Projection type image display device

Abstract

The present invention provides a projection type image display device which is corresponding with the requirement of wide angle. The projection type image display device can reduce the deterioration of imaging capability and the reflection at the surface and is provided with a small-size cover plate. A refractive optical surface (40b) of the amplifying side of concavo-convex lens (41) at the amplifying side is provided with a convex surface shape projected to the amplifying side, so the second refractive optical part (40) can function as a protecting cover of projection optical system (50) when the projection is executed with a wide visual angle. Thus the thickness of concavo-convex lens (41) is approximately uniform, and furthermore the concavo-convex lens (41) is set to a convex surface shape projected to the amplifying side, so the surface area as protecting cover can be reduced, and the effect to imaging can be reduced. Additionally, as the concavo-convex lens (41) is formed to a concentric sphere shaped dome that the curvature center of lens surface is collocated adjacently to the position of exit pupil of reflective optical part (30), the effect caused by the concavo-convex lens (41) to the imaging effect can be reduced.

Description

technical field [0001] The present invention relates to a projection type image display device incorporating a projection optical system for projecting an image formed by a liquid crystal panel or the like on a screen. Background technique [0002] As a projection optical system for disposing the projection device near the screen and projecting its image on the screen, there is a device having a refractive optical system including a plurality of lenses arranged on the reduction side, and a refraction optical system arranged on the enlargement side. The concave reflector that makes the optical path turn back to the side, enlarges and approaches the projection on the screen (for example, patent documents 1 and 2). [0003] Patent Document 1: JP-A-2004-258620 [0004] Patent Document 2: JP-A-2006-235516 [0005] However, the above-mentioned projection optical system has an ultra-wide angle of view, so the focal length becomes extremely short, and the diameter of the beam near...

AI Technical Summary

Problems solved by technology

[0005] However, the above-mentioned projection optical system has an ultra-wide angle of view, so the focal length becomes extremely short, and the diameter of the beam near the optical axis becomes narrow. rough beam

Therefore, when a parallel plane cover is arranged near the concave reflector in order to protect the concave reflector, the angle of light incident on the peripheral portion of the cover becomes very shallow due to the wide-angle projection, and the imaging performance is affected. Deterioration, reflection at the surface of the cover becomes impossible to ignore

In addition, in the projection optical system using such a concave mirror, the optical path converges near the focal point or near the exit pupil position of the concave mirror. Therefore, it is preferable to arrange the cover plate at a position slightly away from the converging part from the viewpoint of safety. However, As the parallel plane cover is separated from the converging position, the size of the cover tends to increase, and problems arise in terms of the strength of the cover and the method of supporting it.

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