Digital cinema projector

• US 6,585,378 B2
• Filed: 03/20/2001
• Issued: 07/01/2003
• Est. Priority Date: 03/20/2001
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Eastman Kodak Company
• Inventors: Kurtz, Andrew F., Silverstein, Barry D., Kessler, David, Cobb, Joshua M., Harrigan, Michael E.
• Primary Examiner(s): Mahoney, Christopher
• Assistant Examiner(s): Cruz, Magda
• Application Number:
  US09/813,207
• Publication Number:
  US 20020171809A1
• Time in Patent Office: 833 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/38, 353/98, 353/84, 359/489, 359/668, 359/670
• US Class Current: 353/31
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• 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

Abstract

A digital cinema projector (100) for projection of color images onto a display surface comprises a light source (116), which produces a beam of light. Beam-shaping optics (130) homogenize and focus the beam of light and color splitting optics (132) separate focus beam of light into separate color beams. A first modulation optics system comprises a prepolarizer (212), which prepolarizes a first color beam; a wire grid polarization beamsplitter (224), which transmits a first predetermined polarization state of the prepolarized beam; a reflective spatial light modulator (204), which alters the transmitted prepolarized beam with information and reflects the image bearing first color beam through the wire grid polarization beamsplitter (224); and a wire grid polarization analyzer (228), which transmits the image bearing first color beam and attenuates unwanted polarization components. A recombination prism (232) combines the first color beam from the first modulation optical system with other image bearing color beams to create a full color image bearing beam. A projection lens system (150) projects the full color image bearing beam onto the display surface (140).

Claims

1. A digital cinema projector for projection of color images onto a display surface comprising:

(a) a light source which produces a beam of light;

(b) beam shaping optics for homogenizing and focusing said beam of light to provide a homogenized focused light beam;

(c) color splitting optics for separating said homogenized focused light beam into a plurality of color beams;

(d) a first modulation optical system for modulating a first color beam to provide an image-bearing first color beam, said first modulation optical system comprising;

(1) a prepolarizer for prepolarizing said first color beam;

(2) a wire grid polarization beamsplitter which transmits a first predetermined polarization state of said prepolarized first color beam and reflects remaining portions of said prepolarized first color beam having a second polarization state orthogonal to said first predetermined polarization state and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(3) said reflective spatial light modulator having a plurality of individual elements which alter said predetermined polarization state of said transmitted prepolarized first color beam to provide said image-bearing first color beam, which reflects said image-bearing first color beam off of said wire grid polarization beamsplitter;

(4) a polarization analyzer which transmits said image-bearing first color beam and attenuates unwanted polarization components of said image-bearing first color beam;

(e) a recombination prism which combines said image-bearing first color beam from said first modulation optical system with other image-bearing color beams to provide a full-color image-bearing beam; and

(f) a projection lens system for projecting said full-color image-bearing beam onto said display surface.

2. A digital cinema projector as in claim 1 comprising:

(g) a second modulation optical system for modulating a second color beam to provide an image-bearing second color beam, said second modulation optical system comprising;

(1) a prepolarizer for prepolarizing said second color beam;

(2) a wire grid polarization beamsplitter which transmits said first predetermined polarization state of said second prepolarized second color beam and reflects remaining portions of said prepolarized second color beam having a second polarization state orthogonal to said first predetermined polarization state and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(3) said reflective spatial light modulator having a plurality of individual elements which alter said first polarization state of said transmitted prepolarized second color beam to provide said image-bearing second color beam, which reflect said image-bearing second color beam off of said wire grid polarization beamsplitter; and

(4) a polarization analyzer which transmits said image-bearing first color beam and attenuates unwanted polarization components of said image-bearing second color beam.

3. The digital cinema projector of claim 1 wherein said separated color beams comprise red, green, and blue beams.

4. The digital cinema projector of claim 1 wherein said color splitting optics comprise a recombination prism.

5. The digital cinema projector of claim 1 wherein said prepolarizer optics comprise a wire grid polarizer.

6. The digital cinema projector of claim 1 wherein said reflective spatial light modulator comprises a liquid-crystal device.

7. The digital cinema projector of claim 6 wherein said liquid-crystal device employs vertically aligned liquid crystal molecules.

8. The digital cinema projector of claim 1 wherein said projection lens system comprises an integrated anamorphic lens.

9. The digital cinema projector of claim 8 wherein said integrated anamorphic lens comprises a base lens comprising spherical lens elements.

10. The digital cinema projector of claim 9 wherein said anamorphic lens further comprises an anamorphic attachment.

11. The digital cinema projector of claim 10 wherein said anamorphic attachment comprises spherical lens elements.

12. The digital cinema projector of claim 11 wherein said anamorphic attachment further comprises cylindrical lens elements.

