High dynamic range display devices

• US 20040095558A1
• Filed: 08/27/2003
• Published: 05/20/2004
• Est. Priority Date: 02/27/2001
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated), University of British Columbia
• Original Assignee: University of British Columbia
• Inventors: Seetzen, Helge, Stuerzlinger, Wolfgang, Ward, Greg, Whitehead, Lorne
• Granted Patent: US 6,891,672 B2
• Time in Patent Office: Days
• US Class Current: 353/30
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/2053 Intensity control of illuminating light controlled by video signal processing H04N5/74 or H04N9/31
• CPC Class Codes: G03B 21/26 Projecting separately subsidiary matter simultaneously with main image
• CPC Class Codes: G03B 21/56 Projection screens
• CPC Class Codes: G03B 21/567 for colour projection G03B21/58, G03B21/60 take precedence
• CPC Class Codes: G03B 21/60 characterised by the nature of the surface
• CPC Class Codes: G03B 21/625 Lenticular translucent screens
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 3/001 using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 5/7416 : involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 9/31 : Projection devices for colour picture display , e.g. using electronic spatial light modulators [ESLM]
• CPC Class Codes: H04N 9/3126 : for spatial light modulators in series
• CPC Class Codes: H04N 9/3138 : using arrays of modulated light sources electroluminescent display devices G09G3/30
• CPC Class Codes: H04N 9/3188 : Scale or resolution adjustment scaling in general G06T3/40; resolution modifying circuits for displays in general G09G5/391

Abstract

A display has a screen which incorporates a light modulator. The screen may be a front projection screen or a rear-projection screen. Elements of the light modulator may be controlled to adjust the intensity of light emanating from corresponding areas on the screen. The display may provide a high dynamic range.

Claims

1. A display comprising:

a light source;

a first spatial light modulator located to modulate light from the light source;

a display screen comprising a second spatial light modulator; and

,

an optical system configured to image light modulated by the first spatial light modulator onto a first face of the display screen.

2. The display of claim 1 wherein the display screen comprises a diffuser.

3. The display of claim 2 wherein the display screen comprises a collimator located to collimate light incident from the first spatial light modulator.

4. The display of claim 1 wherein the display comprises a rear-projection-type display and the display screen is configured to transmit light to a viewer on a side of the display screen opposite to the first face of the display screen.

5. The display of claim 4 wherein the display screen comprises a collimator located to collimate light incident from the first spatial light modulator.

6. The display of claim 5 wherein the collimator comprises a Fresnel lens.

7. The display of claim 6 wherein the diffuser comprises a large number of scattering centers distributed in the Fresnel lens.

8. The display of claim 5 wherein the collimator comprises a holographic lens.

9. The display of claim 8 wherein the diffuser comprises a large number of scattering centers distributed in the holographic lens.

10. The display of claim 4 wherein the diffuser is on a face of the screen opposite to a face on which light from the first spatial light modulator is incident.

11. The display of claim 4 wherein the second spatial light modulator comprises an array of liquid crystal display elements each having a transmissivity controllable by a control signal.

12. The display of claim 4 wherein, each of the first and second spatial light modulators comprises a plurality of controllable elements and for each controllable element of one of the first and second spatial light modulators, the other one of the first and second spatial light modulators has more than one corresponding controllable elements.

13. The display of claim 4 wherein each of the first and second spatial light modulators comprises a plurality of controllable elements and a plurality of the controllable elements of the first spatial light modulator correspond to each controllable element of the second spatial light modulator.

14. The display of claim 13 wherein the first spatial light modulator comprises a color spatial light modulator.

15. The display of claim 13 wherein, for each controllable element of one of the first and second spatial light modulators, the other one of the first and second spatial light modulators has more than eight corresponding controllable elements.

16. The display of claim 15 wherein each controllable element of the other one of the first and second spatial light modulators comprises a plurality of color sub pixels.

17. The display of claim 4 wherein, each of the first and second spatial light modulators comprises a plurality of controllable elements and for each controllable element of one of the first and second spatial light modulators, the other one of the first and second spatial light modulators has in the range of eight to one hundred forty four corresponding controllable elements.

