HIGH EFFICIENCY DIGITAL CINEMA PROJECTION SYSTEM WITH INCREASED ETENDUE

• US 20070273796A1
• Filed: 04/25/2007
• Published: 11/29/2007
• Est. Priority Date: 05/26/2006
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Kircher, James R., Bietry, Joseph R., Silverstein, Barry D.
• Granted Patent: US 7,458,687 B2
• Time in Patent Office: Days
• US Class Current: 348/752
• CPC Class Codes: G02B 13/22 Telecentric objectives or lens systems
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/10 with curved faces
• 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 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

A digital cinema projection apparatus having an illumination source with a first etendue value for providing polarized polychromatic light. A first lens element lies in the path of the polarized polychromatic light for forming a substantially telecentric polarized polychromatic light beam. A color separator separates the telecentric polarized polychromatic light beam into at least two telecentric color light beams. At least two transmissive spatial light modulators modulate the two telecentric color light beams. There is an etendue value associated with each spatial light modulator. The etendue value is within 15% or greater than the first etendue value corresponding to the illumination source. A color combiner combines the modulated color beams along a common optical axis, forming a multicolor modulated beam thereby; and a projection lens directs the multicolor modulated beam toward a display surface.

Claims

1. A digital cinema projection apparatus comprising:

a) an illumination source having a first etendue value for providing polarized polychromatic light;

b) a first lens element in the path of the polarized polychromatic light for forming a substantially telecentric polarized polychromatic light beam;

c) a color separator for separating the telecentric polarized polychromatic light beam into at least two telecentric color light beams;

d) at least two transmissive spatial light modulators that modulate the two telecentric color light beams and form at least two modulated color beams,

wherein there is an etendue value associated with each spatial light modulator, and wherein the etendue value is within 15% or greater than the first etendue value corresponding to the illumination source;

e) a color combiner for combining the modulated color beams along a common optical axis, forming a multicolor modulated beam thereby; and

f) a projection lens for directing the multicolor modulated beam toward a display surface.

2. The apparatus of claim 1 wherein the first spatial light modulator has a active surface diagonal of greater than about 5 inches.

3. The apparatus of claim 1 wherein the multicolor modulated beam exceeds 5,000 lumens.

4. The apparatus of claim 1 wherein the first lens element comprises a Fresnel lens.

5. The apparatus of claim 1 further comprising a second lens element in the path of at least one modulated color beam.

6. The apparatus of claim 1 further comprising a first compensator in the path of at least one modulated color beam.

7. The apparatus of claim 6 further comprising a first polarization analyzer disposed between the first compensator and the projection lens.

8. The apparatus of claim 6 further comprising a second compensator in the path of at least one telecentric color light beam.

9. The apparatus of claim 1 further comprising a polarization rotator in the path of at least one modulated color beam.

10. The apparatus of claim 1 further comprising an uniformizer optically coupled to the illumination source.

11. The apparatus of claim 1 wherein the illumination source comprises an element taken from the group consisting of an LED, an LED array, a Xenon lamp, a laser and a Mercury lamp.

12. The apparatus of claim 10 wherein the uniformizer comprises a lenslet array.

13. The apparatus of claim 10 wherein the uniformizer comprises an integrating bar.

14. The apparatus of claim 1 wherein the illumination source further comprises a polarization rotation element for at least a portion of the illumination.

15. The apparatus of claim 1 further comprising a reflective color filter array that provides color recycling.

16. The apparatus of claim 1 wherein at least one spatial modulator is a transmissive thin-film transistor liquid crystal modulator.

17. The apparatus of claim 16 wherein the thin film transistors are organic thin film transistors.

18. The apparatus of claim 16 wherein the thin film transistors comprise carbon nanotubes.

19. The apparatus of claim 1 wherein the illumination source further comprises a wire grid polarizer.

20. The apparatus of claim 1 further comprising a polarizer in the path of at least one modulated color beam.

21. The apparatus of claim 20 wherein the polarizer is taken from the group consisting of an absorptive polarizer and a reflective polarizer.

22. The apparatus of claim 1 further comprising a diffuse reflective polarizer film in the path of the telecentric polarized polychromatic light.

23. The apparatus of claim 1 further comprising a dispersive optical component in the path of the first telecentric color light beam.

24. The apparatus of claim 1 wherein at least one transmissive liquid crystal spatial light modulator has a active surface diagonal of greater than about 10 inches.

25. The apparatus of claim 1 wherein at least one transmissive liquid crystal spatial light modulator is formed on a non-crystalline substrate.

26. The apparatus of claim 1 wherein the color separator further forms a third telecentric color light beam and the apparatus further comprises a third transmissive spatial light modulator in the path of the third telecentric color light beam and modulating the third telecentric color beam to form a third modulated color beam,

and wherein the color combiner further combines the third modulated color beam with the first and second modulated color beams along the common optical axis, forming the multicolor modulated beam thereby.

