Projection display device

• US 7,118,227 B2
• Filed: 04/23/2002
• Issued: 10/10/2006
• Est. Priority Date: 04/25/2001
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yoshikawa, Takamasa, Sannohe, Shinya, Ishinaga, Hideki
• Primary Examiner(s): Perkey, W. B.
• Assistant Examiner(s): BLACKMAN, ROCHELLE ANN J
• Application Number:
  US10/470,977
• Publication Number:
  US 20050073659A1
• Time in Patent Office: 1,631 Days
• Field of Search: 353/97, 353/31, 353/33, 353/34, 353/60, 353/61, 353/122, 353/37, 353/81, 353/82, 353/98, 353/99, 355/53, 355/67, 355/71, 355/77, 349/8, 349/10, 349/86, 349/113, 349/7, 359/738, 359/227, 359/233, 359/739, 356/400, 356/401, 362/268, 348/771
• US Class Current: 353/97
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03B 21/006 using LCD's

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.

Claims

1. 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.

2. The projection-type display apparatus according to claim 1, comprising a prism for both reflecting an illuminating light from the illuminating optical system toward the reflecting light valve and transmitting the reflected light from the reflecting light valve.

3. The projection-type display apparatus according to claim 1, wherein the number of the reflecting light valves is three, and

the projection type display apparatus further comprises

a first prism for reflecting an illuminating light from the illuminating optical system toward the reflecting light valves and transmitting the light from the reflecting light valves, and

a second prism for separating the illuminating light into three components of primary colors of red, blue and green and combining into one the three components that are reflected by the corresponding reflecting light valves.

4. The projection-type display apparatus according to claim 1, wherein the reflecting light valve has an image formation surface and a transparent plate that is disposed on an exit side of the image formation surface and in parallel with the image formation surface.

5. The projection-type display apparatus according to claim 1, wherein the reflecting light valve is formed of a plurality of mirror elements that are arranged in a matrix pattern and control a reflecting direction of light according to a video signal.

6. The projection-type display apparatus according to claim 1, wherein the diaphragm is constituted by the movable light-shielding plate having at least one straight side and the fixed diaphragm having a circular opening.

7. The projection-type display apparatus according to claim 1, wherein the diaphragm is constituted by the movable light-shielding plate having a circular opening and the fixed diaphragm having a circular opening.

8. The projection-type display apparatus according to claim 1, wherein the diaphragm is constituted by the movable light-shielding plate having a circular opening whose diameter is changeable and the fixed diaphragm having a circular opening, and a centroid of the opening of the movable light-shielding plate is shifted from the opening of the fixed diaphragm.

9. The projection-type display apparatus according to claim 1, further comprising a moving system for moving the movable light-shielding plate, a control system for controlling how much the movable light-shielding plate is displaced by the moving system,

wherein an opening area of the diaphragm is controlled automatically according to a level of an input video signal.

10. A projection-type display apparatus comprising:

a light source;

a diaphragm having an opening and shielding a part of a light;

a reflecting light valve having a mirror element for reflecting a light from the light source; and

a projection lens;

wherein the mirror element has an inclination angle that is changeable so as to reflect an incident light in a first direction for allowing the incident light to enter the projection lens or a second direction for not allowing the incident light to enter the projection lens, and

a centroid of the opening is shifted from an optical axis of the light from the light source so that a part of a flux of rays of the light reflected in the second direction at a position close to the projection lens is cut off.

11. The projection-type display apparatus according to claim 10, wherein the opening of the diaphragm has a shape surrounded by a circular arc and a straight line.

12. The projection-type display apparatus according to claim 10, wherein the opening of the diaphragm has a shape of an overlapping portion of two circles.

13. A projection-type display apparatus comprising:

a light source;

a reflecting light valve having a mirror element for reflecting a light from the light source;

a diaphragm having an opening and shielding a part of a light; and

a projection lens;

wherein the mirror clement has an inclination angle that is changeable so as to reflect an incident light in a first direction for allowing the incident light to enter the projection lens or a second direction for not allowing the incident light to enter the projection lens, and

a centroid of the opening is shifted from an optical axis of the light reflected in the first direction towards a position further away from the light reflected in the second direction.

14. The projection-type display apparatus according to claim 13, wherein the opening of the diaphragm has a shape surrounded by a circular arc and a straight line.

15. The projection-type display apparatus according to claim 13, wherein the opening of the diaphragm has a shape of an overlapping portion of two circles.

16. A projection-type display apparatus comprising:

a light source;

a diaphragm having an opening and shielding a part of a light;

a reflecting light valve having a mirror element for reflecting a light from the light source; and

a projection lens;

wherein the mirror element has an inclination angle that is changeable so as to reflect an incident light in a first direction for allowing the incident light to enter the projection lens or a second direction for not allowing the incident light to enter the projection lens,

the opening has a first edge portion and a second edge portion that face each other with an optical axis of the light from the light source located therebetween, and a distance between the first edge portion and the optical axis is smaller than that between the second edge portion and the optical axis, and

the light that passes near the first edge portion and is reflected in the second direction at the reflecting light valve constitutes a part closer to the projection lens than the light that passes near the second edge portion and is reflected in the second direction at the reflecting light valve.

17. The projection-type display apparatus according to claim 16, wherein the opening of the diaphragm has a shape surrounded by a circular arc and a straight line.

18. The projection-type display apparatus according to claim 16, wherein the opening of the diaphragm has a shape of an overlapping portion of two circles.

19. A projection-type display apparatus comprising:

a light source;

a reflecting light valve having a mirror element for reflecting a light from the light source;

a diaphragm having an opening and shielding a part of a light; and

a projection lens;

wherein the mirror element has an inclination angle that is changeable so as to reflect an incident light in a first direction for allowing the incident light to enter the projection lens or a second direction for not allowing the incident light to enter the projection lens, and

the opening has a first edge portion and a second edge portion that face each other with an optical axis of the projection lens located therebetween, a distance between the first edge portion and the optical axis is smaller than that between the second edge portion and the optical axis, and the first edge portion is closer than the second edge portion to the light reflected in the second direction.

20. The projection-type display apparatus according to claim 19, wherein the opening of the diaphragm has a shape surrounded by a circular arc and a straight line.

21. The projection-type display apparatus according to claim 19, wherein the opening of the diaphragm has a shape of an overlapping portion of two circles.