CRI of LED light source

　　The ability of a light source to reveal the color an object is called color rendering, which is in comparison with an ideal or natural light source under the same color temperature. The spectral content of the light determines the color of the light source, but the same color of light source can be composed of many, a few or even only two monochromatic light waves and has different requirements on the color rendering of the light. Light source with the same color can be composed of different light spectral. Light source with the wider light spectral perhaps can provide better color rendering quality. When the light source spectrum has little or no object at the reference light reflected from the primary wave, it would produce significant color shift. The greater the degree of color shift is, the worse the color rendering ability of the light source. CRI coefficient (Kaufman) is currently still a common method to define the evaluation of light color display.

　　CRI of incandescent lamp is 100 and is defined as the ideal benchmark light source. This system uses eight samples with standard color saturation to test the color deviation with the tested light source under the same benchmark color temperature so as to test the color rendering index of this light source. Taking the average deviation of Ra20-100, 100 is the maximum. The larger the average color difference is, the lower the Ra index. Light source less than 20 is not suitable for general use.

　　Index (Ra) grade CRI general application

　　90-100 1A excellent places require accurate color comparisons

　　80-89 1B places need correct judgment of color

　　60-792 2 general spaces need moderate color

　　40-59 3 low requirements on the color rendering index, low color shift

　　20-39 4 poor places without the specific requirements color rendering

　　The theoretical CRI of incandescent lamp is 100, but in real life there is a wide range of different incandescent lamps, so its Ra value is not entirely consistent. We might say that the closer to 100, the better the color rendering index. Specific lamps Ra values ??cited in the table below.

　　CRI Ra

　　Incandescent 97

　　Daylight Fluorescent 80-94

　　White fluorescent 75-85

　　Warm white fluorescent 80-90

　　Tungsten halogen 95-99

　　High-pressure mercury lamp 22-51

　　HPS 20-30

　　Metal halide lamps 60-65

　　Natayindeng 60-65

　　Dysprosium lamp 85 or more