AD: What are some of the advantages of LEDs over incandescent, fluorescent or halogen bulbs?
WR: Because of their long life, LEDs don't need to be replaced as often as other lightbulbs, if ever. Also, because they are either flat or tiny, LEDs allow you to sneak light into places where lightbulbs can't go. For instance, in car design, they could be embedded in mirrors to serve as turn signals or go behind the front seats, so that backseat passengers could read without distracting the driver.
LEDs also turn on much more quickly than typical lights, because there's almost no delay in light emission once you power them up. Incandescent bulbs take time to warm up before light is emitted. So, for instance, if LEDs are used in brake lights, and the guy in front of you stops suddenly, you would see it sooner.
Another feature of LEDs is that the colder they get, the brighter they get, making them good for innovations in refrigerator lighting. And because the front of an LED doesn't emit heat, just light, you could conceivably light every shelf in your refrigerator and have better visibility.
AD: What other applications may we see in the short term and in the future?
WR: In the next three to five years, I think we'll see LEDs in more general lighting applications, such as the interiors and exteriors of cars. By 2010, I expect LED programmability will be integrated into new building construction. LEDs would be more easily controlled via computers hooked to a building's lighting system, which isn't possible with incandescent or fluorescent bulbs.
For example, right now there is wasted energy on the far side of my office, which is as bright as the light over my desk. But if I wore a little mobile tracking device that could tell the building's computer system where I was, the lighting system could adjust lighting levels according to my needs. When I'm at the desk, the lights could be brighter there than by the conference table. This would potentially save energy, because the light in unused parts of the office would be dimmed 50 percent automatically. If every office did that, a fair amount of energy would be saved.
AD: As they evolve further, could LEDs brighten parts of our homes?
WR: Yes. So far, we've talked mostly about inorganic LEDs, which have been around awhile. But another, less mature, form of LED â€” known as organic LEDs, or OLEDs â€” is potentially much less expensive to manufacture because it is made of flexible plastic and can be produced in sheets by the mile instead of in small batches, like inorganic LEDs. The potential cost reduction might translate into broader market penetration or more diverse applications.
Because their light output is relatively low, these OLEDs will most likely be used for area lights and general decorative applications, as opposed to general lighting, which is far more intense. As OLEDs permeate the lighting industry during the next 10 years, we could see a coffee table with a glowing surface.
AD: How big is the market for LEDs?
WR: Depending on whose numbers you look at, the lighting market globally is $40 billion. In the U.S., the lightbulb market is $3 billion to $4 billion. If all goes as planned, by 2012, LEDs could make up 25 percent of the market for fluorescent lighting â€” that's the Department of Energy's target. But the long-term future market for LEDs is likely to be even larger, as new and creative applications continue to emerge.
WILLIAM T. RYAN
Imagine you're driving down a crowded highway during peak traffic. You squint as the glare of the setting sun makes the lanes blur. Wouldn't it help if beams of light pierced the haze and illuminated the lanes, so you could find your way more easily?
That's just one of the applications that may soon be possible with advanced light-emitting diode (LED) technology. LEDs are semiconducting chips made of chemicals and gases that produce light when a current passes through them. Among their advantages is that they consume less energy than regular incandescent or fluorescent lightbulbs. They last up to 10 times as long, typically 10 to 15 years, and tend to fade gradually rather than suddenly flickering out.
While it may sound like New Age technology, LED circuitry has been part of our lives since the 1960s, when it first appeared in the indicator lights of stereo systems. Since then, LEDs have glowed from computer screens and cell phone displays. They illuminate one-third of traffic lights and 80 percent of all new exit signs.
Recent advances have increased LEDs' light output, their range of colors and the variety of physical forms they can take, paving the way for wider applications. â€œWe're going to see an evolution of lighting that's different from anything we've ever experienced before,â€? says William T. Ryan, group product manager for LEDs for Philips Lighting in Somerset, N.J. American Demographics' Sandra Yin recently asked him to shed some light on LEDs.