Polarization conversion system and method for projecting polarization encoded imagery

• US 10,203,511 B2
• Filed: 07/20/2017
• Issued: 02/12/2019
• Est. Priority Date: 05/09/2007
• Status: Active Grant

• Current Assignee: RealD Incorporated
• Original Assignee: RealD Incorporated
• Inventors: Schuck, Miller H., Robinson, Michael G., Sharp, Gary D.
• Primary Examiner(s): Le, Bao-Luan
• Application Number:
  US15/655,693
• Publication Number:
  US 20180074337A1
• Time in Patent Office: 572 Days
• CPC Class Codes: G02B 13/00 Optical objectives specially designed for the purposes specified below with variable magnification in general G02B15/00
• CPC Class Codes: G02B 26/008 in the form of devices for effecting sequential colour changes, e.g. colour wheels
• CPC Class Codes: G02B 30/24 involving temporal multiplexing, e.g. using sequentially activated left and right shutters
• CPC Class Codes: G02B 30/25 using polarisation techniques
• CPC Class Codes: H04N 13/337 using polarisation multiplexing
• CPC Class Codes: H04N 13/341 using temporal multiplexing

Abstract

A polarization conversion system separates light from an unpolarized image source into a first state of polarization (SOP) and an orthogonal second SOP, and directs the polarized light on first and second light paths. The SOP of light on only one of the light paths is transformed to an orthogonal state such that both light paths have the same SOP. A polarization modulator temporally modulates the light on the first and second light paths to first and second output states of polarization. First and second projection lenses direct light on the first and second light paths toward a projection screen to from substantially overlapping polarization encoded images. The polarization modulator may be located before or after the projection lenses. The polarization-encoded images may be viewed using eyewear with appropriate polarization filters.

Claims

1. A polarization conversion system for transmitting polarization encoded imagery to a projection screen, comprising:

a polarization beam splitter operable to receive image light from an image source, operable to transmit image light of a first polarization state toward a first image light path, and operable to reflect image light of a second polarization state toward a second image light path;

a first polarization switch located on at least one of the first image light path and the second image light path, the polarization switch operable to selectively alternate the polarization of image light passing therethrough between a first output state of polarization and a second output state of polarization so that the image light passing therethrough has sequentially alternating polarizations;

a first projection lens located on the first image light path, wherein the first projection lens is operable to project the image light of the first image light path onto the projection screen as a first diverging light beam between the first projection lens and the projection screen;

a second projection lens located on the second image light path, wherein the second projection lens is operable to project the image light of the second path image light onto the projection screen as a second diverging light beam between the second projection lens and the projection screen;

wherein the first and second projection lenses are further operable to direct the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen;

wherein the polarization conversion system is positioned between the image source and the projection screen; and

wherein the first polarization switch operates such that the first and second diverging light beams have the same state of polarization as they simultaneously reach the projection screen.

2. The polarization conversion system of claim 1, wherein the image light received at polarization beam splitter is randomly polarized light.

3. The polarization conversion system of claim 1, wherein of the light received at the polarization beam splitter is imaged at the projection screen with a single polarization state.

4. The polarization conversion system of claim 1, further comprising a reflector positioned on the second image light path, wherein the reflector is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

5. The polarization conversion system of claim 4, wherein the reflector is a mirror.

6. The polarization conversion system of claim 4, wherein the reflector is a prism.

7. The polarization conversion system of claim 1, further comprising a relay lens located optically after the first polarization switch.

8. The polarization conversion system of claim 1, further comprising a polarization rotator located optically before the first polarization switch.

9. The polarization conversion system of claim 8, wherein the polarization rotator is a half-wave plate.

10. The polarization conversion system of claim 8, wherein the polarization rotator is optically adjacent to the first polarization switch.

11. The polarization conversion system of claim 1, further comprising a second polarization switch located on the other of the first image light path and the second image light path relative to the first polarization switch.

12. The polarization conversion system of claim 11, further comprising a relay lens located optically after the second polarization switch.

13. The polarization conversion system of claim 11, further comprising a polarization rotator located optically before the second polarization switch.

14. The polarization conversion system of claim 13, wherein the polarization rotator is a half-wave plate.

15. The polarization conversion system of claim 13, wherein the polarization rotator is optically adjacent to the second polarization switch.

