LED Knowledge

At present, LED lighting has basically completely replaced incandescent light in the lighting field. Compared with Compact Fluorescent Lamp (CFL), LED lights also have obvious advantages. How do LED lights emit light? How were LEDs used for white lighting developed? Compared to traditional incandescent lights and CFLs, what are the advantages of LED lights?

1 LED lighting principle

The symbol of the LED light-emitting diode in the circuit is very similar to that of the diode, and its physical structure is also similar to a diode. There is a very small wafer on its lamp beads. This wafer is composed of multiple layers. The uppermost layer is the P-type semiconductor layer, the lowermost layer is the N-type semiconductor layer, and the light-emitting layer is in the middle. If a proper forward voltage is applied to the two layers of PN, the light-emitting layer in the middle will generate photons visible to the human eye due to the current flowing through it, which is the reason why it can emit light.

2.The Colors of light-emitting diodes

There are many different colors of light-emitting diodes, such as red, yellow, green, blue, etc. Since semiconductor devices have not been found to directly emit white light, there is no light-emitting diode that directly emits white light. But how did the common white light diodes in our life come from? Here we must mention a Japanese Nobel Prize winner, Dr. Shuji Nakamura, who invented the blue LED in the 1990s, and then in 1998, conducted research and development on the basis of the blue LED, and successfully developed white light. LED white light is to add a layer of phosphor in the middle layer. And the energy of blue photon is high, which can excite the phosphor. Therefore, some of them will pass through the phosphor layer, and some of them will interact with the layer after hitting this layer. The yellow light is produced by the interaction of the fluorescent substance, and the combination of blue and yellow light produces white light. Dr. Shuji Nakamura also won the Nobel Prize in Physics in 2014 for his contributions in the field of LED light-emitting diodes.

3.White light's color temperature

According to the proportion of blue light and yellow light, the white light will show different color temperatures. If the proportion of blue light is larger, the color temperature of white light will be higher, giving people the impression that it is a little bluish. On the contrary, if the proportion of yellow light is larger, the color temperature of the white light will be lower, giving people the impression that it is a bit yellowish.

4.LED light's application

At present, LED lights are widely used. They can be seen indoors and outdoors. You can see streetlights and tree decoration lights on the roadside, car lights and brake lights, guide lights in corridors, projection lights of buildings, and so on outside. There are home lighting, flat-panel TV backlights, projection lights of the projector, and LED flashlights indoor, etc. These traditional applications that use incandescent lamps or CFLs are now switched to LED lights.

5.LED light's advantages

Compared with traditional incandescent lights, LED lights have many advantages. Firstly, they have high luminous efficiency and good energy-saving performance. Under the same luminous intensity, the power consumption of LEDs is only one-tenth of that of incandescent lamps. Even compared with CFLs, the power consumption of LED lights is only a quarter of that of CFLs. Secondly, LED light has a longer service life. LED lamps are composed of PN junctions and light-emitting layers. They do not have filaments like incandescent lamps, so their lifespan can be as long as 50,000 hours, while the lifespan of ordinary incandescent lights is generally only about 1,000 hours. The lifespan of ordinary energy-saving lamps is only about 8,000 hours.


As Nobel laureate Dr. Shuji Nakamura said, incandescent lights illuminate the earth in the 20th century, and LED lights illuminate the earth in the 21st century.