COLOR-RENDERING-PROPERTY EVALUATING APPARATUS FOR FLUORESCENT LAMP OF HIGH COLOR TEMPERATURE THREE-WAVELENGTH REGION LIGHT EMITTING TYPE

摘要

PURPOSE:To evaluate the color rendering properties of a lamp, by computing an average color rendering index DELTARa based on the values of XY chromaticity points of a sample light source, and clarifying the relation-ship between Ra in JIS and Ra in the second edition of CIE. CONSTITUTION:When a light emitting type fluorescent lamp in three-wavelength regions at XY chromaticity points (0.3119, 0.3127) is used as a sample light source, the uv coordinates of the fluorescent lamp are computed by an expression of relation with a uv coordinate operator 2, and the uv coordinates (0.2035, 0.3061) are obtained. Then the correlated color temperature of the fluorescent lamp is computed with a color temperature operator 3, and 6,700K is obtained. Then, the DUV (value obtained by multiplying the distance between the chromaticity point of the light source and the locus of a block body by 103 times on the uv chromaticity diagram) is computed by an expression of relation with a DUV operator 4, and the DUV value of -5.0 is obtained. The difference DELTARa between the Ra in JIS and the Ra in the second edition of CIE is computed in a DUV-DELTARa converter 5. In this way, the relationship between the Ra in JIS and the Ra in the second edition of CIE is clarified, and the color rendering properties of the lamp can be evaluated.