Two-dimensional image forming apparatus

• US 20060227293A1
• Filed: 07/22/2004
• Published: 10/12/2006
• Est. Priority Date: 07/22/2003
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mizuuchi, Kiminori, Kasazumi, Ken'ichi, Yamamoto, Kazuhisa
• Granted Patent: US 7,271,962 B2
• Time in Patent Office: Days
• US Class Current: 353/30
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0278 used in transmission
• 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 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129

Abstract

A two-dimensional image formation apparatus according to the present invention is provided with laser sources (1a)˜(1c), diffusers (6a)˜(6c) for diffusing light, illumination optical systems for irradiating the diffusers (6a)˜(6c) with lights emitted from the laser sources (1a)˜(1c), diffuser vibration units (13a)˜(13c) for vibrating the diffusers (6a)˜(6c), and spatial light modulators (7a)˜(7c) disposed near the diffusers (6a)˜(6c), for modulating the lights emitted from the laser sources (1a)˜(1c) and diffused by the diffusers (6a)˜(6c), wherein the diffusers (6a)˜(6c) are vibrated by the diffuser vibration units (13a)˜(13c) at a velocity that satisfies a relationship, V>d×30 (millimeters/sec), which is established between the grain size d of the diffusers and the vibration speed V of the diffusers, whereby speckle noise existing in an image projected on a screen (11) can be effectively reduced.

Claims

1. An apparatus for forming a two-dimensional image by light modulation, comprising:

a coherent light source;

a diffuser for diffusing light;

an illumination optical system for irradiating the diffuser with light emitted from the coherent light source;

a diffuser vibration unit for vibrating the diffuser; and

a spatial light modulator disposed near the diffuser, said modulator modulating the light that is emitted from the coherent light source and diffused by the diffuser;

wherein said diffuser vibration unit vibrates the diffuser at a velocity that satisfies an expression,

V>

d×

30 (millimeters/sec)

which is established between the grain size d of the diffuser and the velocity V for vibrating the diffuser.

8. A two-dimensional image formation apparatus as defined in claim 1 wherein said illumination optical system includes a light integrator.

9. A two-dimensional image formation apparatus as defined in claim 8 wherein said light integrator comprises at least two lens arrays.

10. A two-dimensional image formation apparatus as defined in claim 8 wherein said light integrator comprises a rod type light integrator.

11. A two-dimensional image formation apparatus as defined in claim 1 wherein said diffuser comprises a pseudo random diffuser having a surface which is processed so as to obtain a desired diffusion angle.

12. A two-dimensional image formation apparatus as defined in claim 11 wherein said pseudo random diffuser is obtained by partitioning a surface of a transparent substrate in a lattice pattern to provide plural cell areas, and processing the cell areas so that adjacent cell areas have different heights.

13. A two-dimensional image formation apparatus as defined in claim 12 wherein in said pseudo random diffuser obtained by processing a transparent substrate, a difference in heights between adjacent cell areas is set so that the phases of light beam passing through these cell areas are shifted by π

/4 from each other.

14. A two-dimensional image formation apparatus as defined in claim 11 wherein said pseudo random diffuser has a concave-convex surface configuration in which the level of the surface thereof varies continuously.

2. An apparatus for forming a two-dimensional image by light modulation, comprising:

a coherent light source;

a diffuser for diffusing light;

an illumination optical system for irradiating the diffuser with light emitted from the coherent light source;

a spatial light modulator disposed near the diffuser, said modulator modulating the light that is emitted from the coherent light source and diffused by the diffuser; and

a projector lens for projecting an image which is obtained by light modulation by the spatial light modulator, on a certain plane in space;

wherein a diffusion angle of the diffuser is determined on the basis of a substantial numerical aperture of the illumination optical system, and a brightness of the projector lens.

3. A two-dimensional image formation apparatus as defined in claim 2 wherein a relationship,

θ

/2+Sin<sup>−

1</sup>(NAin)<

2×

Tan<sup>−

1</sup>(½

f)

is established among the diffusion angle a of the diffuser, the substantial numerical aperture NAin of the illumination optical system, and the brightness f of the projector lens.

15. A two-dimensional image formation apparatus as defined in claim 2 wherein said illumination optical system includes a light integrator.

16. A two-dimensional image formation apparatus as defined in claim 15 wherein said light integrator comprises at least two lens arrays.

17. A two-dimensional image formation apparatus as defined in claim 15 wherein said light integrator comprises a rod type light integrator.

24. A two-dimensional image formation apparatus as defined in claim 2 wherein said diffuser comprises a pseudo random diffuser having a surface which is processed so as to obtain a desired diffusion angle.

25. A two-dimensional image formation apparatus as defined in claim 24 wherein said pseudo random diffuser is obtained by partitioning a surface of a transparent substrate in a lattice pattern to provide plural cell areas, and processing the cell areas so that adjacent cell areas have different heights.

