An LED, that is, a light emitting diode, is a light-emitting device made of a semiconductor homogenous PN junction, a heterojunction PN junction, a metal-semiconductor (MS) junction, and a metal-insulator-semiconductor (MIS) junction.
Its working principle and some electrical characteristics are the same as those of a general crystal diode, but the crystal materials used are different. LEDs include different types of visible light, invisible light, laser, etc., and visible light LEDs are common in life. The color of the light-emitting diode is determined by the materials used. Currently, there are various colors such as yellow, green, red, orange, blue, purple, cyan, white, and full color, which can be made into various shapes such as a rectangle or a circle. LED has the advantages of long life, small body weight, low power consumption (energy saving), low cost, low operating voltage, high luminous efficiency, short response time, wide operating temperature range, pure light color and firm structure. A series of characteristics, such as impact resistance and vibration resistance, stable and reliable performance, are favored by people.
Since the illuminator of the LED is close to the "point" light source, the luminaire design is convenient, but if it is displayed as a large area, the current and power consumption are large. LEDs are generally used for display devices and optocouplers of electronic devices such as indicator lights, digital tubes, display panels, etc., and are also commonly used in optical communications, as well as in building outlines, amusement parks, billboards, streets, stages, and the like.