LED white light created by LED chips and fluorescent powder

There are two methods for producing LED white light: LED chips together with fluorescent powder; combination of multi-single-color LED chips.

 

Blue-ray LED High Bay chips with fluorescent powder is the most commonly used method to generate white rays. With current fluorescent powder technique, man-made LED white rays still have big differences with natural white rays. That is the reason why white LED lamps usually have low color rendering index. Feature below shows the light spectrum distribution. From it we can see that the blue-green rays and red rays are insufficient. However, the blue rays are excessive. R9 (color rendering index for crimson) = 0.

 

Many people raised doubts about this colorimetric method. LED lighting sources have discrete light distributions while colorimetric method is typically used for testing continuous light spectrum. However, those who hold such views misunderstand the lighting principle of this LED white light. The lights emit by fluorescent powder (after being stimulated by blue rays) are not single-color rays, but contained most of visible lights. In fact, no matter what type of spectrum distribution, if it has a spectrum distribution very closed to natural white rays, it has a very high color rendering index.

 

There are two methods for producing LED white light: LED chips together with fluorescent powder; combination of multi-single-color LED chips.

 

Some people also come up with the concept that LED white light must have a relatively high color rendering index, since objects under LED white rays will be more bright-colored. However, this view is totally wrong. LED white lights indeed have very strong light intensity within some wavelength region (blue and yellow), but weak light intensity in other regions, like blue-green and red. Therefore, they just make some color of these objects look brighter. In fact, this is a performance of distortion. These objects will have different color if they in the sun. LED white lamps on the one hand excessively reveal some rays, and on the other hand insufficiently reveal some other rays. Some objects will look gloomy under LED white lights, like meat. In some LED-lights-decorated supermarkets, shopkeeper often installed some additional filament lamps in meat region to make their meat look brighter and more attractive.

 

With current technique, the distortion of LED white lamps (LED chips with fluorescent powder) cannot be eliminated. However, with the continuous development of LED Street Light technique, we believe this problem will be solved in future.