Spatio-Temporal Directional Light Modulator

• US 20130258451A1
• Filed: 07/11/2012
• Published: 10/03/2013
• Est. Priority Date: 03/27/2012
• Status: Active Grant

• Current Assignee: Ostendo Technologies Inc.
• Original Assignee: Ostendo Technologies Inc.
• Inventors: El-Ghoroury, Hussein S., Alpaslan, Zahir Y., Cai, Jingbo, McNeill, Dale A., Maiers, Marty, Warner, Philip
• Granted Patent: US 8,854,724 B2
• Time in Patent Office: Days
• US Class Current: 359/298
• CPC Class Codes: G02B 26/08 for controlling the direction of light in light guides G02B6/35
• CPC Class Codes: G02B 26/101 with both horizontal and vertical deflecting means, e.g. raster or XY scanners colour television using laser beams scanning a display screen H04N9/3129
• CPC Class Codes: H04N 13/307 using fly-eye lenses, e.g. arrangements of circular lenses
• CPC Class Codes: H04N 13/32 using arrays of controllable light sources; using moving apertures or moving light sources
• CPC Class Codes: H04N 13/356 having separate monoscopic and stereoscopic modes
• CPC Class Codes: Y10T 29/4978 Assisting assembly or disassembly
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

A spatio-temporal directional light modulator is introduced. This directional light modulator can be used to create 3D displays, ultra-high resolution 2D displays or 2D/3D switchable displays with extended viewing angle. The spatio-temporal aspects of this novel light modulator allow it to modulate the intensity, color and direction of the light it emits within an wide viewing angle. The inherently fast modulation and wide angular coverage capabilities of this directional light modulator increase the achievable viewing angle, and directional resolution making the 3D images created by the display be more realistic or alternatively the 2D images created by the display having ultra high resolution.

Claims

1. A directional light modulator comprising:

a two dimensional emissive micro emitter array device;

a micro lens array of micro lens elements;

the two dimensional emissive micro emitter array device and the micro lens array being assembled together and angularly articulated as a single assembly to emit light around two axes within a plane of an emissive surface of the emissive micro emitter array and within a range of plus and minus a maximum angular articulation in each respective axis.

2. The directional light modulator of claim 1 wherein the two dimensional emissive micro emitter array comprises an array of pixels wherein each pixel is a solid state light emitter that is individually addressable.

3. The directional light modulator of claim 2 wherein each pixel of the two dimensional emissive micro emitter array has dimensions not exceeding 20 by 20 microns.

4. The directional light modulator of claim 2 wherein each pixel is individually addressable to modulate light it emits in both color and intensity.

5. The directional light modulator of claim 2 comprising a plurality of two dimensional emissive micro emitter array devices and a plurality of micro lens arrays being comprised of a plurality of micro lens arrays fabricated using ultraviolet imprint lithography at the wafer level to be precisely aligned relative to one another and relative to the pixel array using semiconductor wafer level alignment techniques.

6. The directional light modulator of claim 1 wherein each micro lens element of the micro lens array is associated and aligned with a plurality of micro emitters forming a pixel group within the two dimensional array of micro emitters, with each micro lens element optically mapping light emitted from the plurality of micro emitters associated with that micro lens element into a corresponding set of directions within an angular extent in each of the two axes defined by a numerical aperture of each micro lens element.

7. The directional light modulator of claim 6 comprising a two dimensional array of the pixel groups whereby each of the individual pixels in each of the pixel groups is individually addressable to generate light that is modulated in color, intensity and direction, thereby enabling the light modulator to generate spatially modulated light that is also modulated in color, intensity and direction.

8. The directional light modulator of claim 7 having a spatial resolution that is determined by the number of pixel groups along each axis of the two dimensional array of pixel groups and having a directional resolution that is determined by the number of individual light directions within the temporally expanded set of light directions.

9. The light modulator of claim 7 being capable of generating a light field defined by the two dimensional array of the pixel groups, the set of directions within the angular extent in each of the two axes, and the articulation in each respective axis.