13. The digital cinema projector of claim 10 wherein said anamorphic attachment comprises cylindrical lens elements.

14. The digital cinema projector of claim 1 wherein said projection lens system provides anamorphic magnification at 1.39×

on the display surface.

15. The digital cinema projector of claim 14 wherein said projection lens system provides anamorphic magnification to provide cinemascopic format on the display surface.

16. The digital cinema projector of claim 1 wherein said modulation optical system further comprises a compensator to correct for residual polarization errors of said spatial light modulator or of said wire grid polarization beamsplitter.

17. The digital cinema projector of claim 1 wherein said modulation optical system further comprises a color-tuning waveplate.

18. The digital cinema projector of claim 1 wherein an aperture of said projection lens system operates at f/2.3 at an object plane which contains said spatial light modulator.

19. The digital cinema projector of claim 1 wherein a half-wave plate is disposed prior to said recombination prism for said green image-bearing color beam.

20. The digital cinema projector of claim 1 wherein said beam-shaping optics comprise an integrating bar.

21. The digital cinema projector of claim 1 wherein image-bearing separated color beams are vignetted by said recombination prism.

22. A digital cinema projector as in claim 1 wherein said wire grid polarization beamsplitter is in a telecentric space.

23. A digital cinema projector as in claim 1 wherein said recombination prism is an x-prism.

24. A digital cinema projector for projecting color images onto a display surface comprising:

(a) a light source which produces a beam of light;

(b) beam shaping optics for homogenizing and focusing said beam of light to provide a homogenized focused light beam;

(c) color splitting optics for separating said homogenized focused light beam into a plurality of color beams;

(d) a plurality of modulation optical systems for modulating each of said color beams to provide image-bearing color beams, each of said modulation optical systems comprising;

(1) a prepolarization optic for prepolarizing one of said color beams;

(2) a wire grid polarization beamsplitter which reflects one of said prepolarized color beams having a predetermined polarization state and transmits remaining portions of said prepolarized color beams having an orthogonal polarization state and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(3) said reflective spatial light modulator having a plurality of individual elements which alter said predetermined polarization state of said transmitted prepolarized color beam to provide said image-bearing separated color beam, and which transmits said image-bearing color beam through said wire grid polarization beamsplitter;

(4) a polarization analyzer which transmits said image-bearing color beam and attenuates unwanted polarization components of said image-bearing color beam;

(e) a recombination prism which combines each of said image-bearing color beams from each of said modulation optical systems to provide a full-color image-bearing beam; and

(f) a projection lens system for projecting said full-color image-bearing beam onto said display surface.

25. The digital cinema projector of claim 24 wherein said separated color beams comprise red, green, and blue beams.

26. The digital cinema projector of claim 24 wherein said projection lens system further comprises a wedge compensator.

27. The digital cinema projector of claim 24 wherein said projection lens system further comprises a cylindrical lens at the stop of said base lens.

28. A method for electronic projection of sequential color image frames onto a display surface for digital cinema comprising:

(a) providing a light source;

(b) focusing and homogenizing light from said light source;

(c) splitting said homogenized focused light beam into a red beam, a green beam, and a blue beam;

(d) modulating each of said red beam, green beam, and blue beam to provide an image-bearing red beam, an image-bearing green beam, and an image-bearing blue beam by;

(1) prepolarizing each of said red beam, green beam, and blue beam;

(2) disposing wire grid polarization beamsplitters in front of each of said prepolarized red beam, green beam, and blue beam wherein said wire grid polarization beamsplitters transmit a portion of said prepolarized red beam, green beam, and blue beam having a preferred polarization state and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(3) modulating each of said transmitted red beam, green beam, and blue beam to provide an image-bearing red beam, an image-bearing green beam, and an image-bearing blue beam;

(4) reflecting each of said image-bearing red beam, image-bearing green beam, and image-bearing blue beam off of said wire grid polarization beamsplitter;

(5) analyzing each of said image-bearing red beam, image-bearing green beam, and image-bearing blue beam using a polarization analyzer to attenuate unwanted polarization components;

(e) recombining each said image-bearing red beam, image-bearing green beam, and image-bearing blue beam to provide a full-color image-bearing beam; and

(f) projecting said full-color image-bearing beam onto said display surface.

29. The method of claim 28 wherein the step of focusing and homogenizing light from said light source using beam shaping optics comprises the step of using an integrating bar.

30. The method of claim 28 wherein the step of projecting said full-color image-bearing beam comprises the step of anamorphically projecting said full-color image-bearing beam.

31. The method of claim 28 wherein the step of modulating each said transmitted prepolarized red beam, green beam, and blue beam comprises the step of providing a liquid-crystal device as said spatial light modulator.

