N-MODULATION DISPLAYS AND RELATED METHODS

• US 20100007577A1
• Filed: 09/23/2009
• Published: 01/14/2010
• Est. Priority Date: 03/13/2002
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: NINAN, Ajit, SEETZEN, Helge
• Granted Patent: US 8,199,401 B2
• Time in Patent Office: Days
• US Class Current: 345/1.300
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133613 characterized by the sequence of light sources
• 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: 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 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• 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 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2330/08 Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/3426 : the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3611 : Control of matrices with row and column drivers
• CPC Class Codes: H01J 63/06 : Lamps with luminescent screen excited by the ray or stream
• CPC Class Codes: H04N 9/3102 : using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3126 : for spatial light modulators in series
• CPC Class Codes: H04N 9/3155 : for controlling the light source light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406
• CPC Class Codes: H04N 9/3194 : including sensor feedback
• CPC Class Codes: H04N 9/3197 : using light modulating optical valves
• CPC Class Codes: H05B 45/20 : Controlling the colour of the light

Abstract

A display has a light source, a spatial light modulator and an intermediate spatial light modulator. The display may be a front projection display or a rear-projection display. The spatial light modulator is illuminated with light from a light source. The intermediate spatial light modulator is located in a light path between the light source and the spatial light modulator. The light source may comprise an array of controllable light-emitters. The display may provide a high dynamic range.

Claims

1. A display comprising:

a light source;

a spatial light modulator comprising a plurality of controllable elements located to modulate light from the light source, each of the plurality of controllable elements having a controllable transmissivity;

an intermediate spatial light modulator comprising a plurality of controllable elements located in a light path between the light source and the spatial light modulator, the intermediate spatial light modulator characterized by a maximum transmissivity of at least ½

; and

a controller configured to control the controllable elements of the spatial light modulator and the controllable elements of the intermediate spatial light modulator in response to image data to display an image specified by the image data.

2. A display according to claim 1 wherein the controllable elements of the intermediate spatial light modulator comprises electro-wetting light valves.

3. A display according to claim 1 wherein the controllable elements of the intermediate spatial light modulator comprise dye-doped PSCT elements.

4. A display according to claim 1 wherein the light source comprises a two-dimensional array of light-emitting elements each having a controllable light output and the controller is configured to generate driving values for the light-emitting elements based at least in part on the image data.

5. A display according to claim 4 wherein the controller is configured to estimate first light intensities at the controllable elements of the intermediate spatial light modulator based on the driving values for the light-emitting elements.

6. A display according to claim 5 wherein the controller is configured to estimate the first light intensities by, for each of the first light intensities, combining contributions to the first light intensity from a plurality of the light-emitting elements.

7. A display according to claim 5 wherein the controller is configured to estimate second light intensities at the controllable elements of the spatial light modulator based on the estimated first light intensities and driving values for the elements of the intermediate spatial light modulator.

8. A display according to claim 7 wherein the controller is configured to estimate the second light intensities by, for each of the second light intensities, combining contributions to the second light intensity from a plurality of the controllable elements of the intermediate spatial light modulator.

9. A display according to claim 5 wherein the controller is configured to generate the driving values for the elements of the intermediate spatial light modulator based at least in part upon the estimated first light intensities.

10. A display according to claim 5 wherein the controller is configured to generate the driving values for the elements of the intermediate spatial light modulator based at least in part upon the image data.

11. A display according to claim 4 wherein the controller is configured to update the driving values for the light-emitting elements at a first frequency and to update the driving values for the controllable elements of the intermediate spatial light modulator at a second frequency different from the first frequency.

12. A display according to claim 11 wherein the image data comprises video data defining a sequence of video frames and the controller is configured to update the driving values for the light emitting elements in each frame and to update the driving values for the controllable elements of the intermediate spatial light modulator less often than every frame.

13. A display according to claim 4 wherein the light-emitting elements each comprise a tile comprising one or more light-emitting devices and a waveguide, the waveguide configured to emit light from the light-emitting devices on a face thereof.

14. A display according to claim 12 wherein the intermediate spatial light modulator comprises a plurality of modules each module comprising a plurality of pixels of the spatial light modulator wherein each of the tiles illuminates the pixels of one of the modules.

15. A display according to claim 3 wherein the light source comprises no more than 400 of the light-emitters.

16. A display comprising:

a light source;

a first spatial light modulator;

a control system configured to receive image data defining an image to be displayed on the display and to control pixels of the first spatial light modulator in response to the image data;

an intermediate spatial light modulator located in an optical path between the light source and the first spatial light modulator;

wherein the control system is configured to control pixels of the intermediate spatial light modulator at least in part in response to the image data to provide or refine an approximation of the desired image on the first spatial light modulator.