10. The directional light modulator of claim 6 wherein each of the micro lens elements of the micro lens array is comprised of at least one lens element having at least one refracting surface whereby the number of lens elements and the number of their associated refracting surfaces determines the angular extent and angular resolution.

11. The directional light modulator of claim 6 wherein spatial and directional resolution are determined by the size of the pixel group, a resolution and pixel pitch of the two dimensional emissive micro emitter array device, lens pitch of the micro lens array, the angular extent and a maximum articulation angle.

12. The directional light modulator of claim 1 wherein the angular articulation is provided by a gimbal support for the assembly of the two dimensional emissive micro emitter array device and the micro lens array for temporally expanding the angular extent in each of the two axes by the angular articulation of the gimbal support, thereby temporally expanding the set of light directions along each of the two axes.

13. The directional light modulator of claim 12 wherein the two dimensional emissive micro emitter array comprises an array of pixels wherein each pixel is individually addressable, and wherein the individual addressability of the pixels within a respective pixel group together with the temporally expanded set of directions by the angular articulation of the gimbal support enables the individual pixel addressability within the temporally expanded set of directions, thereby enabling the directional light modulator to generate light that is directionally modulated in any of the directions comprising the temporally expanded set of light directions.

14. The directional light modulator of claim 13 wherein the two dimensional emissive micro emitter array comprises an array of pixels wherein each pixel is individually addressable, and wherein the individual pixel addressability includes individual pixel color and intensity modulation addressability, wherein the temporal association of the pixels within a pixel group with the temporally expanded set of light directions enables the modulation of the color and the intensity of the light emitted in each of the temporally expanded set of directions, thereby enabling the light modulator to generate light that is modulated in color, intensity and direction over the expanded angular extent.

15. The directional light modulator of claim 12 wherein the temporally expanded angular extent is temporally continuous or discrete and has a repetition rate that is proportional to and synchronized with an image input data frame rate, whereby the maximum angular articulation around each of the two axes determines the expanded angular extent of the directional light modulator, the angular coverage, shape and aspect ratio.

16. The directional light modulator of claim 15 wherein the angular articulation around each of the two axes is at least equal to the frame rate of the input image data multiplied by a factor that equals the ratio of the expanded angular extent to the angular extent along each respective axis.

17. The directional light modulator of claim 12 wherein the annular articulation causes any light direction within the increased set of light directions to be modulated during the time interval during which the light direction falls with the articulated angular extent.

18. The directional light modulator of claim 12 having a directional resolution which is the angular separation between the individual light directions within the temporally expanded set of light directions.

19. The directional light modulator of claim 12 wherein the angular articulation is selected to affect an increase in either the expanded angular extent or spatial resolution for a given value of angular resolution.

20. The directional light modulator of claim 1 being used as a display that can be switched to operate either in a 3D display mode or in a high resolution 2D display mode by adapting a format of input data to be commensurate with the desired mode.

21. The directional light modulator of claim 1 being used as a backlight for a liquid crystal display (LCD) that can be switched to operate either as a 3D display or as a high resolution 2D display.

22. The directional light modulator of claim 1 capable of modulating within its expanded angular extent a multiplicity of views with an angular resolution value commensurate with the human visual system eye angular separation, thus making it a 3D display that will not require the use of glasses to view the 3D content it displays.

23. The directional light modulator of claim 22 capable of modulating a 3D image with a sufficient angular resolution value between generated multiple views that will eliminate the vergence-accommodation conflict (VAC) which typically hinders the performance of 3D displays and causes visual fatigue.

24. The directional light modulator of claim 1 wherein light field modulation capabilities of the directional light modulator makes it the underlying basis of a 3D light field display that can be used to implement a synthetic holography 3D display.

