Locally dimmed display

• US 8,419,194 B2
• Filed: 07/11/2012
• Issued: 04/16/2013
• Est. Priority Date: 02/27/2001
• Status: Expired due to Term

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Whitehead, Lorne A., WARD, Gregory John, Stuerzlinger, Wolfgang, Seetzen, Helge
• Primary Examiner(s): Dowling, William C
• Application Number:
  US13/546,184
• Publication Number:
  US 20120274674A1
• Time in Patent Office: 279 Days
• Field of Search: 353/30, 353/31, 353/79, 353/85, 353/121, 349/5, 349/7
• US Class Current: 353/85
• 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 locally dimmed display has a spatial light modulator illuminated by a light source. The spatial light modulator is illuminated with a low resolution version of a desired image. The illumination may comprise a series of lighting elements that vary smoothly from one element to another at the spatial light modulator.

Claims

1. A display comprising:

an input configured to receive an image signal representative of a desired image;

a spatial light modulating panel;

a light source configured to illuminate the spatial light modulating panel;

a controller configured to energize the light source and the spatial light modulating panel based on the image signal;

wherein the controller is further configured to energize the light source according to a luminance of the desired image, and energize pixels of the spatial light modulating panel according to an amount of smoothly varying luminance illuminating the pixels of the spatial light modulating panel and a corresponding amount of luminance in the desired image.

2. The display according to claim 1, wherein the light source is at an edge and behind the spatial light modulating panel.

3. The display according to claim 1, wherein the light source is outside and behind the spatial light modulating panel.

4. The display according to claim 1, wherein the light source is above and behind the spatial light modulating panel.

5. The display according to claim 1, wherein the light source is configured to illuminate the spatial light modulating panel in a manner that varies across the spatial light modulating panel.

6. The display according to claim 1, wherein the illumination varies across the spatial light modulating panel.

7. The display according to claim 1, wherein the illumination varies across the spatial light modulating panel and the spatial light modulating panel is controlled by the controller in a manner that accounts for the illumination variations and causes a resulting image of the spatial light modulator to approach the desired image.

8. The display according to claim 7, wherein the controller accounts for the illumination by adjusting modulation of pixels of the spatial light modulator.

9. The display according to claim 1, wherein the controller divides the desired image by the luminance illuminating the pixels to determine energization of the spatial light modulating panel.

10. The display according to claim 1, further comprising a light re-directing mechanism configured to redirect light from the light source to the spatial light modulating panel.

11. The display according to claim 10, wherein the light re-directing mechanism comprises a reflection and diffusion.

12. The display according to claim 10, wherein the light source is configured to emit light in a direction primarily parallel to a plane of the spatial light modulating panel and the light re-direction mechanism is configured to reflect light primarily in a direction toward the spatial light modulating panel.

13. The display according to claim 1, wherein the light source comprises a plurality of light sources.

14. The display according to claim 13, wherein the light source is configured to illuminate the spatial light modulator in a manner that varies across the spatial light modulating panel, and the controller considers the varying nature of the luminance on the spatial light modulating panel when energizing the pixels of the spatial light modulating panel.

15. The display according to claim 13, further comprising a light re-directing mechanism configured to redirect light from the light source to the spatial light modulating panel.

16. The display according to claim 15, wherein the light re-directing mechanism comprises a reflection and diffusion.

17. The display according to claim 15, wherein the light source is configured to emit light in a direction primarily parallel to a plane of the spatial light modulator and the light re-direction mechanism is configured to reflect light primarily in a direction toward the spatial light modulating panel.

18. The display according to claim 1, wherein the light source comprises an array of light sources.

19. The display according to claim 18, further comprising a light re-directing mechanism configured to redirect light from the light source to the spatial light modulating panel.

20. The display according to claim 19, wherein the light re-directing mechanism comprises a reflection and diffusion.

21. The display according to claim 19, wherein the light source is configured to emit light in a direction primarily parallel to a plane of the spatial light modulating panel and the light re-direction mechanism is configured to reflect light primarily in a direction toward the spatial light modulating panel.

