There are several types of light sources:
1, two primary phosphor conversion white LED light source Two primary white LED is made of blue LED chip and YAG phosphor. The commonly used blu-ray chip is the InGaN chip, and the A1InGaN chip can also be used.
The advantages of blue chip LED with YAG phosphor method are: simple structure, low cost, relatively simple production process, and YAG phosphor has been used in fluorescent lamps for many years, and the process is relatively mature.
The disadvantage is that the efficiency of blue LED is not high enough, so that the efficiency of LED is low; The phosphor itself has energy loss; Phosphors and packaging materials age with time, resulting in color temperature drift and shortening of life.
2, three primary color phosphor conversion white LED light source in the premise of high efficiency effectively improve the color rendering of LED.
The most common way to get a tricolor white LED is to use an ultraviolet LED to excite a group of tricolor phosphors that can be radiated effectively.
This type of white LED has high color rendering, light color and color temperature can be adjusted, and the use of phosphors with high conversion efficiency can improve the light efficiency of the LED.
However, the method of UV LED tricolor phosphor still has certain defects, such as the low efficiency of phosphor in converting ultraviolet radiation; Powder mixing is difficult; The packaging material is easy to age under ultraviolet irradiation, and its life is short.
3, multi-chip white LED light source red, green, blue LED chip package together, the light they emit mixed together, you can also get white light.
This type of white LED light source is called multi-chip white LED light source.
Compared with phosphor conversion white LED, the advantage of this type of LED is to avoid the energy loss of phosphor in the light conversion process, and can obtain higher light efficiency; Moreover, the light intensity of the LED with different light colors can be separately controlled to achieve full color discoloration effect, and better color rendering can be obtained through the selection of the wavelength and intensity of the LED.
The disadvantage of this method is that the semiconductor materials of LED chips with different light colors are very different, the quantum efficiency is different, the light color changes with the drive current and temperature, and the decay speed is different with time.
In order to maintain the stability of the color, it is necessary to compensate and adjust the feedback circuit of the three colors of the LED, which makes the circuit too complex. In addition, heat dissipation is also the main problem plaguing multi-chip white LED light source.