Method and apparatus for using an array of grating light valves to produce multicolor optical images

• US 6,219,015 B1
• Filed: 01/18/1996
• Issued: 04/17/2001
• Est. Priority Date: 04/28/1992
• Status: Expired due to Term

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Bloom, David M., Huibers, Andrew
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US08/591,231
• Time in Patent Office: 1,916 Days
• Field of Search: 345/100, 345/87, 345/88, 348/744, 348/750, 348/751, 348/752, 353/88, 353/89
• US Class Current: 345/87
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• CPC Class Codes: B81C 2201/115 Roughening a surface
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955

Abstract

A multicolor optical image-generating device comprised of an array of grating light valves (GLVs) organized to form light-modulating pixel units for spatially modulating incident rays of light. The pixel units are comprised of three subpixel components each including a plurality of elongated, equally spaced apart reflective grating elements arranged parallel to each other with their light-reflective surfaces also parallel to each other. Each subpixel component includes means for supporting the grating elements in relation to one another, and means for moving alternate elements relative to the other elements and between a first configuration wherein the component acts to reflect incident rays of light as a plane mirror, and a second configuration wherein the component diffracts the incident rays of light as they are reflected from the grating elements. The three subpixel components of each pixel unit are designed such that when red, green and blue light sources are trained on the array, colored light diffracted by particular subpixel components operating in the second configuration will be directed through a viewing aperture, and light simply reflected from particular subpixel components operating in the first configuration will not be directed through the viewing aperture.

Claims

1. Display apparatus for generating multi-colored optical images, comprising:

housing means having an optical aperture through which light may be passed;

light valve means disposed within said housing means and forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component being adapted to selectively have a reflective state and a diffractive state;

means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

a plurality of colored light sources respectively positioned to illuminate particular subpixel components of each pixel unit of said array such that no light reflected from any of said subpixel components in a reflective state passes through said aperture, but such that light diffracted from corresponding ones of said subpixel components of each said pixel unit in a diffractive state is directed through said aperture.

2. Display apparatus as recited in claim 1 wherein the grating elements of a first of said subpixel components of each said pixel unit have a first orientation and the grating elements of a second of said subpixel components of each said pixel unit have a second orientation which is at 90 degrees relative to the first orientation.

3. Display apparatus as recited in claim 2 wherein each said pixel unit has a third subpixel component, and wherein the grating elements of said third subpixel component of each said pixel unit have an orientation that is neither said first orientation nor said second orientation.

4. Display apparatus as recited in claim 3 wherein the grating periods of the grating elements of the three subpixel components of each pixel unit are equal.

5. Display apparatus as recited in claim 1 wherein the grating elements of the first of said subpixel components of each said pixel unit have a first orientation and a first grating period, wherein the grating elements of the second subpixel component of each said pixel unit have a second orientation which is at 90 degrees relative to the first orientation and said first grating period, and wherein the grating elements of a third subpixel component of each said pixel unit have said first orientation and a second grating period different from said first grating period.

6. Display apparatus as recited in claim 1 wherein the grating elements of the first subpixel component of each said pixel unit have a first angular orientation, wherein the grating elements of the second subpixel component of each said pixel unit have a second angular orientation relative to the grating elements of said first subpixel component, and wherein the grating elements of a third subpixel component of each said pixel unit have a third angular orientation relative to the angular orientations of the grating elements of said first and second subpixel components.

7. Display apparatus as recited in claim 6 wherein said first angular orientation, said second angular orientation and said third angular orientation are respectively separated by angles of 120°

.

8. Display apparatus as recited in claim 7 wherein said first, second and third subpixel components each have rhombic perimetric boundaries and are positioned contiguous to each other, such that the collective perimetric boundary of each pixel unit has a generally hexagonal shape.

9. Display apparatus as recited in any one of the claims 1-8 wherein the grating elements of each said subpixel component are arranged parallel to each other, with the light-reflective surfaces of the grating elements normally lying in a first plane, and wherein each said control means includes:

means for supporting alternative ones of the grating elements in a fixed position; and

means for moving the remaining grating elements relative to the fixed grating elements and between a first configuration wherein all of the grating elements lie in the first plane and the subpixel component acts to reflect incident light as a plane mirror, and a second configuration wherein said remaining grating elements lie in a second plane parallel to the first plane and the subpixel component diffracts incident light as it is reflected from the planar surfaces of the grating elements.

