At present, the LED to achieve white light there are three main methods:
1, through the LED red, green and blue three-color multi-chip group and light-emitting white light.
Advantages: high efficiency, color temperature control, color is better.
Disadvantages: three primary colors of light caused by different color temperature instability, the control circuit is more complex and costly.
2, blue LED chip to stimulate the yellow phosphor, LED blue light and phosphor issued by the yellow-green light synthesis of white light, in order to improve the color performance can also add a small amount of red phosphor or add appropriate amount of green, red phosphor.
Advantages: high efficiency, simple preparation, good temperature stability, good color rendering.
Disadvantages: poor consistency, color temperature changes with the angle.
3, UV LED chip to stimulate the phosphor to produce three primary colors of synthetic white light.
Advantages: good color rendering, simple preparation.
Disadvantages: At present, LED chip efficiency is low, there are UV light leakage problem, the temperature stability of the phosphor to be resolved.
UV LED + RGB three-color fluorescence program features
Advantages:
1) The white coordinate point is determined only by the phosphor itself, independent of the excitation wafer (which can tolerate the discretization of the LED chip).
2) can achieve very high color reduction index RI.
3) theoretically the simplest manufacturing plan.
4) The stability of the shade depends only on the phosphor and can be very stable.
Disadvantages:
1) Leakage of UV light can damage the LED sealant, resulting in device life problems.
2) light conversion efficiency is not high, their absorption, light transmission and so on.
Challenges:
1) has not been successfully tested so far.
2) There is no phosphor that can stimulate blue light.
3) The color will change with the angle of observation.
4) sealant must be able to resist UV damage.
5) RGB phosphor stability has yet to be further improved.
LED (Blue) + phosphor (Yellow) program features
Advantages:
1) only a single phosphor, making relatively simple.
2) single blue phosphor has been mature, abundant supply.
3) The color of the white light is moderate (RI? 75%).
4) The stability of the phosphor has been able to meet the requirements of color reduction.
Disadvantages:
1) light conversion efficiency is not high, their absorption, light transmission and so on.
2) color reduction is not high enough.
3) The stability of the color by the temperature and drive current greater impact.
4) the color will change with the observation angle changes.
RGB three primary colors LED color scheme
Advantages:
1) Optoelectronic efficiency is the highest. From the long-term development point of view, this program will be the mainstream program.
2) can be free to adjust the color.
3) Excellent color rendering ability (RI).
4) Very wide gamut range.
Disadvantages:
1) the need for complex shade feedback control, compensation LED material characteristics with temperature changes and changes in the characteristics of the LED light failure characteristics.
2) the color adjustment is very strange and changeable.