introduction
LED is a light-emitting device that can directly convert electrical energy into visible light. It has many advantages such as small size, low power consumption, long service life, high luminous efficiency, high brightness, low heat, environmental protection, durability and controllability. With rapid advancement, it is now able to mass produce high-brightness, high-performance products of various colors in the entire visible spectrum. In recent years, LED has been widely used in large-area graphic display, status indication, sign illumination, signal display, automobile combination taillights and interior lighting. It is known as a new light source in the 21st century, but it exists in its packaging process. Pollutants have always been a roadblock on the road to rapid development. How to solve this problem simply and quickly and without pollution has been plaguing people. Plasma cleaning, a new type of cleaning without any environmental pollution, will solve this problem.
1, LED lighting principle and basic structure
Light-emitting principle: LED (light emitting diode), a solid-state semiconductor light-emitting device, which can directly convert electricity into light, the core part of which is a wafer composed of p-type semiconductor and n-type semiconductor, in p-type There is a transition layer between the semiconductor and the n-type semiconductor, called pn junction, so it has the IN characteristic of the general pn junction, ie, forward conduction, reverse cut-off and breakdown characteristics. Under certain conditions, it also has luminescence characteristics. . At the forward voltage, in the pn junction of these semiconductor materials, current flows from the anode of the LED to the cathode, and the injected minority carriers recombine with the majority carriers to release excess energy as light. The semiconductor crystal can emit light of different colors from ultraviolet to infrared. The wavelength and color are determined by the forbidden band energy of the semiconductor material constituting the pn junction, and the intensity of the light is related to the current.
Basic structure: In simple terms, an LED can be thought of as an electroluminescent semiconductor material chip that is sealed with epoxy resin by wire bonding. The basic structure of the chip and typical products is shown in Figure 1 (the potting glue is between the chip and the lens).
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