Patent ID: 7914153

Claim:
A projection type image display apparatus, comprising: a lens group, being disposed adjacent to an image display element, which is configured to include a plural number of lenses; and a mirror, which is configured to reflect emission lights from said lens group, so as to project upon a screen obliquely; wherein a ratio (Lo/Lp) between a distance (Lp) from a center of said mirror up to said screen and a diagonal size (Lo) of said screen is at least 2; wherein said lens group comprises a first lens group, which is disposed beside said image display element, and a second lens group, which is disposed between said first lens group and said mirror; wherein an optical path distance starting from a final surface of said second lens group and reaching to a reflection surface of said mirror, on a path, along which a central light beam of the projection type image display apparatus propagates to said screen, is at least five times 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.