Issue 11.01 - January 2003

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Why LEDs Are Everywhere

Good-bye, little red diode. Hello, spotlights!

		START
		The New Electric Company
		signal : noise
		The Outlook Killer?
		Duck! It's a Low-Flying Gigaplane
		But Can It Run Doom?
		The Next Plastic Revolution
		The Rocketeer
		Why LEDs Are Everywhere
		Light It Up
		Poison Is Your Friend
		jargon watch
		Hey, Mr. Mugger - It's for You
		Fighting for Copy Rights
		Wired | Tired | Expired

Gas, glass, and brass are so pre-millennium. LEDs are the lights of the digital age - and they're everywhere. Those bright new dotted traffic signals? Energy-efficient light-emitting diodes in green, yellow, and red. LEDs are also showing up on bicycles, buses, and subway cars, and in a variety of architectural lighting situations - for example, to throw a color wash onto a wall. In a few years, they'll illuminate automobile headlights, homes, and offices, too. Here's why.

They're Colorful

LEDs have come a long way since the red-only glow of early Texas Instruments calculator. Today, the lights range from far infrared to near ultraviolet. The most advanced way to mix them: pulse-width modulation, which varies each diode's duty cycle. Boston-based Color Kinetics has a patent on this technique, which is the basis for its color-changing floodlights, spotlights, and night-lights.

They're Bright

During the past four decades, output per LED has increased an average of 40 percent a year, while prices have dropped 20 percent annually. Still, today's white LEDs can produce only 130 lumens each, so it takes nine to equal the 1,100 lumens put out by a standard 75-watt incandescent bulb. Yet, because they focus all of their light in the same direction, those nine LEDs actually appear much brighter - roughly the same as a typical 300-watt bulb.

They're White

White light can be made two ways - by mixing reds, greens, and blues, or by using an ultraviolet LED to stimulate a white phosphor (the same stuff that's inside a fluorescent bulb). Combine a white phosphor LED with a few amber ones, and you can create a range of different whites - from the romantic glow of a candle flame to the hot, bright light of the sun.

They're Green

LEDs consume a fraction of the power of incandescents. For example, LED flashlights squeeze as much life out of 1 battery as incandescents get from 20. The result: less toxic trash. LEDs also throw off almost no heat and last longer.

They're Cheap

Each has a lifespan of 50,000 to 100,000 hours - 10 to 30 years. This can mean huge savings in atriums, auditoriums, and high-ceilinged offices, where replacing a bulb can cost more than the bulb itself. A single 700-lumen LED panel runs about $1,000, but the lifetime price tag is lower than incandescent and almost on par with halogen (see "Light It Up). Predictions are that by 2006, they'll be cheaper than even supercheap fluorescents.

- Simson Garfinkel

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