Term of the Moment
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Definition: LED
(Light Emitting Diode) A display and lighting technology used in almost every electrical and electronic product on the market, from a tiny on/off light to digital readouts, flashlights, traffic lights and perimeter lighting. LEDs are also used as the light source in multimode fibers, optical mice and laser-class printers. See LED bulb.
LEDs vs. LCDs
In the early 1970s, red LEDs were used in the first digital watches, but were superseded by lower-power LCDs within a few years. LEDs still use more power than LCDs, but less power than incandescent bulbs. They also last for decades and are virtually indestructible.
Several Colors
LEDs are semiconductor diodes that typically emit a single wavelength of light when charged with electricity. Originally red, today, several colors can be generated based on the material used for the tips of the probes. Aluminum indium gallium phosphide (AlInGaP) is used for red and yellow. Indium gallium nitride (InGaN) is used for green and blue, and with the addition of phosphor, for white light as well. See digital billboard, OLED, IRED, LED printer, fiber optics glossary and Nixie tube.
An LED Unit
LEDs and LCDs Are Used Together
First LED Watch
LEDs Offer Flexibility
LEDs vs. LCDs
In the early 1970s, red LEDs were used in the first digital watches, but were superseded by lower-power LCDs within a few years. LEDs still use more power than LCDs, but less power than incandescent bulbs. They also last for decades and are virtually indestructible.
Several Colors
LEDs are semiconductor diodes that typically emit a single wavelength of light when charged with electricity. Originally red, today, several colors can be generated based on the material used for the tips of the probes. Aluminum indium gallium phosphide (AlInGaP) is used for red and yellow. Indium gallium nitride (InGaN) is used for green and blue, and with the addition of phosphor, for white light as well. See digital billboard, OLED, IRED, LED printer, fiber optics glossary and Nixie tube.
The LED is the semiconductor die, which sits in a reflective cup that is also a heat sink. Voltage is applied to the LED, and electrons and holes in the two semiconductor layers are attracted to each other at the junction. When they combine, photons are created.
Small alphanumeric readouts can be LED or LCD, but the indicator lights on countless products are LEDs.
The Synchronar 2100 was the first LED watch and the first solar powered watch. It preceded Hamilton's famous Pulsar LED watch in 1970. (Image courtesy of the private collection of Peter Wenzig.)
A flick of a switch changes the ambience in this Los Angeles bedroom (top), while the Westin Hotel staircase in Shanghai (bottom) cycles colors or becomes a musical light show. (Images courtesy of Color Kinetics, Inc., Bedroom design and photo by Steven Cordrey. Staircase by Light Directions Hong Kong, photo by Friendly Light.)