Illumination device for illuminating a display device

• US 5,784,181 A
• Filed: 06/23/1992
• Issued: 07/21/1998
• Est. Priority Date: 11/23/1990
• Status: Expired due to Fees

• Current Assignee: Thomson-CSF
• Original Assignee: Thomson-CSF
• Inventors: Nicolas, Christophe, Huignard, Jean-Pierre, Loiseaux, Brigitte, Puech, Claude
• Primary Examiner(s): Epps, Georgia Y.
• Application Number:
  US07/862,537
• Time in Patent Office: 2,219 Days
• Field of Search: 359/1, 359/15, 359/19, 359/483, 359/485, 359/487, 359/488, 359/495
• US Class Current: 359/1
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/203 having holographic or diffractive elements diffraction gratings per se G02B5/18; holographic elements per se G02B5/32; generating the spectrum using diffraction elements G01J3/18
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G03H 2260/12 Photopolymer
• 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 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

The invention relates to an illumination device for illuminating a display device. In a preferred embodiment, non-polarized light from a non-polarized light source is polarized by a holographic polarization beam splitting device and focused onto a liquid crystal display device by a holographic focusing device. The invention is operable with monochrome and color display devices, and allows for a high light yield independent of the useful surface area of each detector element of the display device.

Claims

1. An illumination device for illuminating a display device, said illumination device comprising:

a non-polarized light source for emitting non-polarized light;

holographic polarization beam splitting means for receiving non-polarized light emitted from said non-polarized light source and for outputting first polarized light beams having a first polarization and second polarized light beams having a second polarization, said second polarization being orthogonal to said first polarization; and

holographic focusing means for receiving one of said first polarized light beams and said second polarized light beams output from said holographic polarization beam splitting means and for focusing said one of said first polarized light beams and said second polarized light beams onto detector cells of a display device which is oriented in a plane parallel to a plane containing said holographic focusing means, wherein said holographic polarization beam splitting means is formed on a first face of a prism and said holographic focusing means is formed on a second face of said prism, said first face and said second face of said prism being orthogonal to one another.

2. An illumination device according to claim 1, wherein said holographic focusing device is formed so as to focus polarized light beams having at least one wavelength onto detector cells of said display device by focusing, for each specific one of said at least one wavelength, each component of said polarized light beams having said specific one of said at least one wavelength onto corresponding detector cells of said display device that are formed to modulate polarized light having said specific one of said at least one wavelength.

3. An illumination device according to claim 1, wherein said holographic focusing means is a volume holographic device.

4. An illumination device according to claim 1, wherein said polarization beam splitting means is oriented substantially perpendicular to said holographic focusing means so as to effect anamorphosis of said non-polarized light.

5. An illumination device according to claim 1, wherein said display device comprises a spatially light modulating liquid crystal screen.

6. An illumination device according to claim 5, wherein said spatially light modulating liquid crystal screen is disposed substantially parallel to said holographic focusing means in a plane which contains the focal points of said holographic focusing means.

7. An illumination device according to claim 5, wherein said spatially light modulating liquid crystal screen displays a plurality of colors, said holographic focusing means being capable of focusing polarized light beams having wavelengths corresponding to each of said plurality of colors onto said display device.

8. An illumination device according to claim 1, wherein at least one of said holographic polarization beam splitting means and said holographic focusing means comprises means for converging light beams incident thereon.

9. An illumination device according to claim 1, wherein at least one of said holographic polarization beam splitting means and said holographic focusing means comprises means for diverging light beams incident thereon.

10. An illumination device for illuminating a display device, said illumination device comprising:

a non-polarized light source for emitting non-polarized light;

holographic polarization beam splitting means, formed on a common face of a first prism and a second prism so as to be sandwiched therebetween, for receiving non-polarized light emitted from said non-polarized light source and for outputting first polarized light beams having a first polarization and second polarized light beams having a second polarization, said second polarization being orthogonal to said first polarization;

a half wave device formed on a face of said second prism which is orthogonal to said common face, said half wave device receiving one of said first polarized light beams and said second polarized light beams output from said holographic polarization beam splitting beams as an input and outputting polarized light beams having a polarization orthogonal to that of said input; and

holographic focusing means for receiving polarized light beams output from both of said holographic polarization beam splitting means and said half wave device and for focusing said polarized light beams onto detector cells of a display device which is oriented in a plane parallel to a plane containing said holographic focusing means, wherein said half wave device and a face of said first prism orthogonal to said common face are oriented in a plane parallel to a plane containing said display device so as to align said holographic polarization beam splitting means and said holographic focusing means perpendicular to one another.

11. An illumination device according to claim 10, wherein said holographic polarization beam splitting means is a holographic volume element which reflects light having a first polarization and which retransmits light having a second polarization, said second polarization being orthogonal to said first polarization.

