Projection screen apparatus including holographic optical element

• US 6,768,566 B2
• Filed: 04/15/2002
• Issued: 07/27/2004
• Est. Priority Date: 04/15/1998
• Status: Expired due to Fees

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Walker, Dale S.
• Primary Examiner(s): MAHONEY, CHRISTOPHER E
• Application Number:
  US10/122,138
• Publication Number:
  US 20020159109A1
• Time in Patent Office: 834 Days
• Field of Search: 359/443, 359/453, 359/456, 359/460, 359/1, 359/15
• US Class Current: 359/15
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08
• CPC Class Codes: G02B 5/1885 Arranged as a periodic array
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

A screen apparatus includes a holographic optical element and a diffuser. The holographic optical element may be constructed using standard techniques known in the field of holography. The holographic optical element may be used to replace a typical Fresnel lens used in projection screen apparatuses. In operation, the holographic optical element receives image light from an image engine or projector and redirects the image light to the diffuser for scattering. The holographic optical element can be designed to substantially collimate, converge, or diverge the image light. The combination of the holographic optical element and the diffuser provides improved illumination uniformity that can be perceived by a viewer as the viewer moves in directions transverse to the screen apparatus. The screen apparatus may be designed to provide improved illumination uniformity to optimized or optimal locations in a viewing region. The screen apparatus may be advantageously employed in display apparatuses.

Claims

1. A display apparatus, comprising:

a holographic optical element adapted to receive image light and to redirect the image light; and

a diffuser adapted to receive the redirected image light from the holographic optical element and to scatter the redirected image light, wherein the holographic optical element and the diffuser are disposed adjacent to one another with a gap therebetween that is substantially minimized for reducing effects of chromatic dispersion.

2. The display apparatus of claim 1, wherein the holographic optical element and the diffuser are adapted to provide a substantially uniformly illuminated viewing region.

3. The display apparatus of claim 2, wherein the viewing region comprises an optimized viewing position.

4. The display apparatus of claim 1, wherein the holographic optical element is adapted to substantially collimate the image light.

5. The display apparatus of claim 1, wherein the holographic optical element is adapted to substantially converge the image light.

6. The display apparatus of claim 1, wherein the diffuser comprises two or more immiscible materials.

7. The display apparatus of claim 1, wherein the holographic optical element and the diffuser are disposed adjacent to one another with substantially no air gap therebetween.

8. The display apparatus of claim 1, further comprising an index matching material disposed between the holographic optical element and the diffuser.

9. The display apparatus of claim 1, wherein the holographic optical element and the diffuser are adapted to provide gain profiles of image light substantially directed toward a viewer.

10. The display apparatus of claim 1, wherein the diffuser focuses the redirected image light as it passes through the diffuser.

11. The display apparatus of claim 1, further comprising an image source adapted to provide image light to the holographic optical element, wherein the image light comprises substantially white light.

12. The display apparatus of claim 1, wherein the holographic optical element and the diffuser are comprised in a folded optical system.

13. The display apparatus of claim 1, further comprising:

a display surface; and

a projection apparatus for producing an image on the display surface, the projection apparatus comprising;

an image engine;

an optical device; and

means for transmitting light from the image engine to the display surface such that the light travels an image path which reaches the optical device twice on its way to the display surface for reflecting light from the display surface at one instance, and for passing through the display surface at another instance, wherein the optical element is reflective of some light and transmissive of other light.

14. The display apparatus of claim 1, wherein the holographic optical element and the diffuser comprise a flexible combination.

15. The display apparatus of claim 1, wherein the holographic optical element and the diffuser comprise a laminated element.

16. The display apparatus of claim 1, wherein the holographic optical element comprises a transmission-type holographic optical element.

17. The display apparatus of claim 1, wherein the holographic optical element comprises a reflection-type holographic element.

18. The display apparatus of claim 1, wherein the holographic optical element comprises a photopolymer material.

19. The display apparatus of claim 1, wherein the holographic optical element and the diffuser are adapted to provide the redirected image light predominantly to a particular viewing position.

