Patent ID: 7241015
Filing Date: 2007-07-10
Classification: G03B

Abstract:
1. An optical unit, comprising: a light source; a color separation means for separating a light emitted from said light source into plural pieces of color lights; reflection-type image display elements, upon each being incident the corresponding color of the lights from said color separation means, and for forming an optical image for each of said color lights, depending upon an image signal, with using polarization characteristics which said reflection-type image display elements have; and a color synthesizing means for synthesizing said optical images of said respective color lights, to be projected through a projection lens, enlargedly, and further comprising: a reflection-type polarization plate functioning as a polarization plate due to diffraction, being provided on an optical path extending from said color separation means to said reflection-type image display elements, to be a polarizer and an analyzer to said reflection-type image display elements; and an optical chassis for holding said reflection-type polarization plate and said reflection-type image display elements thereon, and having a translucent window on an incident light side of said reflection-type polarization plate while an exiting light side of said reflection-type polarization plate is sealed with an incident surface of said color synthesizing means, wherein a hermetically sealed space is defined by said optical chassis, said reflection-type image display elements and the incident surface of said color synthesizing means, and within said hermetically sealed space is disposed a translucent liquid having refraction index from 1.2 to 1.9.