32. A method for electronic projection of sequential color image frames onto a display surface for digital cinema comprising:

(a) providing a light source;

(b) focusing and homogenizing light from said light source;

(c) splitting said homogenized focused light beam into a red beam, a green beam, and a blue beam;

(d) modulating each of said red beam, green beam, and blue beam;

(1) prepolarizing each of said red beam, green beam, and blue beam to provide a prepolarized red beam, a prepolarized green beam, and a prepolarized blue beam;

(2) disposing wire grid polarization beamsplitters to reflect a portion of said prepolarized red beam, prepolarized green beam, and prepolarized blue beam having a preferred polarization state and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(3) modulating each of said preferred prepolarized red beam, green beam, and blue beam using a spatial light modulator to provide an image-bearing red beam, an image-bearing green beam, and an image-bearing blue beam;

(4) transmitting each image-bearing red beam, image-bearing green beam, and image-bearing blue beam through said wire grid polarization beamsplitters;

(5) analyzing said image-bearing red beam, green beam, and blue beam using a polarization analyzer to attenuate unwanted polarization components;

(e) recombining each said image-bearing red beam, green beam, and blue beam to provide a full-color image-bearing beam; and

(f) projecting said full-color image-bearing beam onto said display surface with a projection lens system.

33. The method of claim 32 wherein said projection lens system further comprises a wedge compensator and a cylindrical lens at the stop of said projection lens system.

36. The digital cinema projector of claim 32 wherein said digital cinema projection operates at a color averaged frame sequential contrast >

1,000;

1.

34. A digital cinema projector for projecting color images onto a display surface comprising:

(a) a light source which produces a beam of light;

(b) an optical system which separates said beam of light into separate color beams of light, and which provides beam shaping and focusing for each of said color beams of light;

(c) modulation optical systems for each of said color beams of light, said modulation system comprising;

(1) polarization optics including at least two wire grid polarization devices, where at least one of said wire grid polarization devices is a wire grid polarization beamsplitter, and

(2) a reflective spatial light modulator which alters a polarization state of said color beams of light in a controlled manner with image data;

(d) a recombination prism for combining said separated color beams bearing image data into a full color image-bearing beam;

(e) a projection lens system for projecting said full-color image-bearing beam onto said display surface; and

(f) wherein said digital cinema projector provides full color image-bearing beam illumination of said display surface.

35. The digital cinema projector of claim 34 wherein said separated color beams are red, green, and blue respectively.

37. The digital cinema projector of claim 34 wherein said polarization optics comprise a wire grid polarizer to prepolarize each of said color beams of light;

a wire grid polarization beamsplitter used in transmission during illumination of said spatial light modulator array with said color beam of light, and then used in reflection for separating said color beams of light bearing image data; and

a wire grid polarizer to analyze said color beams of light.

38. The digital cinema projector of claim 34 wherein said polarization optics comprise a wire grid polarizer to prepolarize each of said color beams of light;

a wire grid polarization beamsplitter used in reflection during illumination of said spatial light modulator array with said color beam of light, and then used in transmission for separating said color beams of light bearing image data; and

a wire grid polarizer to analyze said color beams of light.

39. An electronic projection apparatus for projection of color images onto a display surface, said apparatus comprising:

(a) a light source which produces a beam of light;

(b) an optical system which separates said beam of light into separate color beams of light, and which provides beam shaping and focusing of said color beams of light;

(c) a modulation optical system for each of said color beams of light, said modulation system comprising;

(1) polarization optics including at least two wire grid polarization devices, where at least one of said wire grid polarization devices is a wire grid polarization beamsplitter and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator; and

(2) said reflective spatial light modulator which alters a polarization state of said color beams of light in a controlled manner with image data;

(d) a recombination prism for combining said separated color beams bearing image data into a full color image bearing beam; and

(e) a projection lens system for projecting said full-color image-bearing beam onto said display surface.

40. A digital cinema projector for projection of color images onto a display surface comprising:

(a) a light source which produces a beam of light;

(b) beam shaping optics for homogenizing and focusing said beam of light to provide a homogenized focused light beam;

(c) color splitting optics for separating said homogenized focused light beam into a plurality of color beams;

(d) a first modulation optical system for modulating a first color beam to provide an image-bearing first color beam, said first modulation optical system comprising;

(1) a prepolarizer for prepolarizing said first color beam;

(2) a wire grid polarization beamsplitter which transmits a first predetermined polarization state of said prepolarized first color beam and reflects remaining portions of said prepolarized first color beam having a second polarization state orthogonal to said first predetermined polarization state and wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(3) said reflective spatial light modulator having a plurality of individual elements which alter said predetermined polarization state of said transmitted prepolarized first color beam to provide said image-bearing first color beam, which reflects said image-bearing first color beam off of said wire grid polarization beamsplitter;

(4) a polarization analyzer which transmits said image-bearing first color beam and attenuates unwanted polarization components of said image-bearing first color beam;

(e) a recombination prism which combines said image-bearing first color beam from said first modulation optical system with other image-bearing color beams to provide a full-color image-bearing beam;

(f) a projection lens system for projecting said full-color image-bearing beam onto said display surface; and

(g) wherein said wire grid polarization beamsplitter is in a telecentric space.

