LED lamp bead structure and principle of illumination
The core of the LED lamp bead is a wafer composed of a P-type semiconductor and an N-type semiconductor. There is a transition layer between the P-type semiconductor and the N-type semiconductor, which is called a PN junction. In some PN junctions of semiconductor materials, the injected minority carriers recombine with the majority carriers to release excess energy in the form of light, thereby directly converting electrical energy into light energy.
The PN junction is added with a reverse voltage, and minority carriers are difficult to inject, so they do not emit light. The diode made by the principle of injection electroluminescence is called LED lamp bead, and is called LED. When it is in the forward working state (ie, the forward voltage is applied to both ends), when the current flows from the anode of the LED to the cathode, the semiconductor crystal emits light of different colors from ultraviolet to infrared, and the intensity of the light is related to the current.
1. Voltage: LED lamp bead uses low voltage power supply, the supply voltage is between 6-24V, depending on the product, so it is a safer power supply than using high voltage power supply, especially suitable for public places.
2. Performance: Energy consumption is reduced by 80% compared to incandescent lamps with the same efficacy.
3. Applicability: Very small, each unit LED small piece is 3-5mm square, so it can be prepared into various shapes of devices, and is suitable for a variable environment.
4. Stability: 100,000 hours, the light decay is the initial 50%.
5. Response time: The response time of its incandescent lamp is millisecond, and the response time of LED light is nanosecond.
6. Environmental pollution: no harmful metal mercury.
7. Color: Change the current to change color. LED lamp beads can be easily adjusted by chemical modification method to adjust the energy band structure and band gap of the material to realize multi-color luminescence of red, yellow, green and blue. For example, a red LED with a small current can change to orange, yellow, and finally green as the current increases.
8. Price: The price of LED is relatively expensive. Compared with incandescent lamps, the price of several LEDs can be comparable to the price of an incandescent lamp. Usually, each group of signal lamps needs to consist of 300 to 500 diodes.