18. The display of claim 4 wherein the first spatial light modulator is higher in resolution than the second spatial light modulator.

19. The display of claim 18 wherein the light source and first spatial light modulator comprise the light source and first spatial light modulator of a digital projector and the digital projector comprises imaging optics which image the first spatial light modulator onto the second spatial light modulator.

20. The display of claim 19 comprising a controller connected to deliver image data to both the first and second spatial light modulators.

21. The display of claim 1 comprising one or more additional light modulation stages between the first spatial light modulator and the second spatial light modulator.

22. The display of claim 21 wherein the one or more additional light modulation stages each comprise a collimator and a spatial light modulator onto which light modulated by a previous spatial light modulator is imaged.

23. The display of claim 22 wherein the one or more additional light modulation stages each comprise a diffuser.

24. The display of claim 4 wherein the screen is larger in area than the first light modulator.

25. The display of claim 1 wherein a ratio of a luminance of points on the display screen for which corresponding controllable elements of each of the first and second spatial light modulators are both set to provide a maximum illumination and a luminance points on the display screen for which corresponding controllable elements of each of the first and second spatial light modulators are both set to provide a minimum illumination of have a ratio exceeding 1000:

1.

26. The display of claim 1 wherein a ratio of a luminance of points on the display screen for which corresponding controllable elements of each of the first and second spatial light modulators are both set to provide a maximum illumination and a luminance points on the display screen for which corresponding controllable elements of each of the first and second spatial light modulators are both set to provide a minimum illumination of have a ratio exceeding 1500:

1.

27. The display of claim 1 wherein the display comprises a front-projection-type display and the display screen is configured to reflect light to a viewer.

28. The display of claim 27 wherein the second spatial light modulator comprises a transmission-type spatial light modulator.

29. The display of claim 27 wherein the second spatial light modulator comprises an array of variable transmissivity liquid crystal display elements.

30. The display of claim 27 wherein the second light modulator comprises an array of retro-reflective display elements.

31. The display of claim 27 wherein the second light modulator comprises an array of electrophoretic display elements.

32. The display of claim 27 wherein the second light modulator comprises an array of variable-transmissivity elements located in front of a reflector.

33. The display of claim 32 wherein the reflector has a roughened surface and the reflector both scatters and reflects light incident on it through the variable-transmissivity element.

34. The display of claim 32 wherein the variable-transmissivity element comprises a liquid crystal display element.

35. The display of claim 34 wherein the reflector has a roughened surface and the reflector both scatters and reflects light incident on it through the liquid crystal display element.

36. The display of claim 27 wherein each of the first and second spatial light modulators comprises a plurality of controllable elements and a plurality of the controllable elements of the first spatial light modulator correspond to each controllable element of the second spatial light modulator.

37. The display of claim 36 wherein the first spatial light modulator comprises a color spatial light modulator.

38. The display of claim 37 wherein the second spatial light modulator comprises a monochrome spatial light modulator.

39. The display of claim 36 wherein, there are more than eight controllable elements of the first spatial light modulator corresponding to each controllable element of the second spatial light modulator.

40. The display of claim 36 wherein, there are between eight and one hundred forty four controllable elements of the first spatial light modulator corresponding to each controllable element of the second spatial light modulator.

41. The display of claim 40 wherein each controllable element of the first spatial light modulator comprises a plurality of color sub pixels.

42. The display of claim 26 wherein the light source and first spatial light modulator comprise the light source and first spatial light modulator of a digital projector and the digital projector comprises imaging optics which image the first spatial light modulator onto the second spatial light modulator.

43. The display of claim 42 comprising a controller connected to deliver image data to both the first and second spatial light modulators.

44. The display of claim 26 wherein the screen is larger in area than the first light modulator.

45. The display of claim 1 wherein, each of the first and second spatial light modulators comprises a plurality of controllable elements and for each controllable element of the first spatial light modulator, the second spatial light modulator has more than one corresponding controllable elements.