25. A directional light modulator comprising:

an emissive micro emitter array device comprising a multiplicity of pixels;

a micro lens array aligned and physically bonded to the emissive micro emitter array device; and

,

a two axis gimbal having a bonding pad upon which the emissive micro emitter array device and the micro lens array assembly is physically and electrically bonded;

the two axis gimbal having two sets of electromagnetic actuators aligned with the two axes of the gimbal to affect temporal angular articulation of said bonding pad around the two axes of the gimbal, and

a set of electrical contacts connecting said bonding pad to a set of device interface contacts.

26. The directional light modulator of claim 25 wherein the two axis gimbal is implemented using multiple silicon substrate layers to realize a two axis pivot of the gimbal and a mechanical resistance spring that defines the neutral position of the gimbal relative to a gimbal base.

27. The directional light modulator of claim 26 wherein the two axis pivot is realized by etching, using semiconductor lithography, of an inner ring and an outer ring around the periphery of the bonding pad and leaving two sets of silicon bridges connecting the rings along both axes.

28. The directional light modulator of claim 27 wherein the mechanical resistance spring comprises the two sets of silicon bridges.

29. The directional light modulator of claim 27 wherein electrical connections between the bonding pad and the set of device interface contacts are routed through the two sets of silicon bridges of the two axis pivot.

30. The directional light modulator of claim 27 wherein the electromagnetic actuators are bonded to a backside of the bonding pad and to a topside of a gimbal base layer of the multiple silicon substrate layers.

31. The directional light modulator of claim 26 wherein drive electrical signals to the electromagnetic actuators provide temporal angular articulation that is either temporally continuous or discrete and having a repetition rate that is proportional to and synchronized with an image input data frame rate provided through the device interface contacts, and wherein the drive electrical signals include correction values provided by a set of sensors bonded to a backside of the contact pad and a topside of a base layer of the gimbal.

32. The directional light modulator of claim 25 wherein the two axis gimbal has a spherical pivot on the backside of the bonding pad and a matched spherical socket on a topside of a gimbal base.

33. The directional light modulator of claim 32 further comprising a mechanical resistance spring that defines the neutral position of the gimbal relative to a gimbal base, the mechanical resistance spring being provided by a set of four spiral shaped springs etched onto a spring layer bonded at its inner end at a backside of four corners of the bonding pad and at its outer end at a topside of the gimbal base.

34. The directional light modulator of claim 33 wherein electrical connections between the bonding pad and the set of device interface contacts are routed through the four spiral shaped springs.

35. The directional light modulator of claim 32 wherein the electromagnetic actuators are embedded in the spherical pivot and spherical socket.

36. The directional light modulator of claim 25 wherein the temporal angular articulation affected by the electromagnetic actuators has a maximum angular articulation value around each of the two axes of the gimbal.

37. The directional light modulator of claim 25 wherein the micro lens array is comprised of a plurality of micro lens arrays fabricated using ultraviolet imprint lithography at the wafer level to be precisely aligned relative to one another and relative to the multiplicity of pixels of the emissive micro emitter array device.

38. The directional light modulator of claim 25 wherein in the micro lens array, each of its constituent lenses is associated and precisely aligned with a respective plurality of pixels within a two dimensional array of pixel groups, with each constituent lens optically mapping the light emitted from the respective plurality of pixels into a corresponding discrete set of directions within an angular extent defined by a numerical aperture of the respective constituent lens.

39. The directional light modulator of claim 38 wherein each of the pixels within each of the pixel groups is individually addressable through the device interface contacts to enable the directional light modulator to generate light from each pixel that is modulated in color, intensity and direction.

40. The directional light modulator of claim 39 capable of generating a light field defined by the spatial coordinates within the two dimensional array of the pixel groups, a set of angular directional coordinates defined by the two dimensional array pixel group and the temporal values of the articulation.

41. The directional light modulator of claim 39 wherein the addressability of each pixel is accomplished using a multiple field data input to the directional light modulator whereby for each designated pixel group address within the spatial array of the pixel groups, at least one input data field is used to specify the direction of the emitted light and at least one field is used to specify the color and intensity of the light emitted in that designated direction.

