Light reflective polarizer and projector using the same

• US 20030179345A1
• Filed: 05/15/2003
• Published: 09/25/2003
• Est. Priority Date: 01/28/2000
• Status: Active Grant

• Current Assignee: Hidefumi Sakata, Yoshitaka Ito
• Original Assignee: Hidefumi Sakata, Yoshitaka Ito
• Inventors: Ito, Yoshitaka, Sakata, Hidefumi
• Granted Patent: US 6,764,182 B2
• Time in Patent Office: Days
• US Class Current: 353/20
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: G02B 5/1809 with pitch less than or comparable to the wavelength
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02B 5/3066 involving the reflection of light at a particular angle of incidence, e.g. Brewster's angle
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70566 Polarisation control
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells

Abstract

The present invention provides a projector that stably displays high-contrast, bright images by improving light resistance and heat resistance of a polarizer. The projector includes: a light source device; an electro-optic device that modulates light emitted from the light source device; two polarizers that are disposed respectively on a light incoming side and a light outgoing side of the electro-optic device; and a projection optical system that projects light output from the electro-optic device. At least one of the two polarizers is a structural birefringent polarizing plate.

Claims

1. A projector, comprising:

a light source device;

an electro-optic device that modulates light emitted from the light source device;

two polarizers that are disposed respectively on a light incoming side and a light outgoing side of the electro-optic device; and

a projection optical system that projects light output from the electro-optic device,

wherein at least one of the two polarizers is a structural birefringent polarizing plate.

2. The projector in accordance with claim 1, wherein the structural birefringent polarizing plate is a wiregrid polarizing plate.

3. The projector in accordance with claim 1, wherein the structural birefringent polarizing plate comprises:

a light transmissive crystal substrate; and

a fine periodic structure periodically formed in a predetermined direction on the light transmissive crystal substrate.

4. The projector in accordance with any one of claims 1 to 3, wherein the structural birefringent polarizing plate is inclined to a center axis of light illuminating the electro-optic device.

5. The projector in accordance with claim 4, wherein the structural birefringent polarizing plate is arranged at an inclination of about 45 degrees relative to the center axis.

6. The projector in accordance with any one of claims 1 to 3, wherein the structural birefringent polarizing plate is divided into a plurality of areas, and at least one of the plurality of areas is inclined to a center axis of light illuminating the electro-optic device.

7. The projector in accordance with claim 6, wherein at least one of the plurality of areas in the structural birefringent polarizing plate is arranged at an inclination of about 45 degrees relative to the center axis.

8. The projector in accordance with any one of claims 1 to 3, wherein a light absorbing polarizing plate is further arranged on a light outgoing side of the structural birefringent polarizing plate.

9. The projector in accordance with claim 8, wherein a light transmissive crystal substrate is further arranged on a light outgoing side of the light absorbing polarizing plate, and the light transmissive crystal substrate is appressed to the light absorbing polarizing plate.

10. The projector in accordance with any one of claims 1 to 3, wherein a light reflective polarizing plate is further arranged on a light outgoing side of the structural birefringent polarizing plate.

11. The projector in accordance with claim 10, wherein the light reflective polarizing plate is a multi-layered polarizing plate that is obtained by alternatively laminating a birefringent film and non-birefringent film.

12. A projector, comprising:

a light source device;

an electro-optic device that modulates light emitted from the light source device;

two polarizers that are disposed respectively on a light incoming side and a light outgoing side of the electro-optic device; and

a projection optical system that projects light output from the electro-optic device,

at least one of the two polarizers comprising;

a first prism having a light incoming surface and a light outgoing surface, which face to each other in a non-parallel orientation; and

a light reflective polarizing plate that is disposed on a side of the light outgoing surface of the first prism,

wherein the light reflective polarizing plate divides light emitted from the first prism into first and second polarized lights having different polarizing directions, and transmits the first polarized light while reflecting the second polarized light, and

an angle defined by the light incoming surface and the light outgoing surface of the first prism is set to cause the second polarized light, which has been reflected by the light reflective polarizing plate and returned to the first prism, to be totally reflected by the light incoming surface.

13. The projector in accordance with claim 12, wherein the first prism has an intersection line defined by the light incoming surface and the light outgoing surface, the intersection line being substantially parallel to longer sides of a rectangular display area on the electro-optic device.

14. The projector in accordance with claim 12, wherein a face of the first prism opposite to a vertical angle defined by the light incoming surface and the light outgoing surface of the first prism is set to cause the second polarized light totally reflected by the light incoming surface to enter the opposite face at substantially right angles.

15. The projector in accordance with claim 12, wherein the first prism is composed of a material having a photoelastic constant of not higher than about 1 nm/cm/10⁵ Pa.

16. The projector in accordance with claim 12, further comprising a second prism, which is disposed on a light outgoing side of the light reflective polarizing plate to receive the first polarized light transmitted through the light reflective polarizing plate.

17. The projector in accordance with claim 16, wherein at least one of the first prism and the second prism is composed of a material having a photoelastic constant of not higher than about 1 nm/cm/10⁵ Pa.