20. The display apparatus of claim 1, wherein the gap is on the order of microns.

21. The display apparatus of claim 1, wherein the holographic optical element and the diffuser are formed as layers, coatings, or are bonded to one another.

22. The display apparatus of claim 1, wherein the diffuser is a non-holographic diffuser.

23. The display apparatus of claim 1, further comprising:

a display surface;

a projection apparatus configured to produce an image to be displayed on the display surface; and

at least one reflector, wherein the image to be displayed is reflected off of the at least one reflector before passing through the holographic optical element and the diffuser.

24. The display apparatus of claim 23, wherein the at least one reflector comprises at least two reflectors and wherein the image to be displayed is reflected off of the at least two reflectors before passing through the holographic optic element and the diffuser.

25. The display apparatus of claim 23, further comprising:

an optical device, wherein an image to be displayed reaches the optical device twice on its way to the display surface.

26. The display apparatus of claim 25, wherein the optical device is a reflecting polarizer.

27. The display apparatus of claim 25, wherein the image to be displayed passes through the optical device prior to passing through the holographic optical element and the diffuser.

28. The display apparatus of claim 25, further comprising:

a reflector, wherein at least a portion of the image to be displayed first reaches the optical device and is reflected therefrom, reaches the reflector and is reflected therefrom, and then reaches the optical device again and passes therethrough.

29. The display apparatus of claim 28, further comprising a polarizer disposed between the reflector and the optical device.

30. The display apparatus of claim 1, further comprising:

a display surface optically coupled to the diffuser, the display surface and the diffuser collectively forming a display screen; and

folded optics adapted to receive image light from an imager, wherein the holographic optical element receives image light from the folded optics and redirects the image light to the display screen.

31. The display apparatus of claim 30, wherein the display screen comprises a beaded screen.

32. The display apparatus of claim 31, wherein the beaded screen comprises a black matrix.

33. The display apparatus of claim 30, wherein the folded optics, the holographic optical element, and the display screen are configured as part of a television display or a computer display.

34. The display apparatus of claim 33, wherein the diffusive screen comprises a bulk diffusive screen.

35. The display apparatus of claim 33, wherein the diffusive screen comprises surface diffusers.

36. The display apparatus of claim 35, wherein the surface diffusers comprise ground glass.

37. The display apparatus of claim 30, wherein the folded optics, the holographic optical element, and the display screen are comprised in a rear projection system.

38. The display apparatus of claim 30, wherein the folded optics, the holographic optical element, and the display screen are comprised in a front projection system.

39. The display apparatus of claim 30, wherein the display screen comprises a diffusive screen.

40. The display apparatus of claim 30, wherein the folded optics comprises a polarizing reflector positioned adjacent the holographic optical element.

41. The display apparatus of claim 40, wherein the polarizing reflector comprises double brightness enhancement film (DBEF).

42. The display apparatus of claim 30, wherein the folded optics comprises a back reflector disposed between the holographic optical element and the imager.

43. The display apparatus of claim 42, wherein the back reflector comprises a mirror and a polarizer.

44. The display apparatus of claim 30, wherein the imager comprises a liquid crystal display imager, a light source, and the projection lens and produces image light in response to input electronic, video, or other signals.

45. A television, comprising:

a holographic optical element adapted to receive image light and to redirect the image light; and

a diffuser adapted to receive the redirected image light from the holographic optical element and to scatter the redirected image light, wherein the holographic optical element and the diffuser are disposed adjacent to one another with a gap therebetween that is substantially minimized for reducing effects of chromatic dispersion.

46. A computer display, comprising:

a holographic optical element adapted to receive image light and to redirect the image light; and

a diffuser adapted to receive the redirected image light from the holographic optical element and to scatter the redirected image light, wherein the holographic optical element and the diffuser are disposed adjacent to one another with a gap therebetween that is substantially minimized for reducing effects of chromatic dispersion.

47. A display apparatus, comprising

folded optics adapted to receive image light from an imager;

a holographic optical element adapted to receive the image light from the folded optics and to redirect the image light; and

a display screen comprising a non-holographic diffuser adapted to receive the redirected image light from the holographic optical element and to scatter the redirected image light.