42. The directional light modulator of claim 38 wherein the temporal angular articulation causes the directional light modulator to have an expanded angular extent that includes the angular extent of each pixel group plus twice the maximum angular articulation, with a corresponding number of expanded directions that is equal to the number of directions of each pixel group multiplied by the ratio of the expanded angular extent to the angular extent of each pixel group along each of the two articulation axes.

43. The directional light modulator of claim 42 having a spatial resolution that is determined by the number of pixel groups along each axis of the two dimensional array of pixel groups and having a directional resolution that is determined by the number of individual light directions within the expanded angular extent.

44. The directional light modulator of claim 42 having an angular or directional resolution that is defined as the angular separation between the individual light directions within the temporally expanded set of light directions and determined by the fractional value of the angular extent being addressed by each one pixel within a pixel group.

45. The directional light modulator of claim 44 wherein the maximum angular articulation is selected to affect an increase in either the expanded angular extent or the spatial resolution for a given value of the angular resolution.

46. The directional light modulator of claim 44 wherein each of the constituent lenses of the micro lens array is comprised of at least one lens element having at least one refracting surface whereby the number of lens elements and the number of their associated refracting surfaces determines the angular extent and affects the value of the expanded angular extent and the angular resolution.

47. The directional light modulator of claim 44 having a spatial resolution that is determined by the number of pixel groups along each axis of the two dimensional array of pixel groups and having a directional resolution that is determined by the number of individual light directions within the expanded angular extent, wherein the temporal angular articulation has a maximum angular articulation value around each of the two axes of the gimbal, the spatial resolution and the directional resolution of the directional light modulator being determined by the size of the pixel group, the directional resolution and pixel pitch of the emissive micro emitter array, the lens pitch of the micro lens array, the angular extent and a maximum articulation angle.

48. The directional light modulator of claim 25, used in plurality to form a tiled array of the directional light modulators having an expanded spatial aperture.

49. The directional light modulators of claim 48 wherein in the micro lens arrays, each of its constituent lenses is associated and precisely aligned with a respective plurality of pixels within a two dimensional array of pixel groups, with each constituent lens optically mapping the light emitted from the respective plurality of pixels into a corresponding discrete set of directions within an angular extent defined by a numerical aperture of the respective constituent lens, and further comprised of a collective set of the spatial arrays of the pixel groups whereby each pixel within each pixel group is individually addressable to generate light that is modulated in color, intensity and direction, thereby enabling the expanded spatial aperture directional light modulator device to generate spatially modulated light across a spatial aperture spanning the collective set of the spatial arrays that is also modulated in color, intensity and direction.

50. The directional light modulators of claim 49 wherein the spatial, direction, color and intensity modulation addressability of the expanded spatial aperture directional light modulator is accomplished using a multiple field data input to the individual directional light modulators whereby for each designated pixel group within the spatial array of the pixel groups, at least one input data field is used to specify the direction of the emitted light and at least one field is used to specify the color and intensity of the light emitted in that designated direction.

51. The directional light modulators of claim 48 being used as a display that can be switched to operate either in a 3D display mode or in a 2D display mode by adapting a format of input data to be commensurate with the desired mode.

52. The directional light modulators of claim 48 being used as a backlight for a liquid crystal display (LCD) to create either a 3D display or 2D display that can be switched to operate either as a 3D display or as a high resolution 2D display.

53. The directional light modulators of claim 48 capable of modulating within its expanded angular extent a multiplicity of views with an angular resolution value commensurate with the human visual system eye angular separation, thus making it a 3D display that will not require the use of glasses to view the 3D content it displays.

54. The directional light modulator of claim 53 capable of modulating a 3D image with sufficient angular resolution value between the generated multiple views that will eliminate the vergence-accommodation conflict (VAC) which typically hinders the performance of 3D displays and causes visual fatigue.

