Polarization illumination device and projector having the same

• US 5,387,953 A
• Filed: 12/23/1991
• Issued: 02/07/1995
• Est. Priority Date: 12/27/1990
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kimura, Kazumi, Minoura, Nobuo
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Dowling, William C.
• Application Number:
  US07/812,758
• Time in Patent Office: 1,142 Days
• Field of Search: 353/20, 353/31, 353/30, 353/33, 353/34, 353/37, 353/122, 353/81, 359/63, 359/488, 359/487, 359/485, 359/494, 359/495, 359/496, 359/497, 359/48, 359/49, 359/40, 359/41
• 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 1/133543 Cholesteric polarisers
• 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 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A polarization illumination device and projector having the polarization illumination device are provided. An example of the polarization illumination device comprises an illuminator and a polarized including a polarization splitting surface and a reflecting surface, the splitting surface and the reflecting surface form an inverted V shape. The splitting surface splits part of the light into a transmitted component and a reflected component and directs the former in a first direction and the latter toward the reflecting surface. The reflecting surface reflects a remaining part of the light and directs it toward the splitting surface. The splitting surface splits the remaining part of the light into a transmitted component and a reflected component. The former directed toward a second direction different from the first direction, and the latter is returned to the illuminator. The illuminator modulates a plane of each returned reflected light component and causes each returned reflected component to be incident on the polarizer again.

Claims

1. A method of splitting a substantially collimated radiation beam from a radiation source into first and second polarized beams having different polarization planes by a polarization splitting surface, directing the first beam in a predetermined direction, causing a returning member to return the second beam to said radiation source, reflecting the second beam toward said polarization splitting surface by a reflector located behind said radiation source, and converting the second beam so as to have the same polarization plane as said first polarized beam, wherein said returning member is a reflecting surface oriented so as to return the second beam to said radiation source along an optical path different than that of said substantially collimated radiation beam, where said different optical path passes near but does not substantially impinge on said radiation source.

2. A method according to claim 1, wherein said,

reflecting surface is inclined with respect to said substantially collimated radiation beam.

3. A method according to claim 2, wherein said reflecting surface has an optical power.

4. A method of splitting a substantially collimated radiation beam from a radiation source into first and second polarized beams having different polarization planes by a polarization splitting surface, directing the first beam in a predetermined direction, causing a returning member to return the second beam to said radiation source, reflecting the second beam toward said polarization splitting surface by a reflector located behind said radiation source, converting the second beam so as to have the same polarization plane as said first polarized beam, and modulating said polarized beams to form an image, wherein said returning member is a reflecting surface oriented so as to return the second beam to said radiation source along an optical path different than that of said substantially collimated radiation beam, where said different optical path passes near but does not substantially impinge on said radiation source.

5. A method according to claim 4, wherein said,

reflecting surface is inclined with respect to said substantially collimated radiation beam.

6. A method according to claim 5, wherein said reflecting surface has an optical power.

7. A method of splitting a radiation beam from a radiation source into first and second polarized beams having different polarization planes by a polarization splitting surface, directing the first beam in a predetermined direction, causing a reflecting surface to return the second beam to said radiation source, coinciding the plane of at least part of the second beam with that of the first beam, reflecting the second beam toward said polarization splitting surface by a reflector located behind said radiation source, and converting the second beam so as to have the same polarization plane as said first polarized beam, comprising setting said reflecting surface and said polarization splitting surface in an inverted V shape in a path of the radiation beam so that said reflecting surface receives part of the radiation beam and said polarization splitting surface receives a remaining part of the radiation beam to split the remaining part into the first polarized beam and the second polarized beam, thereby causing said reflecting surface to reflect said part of the radiation beam toward said polarization splitting surface.

