Display illumination system

• US 6,433,935 B2
• Filed: 09/10/1999
• Issued: 08/13/2002
• Est. Priority Date: 07/02/1996
• Status: Expired due to Term

• Current Assignee: Compound Photonics Limited
• Original Assignee: Three-Five Systems, Inc.
• Inventors: Kintz, Gregory J., Li, Zheng-Wu, Curley, Michael J., Chuang, Chih-Li
• Primary Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US09/394,014
• Publication Number:
  US 20020003667A1
• Time in Patent Office: 1,068 Days
• Field of Search: 359/630, 359/631, 359/633, 359/634, 359/638, 345/7, 345/8, 345/9
• US Class Current: 359/630
• CPC Class Codes: G02B 17/04 using prisms only
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00

Abstract

A virtual image display system is provided which comprises a non-emissive, reflective microdisplay which forms a source object; an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay; a light source system which produces light to illuminate the display system; and an illumination system which forms at least two virtual light sources to illuminate the display system.

Claims

1. A virtual image display system comprising:

a non-emissive, reflective microdisplay which forms a source object;

an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay;

a light source system which produces light to illuminate the microdisplay; and

an illumination system which forms at least two virtual light sources to illuminate the microdisplay.

2. A virtual image display system according to claim 1 wherein the at least two virtual light sources include a first virtual light source positioned approximately in front of and directly over the microdisplay and second virtual light source positioned over and to one side of the microdisplay.

3. A virtual image display system according to claim 2 wherein the optical system has a folded optical path which is aligned within an optical plane, the first and second virtual light sources being aligned with the optical plane.

4. A virtual image display system according to claim 1 wherein the illumination system forms at least three virtual light sources to illuminate the display system.

5. A virtual image display system according to claim 4 wherein the at least three virtual light sources include a first virtual light source positioned approximately in front of and directly over the microdisplay, a second virtual light source positioned over and to a first side of the microdisplay, and a third virtual light source positioned over and to second side of the microdisplay.

6. A virtual image display system according to claim 4 wherein the optical system has a folded optical path which is aligned within an optical plane, the first, second and third virtual light sources being aligned with the optical plane.

7. A virtual image display system according to claim 1 wherein the illumination system comprises an illumination body which forms the at least two virtual light sources.

8. A virtual image display system according to claim 7 wherein the illumination body comprises a prism which forms the at least two virtual light sources.

9. A virtual image display system according to claim 8 wherein the light source system is positioned adjacent a first surface of the prism, the microdisplay is positioned adjacent a second surface of the prism, and the optical system is positioned adjacent a third surface of the prism.

10. A virtual image display system according to claim 9 wherein the light source system produces polarized light and the third prism surface is attached to a reflective polarizer.

11. A virtual image display system according to claim 9 wherein the angle between the third prism surface and the second prism surface is less than 45 degrees.

12. A virtual image display system according to claim 9 wherein the angle between the third prism surface and the second prism surface is between 20 and 35 degrees.

13. A virtual image display system according to claim 9 wherein the angle between the first prism surface and the second prism surface is between about 1.7 and 2.3 times the size of the angle between the third prism surface and the second prism surface.

14. A virtual image display system comprising:

a non-emissive, reflective microdisplay which forms a source object;

an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay;

a light source system which produces light to illuminate the display system; and

an illumination system which directs light from the light source system through the illumination system to the microdisplay such that the angles of incidence of light which illuminates the microdisplay varies across the microdisplay over an angular range that is greater than would be provided by the light source system if the light source svstem were to directly illuminate the microdisplay.

15. A virtual image display system comprising:

a non-emissive, reflective microdisplay which forms a source object;

an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay;

a light source system which produces light to illuminate the microdisplay; and

an illumination system which directs light from the light source system through the illumination system to the microdisplay such that the angles of incidence of light which illuminates the microdisplay varies across the microdisplay over an angular range of at least 40 degrees.

16. A virtual image display system according to claim 15 wherein the angles of incidence of light which illuminates the display system vary over an angular range of at least 60 degrees.

17. A virtual image display system according to claim 15 wherein the angles of incidence of light which illuminates the display system vary over an angular range of between about 40 degrees and 120 degrees.

