PURPOSE: To make it possible to discriminate colors highly accurately, by limiting the amount of transmitted light by using interference filters, thereby obtaining the outputs of the photoelectric elements corresponding to tristimulus values of spectrum.
CONSTITUTION: White light emitted from a light projector 31 is diffused and reflected by the surface of a detecting body 32. The diffused reflected light 33 which has a specific spectral energy distribution based on th colors of the body 32 is condensed by a lens 34 and inputted to the interference filters 35W37 as the parallel light. The filters 35W37 are constituted by a metallic film 51 and an intermediate layer 52. If the film thickness (d) of the intermediate layer 52 changes, the central wavelength λ. changes. The ares of an aperture part 53 of shielding plates 38W40 is the area corresponding to the tristimulus values of the spectrum, and the amount of the light passing the shielding plate is limited. Thus the spectral energy distributions for the decomposed elements of the tristimulus values of the spectrum are obtained. Therefore the tristimulus values of the spectrum are obtained as the outputs of the photoelectric elements 41W43. The outputs are given to a computing circuit 47, chromaticity coordinates X and Y are obtained, and an output switching circuit can be operated.
HINOTA SEISUKE
KATOU MITSUTAKA
YASUDA HIROHIKO
