Patent ID: 6130786
Filing Date: 2000-10-10
Classification: G02B

Abstract:
A rear projection type image displaying apparatus comprising:a projection tube for outputting an image light;a projection lens system for enlarging the image light outputted from the projection tube and projecting the image light;a mirror for reflecting the image light projected from the projection lens system; anda screen for receiving the image light reflected by the mirror and displaying an image corresponding to the image light at a front side of the apparatus;wherein the projection lens system comprises:a first meniscus lens being concave toward the screen and disposed at a nearest position to an image displaying device and having a smallest amount of power among elements forming the projection lens system;a first aspherical lens made of plastic material and having the center of curvature at the center portion including the axis of the lens surface at the image displaying device side being positioned toward the screen side;a biconvex lens made of a glass material having a positive power not lower than 70% of a total power of the projection lens system;a second aspherical lens; anda second meniscus lens disposed at the nearest position to the screen, and having a positive power with a convex surface toward the screen for effecting a light collecting function at the center portion including the axis and dispersing function at the peripheral portion apart from the axis in the radius direction;wherein the displaying surface of the image displaying device is curved in a circular arc having a center of curvature toward the screen; andwherein a distance d between the surface of the first meniscus lens toward the screen and the displaying surface of the image displaying device is set as d/f.sub.0 .gtoreq.0.35 where f.sub.0 is focal length of the projection lens system.