How is the LED light source so cold?

　　 LED literacy, about LED is a cold light source, why is it so hot ?

We often hear about the Internet. The media is saying that LED is the fourth generation of environmentally friendly, green lighting source and cold light source. That is a cold light source, why the LED external temperature of the energy-saving lamp is high, why a large radiator is needed, and the LED heat dissipation problem is everywhere . . .

The difference between a hot light source and a cold light source:

The heat source means that after the object is heated, the object emits light, and the cold light source means that the principle of light is not heated.

In fact, this should start from the characteristics of cold light source. The characteristic of cold light source is that almost all of the energy of electricity is converted into visible light. The light of other wavelengths is very small, and the heat source is different. In addition to visible light, there is a large amount of infrared light. A considerable part of the energy is converted into infrared light that does not contribute to the illumination.

The traditional incandescent lamp uses tungsten filament to emit light, and about 90 % of its electricity is converted into heat, and only about 10 % of the electric energy is converted into visible light for illumination. And when it is working, the temperature is very high, and the temperature of a filament of a lit incandescent lamp is as high as 3000 °C .

　　 LED light source uses semiconductor chip to emit light, its electro-optical conversion rate is much higher than incandescent lamp, and with the advancement of technology, the efficiency of converting electrical energy into light energy is still increasing. Even when the small LED chip is working, the junction temperature ( chip temperature ) is not as high as that of incandescent lamps, it will not exceed 200 °C , and companies are trying to reduce the ideal temperature, and the ideal temperature is controlled below 100 °C . Or you can check: How to solve the heat problem with LED lights

Therefore, the LED is called a cold light source and there is no problem.

　　 The reason why LED lamps generate a lot of heat, we must start from the way of cooling LEDs .

　　 Unlike most traditional lighting fixtures, LEDs are large enough in size and volume to be mounted and fixed directly. During operation, heat is dissipated directly through radiation and air conduction. Its illuminating part is a very small chip, that is, it is inconvenient to install directly in an incandescent bulb, and it cannot quickly transmit heat during operation by air conduction.