The object is called thermoluminescence because of its high temperature. This kind of light source is called thermal light source. Thermal light source refers to the light source stimulated by thermal energy, such as incandescent lamp, arc lamp, halogen tungsten lamp and so on.
The incandescent lamp emits thermal radiation at 3000-4000K temperature. 80-90% of its energy is converted to thermal energy, and about 10% of its energy is converted to light energy, so its luminous efficiency is relatively low.
Cold light source is a kind of light source which almost does not contain infrared spectrum. For example, the popular LED light source is a typical cold light source, as well as fluorescent lamp, neon lamp and so on. When an object emits light, its temperature is not higher than the ambient temperature. This kind of light is called cold luminescence.
The principle of luminescence of cold light source is a phenomenon that the fluorescent material is stimulated by electron collision under the action of electric field. Generally speaking, the cold light source does not heat in normal operation, avoiding a series of problems such as heat accumulation.
In a more stringent sense, LED light-emitting diodes also generate heat when they emit light, but compared with incandescent lamps and other light sources, LED light-emitting diodes generate less heat.
When we distinguish the cold light source from the hot light source, we do not define the temperature of the lamp shell. Generally speaking, the temperature around the lamp can only judge the heat dissipation effect of the lamp.
We often say that the cold light source does not refer to those light sources which do not produce heat in the process of light emission, but refers to the light source which does not change from heat energy to light energy in the traditional way. In fact, cold light source uses chemical energy and electric energy to excite light source, and has flicker characteristics.
The thermal source is a source of light stimulated by thermal energy. In the process of luminescence, most of its energy needs to be converted into thermal energy, and then from thermal energy to light energy. Therefore, the thermal energy loss is relatively high, and the luminous efficiency is not as high as that of cold light source. However, there are also advantages, the thermal light source can be directly connected to the circuit, in the moment of electrification can achieve the maximum brightness, but the cold light source can not.