Rear projection screen and manufacturing method therefor as well as molding die for shaping rear projection screen, overhead projector and projection television set

摘要

In a rear projection screen, a plurality of convex lenses of the prescribed configuration are made of photoresist and formed and arranged on a surface or surfaces of a substrate in the prescribed pattern. In case that the convex lenses are formed in the shapes of ellipsoid, the longer radial direction of the ellipsoid is made to coincide with the horizontal direction and shapes of the lenses are changed gradually from the center of the screen to the extremity thereof. Bottom surfaces of non- lens boundary grooves between adjacent convex lenses are made rougher than the convex lens surfaces. A screen manufacturing method comprises the steps of applying photoresist onto a surface or surfaces of a substrate, exposing a patttern of boundary grooves onto the photoresist by photolithography, forming the boundary grooves by etching, and heating and melting the photoresist which is formed with the boundary grooves so as to form a plurality of convex lenses having the prescribed configuration. Further, it is possible to form a plurality of convex lenses of the prescribed configuration by rotating the substrate about the center thereof in the horizontal plane following the heating and melting step. In addition, it is possible, in forming the boundary grooves, to change the setting conditions of etching so that the bottom surfaces of the boundary grooves are made rougher than the convex lens surfaces.