46. The display of claim 45 wherein, at the second spatial light modulator, a distribution of the light modulated by each of a plurality of controllable elements of the first spatial light modulator comprises a convolution of a rectangular distribution and a spread function wherein the spread function has a full width at half maximum in the range of 0.3×

d₂ to 3×

d₂, where d₂ is a center-to-center spacing on the second light modulator of distributions of light modulated by adjacent controllable elements of the first spatial light modulator.

47. The display of claim 45 wherein each of a plurality of controllable elements of the first spatial light modulator produces a distribution of light on the second spatial light modulator and the distributions of light on the second spatial light modulator arising from adjacent controllable elements of the first spatial light modulator overlap with one another.

48. The display of claim 45 comprising a controller connected to drive each of the first and second spatial light modulators, the controller configured to provide a first control signal to control the controllable elements of the first spatial light modulator to provide an approximation of a desired image and to provide a second control signal to control the controllable elements of the second spatial light modulator to correct the approximate image.

49. The display of claim 48 wherein the first control signal controls each controllable element of the first spatial light modulator to contribute a luminance which is an average, or weighted average, of a plurality of desired luminance values for image areas corresponding to the controllable element of the first spatial light modulator.

50. The display of claim 49 wherein the second control signal controls the controllable elements of the second spatial light modulator to modulate light incident on them by an amount based upon the desired luminance values divided by a known intensity of light incident from the first spatial light modulator on the controllable element of the second spatial light modulator.

51. The display device of claim 1 wherein each of the first and second spatial light modulators comprises a plurality of controllable elements, the controllable elements of the first light modulator have a number N of discrete selectable brightness levels, the controllable elements of the second light modulator have a number M of discrete selectable brightness levels and N>

M.

52. The display device of claim 1 wherein each of the first and second spatial light modulators comprises a plurality of controllable elements, the controllable elements of the first light modulator have a number N of discrete selectable brightness levels, the controllable elements of the second light modulator have a number M of discrete selectable brightness levels and N<

M.

53. The display of claim 1 wherein the first spatial light modulator comprises a deformable mirror device.

54. The display of claim 53 wherein the second spatial light modulator comprises an array of liquid crystal display elements.

55. A display comprising:

a light source;

a first spatial light modulator located to modulate light from the light source, the first spatial light modulator comprising an array of controllable pixels; and

,

a second spatial light modulator located to modulate light modulated by the first spatial light modulator the second spatial light modulator comprising an array of controllable pixels;

wherein each pixel of one of the first and second spatial light modulators corresponds to a plurality of pixels of the other one of the first and second spatial light modulators.

56. The display device of claim 55 comprising a collimator located to collimate light modulated by the first spatial light modulator before the light is modulated by the second spatial light modulator.

57. The display device of claim 55 comprising a diffuser located to scatter light modulated by the first and second spatial light modulators.

58. The display of claim 55 wherein the first spatial light modulator comprises a color spatial light modulator.

59. The display device of claim 55 wherein the light source and first spatial light modulator comprise the light source and first spatial light modulator of a digital projector and the digital projector comprises imaging optics which image the first spatial light modulator onto the second spatial light modulator.

60. The display device of claim 55 wherein there are between eight and one hundred forty four pixels of the first spatial light modulator corresponding to each pixel of the second spatial light modulator.

61. The display device of claim 55 wherein for each pixel of one of the first and second spatial light modulators, the other one of the first and second spatial light modulators has between eight and one hundred forty four corresponding pixels.

62. The display device of claim 55 wherein each pixel of the first spatial light modulator corresponds to a plurality of pixels of the second spatial light modulator.

63. A display device comprising:

first spatial modulation means for providing light spatially modulated at a first spatial resolution;

second spatial modulation means for further spatially modulating the light at a second resolution different from the first resolution; and

,

means for controlling the first and second spatial modulation means to display an image defined by image data.

64. A method for displaying an image having a high dynamic range, the method comprising:

generating light,

spatially modulating the light according to image data in a first light modulating step; and

,

imaging the spatially modulated light onto a screen comprising a light modulator.