10. Display apparatus as recited in claim 9 wherein said means for moving said remaining grating elements includes means for applying an electrostatic force to said remaining grating elements.

11. Display apparatus as recited in claim 9 and further comprising electronic communication means for receiving transmitted data and for generating signals for causing certain ones of said subpixel components to assume a reflective state and other ones of said subpixel components to assume a diffractive state.

12. Display apparatus for generating multi-colored optical images, comprising:

housing means having an optical aperture through which light may be passed;

light valve means disposed within said housing means and forming an array of discrete light-modulating pixel units each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component being adapted to selectively have a reflective state and a diffractive state;

means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

a plurality of colored light sources respectively positioned to illuminate particular subpixel components of each pixel unit of said array such that no light diffracted from any of said subpixel components in a diffractive state passes through said aperture, but such that light reflected from corresponding ones of said subpixel components of each said pixel unit in a reflective state is directed through said aperture.

13. Display apparatus as recited in claim 12 wherein the grating elements of the first of said subpixel components of each said pixel unit have a first orientation and the grating elements of the second of said subpixel components of each said pixel unit have a second orientation which is at 90 degrees relative to the first orientation.

14. Display apparatus as recited in claim 13 wherein each said pixel unit has a third subpixel component, wherein the grating elements of said third subpixel component of each said pixel unit have an orientation that is neither said first orientation nor said second orientation.

15. Display apparatus as recited in claim 14 wherein the grating periods of the grating elements of the three subpixel components of each pixel unit are equal.

16. Display apparatus as recited in claim 12 wherein the grating elements of the first of said subpixel components of each said pixel unit have a first orientation and a first grating period, wherein the grating elements of the second subpixel component of each said pixel unit have a second orientation which is at 90 degrees relative to the first orientation and said first grating period, and wherein the grating elements of a third subpixel component of each said pixel unit have said first orientation and a second grating period different from said first grating period.

17. Display apparatus as recited in claim 12 wherein the grating elements of the first subpixel component of each said pixel unit have a first angular orientation, wherein the grating elements of the second subpixel component of each said pixel unit have a second angular orientation relative to the grating elements of said first subpixel component, and wherein the grating elements of a third subpixel component of each said pixel unit have a third angular orientation relative to the angular orientations of the grating elements of said first and second subpixel components.

18. Display apparatus as recited in claim 17 wherein said first angular orientation, said second angular orientation and said third angular orientation are respectively separated by angles of 120°

.

19. Display apparatus as recited in claim 18 wherein said first, second and third subpixel components each have rhombic perimetric boundaries and are positioned contiguous to each other, such that the collective perimetric boundary of each pixel unit has a generally hexagonal shape.

20. Display apparatus as recited in any one of claims 12-19 wherein the grating elements of each said subpixel component are arranged parallel to each other, with the light-reflective surfaces of the grating elements normally lying in a first plane, and wherein each said control means includes:

means for supporting alternate ones of the grating elements in a fixed position; and

means for moving the remaining grating elements relative to the fixed grating elements and between a first configuration wherein all of the grating elements lie in the first plane and the subpixel component acts to reflect incident light as a plane mirror, and a second configuration wherein said remaining grating elements lie in a second plane parallel to the first plane and the subpixel component diffracts incident light as it is reflected from the planar surfaces of the grating elements.

21. Display apparatus as recited in claim 20 wherein said means for moving said remaining grating elements includes means for applying an electrostatic force to said remaining grating elements.

22. Display apparatus as recited in claim 20 and further comprising electronic communication means for receiving transmitted data and for generating signals for causing certain ones of said subpixel components to assume a reflective state and other ones of said subpixel components to assume a diffractive state.

