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LEDs shine in solid-state lighting

Posted: 17 Mar 2008 ?? ?Print Version ?Bookmark and Share

Keywords:LED? solid-state lighting? illumination market?

The use of LEDs for solid-state lighting, rather than as indicators, is poised to make inroads in applications in the automotive, architectural and general illumination markets, according to market analysis firm Yole Developpement.

But for the growth to pan out, particularly in the general illumination market, there is still technical work to be accomplished. Although LEDs are prized for their energy efficiency, a great deal of color performance and design and cost optimization remains to be done, and semiconductor companies need to keep improving manufacturing processes.

Billion-dollar potential
Yole projects a market size for all types of LEDs of $10.3 billion by 2012. High- and ultrahigh-brightness LEDs, combined, will be responsible for about $4.45 billion of that totalalmost 5.5 times the $783 million market size, based on packaged LEDs, estimated for 2007.

With such a large part of the growth driven by bright-LED varieties, the two key criteria for the new market segments are luminous efficacy in lumens per watt and cost efficiency in dollars per lumen.

Manufacturing advances
Until now, LED manufacturers have focused on light efficiency and light output, said a spokesman for Philips Lumileds. "They are critical, but only two parts of the system," he said.

Upcoming issues to address include thermal management, drive electronics and consistency, and range of color temperature. Resolving them will require manufacturing advances in optics, packaging, testing and binning.

Positioning light
LED-based lighting systems are often seen as an alternative to incandescent, halogen and fluorescent lights. The technology's lack of mercury and low power consumption are obvious pluses.

However, LEDs are still an emerging technology in this segment. "It is a misconception that LEDs will take the place of the bulb for general lighting," said Tom Pearsall, general secretary of the European Photonics Industry Consortium.

"The risk of promoting LEDs before they have reached a level of efficacy at least as good as the compact fluorescent bulb is that early adopters will be disappointed," said Rainer Beccard, director of marketing at Aixtron AG, a German supplier of manufacturing equipment for the compound semiconductors used to make LEDs.

Nonetheless, "LEDs have a niche market opportunityliterally and figuratively," said Pearsall. "They can be used for lighting up shelf space or counter nooks, or the insides of drawers in a kitchen, for example."

Zumtobel's Tempura LED spotlight is a 442 unit that emits 1,000 lumens of projected light, equivalent to a 100W halogen's output.
Click to view full image)

Emerging niches for solid-state lighting technology include the illumination of architectural elementsa staircase, for instanceas well as less glamorous but no less technology-appropriate applications such as refrigerated display units.

New concepts needed
Pearsall went on to add an important condition to growth in general illumination: "Until I see manufacturers coming out with a new concept for lighting and not producing LED lamps that are shaped for and fit into fixtures suitable for incandescent bulbs, then even that niche market will remain unexploited."

For Pearsall, moving away from the glass envelope of the incandescent bulb should be a liberating experience. In other words, it is not a matter of designing products that enable swapping out an old incandescent bulb for an LED-based one. Such thinking leads to strange-looking creations, such as bulb-shaped LED lights encrusted with bulky heat sinks.

Even in the higher end of the lighting market, industrial designers still have to go to some lengths to draw heat away from drivers and semiconductor components so that longevity and peak performance are maintained.

Needed, said Pearsall, is a "revolution in lighting design" that takes advantage of the unique properties of LEDs, such as their ability to support digital color control, light shaping, and rapid and frequent on/off switching, as well as their excellence as a point-source light.

- Valerie Thompson
EE Times

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