16. The polarization conversion system of claim 1, wherein the first polarization switch is located optically before the first or the second projection lens on the respective first or second image light path.

17. The polarization conversion system of claim 1, wherein the first polarization switch is located optically after the first or the second projection lens on the respective first or second image light path.

18. The polarization conversion system of claim 11, wherein the second polarization switch is located optically before the first or the second projection lens on the respective first or second image light path.

19. The polarization conversion system of claim 11, wherein the second polarization switch is located optically after the first or the second projection lens on the respective first or second image light path.

20. The polarization conversion system of claim 1, further comprising a prism positioned on the second image light path, wherein the prism is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

21. The polarization conversion system of claim 20, wherein the prism is a glass prism.

22. The polarization conversion system of claim 20, wherein the prism comprises an angled surface that optically operates as a fold mirror.

23. The polarization conversion system of claim 22, wherein the angled surface operates to reflect the image light striking it through total internal reflection.

24. The polarization conversion system of claim 22, wherein the angled surface is coated with a mirror layer.

25. The polarization conversion system of claim 24, wherein the coated mirror layer comprises silver.

26. The polarization conversion system of claim 20, further comprising an aperture stop optically before the prism.

27. The polarization conversion system of claim 20 wherein the prism is operable to be tilted in order to facilitate the directing of the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen.

28. The polarization conversion system of claim 1 wherein the polarizing beam splitter is operable to be tilted in order to facilitate the directing of the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen.

29. The polarization conversion system of claim 1 wherein the projection lenses are operable to be laterally displaced from the light path in order to facilitate the directing of the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen.

30. The polarization conversion system of claim 1, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between horizontal and vertical linear polarization.

31. The polarization conversion system of claim 1, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between left- and right-handed circular polarization.

32. A polarization conversion system for transmitting polarization encoded imagery to a projection screen, comprising:

a polarization beam splitter operable to receive image light from an image source, operable to transmit image light of a first polarization state toward a first image light path, and operable to reflect image light of a second polarization state toward a second image light path;

a first polarization switch located on at least one of the first image light path and the second image light path, the polarization switch operable to selectively alternate the polarization of image light passing therethrough between a first output state of polarization and a second output state of polarization so that the image light passing therethrough has sequentially alternating polarizations;

a first projection lens located on the first image light path, wherein the first projection lens is operable to project the image light of the first image light path onto the projection screen as a first diverging light beam between the first projection lens and the projection screen;

a second projection lens located on the second image light path, wherein the second projection lens is operable to project the image light of the second path image light onto the projection screen as a second diverging light beam between the second projection lens and the projection screen; and

a reflector positioned on the second image light path, wherein the reflector is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path;

wherein the image light received at polarization beam splitter is randomly polarized light;

wherein the first and second projection lenses are further operable to direct the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen;

wherein the polarization conversion system is positioned between the image source and the projection screen;

wherein the first polarization switch operates such that the first and second diverging light beams have the same state of polarization as they simultaneously reach the projection screen; and

wherein of the light received at the polarization beam splitter is imaged at the projection screen with a single polarization state.

33. The polarization conversion system of claim 32, wherein the reflector is a mirror.

34. The polarization conversion system of claim 32, wherein the reflector is a prism.

35. The polarization conversion system of claim 32, further comprising a polarization rotator located optically before the first polarization switch.

36. The polarization conversion system of claim 32, wherein the polarization rotator is a half-wave plate.

37. The polarization conversion system of claim 32, wherein the polarization rotator is optically adjacent to the first polarization switch.

38. The polarization conversion system of claim 32, further comprising a second polarization switch located on the other of the first image light path and the second image light path relative to the first polarization switch.

39. The polarization conversion system of claim 38, further comprising a polarization rotator located optically before the second polarization switch.

40. The polarization conversion system of claim 38, wherein the polarization rotator is a half-wave plate.

41. The polarization conversion system of claim 38, wherein the polarization rotator is optically adjacent to the second polarization switch.

42. The polarization conversion system of claim 32, wherein the first polarization switch is located optically before the first or the second projection lens on the respective first or second image light path or after the first or the second projection lens on the respective first or second image light path.