23. Apparatus for generative a multi-colored optical image, comprising:

means forming an optical aperture through which light may be passed;

means forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each said pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component having a fixed configuration, wherein said component either completely reflects incident light, completely diffracts incident light, or partially diffracts and partially reflects incident light; and

a plurality of colored light sources respectively positioned to simultaneously illuminate at least one pixel unit of said array such that no light reflected from any illuminated subpixel component of said one pixel unit in a reflective state passes through said aperture, but such that light diffracted from any illuminated subpixel component of said one pixel unit in a diffractive state is directed through said aperture.

25. Apparatus as recited in claim 23 or 24 wherein the grating elements of the first of said subpixel components of each said pixel unit have a first orientation and the grating elements of the second of said subpixel components of each said pixel unit have a second orientation which is at 90 degrees relative to the first orientation.

26. Apparatus as recited in claim 25 wherein each said pixel unit has a third subpixel component, wherein the grating elements of said third subpixel component of each said pixel unit have an orientation that is neither said first orientation nor said second orientation.

27. Apparatus as recited in claim 26 wherein the grating periods of the grating elements of the three subpixel components of each pixel unit are equal.

28. Apparatus as recited in claim 23 or 24 wherein the grating elements of the first of said subpixel components of each said pixel unit have a first orientation and a first grating period, wherein the grating elements of the second subpixel component of each said pixel unit have a second orientation which is at 90 degrees relative to the first orientation and said first grating period, and wherein the grating elements of a third subpixel component of each said pixel unit have said first orientation and a second grating period different from said first grating period.

29. Display apparatus as recited in claim 23 or 24 wherein the grating elements of the first subpixel component of each said pixel unit have a first angular orientation, wherein the grating elements of the second subpixel component of each said pixel unit have a second angular orientation relative to the grating elements of said first subpixel component, and wherein the grating elements of a third subpixel component of each said pixel unit have a third angular orientation relative to the angular orientations of the grating elements of said first and second subpixel components.

30. Display apparatus as recited in claim 29 wherein said first angular orientation, said second angular orientation and said third angular orientation are respectively separated by angles of 120°

.

31. Display apparatus as recited in claim 30 wherein said first, second and third subpixel components each have rhombic perimetric boundaries and are positioned contiguous to each other, such that the collective perimetric boundary of each pixel unit has a generally hexagonal shape.

24. Apparatus for generating a multi-colored optical image, comprising:

means forming an optical aperture through which light may be passed;

means forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each said pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component having a fixed configuration in either a reflective state or a refractive state, wherein said subpixel component either completely reflects incident light, completely diffracts incident light, or partially diffracts and partially reflects incident light; and

a plurality of colored light sources respectively positioned to simultaneously illuminate at least one pixel unit of said array such that no light diffracted from any illuminated subpixel component of said one pixel unit in a diffractive state passes through said aperture, but such that light reflected from any illuminated subpixel component of said one pixel unit in a reflective state is directed through said aperture.

32. A method of generating multi-colored optical images, comprising the steps of:

providing an optical aperture through which light may be passed;

forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component being adapted to selectively have a reflective state and a diffractive state, and including means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state;

causing each said subpixel component to assume either said reflective state or said diffractive state; and

positioning a plurality of colored light sources to respectively illuminate particular subpixel components of each pixel unit of said array such that no light reflected from any of said subpixel components in a reflective state passes through said aperture, but such that light diffracted from subpixel components in a diffractive state is directed through said aperture, whereby an optical image corresponding to the states of said pixel units is viewable through said optical aperture.

33. A method as recited in claim 32 including causing the grating elements of the first of said subpixel components of each said pixel unit to have a first orientation and causing the grating elements of the second of said subpixel components of each said pixel unit to have a second orientation which is at 90 degrees relative to the first orientation.

34. A method as recited in claim 33 including causing each said pixel unit to have a third subpixel component, and causing the grating elements of said third subpixel component of each said pixel unit to have an orientation that is different from the orientations of said first and second subpixel components.

35. A method as recited in claim 34 and further including causing the grating periods of the grating elements of the three subpixel components of each pixel unit to be equal.

