TRANSPARENT SPINEL SUBSTRATE, TRANSPARENT SUBSTRATE FOR OPTICAL ENGINE, REAR PROJECTION TELEVISION RECEIVER USING THEM AND IMAGE PROJECTOR USING LIQUID CRYSTAL

摘要

A transparent substrate for an optical engine of a rear-projection television receiver or a liquid crystal image projector, in particular, for protecting an original image forming panel of the optical engine, the transparent substrate characterized by being formed from a transparent highly-thermal-conductive cubic polycrystal plate, exhibiting good transmission of light or the like, good thermal conductivity, and good operability, and a rear-projection television receiver including the transparent substrate. It is favorable that the transparent substrate formed from the transparent highly-thermal-conductive cubic polycrystal and provided with a coating layer on a surface is used. Preferably, the coating layer is a multilayer. It is favorable that the material for the coating is at least two types selected from metal fluorides, metal oxides, and zinc compounds. The optical transparency is improved and the environmental stability is also improved by the coating.