Image display apparatus

• US 5,446,510 A
• Filed: 10/24/1994
• Issued: 08/29/1995
• Est. Priority Date: 12/20/1989
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kimura, Kazumi, Mitsutake, Hideaki, Kurematsu, Katsumi, Minoura, Nobuo
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Dowling, William C.
• Application Number:
  US08/328,406
• Time in Patent Office: 309 Days
• Field of Search: 353/122, 353/31, 353/30, 353/33, 353/34, 353/37, 353/20, 353/81, 359/63, 359/93, 359/485, 359/490, 359/494-496, 359/638, 359/629
• US Class Current: 353/20
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13355 Polarising beam splitters [PBS]
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• 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 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

An image display apparatus has a radiation source, generator for generating an image by modulating a polarized light beam and directing device for directing a light beam from the radiation source toward the generator. The directing device has a conversion optical system for converting the beam from the radiation source into the polarized light beam. The conversion optical system has a polarizing beam splitter for splitting the beam from the radiation source into a first and second beams. In the conversion optical system, a 1/4 wavelength plate and a mirror are arranged so that the plane of polarization of the first beam is rotated to generate a third beam with the plane of polarization same as that of the second beam. The third beam is directed toward the generator through the polarizing beam splitter while the second beam is also directed toward the generator.

Claims

1. An image display apparatus comprising:

a radiation source;

a generator for generating an image by modulating a polarized beam; and

directing means for directing a beam from said radiation source to said generator;

wherein said directing means comprises a conversion optical system for converting the beam from said radiation source into said polarized beam,

wherein said conversion optical system includes a polarizing beam splitter for splitting the beam from said radiation source into a first beam and a second beam of mutually orthogonal polarization directions and an arrangement of a 1/4 wavelength plate and a mirror for changing the direction of polarization of said first beam to generate a third beam of a polarization direction the same as that of said second beam and for directing said third beam to said polarizing beam splitter,

wherein said first beam is formed by reflecting one portion of the beam from said radiation source with a beam splitting surface of said polarizing beam splitter and said second beam is formed by transmitting an another portion of the beam from said radiation source through the beam splitting surface of said polarizing beam splitter, and

wherein said conversion optical system generates said third beam without redirecting said first beam to said radiation source and directs said second and third beams to said generator.

2. An apparatus according to claim 1, wherein said directing means has a collimator for converting the beam from said radiation source into a substantially parallel beam, which is introduced into said conversion optical system.

3. An apparatus according to claim 1 or 2, wherein said polarizing beam splitter is adapted to generate said first beam by reflecting the S-polarized component of the beam from said radiation source and to generate said second beam by transmitting the P-polarized component of said beam.

4. An apparatus according to claim 3, wherein said conversion optical system is so constructed as to direct said second beam in a predetermined direction and has an auxiliary mirror for reflecting said third beam to said predetermined direction.

5. An apparatus according to claim 3, wherein said conversion optical system is so constructed as to direct said third beam to a predetermined direction and has an auxiliary mirror for reflecting said second beam to said predetermined direction.

6. An apparatus according to claim 2, wherein said conversion optical system has an optical filter for compensating an unevenness in intensity between said second and third beams.

7. An apparatus according to claim 6, wherein said conversion optical system is so constructed as to direct said second beam to a predetermined direction and has an auxiliary mirror for reflecting said third beam to said predetermined direction, and said mirror is provided with said optical filter.

8. An apparatus according to claim 6, wherein said conversion optical system is so constructed as to direct said third beam to a predetermined direction and has an auxiliary mirror for reflecting said second beam to said predetermined direction, and said mirror is provided with said optical filter.

9. An apparatus according to claim 6, wherein said mirror is provided with said optical filter.

10. An apparatus according to claim 6, wherein said optical filter is provided between said polarizing beam splitter and said arrangement.

11. An apparatus according to any of claims 6 to 10, wherein said optical filter has a multi-layered structure.

12. An apparatus according to claim 2, wherein said conversion optical system has a color filter for compensating an unevenness in color between said second and third beams.

13. An apparatus according to any of claims 1 to 12, further comprising a projection optical system for projecting said image onto a predetermined plane.