41. An electronic projection apparatus for projection of color images onto a display surface comprising:

(a) a light source which produces a beam of light;

(b) beam shaping optics for homogenizing and focusing said beam of light to provide a homogenized focused light beam;

(c) color splitting optics for separating said homogenized focused light beam into a plurality of color beams;

(d) a first modulation optical system for modulating a first color beam to provide an image-bearing first color beam, said first modulation optical system comprising;

(1) a prepolarizer for prepolarizing said first color beam;

(2) a wire grid polarization beamsplitter which transmits a first predetermined polarization state of said prepolarized first color beam and reflects remaining portions of said prepolarized first color beam having a second polarization state orthogonal to said first predetermined polarization state;

(3) a reflective spatial light modulator having a plurality of individual elements which alter said predetermined polarization state of said transmitted prepolarized first color beam to provide said image-bearing first color beam, which reflects said image-bearing first color beam off of said wire grid polarization beamsplitter;

(4) a polarization analyzer which transmits said image-bearing first color beam and attenuates unwanted polarization components of said image-bearing first color beam;

(e) a recombination prism which combines said image-bearing first color beam from said first modulation optical system with other image-bearing color beams to provide a full-color image-bearing beam; and

(f) a projection lens system for projecting said full-color image-bearing beam onto said display surface.

42. A modulation optical system for providing high contrast modulation of an incident light beam, comprising:

(a) a prepolarizer for prepolarizing said beam of light to provide a polarized beam of light;

(b) a wire grid polarization beamsplitter for receiving said polarized beam of light, for transmitting said polarized beam of light having a first polarization, and for reflecting said polarized beam of light having a second polarization orthogonal to said first polarization, wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(c) wherein said reflective spatial light modulator selectively modulates said polarized beam of light having a first polarization to encode data thereon to form a modulated beam, and for reflecting said modulated beam back to said wire grid polarization beamsplitter; and

(d) a polarization analyzer which receives said modulated light, and which further removes any residual unmodulated light from said modulated light.

43. A modulation optical system as in claim 42 wherein said modulator is a liquid crystal device.

44. A modulation optical system as in claim 43 wherein said liquid crystal display device is comprised of vertically aligned liquid crystal molecules.

45. A modulation optical system as in claim 42 wherein said prepolarizer comprises a wire grid polarizer.

46. A modulation optical system as in claim 42 wherein said polarization analyzer comprises a wire grid polarizer.

47. A modulation optical system for providing high contrast modulation of an incident light beam comprising:

(a) a prepolarizer for pre-polarizing said beam of light to provide a polarized beam of light;

(b) a wire grid polarization beamsplitter for receiving said polarized beam of light, for transmitting said polarized beam of light having a first polarization, and for reflecting said polarized beam of light having a second polarization orthogonal to said first polarization, wherein subwavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(c) wherein said reflective spatial light modulator receives said polarized beam of light, having either a first polarization or a second polarization, and selectively modulates said polarized beam of light to encode data thereon, providing both modulated light and unmodulated light which differ in polarization;

(d) wherein said reflective spatial light modulator reflects back both said modulated light and said unmodulated light to said wire grid polarization beamsplitter;

(e) wherein said wire grid polarization beamsplitter separates said modulated light from said unmodulated light; and

(f) a polarization analyzer receives said modulated light, and which further removes any residual unmodulated light from said modulated light.

48. A modulation optical system as in claim 47 wherein said modulator is a liquid crystal display device.

49. A modulation optical system as in claim 48 wherein said liquid crystal display device is comprised of vertically aligned liquid crystal molecules.

50. A modulation optical system as in claim 47 wherein said prepolarizer comprises a wire grid polarizer.

51. A modulation optical system as in claim 47 wherein said polarization analyzer comprises a wire grid polarizer.

52. A modulation optical system as in claim 47 wherein said reflective spatial light modulator receives said polarized beam of light having a first polarization state transmitted through said wire grid polarization beamsplitter.

53. A modulation optical system as in claim 47 wherein said reflective spatial light modulator receives said polarized beam of light having a second polarization state reflected from said wire grid polarization beamsplitter.