Patent ID: 7857462

Claim:
A projection optical unit for a projection display apparatus, for displaying an image upon a projection surface, obliquely, comprising: a front lens group including a spherical lens and an aspherical lens, being disposed in a direction from an image display element to a projection surface and having rotationally symmetric surface configurations; a rear lens group including a refraction lens having a rotationally symmetric surface configuration and a plural number of lenses having two rotationally asymmetric free curved surface configurations; and a reflection mirror, being convex into a direction of a reflection in a part thereof and having a rotationally asymmetric configuration, and being so formed that a curvature of a portion for reflecting a light beam incident upon a lower end portion of said projection surface is larger than a curvature of a portion for reflecting a light beam incident upon an upper end of said projection surface; wherein an optical axis of said front lens group and said rear lens group is more inclined with respect to a direction of the portion of said reflection mirror for reflecting a light beam incident upon a lower end portion of said projection surface than a normal line direction of said image display element.