14. An image display apparatus comprising:

a radiation source;

a generator for generating an image by modulating a polarized beam; and

directing means for directing a beam from said radiation source to said generator;

wherein said directing means comprises a collimator for substantially collimating the beam from said radiation source and a conversion optical system for converting the collimated beam into said polarized beam, and

wherein said conversion optical system includes a polarizing beam splitter provided with a splitting surface, inclined to the optical axis of said collimator, for splitting said collimated beam by transmitting the P-polarized beam thereof and reflecting the S-polarized beam thereof; and

arrangement of a 1/4 wavelength plate and a mirror for changing the polarization direction of said S-polarized beam to cause the polarization direction thereof to be coincident with the polarization direction of said P-polarized beam and directing said S-polarized beam to a predetermined direction through said polarizing beam splitter without redirecting said S-polarized beam to said radiation source; and

an auxiliary mirror for reflectively deflecting said P-polarized beam to said predetermined direction.

15. An apparatus according to claim 14, wherein said conversion optical system has an optical filter for compensating an unevenness in intensity between said P-polarized beam and said S-polarized beam.

16. An apparatus according to claim 15, wherein the mirror of said arrangement is provided with said optical filter.

17. An apparatus according to claim 15, wherein said auxiliary mirror is provided with said optical filter.

18. An apparatus according to claim 15, wherein said optical filter is provided between said polarizing beam splitter and said arrangement.

19. An apparatus according to claim 14, wherein said conversion optical system has a color filter for compensating the unevenness in color between said P-polarized beam and said S-polarized beam.

20. An apparatus according to any of claims 14 to 19, further comprising a projection optical system for projecting said image onto a predetermined plane.

21. An image display apparatus comprising:

a radiation source;

a generator for generating an image by modulating a polarized beam; and

directing means for directing a beam from said radiation source to said generator;

wherein said directing means comprises a collimator for substantially collimating the beam from said radiation source and a conversion optical system for converting the thus collimated beam into said polarized beam, and

wherein said conversion optical system includes a polarizing beam splitter provided with a splitting surface, inclined to the optical axis of said collimator, for splitting said collimated beam by transmitting the P-polarized beam thereof and reflecting the S-polarized beam thereof into a predetermined direction;

a second polarizing beam splitter provided with a splitting surface inclined to the optical axis of said collimator; and

an arrangement of a 1/4 wavelength plate and a mirror for receiving said P-polarized beam through said second beam splitter, changing the polarization direction of said P-polarized beam to cause the polarization direction thereof to be coincident with the polarization direction of said S-polarized beam so as to form a second S-polarized beam, and causing said second polarizing beam splitter to reflect said second S-polarized beam toward said predetermined direction without redirecting said P-polarized beam to said radiation source.

23. An apparatus according to claim 21, further comprising a projection optical system for projecting said image onto a predetermined plane.

22. An image display apparatus comprising:

a radiation source;

a generator for generating an image by modulating a polarized beam; and

directing means for directing the beam from said radiation source to said generator;

wherein said directing means comprises a collimator for substantially collimating the beam from said radiation source and a conversion optical system for converting the thus collimated beam into said polarized beam; and

wherein said conversion optical system includes a polarizing beam splitter provided with a splitting surface, inclined to the optical axis of said collimator, for splitting said collimated beam by transmitting the P-polarized beam thereof to a predetermined direction and reflecting the S-polarized beam thereof, an arrangement of a 1/4 wavelength plate and a mirror for changing the polarization direction of said S-polarized beam to cause the polarization direction of said S-polarized beam to be coincident with the polarization direction of said P-polarized beam so as to form a second P-polarized beam and directing said second P-polarized beam to said polarizing beam splitter, without redirecting said S-polarized beam to said radiation source, and an auxiliary mirror for reflecting said second P-polarized beam passed through said polarizing beam splitter, toward said predetermined direction.

24. An apparatus according to claim 22, further comprising a projection optical system for projecting said image onto a predetermined plane.

