The Influence Of LED’s Spectral Properties On Color Rendering And Its Application Research

The LED,as a new type of light source has different spectral characteristic from the traditional light source. It had been found that the color rendering of the LED can not be correct evaluated by current CRI standard in practical applications. It was reported that two of the newly proposed standards, CQS and CRI2012, which have better accuracy and universality,are still insufficient for evaluating the color rendering of all kinds of light sources. We got 35 kinds of usually used light source from the market,measured their spectrum and calculated their color rendering index which includes CRI Ra,CQS Qa and CRI Ra,2012.The correlation among the indexs,the spectrum of the tested light sources and the reflection coefficient of the color samples,as well as their relationship were analyzed.The result showed that when evaluating trichromatic fluorescent lamps there are large difference among the three kinds of index.When evaluating the LED,the difference between CRI Ra and CQS Qa is small.However,the difference between CRI Ra,2012 and CRI Ra or CQS Qa is large.21 kinds of LED lights were used for visual experiment.We obtained the data of the color difference of 21 kinds of light source.Then,we summarized the relationships among the ability of color rendering, the spectrum of standard light source and the spectral reflectance of object.It was found that most of tested LED had better ability of color rendering for color sample of blue, green and yellow.And the LED ‘s ability of color rendering was poor for color samples of red, magenta red, purple,etc.Two light sources which have great ability of color rendering were found in test.And we analysed the reasons of their great ability by studying the composition of spectrum.We deduced that red light improved the ability of color rendering. To verify this deduction,we made a light source by spectral constructing technology.We verified this deduction by contrast experiment.A light source was designed by the above conclusion. Firstly we got the built-up spectrum of D65 by spectral constructing technology.Then we analysed the characteristics of D65 and the spectral reflectance of green jade. The spectrum of D65 was pruned.And we got the final ratio of the LED’s numbers. The light source was made on the basis of the ratio.Finally we used it to illuminate green jade.And we found that the difference of illuminating effect between it and D65 is small.