The LED lamp is a piece of electroluminescent semiconductor material chip, which is cured on the bracket with silver glue or white glue, and then connects the chip and the circuit board with silver or gold wire, and is sealed with epoxy resin to protect the inner core wire. Function, finally install the shell, so the LED lamp has good seismic performance.

principle

LED is a solid-state semiconductor device that can convert electrical energy into visible light. It can directly convert electricity into light. The heart of the LED is a semiconductor chip, one end of the chip is attached to a bracket, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the entire chip is encapsulated by epoxy resin.

The semiconductor wafer is composed of two parts, one part is a P-type semiconductor, in which holes dominate, and the other end is an N-type semiconductor, which is mainly electrons. But when these two semiconductors are connected, a P-N junction is formed between them. When the current acts on the chip through the wire, the electrons will be pushed to the P area, where the electrons and holes recombine, and then emit energy in the form of photons. This is the principle of LED light emission. The wavelength of light, or the color of light, is determined by the material forming the P-N junction.

LED can directly emit red, yellow, blue, green, cyan, orange, purple, and white light.

Initially, LEDs were used as indicator light sources for instruments and meters. Later, LEDs of various light colors were widely used in traffic signal lights and large-area display screens, resulting in good economic and social benefits. Take a 12-inch red traffic light as an example. In the United States, a 140-watt incandescent lamp with a long life and low optical efficiency was originally used as the light source, which produces 2000 lumens of white light. After passing through the red filter, the light loss is 90%, leaving only 200 lumens of red light. In the newly designed lamp, Lumileds uses 18 red LED light sources, which consumes a total of 14 watts, including circuit losses, to produce the same light effect. Automotive signal lights are also an important field of LED light source applications.

For general lighting, people need white light sources more. In 1998, the white LED was successfully developed. This type of LED is made by encapsulating GaN chips and Yttrium Aluminum Garnet (YAG) together. The GaN chip emits blue light (λp=465nm, Wd=30nm), and the Ce3+-containing YAG phosphor made by high-temperature sintering is excited by this blue light and emits yellow light with a peak of 550nLED lamp m. The blue LED substrate is installed in a bowl-shaped reflective cavity, covered with a thin layer of resin mixed with YAG, about 200-500nm. Part of the blue light emitted by the LED substrate is absorbed by the phosphor, and the other part of the blue light is mixed with the yellow light emitted by the phosphor to obtain white light.

For InGaN/YAG white LEDs, by changing the chemical composition of the YAG phosphor and adjusting the thickness of the phosphor layer, white light of various colors with a color temperature of 3500-10000K can be obtained. This method of obtaining white light through blue LED has simple structure, low cost, and high technology maturity, so it is most used.

history

origin
In the 1960s, scientific and technological workers used the principle of semiconductor PN junction light to develop LED light-emitting diodes. The material used for the LED developed at that time was GaASP, and its light-emitting color was red. After nearly 30 years of development, the LED, which everyone is very familiar with, can emit red, orange, yellow, green, blue and other colors. However, white LEDs for lighting have only been developed after 2000, and readers will be introduced to white LEDs for lighting.

development of
The first LED light source made using the principle of semiconductor P-N junction light emission came out in the early 1960s. The material used at that time was GaAsP, which emits red light (λp=650nm). When the driving current is 20 mA, the luminous flux is only a few thousandths of a lumens, and the corresponding optical efficiency is about 0.1 lumens/watt.
In the mid-1970s, the elements In and N were introduced to make the LED produce green light (λp=555nm), yellow light (λp=590nm) and orange light (λp=610nm), and the optical efficiency was increased to 1 lumens/watt.
In the early 1980s, GaAlAs LED light sources appeared, making the luminous efficacy of red LEDs reach 10 lumens/watt.
In the early 1990s, the successful development of two new materials, GaAlInP, which emits red and yellow light, and GaInN, which emits green and blue light, greatly improved the optical efficiency of LEDs.
In 2000, the LED made by the former had a luminous efficiency of 100 lumens per watt in the red and orange zone (λp=615nm), while the LED made by the latter had a luminous efficiency of 50 lumens in the green zone (λp=530nm). /watt.

The above is the introduction of LED lights, I hope it will be helpful to everyone. Since 2008 Armor lighting step into the led lighting industry and focus on shelf and retail display lighting area. Armor very experienced and advantageous in products customizing and considering more for our customers. Welcome everyone to come to consult.