18. A virtual image display system according to claim 15 wherein the angles of incidence of light which illuminates the display system vary over an angular range of between about 60 degrees and 100 degrees.

19. A virtual image display system comprising:

a non-emissive, reflective microdisplay which forms a source object;

an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay;

a light source system which produces light to illuminate the microdisplay; and

an illumination system which directs light from the light source system through the illumination system to the microdisplay such that a first portion of the light incident on the microdisplay is approximately perpendicular to the microdisplay, a second portion of the light incident on the microdisplay is positively angularly displaced relative to the perpendicular to the microdisplay, and a third portion of the light incident on the microdisplay is negatively angularly displaced relative to the perpendicular to the microdisplay.

20. A virtual image display system comprising:

a non-emissive, reflective microdisplay which forms a source object;

an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay;

a light source system which generates light to illuminate the microdisplay; and

an illumination system which includes an illumination body which transmits light from the light source system to the display system to illuminate the display system where a first portion of the light is internally reflected off one surface of the illumination body prior to illuminating the display system and a second portion of the light is internally reflected off two surfaces of the illumination body prior to illuminating the display system.

21. A virtual image display system according to claim 20 wherein at least one of the internal reflections is a totally internal reflection.

22. A virtual image display system according to claim 20 wherein the first portion of light from the light source traverses the illumination body by being internally reflected off of a surface of the illumination body adjacent the optical system prior to reaching the microdisplay.

23. A virtual image display system according to claim 20 wherein the second portion of light from the light source traverses the illumination body by being internally reflected off of a surface of the illumination body adjacent the microdisplay, then internally reflected off of a surface of the illumination body adjacent the optical system prior to reaching the microdisplay.

24. A virtual image display system according to claim 20 where a third portion of the light is internally reflected off three surfaces of the illumination body prior to illuminating the display system.

25. A virtual image display system comprising:

a non-emissive, reflective microdisplay which forms a source object;

an optical system which forms a magnified, virtual image of the source object from light reflected off the microdisplay;

a light source system which generates light to illuminate the microdisplay; and

an illumination system which includes an illumination body which transmits light from the light source system to the microdisplay to illuminate the microdisplay, the light source system being positioned adjacent a first surface of the illumination body, the microdisplay being positioned adjacent a second surface of the illumination body, and the optical system being positioned adjacent a third surface of the illumination body, where a portion of the light from the light source traverses the illumination body by being internally reflected off the third surface of the illumination body.

26. A virtual image display system according to claim 25 wherein at least one of the internal reflections is a totally internal reflection.

27. A virtual image display system according to claim 25 wherein a portion of the light from the light source traverses the illumination body by being internally reflected off the second surface of the illumination body and then internally reflected off the third surface of the illumination body.

28. A virtual image display system according to claim 25 wherein a first portion of the light from the light source traverses the illumination body by being internally reflected off the third surface of the illumination body, and a second portion of the light from the light source traverses the illumination body by being internally reflected off the second surface of the illumination body and then internally reflected off the third surface of the illumination body.

29. A virtual image display system according to claim 25 wherein a first portion of the light from the light source traverses the illumination body by being internally reflected off the third surface of the illumination body, a second portion of the light from the light source traverses the illumination body by being internally reflected off the second surface of the illumination body and then internally reflected off the third surface of the illumination body, and a third portion of the light from the light source traverses the illumination body by being internally reflected off the third surface of the illumination body, then internally reflected off the second surface of the illumination body, and then internally reflected off the third surface of the illumination body.

30. An optical method comprising:

directing a source object within a first optical element to a surface of the first optical element where the source object is internally reflected;

directing the source object to a beamsplitter which reflects the source object;

directing the source object to a second optical element which magnifies and reflects the source object to form a magnified virtual image of the source object; and

directing the magnififed virtual image throught the beamsplitter.

31. The optical method according to claim 30, the method futher including forming the source object using a microdisplay.

32. The optical method according to claim 30, wherein the first optical element is formed of an optically transparent material which has a refractive index of at least about 1.3.

33. The optical method according to claim 30, wherein the source object is directed to the internally reflecting surface of the first optical element at an angle of at least about 30 degrees.

