LED (Light Emitting Diode) is a solid-state semiconductor device that converts electrical energy into visible light, which can be directly converted into light.
The heart of the LED is a semiconductor chip, one end of which is connected to the bracket, one end is a cathode, and the other end is connected to the cathode of the power supply. The entire wafer is encapsulated by epoxy resin.
A semiconductor wafer consists of two parts, some of which are P-type semiconductors, in which holes dominate, the other end is an n-type semiconductor, and this side is mainly electrons. But when two semiconductors are connected, they form a p-n junction.
When the current reaches the chip through the wire, electrons are pushed into the P area, the electrons in the P area combine with holes, and then the energy is emitted in the form of photons. This is the principle of LED light emission.
The wavelength of light and the color of light are determined by the materials that make up the p-n junction.
The first led as the indicator light source of the instrument, and later various light color leds have been widely used in traffic lights and large-area display screens, resulting in very good economic and social benefits.
Take the 12-inch red traffic light as an example. It was originally used as a light source in the United States. The 140-watt incandescent lamp has a long life, low-light effect and produces 2000 lumens of white.
After passing through the red filter, the light loss is 90%, leaving only 200 lumens of red. In the newly designed lamps, Lumileds uses 18 red LED light sources, including circuit losses, the total consumption is 14 watts, which can produce the same light effect. Automotive signal lights are also an important field of LED light source applications.