12. An illumination device according to claim 10, wherein said holographic focusing means comprises a first portion for receiving polarized light beams which have been reflected from said holographic polarization beam splitting means, and a second portion for receiving polarized light beams which have been retransmitted from said holographic polarization beam splitting means.

13. An illumination device according to claim 10, wherein said half wave device is placed in the path of one of said first polarized light beams and said second light beams output from said holographic polarization beam splitting means.

14. An illumination device according to claim 10, wherein said holographic focusing means is a volume holographic device.

15. An illumination device according to claim 10, wherein said holographic polarization beam splitting means is oriented substantially perpendicular with respect to said holographic focusing means so as to effect anamorphosis of said non-polarized light.

16. An illumination device according to claim 10, wherein said display device comprises a spatially light modulating liquid crystal screen.

17. An illumination device according to claim 16, wherein said spatially light modulating liquid crystal screen is disposed substantially parallel to said holographic focusing means in a plane which contains the focal points of said holographic focusing means.

18. An illumination device according to claim 16, wherein said spatially light modulating liquid crystal screen displays a plurality of colors, said holographic focusing means being capable of focusing polarized light beams having wavelengths corresponding to each of said plurality of colors onto said display device.

19. An illumination device according to claim 10, wherein at least one of said holographic polarization beam splitting means and said holographic focusing means comprises means for converging light beams incident thereon.

20. An illumination device according to claim 10, wherein at least one of said holographic polarization beam splitting means and said holographic focusing means comprises means for diverging light beams incident thereon.

21. An illumination device for illuminating a display device, said illumination device comprising:

a non-polarized light source for emitting non-polarized light;

a first holographic mirror formed on a first face of a prism, for reflecting said non-polarized light emitted from said non-polarized light source onto a second face of said prism, said first face and said second face of said prism being orthogonal to one another;

holographic matrix means formed on said second face of said prism, for receiving said non-polarized light reflected from said first holographic mirror, for generating first polarized light beams having a first polarization and second polarized light beams having a second polarization, said second polarization being orthogonal to said first polarization, and for focusing one of said first polarized light beams and said second polarized light beams onto detector cells of a display device which is oriented in a plane parallel to a plane containing said holographic matrix means, wherein a second holographic mirror is formed between said holographic matrix means and said display device in a plane parallel to a plane containing said holographic matrix means.

22. An illumination device according to claim 21, wherein said first holographic mirror is oriented substantially perpendicular with respect to said holographic matrix means so as effect anamorphosis of said non-polarized light.

23. An illumination device according to claim 21, wherein said display device comprises a spatially light modulating liquid crystal screen.

24. An illumination device according to claim 23, wherein said spatially light modulating liquid crystal screen is disposed substantially parallel to said holographic matrix means in a plane which contains the focal points of said holographic matrix means.

25. An illumination device according to claim 23, wherein said spatially light modulating liquid crystal screen displays a plurality of colors, said holographic matrix means being capable of focusing polarized light beams of wavelengths corresponding to each of said plurality of colors onto said display device.

26. An illumination device according to claim 21, wherein at least one of said first holographic mirror and said holographic focusing device comprises means for converging light beams incident thereon.

27. An illumination device according to claim 21, wherein at least one of said first holographic mirror and said holographic focusing device comprises means for diverging light beams incident thereon.

28. An illumination device for illuminating a display device, said illumination device comprising:

a non-polarized light source for emitting non-polarized light; and

at least one optical device, each one of said at least one optical device including first holographic polarization beam splitting means for receiving non-polarized light emitted from said non-polarized light source and for reflecting components of said non-polarized light having a first polarization and a specific wavelength while retransmitting a remainder of said non-polarized light and light having a second polarization orthogonal to said first polarization;

a half wave device for converting polarizations of light retransmitted from said first holographic polarization beam splitting means from said second polarization to said first polarization;

second holographic polarization beam splitting means for receiving said remainder of said non-polarized light retransmitted by said first holographic polarization beam splitting means and outputted from said half wave device and for reflecting components of said remainder of said non-polarized light having said first polarization and said specific wavelength while retransmitting all remaining components of said remainder of said non-polarized light having said second polarization and at least one wavelength other than said specific wavelength; and

holographic focusing means for receiving light having said first polarization and said specific wavelength reflected from said first holographic polarization beam splitting means and said at least one second holographic polarization beam splitting means and for focusing said light onto detector cells of a display device which is oriented in a plane parallel to a plane containing said holographic focusing device.

29. An illumination device according to claim 28, wherein each of said first holographic polarization beam splitting means and said second holographic polarization beam splitting means is inclined at an angle of 45°

with respect to said holographic focusing device.

30. An illumination device according to claim 28, wherein said display device comprises a spatially light modulating liquid crystal screen.