43. The polarization conversion system of claim 38, wherein the second polarization switch is located optically before the first or the second projection lens on the respective first or second image light path.

44. The polarization conversion system of claim 38, wherein the second polarization switch is located optically after the first or the second projection lens on the respective first or second image light path.

45. The polarization conversion system of claim 32, further comprising a prism positioned on the second image light path, wherein the prism is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

46. The polarization conversion system of claim 45, further comprising an aperture stop optically before the prism.

47. The polarization conversion system of claim 45, wherein the prism is operable to be tilted in order to facilitate the directing of the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen.

48. The polarization conversion system of claim 32, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between horizontal and vertical linear polarization.

49. A polarization conversion system for transmitting polarization encoded imagery to a projection screen, comprising:

a polarization beam splitter operable to receive image light from an image source, operable to transmit image light of a first polarization state toward a first image light path, and operable to reflect image light of a second polarization state toward a second image light path;

a first polarization switch located on at least one of the first image light path and the second image light path, the polarization switch operable to selectively alternate the polarization of image light passing therethrough between a first output state of polarization and a second output state of polarization so that the image light passing therethrough has sequentially alternating polarizations;

a first projection lens located on the first image light path, wherein the first projection lens is operable to project the image light of the first image light path onto the projection screen as a first diverging light beam between the first projection lens and the projection screen;

a second projection lens located on the second image light path, wherein the second projection lens is operable to project the image light of the second path image light onto the projection screen as a second diverging light beam between the second projection lens and the projection screen; and

a polarization rotator located optically before the first polarization switch;

wherein the image light received at polarization beam splitter is randomly polarized light,

wherein the first and second projection lenses are further operable to direct the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen;

wherein the polarization conversion system is positioned between the image source and the projection screen;

wherein the first polarization switch operates such that the first and second diverging light beams have the same state of polarization as they simultaneously reach the projection screen; and

wherein of the light received at the polarization beam splitter is imaged at the projection screen with a single polarization state.

50. The polarization conversion system of claim 49, wherein the polarization rotator is a half-wave plate.

51. The polarization conversion system of claim 49, wherein the polarization rotator is optically adjacent to the first polarization switch.

52. The polarization conversion system of claim 49, further comprising a reflector positioned on the second image light path, wherein the reflector is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

53. The polarization conversion system of claim 52, wherein the reflector is a mirror.

54. The polarization conversion system of claim 52, wherein the reflector is a prism.

55. The polarization conversion system of claim 49, wherein the first polarization switch is located optically before the first or the second projection lens on the respective first or second image light path or after the first or the second projection lens on the respective first or second image light path.

56. The polarization conversion system of claim 49, further comprising a prism positioned on the second image light path, wherein the prism is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

57. A polarization conversion system for transmitting polarization encoded imagery to a projection screen, comprising:

a polarization beam splitter operable to receive image light from an image source, operable to transmit image light of a first polarization state toward a first image light path, and operable to reflect image light of a second polarization state toward a second image light path;

a first polarization switch located on at least one of the first image light path and the second image light path, the polarization switch operable to selectively alternate the polarization of image light passing therethrough between a first output state of polarization and a second output state of polarization so that the image light passing therethrough has sequentially alternating polarizations;

a first projection lens located on the first image light path, wherein the first projection lens is operable to project the image light of the first image light path onto the projection screen as a first diverging light beam between the first projection lens and the projection screen;

a second projection lens located on the second image light path, wherein the second projection lens is operable to project the image light of the second path image light onto the projection screen as a second diverging light beam between the second projection lens and the projection screen;

a polarization rotator located optically before the first polarization switch;

a reflector positioned on the second image light path, wherein the reflector is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path;

wherein the image light received at polarization beam splitter is randomly polarized light;

wherein the first and second projection lenses are further operable to direct the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen;

wherein the polarization conversion system is positioned between the image source and the projection screen;

wherein the first polarization switch operates such that the first and second diverging light beams have the same state of polarization as they simultaneously reach the projection screen; and

wherein of the light received at the polarization beam splitter is imaged at the projection screen with a single polarization state.

