Patent ID: 7258452

Claim:
A projection type image display apparatus comprising: an image display panel; and a projection optical system which projects an image of the image display panel onto an effective projection region of a predetermined image surface, wherein the projection optical system comprises, a first optical system which includes a zoom portion zooming the projected image on the effective projection region and has coaxial rotationally symmetric lenses, a second optical system which is disposed on the image surface side of the first optical system, and one or more rotatable members which rotate around a position of an exit pupil of the first optical system or its vicinity; wherein, by rotating the one or more rotatable members, the projected image is moved within the effective projection region; and wherein the following expression is satisfied: ∥ω r,z ·S r,z /(M·θ Mr,z L r,z )|−1|<0.2, where θ Mr,z is a rotation amount of the rotatable member in a horizontal or vertical direction at a zoom ratio z of the zoom portion, ω r,z is a maximum half field angle of an exit side of the first optical system, L r,z is half a size of the projected image on the effective projection region, S r,z is a movement amount of the projected image, and M is a parameter depending on the rotatable member, when the rotatable member is the first optical system or the second optical system, M is 1, and when the rotatable member is a planar mirror, M is 2.