Projection type image display apparatus

1. A projection type image display apparatus, comprising:

an image display element;

a projection unit including a first lens group and a second lens group disposed in a direction of propagation light with respect to the image display element, each of the first lens group and the second lens group being formed with a plural number of lenses;

a reflection mirror configured to reflect light emitted from the second lens group thereon after the light passes through the first lens group so as to project the light on a screen obliquely; and

a mechanism configured to enable movement of at least one lens of the second lens group in a direction of an optical axis;

wherein the first lens group is fixed with respect to a bottom portion of the mechanism and is configured to compensate for an aberration of an optical system thereof, at least one lens of the first lens group having rotationally symmetric surfaces; and

wherein the second lens group is configured to enable movement of at least one lens of the second lens group with respect to the first lens group and the bottom portion of the mechanism.

2. The projection type image display apparatus according to claim 1 , further comprising a rotation portion for rotating the at least one lens of the second lens group.

3. The projection type image display apparatus according to claim 1 ,

wherein the second lens group is disposed in a direction of propagation of light with respect to the first lens group and is configured to compensate distortion for an image surface.

4. The projection type image display apparatus according to claim 1 , wherein:

the first lens group is constructed with lenses having only rotationally symmetric surfaces; and

the second lens group includes a rotationally asymmetric free-curved surface lens.

5. The projection type image display apparatus according to claim 2 , wherein the first lens group is constructed with lenses, each having only rotationally symmetric surfaces, and the second lens group includes a rotationally asymmetric free-curved surface lens.

6. The projection type image display apparatus according to claim 1 , wherein an optical axis of the projection lens unit is inclined with respect to a normal line on a display surface of the image display element.

7. The projection type image display apparatus according to claim 1 , further comprising a rod member which is configured to enable movement of the at least one lens of the second lens group.

8. The projection type image display apparatus according to claim 7 , further comprising a housing, configured to receive the reflection mirror and the first and second lens groups therein.

9. The projection type image display apparatus according to claim 8 , wherein an upper part of the housing has a slit, and the rod member projects from the slit portion.

10. The projection type image display apparatus according to claim 7 , wherein the rod member moves the at least one lens of the second lens group in a direction of an optical axis of the projection unit.

11. The projection type image display apparatus according to claim 9 , wherein the image display element is disposed so that a center of a display surface thereof is located on an optical axis of the projection unit.

12. The projection type image display apparatus according to claim 1 , wherein the reflection mirror reflects light emitted from the second lens group onto the screen, the reflection mirror having a convex shape with a curvature at a portion thereof which reflects the light onto a lower portion of the screen which is larger than a curvature at a portion thereof which reflects the light onto an upper portion of the screen.

13. The projection type image display apparatus according to claim 1 , wherein the reflection mirror reflects the light emitted from the second lens group onto the screen, and a distance between the reflection mirror and a surface of a lens of the first lens group which is nearest to the reflection mirror in an optical axis direction of the projection unit is at least 5 times a focus distance of the first lens group.

14. The projection type image display apparatus according to claim 1 , wherein each optical axis of at least two lenses included in the second lens group is eccentric with respect to each other.