36. A method as recited in claim 32 including causing the grating elements of the first of said subpixel components of each said pixel unit to have a first orientation and a first grating period, causing the grating elements of the second subpixel component of each said pixel unit to have a second orientation which is at 90 degrees relative to the first orientation and said first grating period, and causing the grating elements of a third subpixel component of each said pixel unit to have said first orientation and a second grating period different from said first grating period.

37. A method as recited in claim 32 including causing the grating elements of the first subpixel component of each said pixel unit to have a first angular orientation, causing the grating elements of the second subpixel component of each said pixel unit to have a second angular orientation relative to the grating elements of said first subpixel component, and causing the grating elements of a third subpixel component of each said pixel unit to have a third angular orientation relative to the angular orientations of the grating elements of said first and second subpixel components.

38. A method as recited in claim 37 wherein said first angular orientation, said second angular orientation and said third angular orientation are respectively separated by angles of 120°

.

39. A method as recited in claim 38 and further including causing said first, second and third subpixel components to each have rhombic perimetric boundaries and to be positioned contiguous to each other, such that the collective perimetric boundary of each pixel unit has a generally hexagonal shape.

41. A method as recited in any one of claims 32-40 wherein the grating elements of each said subpixel component are arranged parallel to each other, with the light-reflective surfaces of the grating elements normally lying in a first plane, and further including

supporting alternate ones of the grating elements in a fixed position, and

moving the remaining grating elements relative to the fixed grating elements and between a first configuration wherein all of the grating elements lie in the first plane and the subpixel component acts to reflect incident light as a plane mirror, and a second configuration wherein said remaining grating elements lie in a second plane parallel to the first plane and the subpixel component diffracts incident light as it is reflected from the planar surfaces of the grating elements.

40. A method for generating multi-colored optical images, comprising the steps of:

providing a housing means having an optical aperture through which light may be passed;

providing a light valve means disposed within said housing means and forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component being adapted to selectively have a reflective state and a diffractive state, and including means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

positioning a plurality of colored light sources to respectively illuminate particular subpixel components of each pixel unit of said array such that no light reflected from any of said subpixel components in a reflective state passes through said aperture, but such that light diffracted from corresponding ones of said subpixel components of each said pixel unit in a diffractive state is directed through said aperture.

42. A method of generating multi-colored optical images, comprising the steps of:

providing an optical aperture through which light may be passed;

forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each pixel unit being oriented such that the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component being adapted to selectively have a reflective area and a diffractive state, and including means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state;

causing each said subpixel component to assume either said reflective state or said diffractive state; and

positioning a plurality of colored light sources to respectively illuminate particular subpixel components of each pixel unit of said array such that no light diffracted from any of said subpixel components in a diffractive state passes through said aperture, but such that light reflected from subpixel components in a reflective state is directed through said aperture, whereby an optical image corresponding to the states of said pixel units is viewable through said optical aperture.

43. A method as recited in claim 42 including causing the grating elements of the first of said subpixel components of each said pixel to have a first orientation and causing the grating elements of the second of said subpixel components of each said pixel unit to have a second orientation which is at 90 degrees relative to the first orientation.

44. A method as recited in claim 43 including causing each said pixel unit to have a third subpixel component, and causing the grating elements of said third subpixel component of each said pixel unit to have an orientation that is different from the orientations of said first and second subpixel components.

45. A method as recited in claim 44 and further including causing the grating periods of the grating elements of the three subpixel components of each pixel unit to be equal.

46. A method as recited in claim 42 including causing the grating elements of the first of said subpixel components of each said pixel unit to have a first orientation and a first grating period, causing the grating elements of the second subpixel component of each said pixel unit to have a second orientation which is at 90 degrees relative to the first orientation and said first grating period, and causing the grating elements of a third subpixel component of each said pixel unit to have said first orientation and a second grating period different from said first grating period.

47. A method as recited in claim 42 including causing the grating elements of the first subpixel component of each said pixel unit to have a first angular orientation, causing the grating elements of the second subpixel component of each said pixel unit to have a second angular orientation relative to the grating elements of said first subpixel component, and causing the grating elements of a third subpixel component of each said pixel unit to have a third angular orientation relative to the angular orientations of the grating elements of said first and second subpixel components.