27. The apparatus of claim 1 wherein at least one transmissive liquid crystal spatial light modulator comprises an antireflection coating.

28. The apparatus of claim 1 wherein optical path lengths between the illumination source and the at least two spatial light modulators differ.

29. The apparatus of claim 9 wherein the polarizer comprises a stacked polarizer.

30. The apparatus of claim 1 wherein the projection lens comprises an anamorphic lens.

31. The apparatus of claim 1 wherein at least one transmissive liquid crystal spatial light modulator comprises a dust barrier.

32. The apparatus of claim 1 wherein the illumination source comprises a bubble lamp.

33. The apparatus of claim 32 wherein the illumination source images the side profile of the bubble lamp.

34. The apparatus of claim 1 wherein the illumination source comprises at least two LEDs having a different spectral range.

35. The apparatus of claim 1 further comprising at least one dithering actuator taken from the group consisting of a motor, a piezo-electric actuator, and a solenoid.

36. The apparatus of claim 35 wherein the at least one dithering actuator tilts a plano glass plate.

37. The apparatus of claim 1 further comprising a blur filter in the path of at least one modulated color beam.

38. The apparatus of claim 1 further comprising a blur filter in the path of the multicolor modulated color beam.

39. The apparatus of claim 1 further comprising a rotating wedge in the path of the multicolor modulated color beam.

40. The apparatus of claim 1 further comprising a rotating plate in the path of the multicolor modulated color beam.

41. The apparatus of claim 40 wherein the rotating plate is tilted with respect to the common optical axis.

42. The apparatus of claim 1 further comprising a shutter in the path of the telecentric polarized polychromatic light.

43. The apparatus of claim 1 further comprising a concave curved reflective surface for redirecting the multicolor modulated beam toward a convex curved reflective surface.

44. The apparatus of claim 43 wherein the convex curved reflective surface is disposed near the focal plane of the projection lens.

45. The apparatus of claim 43 wherein the convex curved reflective surface is aspheric.

46. The apparatus of claim 43 wherein the concave curved reflective surface is toroidal.

47. The apparatus of claim 1 wherein at least one transmissive spatial light modulators is mounted as a single field-replaceable unit.

48. The apparatus of claim 35 wherein the at least one dithering actuator tilts a wire grid polarizer.

49. The apparatus of claim 1 wherein at least one transmissive spatial light modulator uses magneto-photonic crystal modulation.

50. The apparatus of claim 1 further comprises at least one periscopic mirror assembly to package the projection lenses closer together.

51. A digital cinema projection apparatus comprising:

a) an illumination source comprising a lens element for providing polarized telecentric polychromatic light at a first etendue value;

b) a spectral separator for separating the polarized telecentric polychromatic light beam into at least a first telecentric color light beam and a second telecentric color light beam;

c) a color modulation section comprising at least;

i) a first transmissive spatial light modulator in the path of the first telecentric color light beam and modulating the first telecentric color beam to form a first modulated color beam;

ii) a second transmissive spatial light modulator in the path of the second telecentric color light beam and modulating the second telecentric color beam to form a second modulated color beam,

wherein there is a second etendue value at the first spatial light modulator and wherein the second etendue value is within 15% of the first etendue value;

d) a color combiner for combining at least the first and second modulated color beams along a common optical axis, forming a multicolor modulated beam thereby; and

e) a projection lens coaxial to the common optical axis for directing the multicolor modulated beam toward a display surface.

52. The apparatus of claim 51 wherein at least one transmissive spatial light modulator uses magneto-photonic crystal modulation.

53. A digital cinema projection apparatus comprising:

a) an illumination source comprising a lens element for providing polarized telecentric polychromatic light;

b) a spectral separator for separating the polarized telecentric polychromatic light beam into at least a first telecentric color light beam and a second telecentric color light beam;

c) a color modulation section comprising at least;

i) a first spatial light modulator in the path of the first telecentric color light beam and modulating the first telecentric color beam to form a first modulated color beam;

ii) a second spatial light modulator in the path of the second telecentric color light beam and modulating the second telecentric color beam to form a second modulated color beam,

d) a color combiner for combining at least the first and second modulated color beams along a common optical axis, forming a multicolor modulated beam thereby;

e) a concave curved reflective surface for redirecting the multicolor modulated beam toward a convex curved reflective surface ; and

f) a projection lens coaxial to the common optical axis for directing the multicolor modulator beam toward a display surface.

54. The projection apparatus of claim 53 wherein the convex curved reflective surface is disposed near the focal plane of the projection lens.

55. The projection apparatus of claim 53 wherein the convex curved reflective surface is aspheric.

56. The projection apparatus of claim 53 wherein the concave curved reflective surface is toroidal.

57. The projection apparatus of claim 53 wherein at least one transmissive spatial light modulator is a transmissive liquid crystal formed on a non-crystalline substrate.

58. The apparatus of claim 53 wherein at least one transmissive spatial light modulator uses magneto-photonic crystal modulation.