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What Is The Connection Between Led Cri And Light Efficiency?
- Aug 20, 2018 -

 LED chips, generally speaking, if everything else is the same, only by adjusting the phosphor to obtain different color temperatures, the higher the LED CRI, the lower the light efficiency.


Conversely, the higher the LED efficacy, the lower the color rendering index, which is not necessarily the case. It is not because the light effect is low, so it is high, but to improve the index and sacrifice some light effects. And many people still have some misunderstandings about the light effect.


Luminous flux (lm) / power (W) from the LED source = LED efficacy in lm/W. CRI  is a numerical value that indicates the original color of the object after the light source is illuminated. There is no necessary connection between the two.

            (Color temperature control picture)


Factors affecting the color rendering index


In the past, we have talked about the way to achieve white LED light. Most of them are yellow phosphor chips (YAG) yellow phosphors. The blue light emitted by the chip complements the yellow light emitted by the phosphor to form white light. If you want to improve the color rendering of LEDs, you should adjust the phosphor ratio.


The red R9 (saturated red;) is the indicator for evaluating the quality of red reproduction. For their application, studios, studios, etc. need to reproduce the skin color, and the color reproduction of raw fruits and vegetables is irreplaceable.

The light color of fruits and vegetables under different R9, the larger the R9, the better the expression of red.


This current color rendering index Ra is judged to be far from convincing with the R1-R8 standard. In real life, many manufacturers often hear that they claim to:


Color rendering index >90, R9>50. So how do they do it?


So how can we improve the LED color rendering index? Above we know the role of R9, is it possible to improve the color rendering index of LEDs by increasing R9? Practical experience tells us that it is useful to increase the value of R9. Add a red phosphor to compensate for the lack of red spectrum of the LED to adjust the color rendering index of the white LED. The concentration of red phosphor incorporated is determined by how much to be indicated. For example, if an LED has a color rendering index of 70, to increase the color rendering index to 80, it may only need to blend a little red phosphor. Just fine, and to achieve a color rendering index of 90, you need to double the concentration of red powder. If the color rendering index is higher, the more red phosphors will be added. After reaching a certain distance, it will not have much effect. Generally, the LED does not exceed 93, and the light effect will be lower than the 70 index. 20-30% light efficiency. If the concentration of the red phosphor is too high, the color point of the LED will deviate from the Planck curve, causing severe color cast. Therefore, the proportion of the red phosphor formulation is different, and the effect on the color rendering index and color temperature is also different.


The effect of red powder on color rendering index and light efficiency:


1, will cause LED color cast.


2, seriously affect the LED light efficiency.


How to improve the color rendering index of LED while ensuring the light effect, but also to ensure that it will not be serious color cast, has been the subject of research in the industry.

(Warm colors give a sense of femininity)



 This looks more youthful



Photography also uses the level of light color to make the photos layered.