Projection optical unit, projection-type image displaying apparatus and projection-type image displaying system
View Patent ↗A projection optical unit for a projection display apparatus, which displays an image upon a projection surface, obliquely, includes a front lens group disposed in a direction from an image display element to a projection surface, a rear lens group, and a reflection mirror formed so that a curvature of a portion for reflecting a light beam incident upon a lower end portion of the projection surface is larger than a curvature of a portion for reflecting a light beam incident upon an upper end of the projection surface. An optical axis of the front lens group and the rear lens group is more inclined with respect to a direction of the portion of the reflection mirror for reflecting the light beam incident upon the lower end portion of the projection surface than a normal line direction of the image display element.
1. 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.
2. The projection optical unit, as described in the claim 1 ,
wherein a refraction lens, having a negative power among said rear lens group, is movable in an optical axis direction,
wherein a lens, having a free curved surface configuration, at said image display element side among said rear lens group, is movable in an optical axis direction, as well as, a direction perpendicular to an optical axis within a surface including an optical axis and a normal line of a screen.
3. The projection optical unit, as described in the claim 2 , comprising:
a first mounting base for mounting said front lens group;
a second mounting base for mounting said refraction lens and said lens, having the free curved surface configuration, at said image display element side among said rear lens group; and
a third mounting base for mounting another lens, having a free curved surface configuration, at said reflection mirror side among said rear lens group,
wherein said second mounting base has a curved groove for changing a distance of an optical axis direction between said refraction lens and said lens having a free curved surface configuration.
4. The projection optical unit, as described in claim 3 , wherein said second mounting base is provided so that said second mounting base is movable with respect to said first mounting base.