48. The display apparatus of claim 47, wherein the beaded screen comprises a beaded screen.

49. The display apparatus of claim 47, wherein the beaded screen comprises a black matrix.

50. The display apparatus of claim 47, wherein the folded optics, the holographic optical element, and the display screen are configured as part of a television display or a computer display.

51. The display apparatus of claim 47, wherein the folded optics, the holographic optical element, and the display screen are comprised in a rear projection system.

52. The display apparatus of claim 47, wherein the folded optics, the holographic optical element, and the display screen are comprised in a front projection system.

53. The display apparatus of claim 47, wherein the display screen comprises a bulk diffusive screen.

54. The display apparatus of claim 47, wherein the display screen comprises a diffusive screen comprising surface diffusers.

55. The display apparatus of claim 54, wherein the surface diffusers comprise ground glass.

56. The display apparatus of claim 47, wherein the folded optics comprises a polarizing reflector positioned adjacent the holographic optical element.

57. The display apparatus of claim 56, wherein the polarizing reflector comprises double brightness enhancement film (DBEF).

58. The display apparatus of claim 47, wherein the folded optics comprises a back reflector disposed between the holographic optical element and the imager.

59. The display apparatus of claim 58, wherein the back reflector comprises a mirror and a polarizer.

60. The display apparatus of claim 47, wherein the imager comprises a liquid crystal display imager, a light source, and the projection lens and produces image light in response to input electronic, video, or other signals.

61. A display apparatus, comprising:

folded optics adapted to receive image light from an imager;

a holographic optical element adapted to the receive the image light from the folded optics and to redirect the image light in a non-collimated form; and

a display screen comprising a diffuser adapted to receive the redirected image light from the holographic optical element and to scatter the redirected image light.

62. The display apparatus of claim 61, wherein the display screen comprises a beaded screen.

63. The display apparatus of claim 62, wherein the beaded screen comprises a black matrix.

64. The display apparatus of claim 61, wherein the folded optics, the holographic optical element, and the display screen are configured as part of a television display or a computer display.

65. The display apparatus of claim 61, wherein the folded optics, the holographic optical element, and the display screen are comprised in a rear projection system.

66. The display apparatus of claim 61, wherein the folded optics, the holographic optical element, and the display screen are comprised in a front projection system.

67. The display apparatus of claim 61, wherein the display screen comprises a bulk diffusive screen.

68. The display apparatus of claim 61, wherein the display screen comprises a diffusive screen comprising surface diffusers.

69. The display apparatus of claim 68, wherein the surface diffusers comprise ground glass.

70. The display apparatus of claim 61, wherein the folded optics comprises a polarizing reflector positioned adjacent the holographic optical element.

71. The display apparatus of claim 70, wherein the polarizing reflector comprises double brightness enhancement film (DBEF).

72. The display apparatus of claim 61, wherein the folded optics comprises a back reflector disposed between the holographic optical element and the imager.

73. The display apparatus of claim 72, wherein the back reflector comprises a mirror and a polarizer.

74. The display apparatus of claim 61, wherein the imager comprises a liquid crystal display imager, a light source, and the projection lens and produces image light in response to input electronic, video, or other signals.

75. A display apparatus, comprising:

a holographic optical element adapted to received image light and to redirect the image light; and

a diffuser adapted to receive the redirected image light from the holographic optical element and to scatter the redirected image light; and

a display surface optically coupled to the diffuser, wherein the holographic optical element and diffuser are configured to control a viewer eyebox of the display apparatus.

76. The display apparatus of claim 75, wherein the wherein the holographic optical element and diffuser are configured to provide relative uniformity of intensity of the image light if a viewer moves his or her head transversely while viewing an image on the display surface.

77. The display apparatus of claim 75, wherein the holographic optical element and diffuser are configured to provide the image light in forward extending gain profiles that have their maxima centered in a direction substantially normal to the display surface.

78. The display apparatus of claim 75, wherein the holographic optical element and diffuser are configured to provide the image light in forward extending gain profiles that have their maxima angularly directed toward a particular viewing position.