Patent ID: 8002417
Filing Date: 2011-08-23
Classification: G03B

Abstract:
1. An optic unit of a projection-type image display apparatus for enlargedly projecting an optical image of a liquid crystal video display element, comprising: a front lens group, which includes a plurality of refraction lenses, each having a rotationally symmetric shape, and upon which the optical image is incident; a rear lens group, which includes at least a refraction lens having a rotationally symmetric shape and a refraction lens being rotationally asymmetric and having a shape which differs in curvature between portions thereof, separated in an up-and-down direction, in which an incident light passes through, and upon which an emission light of said front lens group is incident; a reflection mirror, which is rotationally asymmetric and has a shape differing in curvature between portions thereof separated in the up-and-down direction, and upon which an emission light of said rear lens group is incident; and a lens movement means, which is configured to move the plural numbers of refraction lenses of said rear lens group in an optical axis direction; wherein said front lens group and said rear lens group build up a coaxial optic system together with a display surface of said liquid crystal video display element.