26. A two-dimensional image formation apparatus as defined in claim 25 wherein in said pseudo random diffuser obtained by processing a transparent substrate, a difference in heights between adjacent cell areas is set so that the phases of light beam passing through these cell areas are shifted by π

/4 from each other.

27. A two-dimensional image formation apparatus as defined in claim 24 wherein said pseudo random diffuser has a concave-convex surface configuration in which the level of the surface thereof varies continuously.

4. An apparatus for forming a two-dimensional image by light modulation, comprising:

a coherent light source;

a diffuser for diffusing light;

an illumination optical system for irradiating the diffuser with light emitted from the coherent light source;

a spatial light modulator disposed near the diffuser, said modulator modulating the light that is emitted from the coherent light source and diffused by the diffuser; and

a projector lens for projecting an image that is obtained by light modulation by the spatial light modulator, on a certain plane in space;

wherein the spatial light modulator and the diffuser are separated from each other by a distance that is determined on the basis of a diffusion angle of the diffuser, a substantial numerical aperture of the illumination optical system, and a screen size of the spatial light modulator in a diagonal direction.

5. A two-dimensional image formation apparatus as defined in claim 4 wherein a relationship,

(θ

/2+Sin<sup>−

1</sup>(NAin))×

L<

D/3

is established among the diffusion angle θ

of the diffuser, the substantial numerical aperture NAin of the illumination optical system, the distance L between the spatial light modulator and the diffuser, and the screen size D of the spatial light modulator in the diagonal direction.

18. A two-dimensional image formation apparatus as defined in claim 4 wherein said illumination optical system includes a light integrator.

19. A two-dimensional image formation apparatus as defined in claim 18 wherein said light integrator comprises at least two lens arrays.

20. A two-dimensional image formation apparatus as defined in claim 18 wherein said light integrator comprises a rod type light integrator.

28. A two-dimensional image formation apparatus as defined in claim 4 wherein said diffuser comprises a pseudo random diffuser having a surface which is processed so as to obtain a desired diffusion angle.

29. A two-dimensional image formation apparatus as defined in claim 28 wherein said pseudo random diffuser is obtained by partitioning a surface of a transparent substrate in a lattice pattern to provide plural cell areas, and processing the cell areas so that adjacent cell areas have different heights.

30. A two-dimensional image formation apparatus as defined in claim 29 wherein in said pseudo random diffuser obtained by processing a transparent substrate, a difference in heights between adjacent cell areas is set so that the phases of light beam passing through these cell areas are shifted by π

/4 from each other.

31. A two-dimensional image formation apparatus as defined in claim 28 wherein said pseudo random diffuser has a concave-convex surface configuration in which the level of the surface thereof varies continuously.

6. An apparatus for forming a two-dimensional image by light modulation, comprising:

a coherent light source;

a diffuser for diffusing light;

an illumination optical system for irradiating the diffuser with light emitted from the coherent light source;

a spatial light modulator disposed near the diffuser, said modulator modulating the light that is emitted from the coherent light source and diffused by the diffuser; and

a projector lens for projecting an image of the spatial light modulator on a certain plane in space;

wherein the spatial light modulator and the diffuser are separated from each other by a distance that is determined on the basis of a pitch of unevenness in the transmissivity of the diffuser, and a substantial numerical aperture of the illumination optical system.

7. A two-dimensional image formation apparatus as defined in claim 6 wherein a relationship,

L×

NAin>

P

is established among the pitch P of unevenness in the transmissivity of the diffuser, the substantial numerical aperture NAin of the illumination optical system, and the distance L between the spatial light modulator and the diffuser.

21. A two-dimensional image formation apparatus as defined in claim 6 wherein said illumination optical system includes a light integrator.

22. A two-dimensional image formation apparatus as defined in claim 21 wherein said light integrator comprises at least two lens arrays.

23. A two-dimensional image formation apparatus as defined in claim 21 wherein said light integrator comprises a rod type light integrator.

32. A two-dimensional image formation apparatus as defined in claim 6 wherein said diffuser comprises a pseudo random diffuser having a surface which is processed so as to obtain a desired diffusion angle.

33. A two-dimensional image formation apparatus as defined in claim 32 wherein said pseudo random diffuser is obtained by partitioning a surface of a transparent substrate in a lattice pattern to provide plural cell areas, and processing the cell areas so that adjacent cell areas have different heights.

34. A two-dimensional image formation apparatus as defined in claim 33 wherein in said pseudo random diffuser obtained by processing a transparent substrate, a difference in heights between adjacent cell areas is set so that the phases of light beam passing through these cell areas are shifted by π

/4 from each other.

35. A two-dimensional image formation apparatus as defined in claim 32 wherein said pseudo random diffuser has a concave-convex surface configuration in which the level of the surface thereof varies continuously.