US 7,118,227 B2 · Projection display device

Abstract

An illuminating optical system for focusing a radiant light of a light source (1) onto a reflecting light valve (6) and a projection lens (7) for magnifying and projecting a reflected light from the reflecting light valve (6) onto a screen are provided, a diaphragm (31) is disposed at a substantially conjugate position of an entrance pupil of the projection lens (7) on an optical path of the illuminating optical system, the diaphragm (31) has an opening whose area is changed by a light-shielding member, and a shape of a shielded portion of the diaphragm (31) shielded by the light-shielding member is rotationally asymmetric to an optical axis (12) of the illuminating optical system. Accordingly, shielding of necessary light can be better avoided compared with a diaphragm for changing the light-shielding area in a rotationally symmetric manner, for example, a diaphragm for narrowing the opening concentrically, making it possible to improve contrast performance while minimizing brightness reduction.

Claims21

Dependent claims

A projection-type display apparatus comprising:

a light source;
a reflecting light valve for controlling a traveling direction of a reflected light with respect to an incident illuminating light according to a signal;
an illuminating optical system for focusing a light from the light source onto the reflective light valve;
a projection lens for magnifying and projecting the light from the reflecting light valve onto a screen;
and
a diaphragm disposed at a position relative to an entrance pupil of the projection lens or a substantially conjugate position of the entrance pupil and provided with an opening for shielding a part of the radiant light from the light source, the diaphragm including a fixed diaphragm having an opening and a movable light-shielding plate for shielding at least a part of the opening of the fixed diaphragm;
wherein the movable light-shielding plate is operable to shift a centroid of the opening of the diaphragm away from an optical axis of the projection lens or the illuminating optical system so as to suppress a projection of a reflection light reflected by a front surface of the reflecting light valve onto a screen.

4 more elements

Dependencies are inferred from the claim text.

Projection display device

Life of this patent

Projection display device

Life of this patent

Abstract

Claims21