Projection type display apparatus and multi-vision projection type display apparatus

• US 5,738,426 A
• Filed: 12/05/1996
• Issued: 04/14/1998
• Est. Priority Date: 12/08/1995
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kida, Hiroshi, Daijogo, Akira, Shikama, Shinsuke, Okamori, Shinji
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US08/759,634
• Time in Patent Office: 495 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/101, 348/752, 348/751, 348/757, 348/762, 349/5, 349/9
• US Class Current: 353/31
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3182 Colour adjustment, e.g. white balance, shading or gamut white balance per se H04N9/73; control of amplitude of colour signals H04N9/68; colour control circuits for displays in general G09G5/02, G09G3/2003, G09G3/3607
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

A projection type display apparatus includes a light source, color separator, half-wave plate, a plurality of light valves, color synthesizer, and projection lens. The light source emits a substantially parallel illumination flux. The color separator separates the light emitted from the light source into light of three colors including red, green, and blue. The light of the respective color passes through the corresponding half-wave plate which is placed in the light path of the light and causes the plane of vibration of the light to rotate through a predetermined angle. Then, the light of each color exiting the half-wave plate passe through the corresponding light valve, being modulated into a color image. The color synthesizer synthesizes the color images into a single full-color image and the projection lens enlarges and projects the single full-color image formed.

Claims

1. A projection type display apparatus, comprising:

a light source emitting light;

a color separator separating the light emitted from said light source into light of three primary colors;

a plurality of light valves, each light valve receiving light of one of the three primary colors from said color separator to form a color image;

a color synthesizer synthesizing the color images from said plurality of light valves into a single full-color image;

a projection lens which enlarges and projects the single full-color image resulting from said color synthesizer; and

a half-wave plate placed in at least one path of the light resulting from said color separator, said half-wave plate causing the plane of vibration of the light passing therethrough to rotate a predetermined angle,

wherein said half-wave plate is of a disc shape having a diameter and a rectangular effective area through which the light passes to illuminate one of said plurality of light valves, the effective area having a diagonal dimension, and the diameter being equal to or greater than the diagonal dimension.

2. The projection type display apparatus according to claim 1, wherein said half-wave plate has a light incident surface and a light exiting surface, the surfaces having a coating of non-reflecting material thereon.

3. A projection type display apparatus according to claim 1, further including an adjusting mechanism causing said half-wave plate to rotate through an angle, wherein said half-wave plate has an optic axis, a light incident surface, and a light exiting surface, said half-wave plate being rotated about a rotational axis which is normal to the light incident surface and passes through the optic axis.

4. A projection type display system incorporating a plurality of projection type display apparatuses according to claim 1 each of which projects a corresponding image, the system further comprising:

a rear projection type screen, and wherein said apparatuses are arranged in matrix form so as to form a multivision projection type display apparatus.

5. The projection type display system according to claim 4, further including:

a chromaticity detector for detecting chromaticity of an image projected on a corresponding screen segment and outputting a detection signal; and

a controller for controlling said half-wave plate to rotate through an angle in accordance with the detection signal so that there is substantially no difference in detection signal between chromaticity detectors.

6. A projection type display system incorporating a plurality of projection type display apparatuses according to claim 1 each of which projects a corresponding image and includes an adjusting mechanism for causing said half-wave plate to rotate through an angle, wherein

said half-wave plate has an optic axis and a light incident surface, said half-wave plate being rotated about a rotational axis which is normal to the light incident surface and passes through the optic axis, and wherein

said apparatuses are arranged in matrix form so as to form a multivision projection type display apparatus.

8. The apparatus according to claim 1, wherein said light source includes an orthogonal parabolic reflector.

9. The apparatus according to claim 1, wherein said light source includes an elliptical mirror.

10. A projection type display apparatus comprising:

a light source emitting light;

a color separator separating the light emitted from said light source into light of three primary colors;

a plurality of light valves, each light valve receiving light of one of the three primary colors from said color separator to form a color image;

a color synthesizer synthesizing the color images from said plurality of light valves into a single full-color image;

a projection lens which enlarges and projects the single full-color image resulting from said color synthesizer; and

a half-wave plate placed in at least one path of the light resulting from said color separator, said half-wave plate causing the plane of vibration of the light passing therethrough to rotate a predetermined angle;

a chromaticity detector for detecting chromaticity of an image projected on a screen and outputting a detection signal; and

a controller for controlling said half-wave plate to rotate though an angle in accordance with the detection signal.

7. The apparatus according to claim 11, wherein three light valves are provided, one for each of the three primary colors, and a half-wave plate is provided on the light incident side of each of said three light valves.

11. The apparatus according to claim 10, wherein said half-wave plate has a light incident surface and a light exiting surface, each surface having a coating of non-reflecting material thereon.

12. The apparatus according to claim 10, further comprising:

an adjusting mechanism causing said half-wave plate to rotate though an angle, wherein said half-wave plate has an optic axis, a light incident surface, and a light exiting surface, said half-wave plate being rotated about a rotational axis which is normal to the light incident surface and passes through the optic axis.

13. The apparatus according to claim 10, wherein said half-wave plate is disc shaped having a diameter and a rectangular effective area through which the light passes to illuminate one of said plurality of light valves, the effective area having a diagonal dimension, and the diameter being equal to or greater than the diagonal dimension.

14. A projection type display system incorporating a plurality of projection type display apparatuses according to claim 10, each of which projects a corresponding image, the system further comprising:

a rear projection type screen, and wherein said apparatuses are arranged in matrix form so as to form a multivision projection type display apparatus.

15. The apparatus according to claim 10, wherein three light valves are provided, one for each of the three primary colors, and a half-wave plate is provided on the light incident side of each of said three light valves.

16. The apparatus according to claim 10, further comprising:

a memory unit storing desired values of chromaticity for the three primary colors, these desired values being used by said controller for determining the angle of rotation for said half-wave plate.

17. The apparatus according to claim 10, wherein said light source includes an orthogonal parabolic reflector.

18. The apparatus according to claim 10, wherein said light source includes an elliptical mirror.

19. A projection type display system comprising:

(a) plurality of projection type display apparatuses arranged in a matrix to form a multivision projection type display apparatus, each of said plurality of projection type display apparatuses projecting a corresponding image and including;

(i) a light source emitting a substantially parallel illumination flux,

(ii) color separator separating the substantially parallel illumination flux into light of three primary colors including red, green, and blue,

(iii) a plurality of light valves, each of said light valves receiving light of a corresponding color to form a color image,

(iv) a color synthesizer synthesizing the color images from said plurality of light valves into a single full-color image,

(v) a projection lens which enlarges and projects the single full-color image formed by said color synthesizer, and

(vi) a half-wave plate placed in at least one path of the light resulting from said color separator, said half-wave plate causing the plane of vibration of the light passing therethrough to rotate through a predetermined angle;

(b) a rear projection screen, a section of said screen receiving a full color image from one of said plurality of projection type display apparatuses;

(c) a chromaticity detector for detecting chromaticity of an image projected on a corresponding screen segment and outputting a detection signal; and

(d) a controller for controlling said half-wave plate to rotate through an angle in accordance with the detection signal.

20. The projection type display system according to claim 19, wherein a chromaticity detector and controller are provided for each of said plurality of projection type display apparatuses, said controllers each controlling the half-wave plate of a corresponding projection type display apparatus so that there is substantially no difference between the detection signals resulting from said chromaticity detectors.