18. The projector in accordance with claim 16, wherein the second prism is arranged to make a travelling direction of the first polarized light emitted via the second prism substantially coincide with a travelling direction of light entering the first prism.

19. The projector in accordance with any one of claims 12 to 18, wherein a light absorbing polarizing plate is disposed on a light outgoing side of the light reflective polarizing plate.

20. The projector in accordance with any one of claims 12 to 18, wherein the light reflective polarizing plate is a structural birefringent polarizing plate.

21. The projector in accordance with claim 20, wherein the structural birefringent polarizing plate comprises a fine periodic structure periodically formed along a predetermined direction, and the predetermined direction is substantially perpendicular to an intersection line defined by the light incoming surface and the light outgoing surface of the first prism.

22. The projector in accordance with any one of claims 12 to 18, wherein the light reflective polarizing plate is a multi-layered polarizing plate that is obtained by alternatively laminating a birefringent film and non-birefringent film.

23. Aprojector, comprising:

a light source device;

an electro-optic device that modulates light emitted from the light source device;

two polarizers that are disposed respectively on a light incoming side and a light outgoing side of the electro-optic device; and

a projection optical system that projects light output from the electro-optic device,

at least one of the two polarizers including a plurality of polarizer elements,

each polarizer element comprising;

a first prism having a light incoming surface and a light outgoing surface, which face to each other in a non-parallel orientation; and

a light reflective polarizing plate that is disposed on a side of the light outgoing surface of the first prism,

wherein the plurality of polarizer elements are jointed in such a manner that the respective light incoming surfaces of the first prisms are located in a virtually same plane,

wherein in the each polarizer element,

the light reflective polarizing plate divides light emitted from the first prism into first and second polarized lights having different polarizing directions, and transmitting the first polarized light while reflecting the second polarized light, and

an angle defined by the light incoming surface and the light outgoing surface of the first prism is set to cause the second polarized light, which has been reflected by the light reflective polarizing plate and returned to the first prism, to be totally reflected by the light incoming surface.

24. A polarizer, comprising:

a first prism having a light incoming surface and a light outgoing surface, which face to each other in a non-parallel orientation; and

a light reflective polarizing plate that is disposed on a side of the light outgoing surface of the first prism,

wherein the light reflective polarizing plate divides light emitted from the first prism into first and second polarized lights having different polarizing directions, and transmits the first polarized light while reflecting the second polarized light, and

an angle defined by the light incoming surface and the light outgoing surface of the first prism is set to cause the second polarized light, which has been reflected by the light reflective polarizing plate and returned to the first prism, to be totally reflected by the light incoming surface.

25. The polarizer in accordance with claim 24, a face of the first prism opposite to a vertical angle defined by the light incoming surface and the light outgoing surface of the first prism is set to cause the second polarized light totally reflected by the light incoming surface to enter the opposite face at substantially right angles.

26. The polarizer in accordance with claim 24, wherein the first prism is composed of a material having a photoelastic constant of not higher than about 1 nm/cm/10⁵ Pa.

27. The polarizer in accordance with claim 24, further comprising a second prism, which is disposed on a light outgoing side of the light reflective polarizing plate to receive the first polarized light transmitted through the light reflective polarizing plate.

28. The polarizer in accordance with claim 27, wherein at least one of the first prism and the second prism is composed of a material having a photoelastic constant of not higher than about 1 nm/cm/10⁵ Pa.

29. The polarizer in accordance with claim 27, wherein the second prism is arranged to make a travelling direction of the first polarized light emitted via the second prism substantially coincide with a travelling direction of light entering the first prism.

30. The polarizer in accordance with any one of claims 24 to 29, wherein a light absorbing polarizing plate is disposed on a light outgoing side of the light reflective polarizing plate.

31. The polarizer in accordance with any one of claims 24 to 29, wherein the light reflective polarizing plate is a structural birefringent polarizing plate.

32. The polarizer in accordance with claim 31, wherein the structural birefringent polarizing plate comprises a fine periodic structure periodically formed along a predetermined direction, and the predetermined direction is substantially perpendicular to an intersection defined by the light incoming surface and the light outgoing surface of the first prism.

33. The polarizer in accordance with any one of claims 24 to 29, wherein the light reflective polarizing plate is a multi-layered polarizing plate that is obtained by alternatively laminating a birefringent film and non-birefringent film.

34. A polarizer comprising a plurality of polarizer elements, each polarizer element comprising:

a first prism having a light incoming surface and a light outgoing surface, which face to each other in a non-parallel orientation; and

a light reflective polarizing plate that is disposed on a side of the light outgoing surface of the first prism,

wherein the plurality of polarizer elements are jointed in such a manner that the respective light incoming surfaces of the first prisms are located in a virtually same plane,

wherein in the each polarizer element,

the light reflective polarizing plate divides light emitted from the first prism into first and second polarized lights having different polarizing directions, and transmitting the first polarized light while reflecting the second polarized light, and

an angle defined by the light incoming surface and the light outgoing surface of the first prism is set to cause the second polarized light, which has been reflected by the light reflective polarizing plate and returned to the first prism, to be totally reflected by the light incoming surface.