31. An illumination device according to claim 30, wherein said spatially light modulating liquid crystal screen is disposed substantially parallel to said holographic focusing means in a plane which contains the focal points of said holographic focusing means.

32. An illumination device according to claim 30, wherein said spatially light modulating liquid crystal screen displays a plurality of colors, said holographic focusing means being capable of focusing polarized light beams having wavelengths corresponding to each of said plurality of colors onto said display device.

33. An illumination device according to claim 28, further comprising a projection optical device on which an image formed via said display means is projected, wherein said at least one optical device is arranged in series along a path of incident non-polarized light emitted from said non-polarized light source, each one of said at least one optical device reflecting components of said non-polarized light emitted from said non-polarized light source having a given wavelength which is different from that of the polarized focused light reflected from all others of said at least one optical device and retransmitting all remaining components of said non-polarized light emitted from said non-polarized light source having at least one wavelength different from said given wavelength onto said holographic polarization beam splitting means of a different, adjacent, one of said at least one optical device, and wherein said at least one optical device is arranged such that a distance that focused polarized light output from each one of said at least one optical device must travel to impinge upon said projection optical device is identical.

34. An illumination device according to claim 33, wherein focused polarized light beams output from each one of said at least one optical device illuminate a corresponding, separate spatially light modulating liquid crystal screen.

35. An illumination device according to claim 28, wherein at least one of said first holographic polarization beam splitting means, said second holographic polarization beam splitting means, and said holographic focusing means is capable of effecting anamorphosis of said non-polarized light.

36. An illumination device according to claim 28, wherein at least one of said first holographic polarization beam splitting means, said second holographic polarization beam splitting means, and said holographic focusing means comprises means for converging light beams incident thereon.

37. An illumination device according to claim 28, wherein at least one of said first holographic polarization beam splitting means, said second holographic polarization beam splitting means, and said holographic focusing means comprises means for diverging light beams incident thereon.

38. An illumination device for illuminating a display device, said illumination device comprising:

a non-polarized light source for emitting non-polarized light;

and at least one optical apparatus, each one of said at least one optical apparatus including holographic polarization beam splitting means, formed on a common face of a prism and an optical deviating means so as to be sandwiched therebetween, for receiving non-polarized light emitted from said non-polarized light source for outputting first polarized light beams having a first polarization and second polarized light beams having a second polarization, said second polarization being orthogonal to said first polarization;

a holographic device formed on a face of said optical deviating means; and

holographic focusing means for receiving said first polarized light beams and said second polarized light beams outputted from said holographic polarization beam splitting means and for focusing said first polarized light beams and said second polarized light beams onto detector cells of a display device which is oriented in a plane parallel to a plane containing said holographic focusing means, wherein non-polarized light incident on said holographic polarization beam splitting means at an angle other than 45°

with respect thereto is deviated by said holographic device and said optical deviating means so as to impinge upon said holographic polarization beam splitting means at an angle of 45°

with respect thereto.

39. An illumination device according to claim 38, wherein said holographic polarization beam splitting means is oriented substantially perpendicular to said holographic focusing means so as to effect anamorphosis of said non-polarized light.

40. An illumination device according to claim 38, wherein said display device comprises a spatially light modulating liquid crystal screen.

41. An illumination device according to claim 40, wherein said spatially light modulating liquid crystal screen is disposed substantially parallel to said holographic focusing means in a plane which contains the focal points of said holographic focusing means.

42. An illumination device according to claim 40, wherein said spatially light modulating liquid crystal screen displays a plurality of colors, said holographic focusing means being capable of focusing polarized light beams having wavelengths corresponding to each of said plurality of colors onto said display device.

43. An illumination device according to claim 38, wherein at least one of said first holographic polarization beam splitting means and said holographic focusing means comprises means for converging light beams incident thereon.

44. An illumination device according to claim 38, wherein at least one of said first holographic polarization beam splitting means and said holographic focusing means comprises means for diverging light beams incident thereon.

45. An illumination device according to claim 38, further comprising a projection optical device on which an image formed via said display means is projected, wherein said holographic device of each one of said at least one optical apparatus directs components of said non-polarized light emitted from said non-polarized light source having a specific wavelength onto said holographic polarization beam splitting device at an angle of 45°

with respect thereto, and directs all remaining components of said non-polarized light emitted from said non-polarized light source having at least one wavelength different from said specific wavelength onto said holographic device of a different one of said at least one optical apparatus, said specific wavelength of said non-polarized light directed onto said holographic polarization beam splitting means for each one of said at least one optical apparatus being different from that of said non-polarized light diverted onto said holographic polarization beam splitting means of all others of said at least one optical apparatus, and wherein said at least one of said optical apparatus is arranged such that a distance that focused polarized light output from each one of said at least one optical apparatus must travel to impinge upon said projection optical device is identical.