Causes of LED advertising screen heating

The reason for the heating of LED advertising screen is that the added electric energy is not fully converted into light energy, but part of it is converted into heat energy. The light efficiency of LED is only 100lm / W, and its electro-optic conversion efficiency is only about 20 ~ 30%. In other words, about 70% of the electric energy is turned into heat energy.

Specifically, the LED junction temperature is caused by two factors:
1. The internal quantum efficiency is not high, that is, when electrons and holes are combined, they can not produce 100% photons. It is usually called “current leakage”, which reduces the recombination rate of carriers in PN region. The leakage current multiplied by the voltage is the power of this part, that is, it is converted into heat energy, but this part does not account for the main component, because the internal photon efficiency is close to 90%.
2. The photons generated inside cannot all be emitted to the outside of the chip and finally converted into heat. This part is mainly because the external quantum efficiency is only about 30%, and most of them are converted into heat.
Although the light efficiency of incandescent lamp is very low, only about 15LM / W, it converts almost all electric energy into light energy and radiates it. Because most of the radiant energy is infrared, the light efficiency is very low, but it eliminates the problem of heat dissipation.
In general, the luminous efficiency of LED is still relatively low, resulting in the increase of junction temperature and the reduction of service life. In order to reduce the junction temperature and improve the service life, we must pay great attention to the problem of heat dissipation.