1, white light is composed of LED red, green and blue multi-chip sets and luminescence.
Advantages: high efficiency, controllable color temperature and good color rendering.
Disadvantages: Different attenuation of three primary colors leads to unstable color temperature, complicated control circuit and high cost.
2. The blue LED chip excites the yellow phosphor, and the white light is synthesized by the blue light of the LED and the yellow-green light emitted by the phosphor. In order to improve the color rendering performance, a small amount of red phosphor or an appropriate amount of green and red phosphor can be added.
Advantages: high efficiency, simple preparation, good temperature stability and good color rendering.
Disadvantages: poor consistency, color temperature changes with angle.
3. The ultraviolet LED chip excites the fluorescent powder to emit three primary colors to synthesize white light.
Advantages: good color rendering and simple preparation.
Disadvantages: At present, the efficiency of LED chips is low, and there is a problem of ultraviolet light leakage, so the temperature stability of phosphors needs to be solved.
Characteristics of ultraviolet LED+RGB three-color fluorescence scheme
Advantages:
1) The white coordinate point is only determined by the phosphor itself and has nothing to do with the excitation wafer (the discreteness of the LED wafer can be tolerated).
2) A very high color rendering index RI can be achieved.
3) Theoretically, it is the simplest manufacturing scheme.
4) The stability of colored light depends only on the phosphor, which can be very stable.
Disadvantages:
1) leaked ultraviolet light will damage the LED sealant, leading to the problem of device life.
2) Low light conversion efficiency, self-absorption and light transmittance.