What is LED?
LED (light-emitting diode) is lighting source of new generation now. In early 1960s, LED was introduced as a practical electronic component.. After over 40 years, LED become one of main lighting sources.
LED differs from traditional light sources. There are no glass bulbs or filaments to break, or electrodes to decay. So, we also call LED as solid state light. Basically, it's a chemical chip embedded in a plastic capsule. When chips are energized by applying a voltage, LED emits visible light. Because chip's chemical composition is different, color of visible light is different.. The light can then be focused, routed, or scattered using lenses, waveguides or diffusers. LED runs on direct current, so in most of time they must be operated with a transformer (LED Driver).
LED is one kind of diode. It consists of a chip of semiconducting material doped with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers-electrons and holes-flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon. The color of the light depends on the band gap energy of the materials forming the p-n junction.
At first, LED were used as replacements for incandescent and neon indicator lamps. Then, it was used in displays. When LED become more and more powerful, LED was used for lighting. Because of energy saving, eco-friendly and long lifespan, LED become more and more popular.
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