The English word for LED is light emitting diode, which is the abbreviation for LED, a colloquial term.
The voltage at the end of the PN junction forms a certain potential barrier. When the forward bias voltage is added, the barrier drops, and most carriers in the P region and N region diffuse to each other. Because the electron mobility is much larger than the hole mobility, a large number of electrons will diffuse to the P region, forming the injection of a few carriers in the P region. These electrons recombine with the hole in the valence band, and the resulting energy is released as light energy. This is how PN junctions glow.
1. Small power specification of direct plug type: straw hat/helmet, round head, concave, oval, square (2*3*4) bullet, flat head, (3/5/ flat head/bread) piranha, etc.
2. SMD patch is generally divided into (3020/3528/5050 these are the front light) /1016/1024 and these are the side light source.
3. High-power leds cannot be classified into patch series. They have different power and current usage, and their photoelectric parameters differ greatly. A single high-power LED light source without heat dissipation base (generally hexagonal aluminum seat) has the same appearance as ordinary patches. The high-power LED light source is round, and the packaging mode is basically the same as that of SMD patches, but it has essential differences with SMD patches in terms of using conditions/environment/effect.
The characteristics ：
1. Voltage: LED lamp bead USES low-voltage power supply, the supply voltage is between 2-4v, and it varies according to different products, so it is driven by a higher voltage power supply; Safer power supply, especially for public places;
2. Current: the working current is 0 -- 15mA, and the brightness becomes brighter with the increase of current
3. Efficiency: the energy consumption is 80% less than the incandescent lamp with the same luminous effect.
4. Applicability: very small, each unit LED chip is 3-5mm square, so it can be prepared into various
Shape of the device, and suitable for volatile environment.
6. Response time: the response time of incandescent lamp is millisecond and that of LED lamp is nanosecond.
7. Environmental pollution: no harmful metal mercury.
8. Color: changing the current can change color. Led can easily adjust the band structure and band gap of the material through chemical modification, realizing multi-color luminescence of red, yellow, green, blue and orange. For example, LED, which is red when the current is small, can turn into orange, yellow, and finally green as the current increases.