighting Inc. (Framington Hills, Mich.), a subsidiary
of Keito Manufacturing Co. Ltd. of Japan. "It's a
matter of a few cents vs. a few dollars.

"There are also some issues of durability - not in the
LEDs themselves, but in the associated electronic
devices, such as circuit boards. Those still need to
be looked at."

Still, LEDs have been making steady inroads on the
rear exterior of vehicles over the past few years,
particularly for use in center high-mount stop lamps.

Suppliers estimate that between 80 and 90 percent of
the high-mount lamps in current Asian models use LEDs.
Seventy to 80 percent of the high-mounts on European
models and more than 50 percent of those on U.S.-made
vehicles are said to employ LEDs as a light source.

Further, the new breed of brighter products is
expected to take LEDs into rear-vehicle applications,
where they have been used only sparingly up to now.

In stop lamps, for example, LED use over the next few
years is expected to grow far beyond its current
market penetration of about 2 to 3 percent. The same
is expected for turn signals.

"All luxury vehicles in the next two to three years
will have LED signal lamps," predicted Erion of
Visteon.

The key to such success is the availability of
brighter LEDs. At least two suppliers - Lumileds
Lighting (San Jose, Calif.) and Osram Opto
Semiconductors, Inc. (San Jose) - are working on
100-lumen designs that could be employed in
production vehicles as soon as the 2007 model year.
The brighter designs are said to be 10 to 20 times
more powerful than existing products, which
typically range from 1 to 5 lumens in the smallest
devices. Lumileds executives said their company
already markets 30-, 42- and 50-lumen products as
the Luxeon line.

When the 100-lumen products reach the market, a
single such device will reportedly be capable of
replacing dozens of smaller LEDs. In approximately
a decade, suppliers expect vehicles to employ 10
or more of the diodes (six in back, four in front)
on the exterior, ultimately creating an annual
market for at least 160 million exterior LEDs in
the United States alone.

Lumileds engineers say they plan to accomplish all
that by using two key types of semiconductor
materials: indium gallium nitride and aluminum
indium gallium phosphide. AlInGaP, they say, is
the key material for creating red, orange and
amber LEDs, which are mostly employed in the
vehicle's rear exterior. InGaN emits blue light and,
when combined with a phosphor conversion technology,
can be made to produce white light.

"You have to have the best materials, you have to
get the best phosphor and you need to apply the
phosphor in a way that creates a very robust white
emitter, if you want the best optical solution,"
said Leonard Livschitz, director of automotive
business development for Lumileds.

Another key to creating brighter devices, engineers
say, is larger semiconductor dice. "Efficiencies
approaching 100 lumens are realistic as we get to
larger and larger dice," noted Jonathan Wafer,
product-market ing manager for visible LED lamps at
Osram Opto Semiconductor. "To get that kind of
output, you take the big chips and drive them hard,
with currents approaching 1 amp. Then, the
challenge becomes an issue of system thermal
management."

Suppliers claim the higher-power devices are
critical to the LED's success in exterior lighting
applications because they let automakers cope more
with packaging constraints.

"Hypothetically, you can always use LEDs to light
up any function," Livschitz said. "But space is
limited at the rear of the vehicle, so you're
better off with one device that offers higher
power."

For suppliers of automotive LEDs, the holy grail is
the headlight. Most suppliers expect to see the
first all-LED-illuminated vehicle reach the market
within five years.

Copyright 2003 CMP Media
 
 
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