Image projection apparatus

Abstract

A projector includes a plane mirror that is disposed at one end side of an end portion of a screen and a projection optical system that is disposed at a position that is separated from a reflection surface side of the plane mirror. A light shielding plate is provided to at least one of two positions; one is between a fourth mirror and the plane mirror of the projection optical system, and the other is between the plane mirror and the screen.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section showing an image projection apparatus shown in FIG. 2 in detail.

FIG. 2 is a diagram showing a schematic structure of the image projection apparatus.

FIG. 3 is a perspective view showing a xyz orthogonal coordinate system.

FIG. 4 is an explanatory diagram showing image light that deviates from a normal optical path and the state where the image light enters a screen.

FIG. 5 is an explanatory diagram showing a desirable position of a light shielding plate.

FIG. 6 is a cross section showing another example of the image projection apparatus shown in FIG. 2.

FIG. 7 is a diagram showing a schematic structure of a conventional image projection apparatus.

Claims

1. An image projection apparatus comprising: a projection optical system including a plurality of optical elements for emitting image light via the optical elements; anda mirror for reflecting the image light from the projection optical system so as to lead the image light to a screen, whereinthe mirror is disposed at one end side of an end portion of the screen, while the projection optical system is disposed at a position separated from a reflection surface side of the mirror,one of the optical elements disposed at a position that is closest to the mirror in the optical path of the projection optical system is a reflection type optical element, anda light shielding member for shielding image light deviating from an optical path is disposed at a position that is close to at least one of the outer side of an optical path from the reflection type optical element to the mirror and the outer side of an optical path from the mirror to the screen.

2. The image projection apparatus according to claim 1, wherein the light shielding member shields image light that deviates from an optical path from the reflection type optical element to the mirror and travels toward the screen.

3. The image projection apparatus according to claim 1, wherein the light shielding member shields image light that deviates from an optical path from the mirror to the screen and travels toward a holder member of the projection optical system.

4. The image projection apparatus according to claim 1, wherein supposing that image light that enters a surface of projection of the screen at a position that is closest to the mirror among image light entering the screen from the reflection type optical element via the mirror is a first image light, and that image light that enters the surface of projection of the screen at a position that is farthest from the first image light is a second image light, thenthe light shielding member is located in a first space that is separated from an intersection of the first image light traveling from the reflection type optical element to the mirror and the second image light traveling from the mirror to the screen and exists outside the optical path from the reflection type optical element to the mirror as well as the optical path from the mirror to the screen.

5. The image projection apparatus according to claim 4, wherein the light shielding member is located at a position that is closest to the mirror in the first space.

6. The image projection apparatus according to claim 1, wherein supposing that image light that enters a surface of projection of the screen at a position that is closest to the mirror among image light entering the screen from the reflection type optical element via the mirror is a first image light, and that an intersection of an imaginary line extending in the same direction as the normal direction to the surface of projection of the screen from a position on the mirror where the first image light reaches and an screen imaginary plane that is an extended plane of the surface of projection of the screen is an intersection A, and that d denotes a shortest distance between the intersection A and the screen while h denotes a length of the screen in the direction of the shortest distance, thenthe conditional expression (1) below is satisfied. 0<d/h<0.1  (1)

7. The image projection apparatus according to claim 1, wherein supposing that θ max denotes a largest angle while θ min denotes a smallest angle among angles between the normal to the surface of projection of the screen and image light that enters the screen from the mirror, thenthe conditional expression (2) below is satisfied. 10<θ max−θ min<50  (2)

8. An image projection apparatus, comprising: an image display element for displaying a two-dimensional image;a projection optical system for projecting an image on the image display element to a screen from an oblique direction;a plane mirror for reflecting image light from the projection optical system toward the screen; anda light shielding member, whereinthe projection optical system includes a reflection type optical element disposed at a position that is closest to the screen on the optical path in the projection optical system,the plane mirror is disposed at one end side of the screen in a position substantially perpendicular to the screen surface, andthe light shielding member is disposed at a position that is close to an intersection of an optical paths of first image light that is projected from the projection optical system via the plane mirror to an end portion of the screen facings the plane mirror and second image light that is projected from the projection optical system via a plane mirror to an end portion of the screen facing opposed to an end portion of the screen facing the plane mirror, and that is located outside the optical path of the projection optical system and adjacent to the optical paths of the first image light and the second image light.

9. The image projection apparatus according to claim 8, wherein the projection optical system includes the refractive optical element.

10. The image projection apparatus according to claim 8, wherein the projection optical system includes a first reflection surface with a concave surface, a second reflection surface with a convex surface, a third reflection surface with a curved surface, and a fourth reflection surface with a curved surface in this order from the image display element side.

11. The image projection apparatus according to claim 10, wherein the projection optical system includes a refractive optical element, and the refractive optical element is disposed between the reflection surfaces.

12. The image projection apparatus according to claim 10, wherein the projection optical system includes a first refractive optical element and a second refractive optical element, the first refractive optical element is disposed between the first reflection surface and the second reflection surface, and the second refractive optical element is disposed between the second reflection surface and the third reflection surface.

13. The image projection apparatus according to claim 8, wherein the light shielding member shields light that enters not the plane mirror but the screen directly among light emitted from the projection optical system.

14. The image projection apparatus according to claim 10, wherein the light shielding member shields light that is reflected by a holder member for retaining an optical element with the first reflection surface or by a holder member for retaining an optical element with the third reflection surface among light reflected by the plane mirror.