22. The display according to claim 1, wherein the light source is upstream and above an edge of the spatial light modulating panel.

23. The display according to claim 1, wherein the light source is at an edge and in front of the spatial light modulating panel.

24. The display according to claim 1, wherein the light source is outside a perimeter of the spatial light modulating panel and to a side of a plane defined by the spatial light modulator.

25. The display according to claim 1, wherein the light source is the source of a light stream originating at the light source traveling to and through the spatial light modulating panel and thereby illuminating the spatial light modulating panel, and wherein the light source is located at an edge of the spatial light modulating panel such that the light source is outside a perimeter of the spatial light modulating panel and the light source is configured to emit light mainly toward an area that is adjacent and upstream of the spatial light modulating panel;

the display further comprising a re-direction mechanism configured to re-direct the emitted light to illuminate the spatial light modulating panel.

26. The display according to claim 25, wherein the re-directed emitted light is mainly perpendicular to the spatial light modulating panel.

27. The display according to claim 1, wherein the light source is outside a perimeter, adjacent to, and upstream of the spatial light modulating panel.

28. The display according to claim 1, wherein the light source is above an edge of the spatial light modulating panel and upstream of a plane formed by the spatial light modulating panel.

29. The display according to claim 1, wherein the light source is outside an edge of the spatial light modulating panel.

30. The display according to claim 1, wherein the light source is at an edge and in front of the spatial light modulating panel.

31. The display according to claim 1 comprising an optical element adjacent to the spatial light modulating panel, wherein the optical element comprises scattering centers arranged to diffuse light traveling through the optical element.

32. The display according to claim 31 wherein the optical element is co-extensive with the spatial light modulating panel.

33. A display method, comprising the steps of:

energizing a light source to cause a spatially varying illumination on an LCD panel;

calculating amounts of luminance at pixels of the LCD panel;

apportioning the calculated luminance at pixels of the LCD panel by a corresponding luminance of the desired image; and

energizing pixels of the LCD panel according to the apportionment;

wherein;

the steps of calculating, apportioning, and energizing are performed for pixels of the LCD panel in different areas of LCD panel having varying illumination.

34. The method according to claim 33, further comprising the step of re-directing light from the light source to the spatial light modulator.

35. The method according to claim 34, wherein the step of re-directing comprises reflection and diffusion.

36. The method according to claim 35, wherein the light source is configured to emit light in a direction primarily parallel to a plane of the spatial light modulator and the light re-direction step reflects light primarily in a direction toward the spatial light modulating panel.

37. The method according to claim 33, wherein the step of apportioning comprises dividing the calculated luminance on the LCD panel by a luminance of the desired image.

38. The display according to claim 33, wherein the light source is at an edge and behind the spatial light modulating panel.

39. The display according to claim 33, wherein the light source is outside and behind the spatial light modulating panel.

40. The display according to claim 33, wherein the light source is above and behind the spatial light modulating panel.

41. The display according to claim 33, wherein the spatial light modulating panel is controlled by the controller in a manner that accounts for the illumination variations and causes a resulting image of the spatial light modulator to approach the desired image.

42. A controller configured to determine an energization scheme for pixels of a modulator based on a luminance of corresponding pixels in a desired image to be displayed by the modulator and an amount of illumination provided to the pixels of the modulator by a spatially and smoothly varying pattern of light.

43. The controller according to claim 42, wherein the amount of luminance is calculated based on a light re-directed perpendicularly toward a plane of the modulator from a light source located behind and at an edge of the modulator and configured to emit light parallel to the plane of the modulator.

44. The controller according to claim 43, wherein the controller is further configured to:

energize the light source to cause the spatially and smoothly varying pattern of light on the modulator;

calculate amounts of luminance at the pixels of the modulator; and

apportion the calculated luminance at pixels of the modulator by a corresponding luminance of the desired image; and

utilize the apportionment in the energization scheme.