48. A method as recited in claim 47 wherein said first angular orientation, said second angular orientation and said third orientation are respectively separated by angles of 120 degrees.

49. A method as recited in claim 48 and further including causing said first, second and third subpixel components to each have rhombic perimetric boundaries and to be positioned contiguous to each other, such that the collective perimetric boundary of each pixel unit has a generally hexagonal shape.

51. A method as recited in any one of claims 42-50 wherein the grating elements of each said subpixel component are arranged parallel to each other, with the light-reflective surfaces of the grating elements normally lying in a first plane, and further including

supporting alternate ones of the grating elements in a fixed position, and

moving the remaining grating elements relative to the fixed grating elements and between a first configuration wherein all of the grating elements lie in a first plane and the subpixel component acts to reflect incident light as a plane mirror, and a second configuration wherein said remaining grating elements lie in a second plane parallel to the first plane and the subpixel component diffracts incident light as it is reflected from the planar surfaces of the grating elements.

50. A method for generating multi-colored optical images, comprising the steps of:

providing a housing means having an optical aperture through which light may be passed;

disposing a light valve means within said housing means and forming an array of discrete light-modulating pixel units, each including a plurality of subpixel components having elongated grating elements, the grating elements of at least two subpixel components of each pixel unit being oriented such that the grating elements, the grating elements of a first of said two subpixel components extend in a direction different from that of the grating elements of a second of said two subpixel components, each said subpixel component being adapted to selectively have a reflective state and a diffractive state, and including means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

positioning a plurality of colored light sources to respectively illuminate particular subpixel components of each pixel unit of said array such that no light diffracted from any of said subpixel components in a diffractive state passes through said aperture, but such that light reflected from corresponding ones of said subpixel components of each said pixel unit in a reflective state is directed through said aperture.

52. Display apparatus for generating multi-colored optical images, comprising:

means forming an optical aperture through which light may be passed;

light valve means disposed with a predetermined relationship to said aperture and consisting of an array of discrete light-modulating pixel units, each including at least two subpixel components having elongated grating elements, each said subpixel component being adapted to selectively have a reflective state and a diffractive state;

means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

at least two different colored light sources positions to illuminate the pixel units of said array,

the apparatus being characterized in that the grating elements of each subpixel component of each pixel unit selectively cause light from a particular source to be diffracted and directed through said aperture when in said diffractive state or to be reflected away from said aperture when in said reflective state.

55. Display apparatus as recited in any one of claims 52-54 wherein the grating elements of each subpixel component extend in a different direction relative to the grating elements of the other subpixel components of the same pixel unit.

56. Display apparatus as recited in any one of claims 52-54 wherein the subpixel components of each pixel unit have different grating periods.

53. Display apparatus for generating multi-colored optical images, comprising:

means forming an optical aperture through which light may be passed;

light valve means disposed with a predetermined relationship to said aperture and consisting of an array of discrete light-modulating pixel units, each including at least two subpixel components having elongated grating elements, each said subpixel component being adapted to selectively have a reflective state and a diffractive state;

means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

at least two different colored light sources positioned to illuminate the pixel units of said array,

the apparatus being characterized in that the grating elements of each subpixel component of each pixel unit selectively cause light from a particular source to be reflected through said aperture when in said reflective state or to be diffracted and directed away from said aperture when in said diffractive state.

54. Display apparatus for generating multi-colored optical images, comprising:

means forming an optical aperture through which light may be passed;

light valve means disposed with a predetermined relationship to said aperture and consisting of an array of discrete light-modulating pixel units, each including at least two subpixel components having elongated grating elements, each said subpixel component being configured to have either a reflective state or a diffractive state;

means for controlling each said subpixel component by moving selected ones of said grating elements to enable the controlled subpixel component to operate in a reflective state and a diffractive state; and

at least two different colored light sources positioned to illuminate the pixel units of said array,

the apparatus being characterized in that the grating elements of each subpixel component of each pixel unit having said diffractive state cause light from a particular source to be diffracted and directed through said aperture and subpixel components having said reflective state cause light from the particular source to be reflected away from said aperture.