8. A method according to claim 7, wherein said reflecting surface has an optical power.

9. A method of splitting a radiation beam from a radiation source into first and second polarized beams having different polarization planes by a polarization splitting surface, directing the first beam in a predetermined direction, causing a reflecting surface to return the second beam to said radiation source, coinciding the plane of at least part of the second beam with that of the first beam, reflecting the second beam toward said polarization splitting surface by a reflector located behind said radiation source, converting the second beam so as to have the same polarization plane as said first polarized beam, and modulating said polarized beams to form an image, comprising setting said reflecting surface and said polarization splitting surface in an inverted V shape in a path of the radiation beam so that said reflecting surface receives part of the radiation beam and said polarization splitting surface receives a remaining part of the radiation beam to split the remaining part into the first polarized beam and the second polarized beam, thereby causing said reflecting surface to reflect said part of the radiation beam toward said polarization splitting surface.

10. A method according to claim 9, wherein said reflecting surface has an optical power.

11. A polarization illumination device comprising:

illuminating means including a light source and a reflecting mirror located behind said light source; and

polarizing means illuminated with light from said illuminating means and including a polarization splitting surface and a reflecting surface respectively inclined with respect to an optical path of the light from said illuminating means, said reflecting surface having one end in contact with one end of said polarization splitting surface so that said polarization splitting surface and said reflecting surface form an inverted V shape, said polarization splitting surface splitting part of the light from said illuminating means into a transmitted light component and a reflected light component and directing the transmitted light component in a first direction and the reflected light component toward said reflecting surface, said reflecting surface reflecting a remaining part of the light from said illuminating means and directing the reflected remaining part toward said polarization splitting surface, said reflecting surface returning the reflected light component toward said illuminating means, said polarization splitting surface splitting said remaining part of the light emitted from said illuminating means and reflected by said reflecting means into a transmitted light component of said remaining part and a reflected light component of said remaining part, said transmitted light component of said remaining part being directed toward a second direction different from the first direction, and the reflected light component of said remaining part being returned to said illuminating means,

wherein said illuminating means modulates a plane of each returned reflected light component and causes each returned reflected light component to be incident on said polarizing means again.

12. A polarization illumination device comprising:

illuminating means including a light source and a reflecting mirror located behind said light source; and

polarizing means illuminated with light from said illuminating means and having a plurality of units arranged in a first direction perpendicular to an optical path of the light from said illuminating means, each unit including a polarization splitting portion and a reflecting portion respectively inclined with respect to an optical path of the light from said illuminating means, said reflecting portion having upper and lower reflecting surfaces, said reflecting portion having one end in contact with one end of said polarization splitting portion so that said polarization splitting portion and said reflecting portion form an inverted V shape, said polarization splitting portion of said unit splitting part of the light from said illuminating means into a transmitted light component and a reflected light component and directing the transmitted light component in a second direction different form the first direction and the reflected light component toward said upper reflecting surface of said reflecting portion, said upper reflecting surface of said reflecting portion reflecting a remaining part of the light from said illuminating means and directing the reflected remaining part toward said polarization splitting portion, said upper reflecting surface of said reflecting portion returning the reflected light component toward said illuminating means, said polarization splitting portion splitting said remaining part of the light emitted from said illuminating means and reflected by said upper reflecting surface of said reflecting means into a transmitted light component of said remaining part and a reflected light component of said remaining part, the transmitted light component of said remaining part being directed toward the first direction and being reflected by said lower reflecting surface of said reflecting portion of an adjacent unit, and the reflected light component of said remaining part being returned to said illuminating means,

wherein said illuminating means modulates a plane of each returned reflected light component from each unit and causes each returned reflected light component to be incident on said polarizing means again.