17. A display according to claim 16 wherein the control system is configured to refresh the first spatial light modulator at a first rate and to refresh the intermediate spatial light modulator at a second rate different from the first rate.

18. A display according to claim 17 wherein the second rate is less than the first rate.

19. A display according to claim 18 wherein the image data comprises video data and the second rate is less than a frame rate of the video data.

20. A display according to claim 16 wherein the intermediate spatial light modulator is characterized by a maximum transmissivity of at least ½

.

21. A display according to claim 20 wherein the intermediate spatial light modulator is characterized by a maximum transmissivity of 0.85 or more.

22. A display according to claim 20 wherein the light source, intermediate spatial light modulator and spatial light modulator are equal in area and parallel to one another.

23. A display according to claim 16 wherein the pixels of the intermediate spatial light modulator are larger than the pixels of the first spatial light modulator.

24. A display according to claim 23 wherein the first spatial light modulator has more pixels than does the intermediate spatial light modulator.

25. A display according to claim 16 wherein the intermediate spatial light modulator has a contrast ratio of 10:

1 or lower.

26. A display according to claim 16 wherein the intermediate spatial light modulator and first spatial light modulator are supported by a common substrate.

27. A display according to claim 26 wherein the first spatial light modulator is supported on a first face of the common substrate and the intermediate spatial light modulator is supported on a second face of the common substrate.

28. A display according to claim 16 wherein the intermediate spatial light modulator is spaced apart from the first spatial light modulator by a first gap.

29. A display according to claim 28 wherein the light source, intermediate spatial light modulator and spatial light modulator are equal in area and parallel to one another.

30. A display according to claim 28 wherein the intermediate spatial light modulator is spaced apart from the light source by a second gap.

31. A display according to claim 30 comprising an optical diffuser element in at least one of the first and second gaps.

32. A display according to claim 30 comprising an optical element in at least one of the first and second gaps wherein an optical characteristic of the optical element varies according to a spatial pattern that is registered relative to the pixels of the intermediate spatial light modulator.

33. A display according to claim 32 wherein the optical element comprises a diffuser and the optical characteristic is a coefficient characterizing diffusion of light by the diffuser.

34. A display according to claim 16 wherein the light source comprises a plurality of light emitters and the intermediate spatial light modulator is arranged so that light from each of the light emitters of the light source is modulated by a plurality of the pixels of the intermediate spatial light modulator.

35. A display according to claim 16 wherein the light source comprises a plurality of light-emitting tiles, the plurality of tiles each comprising one or more light emitters having optical outputs coupled to a waveguide arranged to distribute light from the one or more light emitters over an area of the tile.

36. A display according to claim 35 wherein the intermediate spatial light modulator comprises a plurality of modules wherein each one of the plurality of modules is associated with and arranged to modulate light from a corresponding one of the plurality of tiles.

37. A display according to claim 36 wherein each module of the spatial light modulator is integrated with a corresponding one of the tiles of the light source.

38. A display according to claim 36 wherein each one of the plurality of modules comprises from 40 to 90 of the pixels of the intermediate spatial light modulator.

39. A display according to claim 38 wherein each one of the plurality of modules comprises an M×

N array of the pixels of the intermediate spatial light modulator wherein M and N are integers, M and N are equal or different, and at least one of M and N is a power of 2.

40. A display according to claim 16 wherein the control system comprises a map, the map providing information regarding non-uniformities in light emission by the light source wherein the control system is configured to adjust driving values for the pixels of the intermediate spatial light modulator to compensate for the non-uniformities.

41. A display according to claim 16 wherein the light source comprises a plurality of individually-controllable light emitters and the control system is configured to generate light source driving signals for the individually-controllable light emitters based at least in part on the image data.

42. A display according to claim 41 wherein the control system is configured to generate a first estimate of light incident from the light source on the intermediate spatial light modulator based at least in part on the light source driving signals and to generate a second estimate of light incident on the first spatial light modulator based at least in part on the first estimate and control values for the pixels of the first spatial light modulator.

43. A display according to claim 41 wherein the control system is configured to generate driving signals for the intermediate spatial light modulator based on the image data.

44. A display according to claim 44 wherein the control system is configured to determine from the image data a desired amount of light to be emitted from each pixel of the intermediate spatial light modulator and to generate driving signals for the intermediate spatial light modulator based on the desired amounts of light.