Part of the reason is that individual LEDs are typically quite small; the surface area of the semiconductor material that emits light is only about one square millimeter. As a consequence, a bright LED, of the kind found in a flashlight, might produce 80 lumens (a lumen is a standard measure of how powerful a light source appears). A 100-watt incandescent bulb, in contrast, typically emits about 1,500 lumens. To approach this level of brightness, lighting manufacturers have arranged LEDs in arrays, which is a bulky solution at best. Some have made individual small LEDs as bright as 1,000 lumens, but these are expensive and still function best as spotlights, not as area lighting for a room.
Now Luminus Devices hopes to break into the general lighting realm with its LED PhlatLight. Derived from research the firm’s founders did at MIT, the PhlatLight is a much bigger LED, with a light-emitting area of 12 square millimeters. A single such LED can generate up to 3,300 lumens. PhlatLights have already been used to backlight large LCD screens, replacing the necessary thousands of LEDs with a few dozen.
For room lighting, a PhlatLight would be placed at the end of a plastic tube similar to those used for fluorescent fixtures. Light from the LED would spread out along the tube, illuminating a wide area. Luminus Devices hopes to have affordable versions of such lighting on the market within a few years.
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