34. The optical method according to claim 31 wherein the microdisplay is a non-emissive, reflective microdisplay.

35. The optical method according to claim 31 wherein the microdisplay imaging surface with an area equal to or less than 400 mm².

36. A compact virtual image display system comprising:

a microdisplay for forming a source object;

an optic formed of an optically transparent material and including a surface positioned such that at least a portion of light forming the source object is totally internally reflected by the surface;

a reflective first magnification optic positioned such that the light totally internally reflected source object within the optic magnified and reflected as a magnified virtual image;

a light source; and

an illumination system which directs light from the light source to the microdisplay, the illumination system comprising a prism where at least a portion of light from the light source is internally reflected within the prism prior to exiting the prism and illuminating the microdisplay.

37. The virtual image display system according to claim 36 wherein the internal reflection of light from the light source is a totally internal reflection.

38. A compact virtual image display system comprising:

a microdisplay for forming a source object;

an optic formed of an optically transparent material and including a surface positioned such that at least a portion of light forming the source object is totally internally reflected by the surface; and

a reflective first magnification optic positioned such that the totally internally reflected source object within the optic is magnified and reflected as a magnified virtual image.

39. The virtual image display system according to claim 38 wherein the optic formed of an optically transparent material has a refractive index of at least about 1.3.

40. The virtual image display system according to claim 38 wherein the microdisplay projects the light which is totally internally reflected to the surface at an angle of at least about 30 degree.

41. The virtual image display system according to claim 38, further including an illumination source for projecting light to the microdisplay.

42. The virtual image display system according to claim 38 wherein the microdisplay is a non-emissive, reflective microdisplay.

43. The virtual image display system according to claim 38 wherein the microdisplay imaging surface with an area equal to or less than 400 mm².

44. An optical method comprising:

directing a source object within a first optical element to a surface of the first optical element wherein the source object is internally reflected;

directing the source object within the first optical element to a surface of the first optical element which magnifies and reflects the source object to form a magnified virtual image of the source object; and

directing the magnified virtual image through the beamsplitter out of the first optical element.

45. The optical method according to claim 44, the method further including forming the source object using a microdisplay.

46. The optical method according to claim 44, wherein the first optical element is formed of an optically transparent material which has a refractive index of at least about 1.3.

47. The optical method according to claim 44, wherein the source object is directed to the internally reflecting surface of the first optical element at an angle of at least about 30 degrees.

48. The optical method according to claim 45 wherein the microdisplay is a non-emissive, reflective microdisplay.

49. The optical method according to claim 45 wherein the microdisplay imaging surface with an area equal to or less than 400 mm².

50. A compact virtual image display system comprising:

a microdisplay for forming a source object; and

a reflective first magnification optic including

a first surface positioned such that at least a portion of light forming the source object thravels within the optic and is totally internally reflected by the first surface, and

a second surface having a magnification and a reflection function which magnifies and reflects the totally internally reflected source object as a magnified virtual image.

51. The virtual image display system according to claim 50 wherein the optic formed of an optically transparent material has a refractive index of at least about 1.3.

52. The virtual image display system according to claim 50 wherein the microdisplay is a non-emissive, reflective microdisplay.

53. The virtual image display system according to claim 50 wherein the microdisplay imaging surface with an area equal to or less than 400 mm².

54. The virtual image display system according to claim 50 wherein the microdisplay projects the light which is totally internally reflected to the surface at an angle of at least about 30 degrees.

55. The virtual image display system according to claim 50, further including an illumination source for projecting light to the microdisplay.

56. A compact virtual image display system comprising:

a microdisplay for forming a source object;

a reflective first magnification optic including

a first surface positioned such that at least a portion of light forming the source object ravels within the optic and is totally internally reflected by the first surface, and

a second surface having a magnification and a reflection funtion which magnifies and reflects the totally internally reflected source object as a magnified virtual image;

a light source; and

an illumination system which directs light from the light source to the microdisplay, the illumination system comprising a prism where at least a portion of light from the light source is internally reflected within the prism prior to exiting the prism and illuminating the microdisplay.

57. The virtual image display system according to claim 56 wherein the internal reflection of light from the light source is a totally internal reflection.