Patent ID: 8020999

Claim:
A projection type image display apparatus, comprising: an image display element; a first lens group, being disposed in a light direction with respect to said image display element, which is configured to include a plural number of lenses; a second lens group, being disposed in a light direction with respect to said first lens group, which is configured to include a plural number of lenses; and a reflection mirror, which is configured to reflect lights emitted from said second lens group, so as to project upon a screen obliquely; wherein between a plural number of lenses making up said second lens group, at least one outer shape configuration thereof is an asymmetric circle configuration with respect to an optical axis of a lens; wherein said first lens group, is disposed beside said image display element, and said second lens group is disposed between said first lens group and said reflection mirror; wherein an optical path length starting from a final surface of said first lens group and reaching to a reflection surface of said reflection mirror, on a path, along which a central light beam of a projection optical unit including said first lens group and said second lens group propagate directing to said screen, is at least five times a length of a focus distance of said first lens group; and wherein said second lens group includes a refractive lens having a negative power, which has a rotationally symmetric surface configuration, and further comprising a rod, which is configured to move in the optical direction, with respect to said first lens group.