58. The polarization conversion system of claim 57, wherein the reflector is a mirror.

59. The polarization conversion system of claim 57, wherein the reflector is a prism.

60. The polarization conversion system of claim 57, wherein the polarization rotator is a half-wave plate.

61. The polarization conversion system of claim 57, wherein the polarization rotator is optically adjacent to the first polarization switch.

62. The polarization conversion system of claim 57, further comprising a second polarization switch located on the other of the first image light path and the second image light path relative to the first polarization switch.

63. The polarization conversion system of claim 62, wherein the first polarization switch is located optically before the first or the second projection lens on the respective first or second image light path or after the first or the second projection lens on the respective first or second image light path.

64. The polarization conversion system of claim 62, wherein the second polarization switch is located optically before the first or the second projection lens on the respective first or second image light path or after the first or the second projection lens on the respective first or second image light path.

65. The polarization conversion system of claim 57, further comprising a prism positioned on the second image light path, wherein the prism is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

66. The polarization conversion system of claim 65, further comprising an aperture stop optically before the prism.

67. The polarization conversion system of claim 57, wherein the polarizing beam splitter is operable to be tilted in order to facilitate the directing of the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen.

68. The polarization conversion system of claim 57, wherein the projection lenses are operable to be laterally displaced from the light path in order to facilitate the directing of the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen.

69. The polarization conversion system of claim 57, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between horizontal and vertical linear polarization.

70. The polarization conversion system of claim 57, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between left- and right-handed circular polarization.

71. A polarization conversion system for transmitting polarization encoded imagery to a projection screen, comprising:

a polarization beam splitter operable to receive image light from an image source, operable to transmit image light of a first polarization state toward a first image light path, and operable to reflect image light of a second polarization state toward a second image light path;

a first polarization switch located on at least one of the first image light path and the second image light path, the polarization switch operable to selectively alternate the polarization of image light passing therethrough between a first output state of polarization and a second output state of polarization so that the image light passing therethrough has sequentially alternating polarizations;

a first projection lens located on the first image light path, wherein the first projection lens is operable to project the image light of the first image light path onto the projection screen as a first diverging light beam between the first projection lens and the projection screen;

a second projection lens located on the second image light path, wherein the second projection lens is operable to project the image light of the second path image light onto the projection screen as a second diverging light beam between the second projection lens and the projection screen;

a second polarization switch located on the other of the first image light path and the second image light path relative to the first polarization switch;

a polarization rotator located optically before the second polarization switch; and

wherein the image light received at polarization beam splitter is randomly polarized light;

wherein the first and second projection lenses are further operable to direct the first diverging light beam and the second diverging light beam to superimpose and substantially overlap with each other on the projection screen;

wherein the polarization conversion system is positioned between the image source and the projection screen;

wherein the first polarization switch operates such that the first and second diverging light beams have the same state of polarization as they simultaneously reach the projection screen; and

wherein of the light received at the polarization beam splitter is imaged at the projection screen with a single polarization state.

72. The polarization conversion system of claim 71, further comprising a reflector positioned on the second image light path, wherein the reflector is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

73. The polarization conversion system of claim 72, wherein the reflector is a mirror.

74. The polarization conversion system of claim 72, wherein the reflector is a prism.

75. The polarization conversion system of claim 71, wherein the polarization rotator is a half-wave plate.

76. The polarization conversion system of claim 71, wherein the polarization rotator is optically adjacent to the second polarization switch.

77. The polarization conversion system of claim 71, wherein the first polarization switch is located optically before the first or the second projection lens on the respective first or second image light path or after the first or the second projection lens on the respective first or second image light path.

78. The polarization conversion system of claim 71, wherein the second polarization switch is located optically before the first or the second projection lens on the respective first or second image light path or after the first or the second projection lens on the respective first or second image light path.

79. The polarization conversion system of claim 71, further comprising a prism positioned on the second image light path, wherein the prism is operable with the second projection lens to direct the second image light from the second image light path to be superimposed on and substantially overlap on the projection screen with the first image light from the first image light path.

80. The polarization conversion system of claim 71, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between horizontal and vertical linear polarization.

81. The polarization conversion system of claim 71, wherein the first polarization switch operates such that the first and second diverging light beams have the same states of polarization as they simultaneously reach the projection screen, and wherein the states of polarization alternative between left- and right-handed circular polarization.