55. The directional light modulators of claim 48 wherein light field modulation capabilities of the directional light modulator makes them the underlying basis of a 3D light field display that can be used to implement a synthetic holography 3D display.

56. The directional light modulator of claim 25 being used as a display that can be switched to operate either in a 3D display mode or in a high resolution 2D display mode by adapting a format of input data to be commensurate with the desired mode.

57. The directional light modulator of claim 25 being used as a backlight for a liquid crystal display (LCD) to create either a 3D display or 2D display that can be switched to operate either as a 3D display or as a high resolution 2D display.

58. The directional light modulator of claim 25 capable of modulating within its expanded angular extent a multiplicity of views with an angular resolution value commensurate with the human visual system eye angular separation, thus making it a 3D display that will not require the use of glasses to view the 3D content it displays.

59. The directional light modulators of claim 58 capable of modulating a 3D image with sufficient angular resolution value between the generated multiple views that will eliminate the vergence-accommodation conflict (VAC) which typically hinders the performance of 3D displays and causes visual fatigue.

60. The directional light modulator of claim 25 wherein light field modulation capabilities of the directional light modulator makes it the underlying basis of a 3D light field display that can be used to implement a synthetic holography 3D display.

61. A method of forming a directional light modulator comprising:

providing an emissive micro emitter array device;

providing a micro lens array of micro lens elements;

aligning the micro lens array with the emissive micro emitter array device into a direction light modulator subassembly so that each micro lens element of the micro lens array is associated and aligned with a corresponding plurality of micro emitters within a two dimensional array of micro emitters of the emissive micro emitter array device to emit light around two axes within the plane of an emissive surface of the emissive micro emitter array within a range of plus or minus a maximum angular extent, whereby each micro lens element optically maps light emitted from the corresponding plurality of micro emitters into a corresponding discrete set of directions within an angular extent defined by a numerical aperture of each micro lens element;

temporally articulating the directional light modulator subassembly about at least a first axis in a plane of the assembly to expand the discrete set of directions responsive to the angular articulation.

62. The method of claim 61 wherein the directional light modulator subassembly is also articulated about a second axis in the plane of the assembly to further expand the discrete set of directions responsive to the angular articulation, the second axis being perpendicular to the first axis.

63. The method of claim 62 wherein:

providing an emissive micro emitter array device comprises providing a matrix of micro emitter array devices on a single substrate;

providing a micro lens array comprises providing a matrix of micro lens arrays;

mounting the matrix of micro lens arrays onto the matrix of micro emitter array devices to form a matrix of directional light modulators, and;

dicing the matrix of directional light modulators to provide a plurality individual directional light modulators.

64. The method of claim 63 wherein the matrix of micro lens arrays are aligned with respect to the matrix of micro emitter array devices to form a matrix of directional light modulators using semiconductor wafer level alignment techniques.

65. The method of claim 63 wherein providing the matrix of micro lens arrays comprises providing a plurality of micro lens array layers, wherein the micro lens array layers are mounted in a stack and aligned with respect to each other to form the matrix of micro lens arrays.

66. The method of claim 63 wherein each micro emitter is individually addressable to control the brightness thereof.

67. The method of claim 63 wherein each micro emitter is individually addressable to control the color and brightness thereof.

68. The method of claim 67 wherein light emitted from the corresponding plurality of micro emitters into a corresponding discrete set of directions within an angular extent defined by a numerical aperture of each micro lens element forms a corresponding pixel group, the association of the pixels within each pixel group with the temporally expanded set of directions together with the individual pixel addressability enabling the individual addressability the temporally expanded set of directions, whereby the directional light modulator generates light that is directionally modulated in any of the directions comprising the set of the temporally expanded set of light directions.

69. The method of claim 68 further comprised of modulating the individual pixel color and brightness with the temporal association of the pixels within a pixel group with the temporally expanded set of light directions, thereby enabling the light modulator to be able to generate light that is modulated in color, intensity and direction over the expanded angular extent.