13. A projector comprising:

illuminating means including a light source and a reflecting mirror located behind said light source;

polarizing means illuminated with light from said illuminating means and including a polarization splitting surface and a reflecting surface respectively inclined with respect to an optical path of the light from said illuminating means, said reflecting surface having one end in contact with one end of said polarization splitting surface so that said polarization splitting surface and said reflecting surface form an inverted V shape, said polarization splitting surface splitting part of the light from said illuminating means into a transmitted light component and a reflected light component and directing the transmitted light component in a first direction and the reflected light component toward said reflecting surface, said reflecting surface reflecting a remaining part of the light from said illuminating means and directing the reflected remaining part toward said polarization splitting surface, said reflecting surface returning the reflected light component toward said illuminating means, said polarization splitting surface splitting said remaining part of the light emitted from said illuminating means and reflected by said reflecting means into a transmitted light component of said remaining part and a reflected light component of said remaining part, said transmitted light component of said remaining part being directed toward a second direction different from the first direction, the reflected light component of said remaining part being returned to said illuminating means, and said polarizing means having a polarizing portion for directing, in substantially the same direction, the respective transmitted light components directed in the first and second directions,

wherein said illuminating means modulates a plane of each returned reflected light component and causes each returned reflected light component to be incident on said polarizing means again;

means for modulating the polarization planes of the transmitted light components from said polarizing means to generate an image; and

means for projecting the image.

14. A projector comprising:

illuminating means including a light source and a reflecting mirror located behind said light source;

polarizing means illuminated with light from said illuminating means and having a plurality of units arranged in a first direction perpendicular to an optical path of the light from said illuminating means, each unit including a polarization splitting portion and a reflecting portion respectively inclined with respect to an optical path of the light from said illuminating means, said reflecting portion having upper and lower reflecting surfaces, said reflecting portion having one end in contact with one end of said polarization splitting portion so that said polarization splitting portion and said reflecting portion form an inverted V shape, said polarization splitting portion of said unit splitting part of the light from said illuminating means into a transmitted light component and a reflected light component and directing the transmitted light component in a second direction different from the first direction and the reflected light component toward said upper reflecting surface of said reflecting portion, said upper reflecting surface of said reflecting portion reflecting a remaining part of the light from said illuminating means and directing the reflected remaining part toward said polarization splitting portion, said upper reflecting surface of said reflecting portion returning the reflected light component toward said illuminating means, said polarization splitting portion splitting said remaining part of the light emitted from said illuminating means and reflected by said upper reflecting surface of said reflecting means into a transmitted light component of said remaining part and a reflected light component of said remaining part, the transmitted light component of said remaining part directed toward the first direction being reflected in the second direction by said lower reflecting surface of said reflecting portion of an adjacent unit, and the reflected light component of said remaining part being returned to said illuminating means,

wherein said illuminating means modulates a plane of each returned reflected light component from each unit and causes each returned reflected light component to be incident on said polarizing means again.

means for modulating the polarization planes of the transmitted light components from said polarizing means to generate an image; and

means for projecting the image.

15. A polarization illumination device comprising:

illuminating means including a light source and a reflecting mirror located behind said light source;

polarizing means illuminated with substantially collimated light from said illuminating means and including polarization splitting means for splitting the light from said illuminating means into a transmitted light component and a reflected light component, and returning means for returning one of the light components to said illuminating means;

wherein said polarization splitting means is re-illuminated by said returned light component by way of said reflecting mirror; and

wherein said returning means is a reflecting surface oriented so as to return said one of the light components to said light source along an optical path different than that of said substantially collimated light, where said different optical path passes near but does not substantially impinge on said light source.

16. A projector comprising:

illuminating means including a light source and a reflecting mirror located behind said light source;

polarizing means, illuminated with substantially collimated light from said illuminating means, for supplying polarized light, said polarizing means including polarization splitting means for splitting the light from said illuminating means into a transmitted light component and a reflected light component, and returning means for returning one of the light components to said illuminating means;

wherein said polarization splitting means is re-illuminated by said returned light component by way of said reflecting mirror;

Wherein said returning means is a reflecting surface oriented so as to return said one of the light components to said light source along an optical path different than that of said substantially collimated light, where said different optical path passes near but does not substantially impinge on said light source;

means for modulating the polarization plane of the polarized light from said polarizing means to generate an image; and

means for projecting the image.