25. A projector comprising:

a radiation source;

a modulator for reflecting a polarized beam incident thereon and for generating a reflection beam indicative of an image by modulating the polarization state of said polarized beam incident thereon according to a video signal;

a converter including a polarizing beam splitter for splitting a beam from said radiation source into P- and S-polarized components, said converter generating said polarized beam by making the polarization directions of said polarized components parallel with each other, wherein said polarizing beam splitter is arranged in a path for said reflection beam so as to function as an analyzer; and

a projection optical system for receiving said reflection beam through said polarizing beam splitter and for projecting said image with said beam.

26. A projector according to claim 25, wherein said modulator has a liquid crystal panel.

27. A light modulating system, comprising:

a radiation source;

a modulator for reflecting a polarized beam incident thereon and modulating a polarization state of said polarized beam to generate a reflected beam; and

a converter including a polarizing beam splitter for splitting a beam from said radiation source into P- and S-polarized components, said converter generating said polarized beam by making the polarization directions of said polarized components parallel with each other wherein said polarizing beam splitter is arranged in a path for said reflection beam so as to function as an analyzer.

28. An image display apparatus comprising:

a radiation source;

a liquid crystal panel for generating an image by modulating a polarized beam having a predetermined polarization direction;

directing means for directing a beam from said radiation source to said generator;

wherein said directing means comprises a conversion optical system for converting the beam from said radiation source into said polarized beam; and

said conversion optical system includes a polarizing beam splitter for splitting the beam from said radiation source into a first beam and a second beam of mutually orthogonal polarization directions; and

an arrangement of a 1/4 wavelength plate and a mirror for changing the polarization direction of said first beam to generate a third beam of a polarization direction the same as that of said second beam and for directing said third beam to said polarizing beam splitter,

wherein said first beam is formed by reflecting one portion of the beam from said radiation source with a beam splitting surface of said polarizing beam splitter and said second beam is formed by transmitting an another portion of the beam from said radiation source through the beam splitting surface of said polarizing beam splitter, and

wherein said conversion optical system generates said third beam without redirecting said first beam to said radiation source and directs said second and third beams to said generator.

29. An image display apparatus comprising:

a radiation source;

a liquid crystal panel for generating an image by modulating a polarized beam having a polarization direction the same as a direction of liquid crystal molecules oriented at an incident side of said liquid crystal panel; and

directing means for directing a beam from said radiation source to said generator,

wherein said directing means comprises a conversion optical system for converting the beam from said radiation source into said polarized beam,

said conversion optical system includes a polarizing beam splitter for splitting the beam from said radiation source into a first beam and a second beam of mutually orthogonal polarization directions; and

an arrangement of a 1/4 wavelength plate and a mirror for changing the polarization direction of said first beam to generate a third beam of a polarization direction the same as that of said second beam and for directing said third beam to said polarizing beam splitter,

wherein said first beam is formed by reflecting one portion of the beam from said radiation source with a beam splitting surface of said polarizing beam splitter and said second beam is formed by transmitting an another portion of the beam from said radiation source through the beam splitting surface of said polarizing beam splitter, and

wherein said conversion optical system generates said third beam without redirecting said first beam to said radiation source and directs said second and third beams to said generator.

30. An image forming apparatus comprising:

a radiation source;

a generator for generating an image by modulating a polarized beam; and

directing means directing a beam from said radiation source to said generator;

wherein said directing means comprises a conversion optical system for converting the beam from said radiation source into said polarized beam,

wherein said conversion optical system includes a polarizing beam splitter for splitting the beam from said radiation source into a first beam and a second beam of mutually orthogonal polarization direction; and

an arrangement of a 1/4 wavelength plate and a mirror for changing the polarization direction of said first beam to generate a third beam of a polarization direction the same as that of said second beam and for directing said third beam to said polarizing beam splitter,

wherein said first beam is formed by reflecting one portion of the beam from said radiation source with a beam splitting surface of said polarizing beam splitter and said second beam is formed by transmitting an another portion of the beam from said radiation source through the beam splitting surface of said polarizing beam splitter, and

wherein said conversion optical system generates said third beam without redirecting said first beam to said radiation source and directs said second and third beams to said generator.