Locally dimmed display

• US 8,408,718 B2
• Filed: 09/26/2012
• Issued: 04/02/2013
• 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:
  US13/627,558
• Publication Number:
  US 20130021394A1
• Time in Patent Office: 188 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:

a light modulating panel comprising a plurality of pixels, the pixels individually controllable to vary transmission of light through the panel at locations corresponding to the pixels;

a light source arranged relative to the light modulating panel, the light source comprising a plurality of light-emitting elements at a corresponding plurality of locations;

an optical system comprising one or more optical elements which cooperate to deliver light from the plurality of light-emitting elements to the light modulating panel, the elements of the light source and the one or more optical elements arranged such that light from the plurality of light-emitting elements of the light source spreads and mixes to illuminate the pixels of the light modulating panel with light having an intensity that is non-uniform across the light-modulating panel;

a controller connectable to receive image data, the image data specifying a desired image, the desired image having a desired luminance corresponding to each of the pixels of the light-modulating panel, the controller configured and connected to control light output of the light-emitting elements of the light source such that the light that non-uniformly illuminates the light-modulating panel approximates the desired image by providing a variation in light intensity with position on the light-modulating panel according to the image data, the controller further configured and connected to control light transmission of the pixels of the panel such that the resulting displayed image approaches the desired image specified by the image data.

2. The display according to claim 1 wherein the light-emitting elements of the light source are located outside a perimeter of the light modulating panel, behind the light modulating panel.

3. The display according to claim 1 wherein the wherein the light source comprises at least one array of the light-emitting elements having at least one dimension.

4. The display according to claim 1 wherein the controller is configured to compute the light intensities of the light from the light-emitting elements of the light source at the pixels of the light-modulating panel.

5. The display according to claim 2 wherein the controller is configured to determine driving values for the separately-controllable light-emitting elements of the light source by determining averages or weighted averages of the desired luminance values for pixels in image areas corresponding to each of the elements of the light source layer.

6. The display according to claim 1 wherein the controller is configured to estimate approximate intensities of light from the light source at the light-modulating panel and to use the estimate and the image data to set the pixels of the light-modulating panel.

7. The display according to claim 1 wherein the display has a dynamic range of 800:

1 or greater.

8. The display according to claim 1 wherein the light source is configured to emit white light.

9. The display according to claim 1 wherein the light-emitting elements of the light source comprise a light-emitting element that is off-axis and to at least one side of the light-modulating panel.

10. The display according to claim 1 wherein the light-emitting elements of the light source comprise light-emitting elements oriented to emit light in a plane parallel to a plane of the light-modulating panel.

11. The display according to claim 10 wherein the emitted light is redirected perpendicularly to the light-modulating panel.

12. The display according to claim 1, wherein the light-emitting elements of the light source are located beyond an edge and behind the light modulating panel.

13. The display according to claim 12 wherein the optical system comprises an optical element configured to redirect light from the light source to illuminate the light modulating panel.

14. The display according to claim 13, wherein the optical system is configured to reflect and diffuse the light from the light emitters of the light source.

15. The display according to claim 13, wherein the optical system redirects light from the light emitters that is mainly emitted in a direction parallel to a plane of the light modulating panel to a direction mainly perpendicular to the plane of the light modulating panel.

16. The display according to claim 13, wherein the optical system is configured to redirect light from the light source that is mainly emitted next to the light modulating panel to a direction mainly into the light modulating panel.

17. The display according to claim 1, wherein the light-emitting elements of the light source are at least one of:

outside an edge and behind the light modulating panel, nearer to an edge than a central portion of the light modulating panel, above and behind the light modulating panel, outside a perimeter of the light modulating panel, behind the light modulating panel, next to and behind the light modulating panel.

18. A display controller for controlling a display in response to image data wherein the display comprises:

a light modulating panel comprising a plurality of pixels, the pixels individually controllable to vary transmission of light through the panel at locations corresponding to the pixels;

a light source arranged relative to the light modulating panel, the light source comprising a plurality of light-emitting elements at a corresponding plurality of locations; and

an optical system comprising one or more optical elements which cooperate to deliver light from the plurality of light-emitting elements to the light modulating panel, the elements of the light source and the one or more optical elements arranged such that light from the plurality of light-emitting elements of the light source spreads and mixes to illuminate the pixels of the light modulating panel with light having an intensity that is non-uniform across the light-modulating panel;

the controller configured to receive the image data specifying a desired image and to determine from the image data a desired luminance corresponding to each of the pixels of the light-modulating panel, the controller further configured and connectable to control light output of the light-emitting elements of the light source such that the light that non-uniformly illuminates the light-modulating panel approximates the desired image by providing a variation in light intensity with position on the light-modulating panel according to the image data, the controller further configured and connectable to control light transmission of the pixels of the light modulating panel such that the resulting displayed image approaches the desired image specified by the image data.

19. The display controller according to claim 18, wherein the controller is further configured to set the signals for controlling the transmissivity of the pixels of the light modulating panel taking into account a light pattern projected onto the light modulating panel from one or more of the light emitters of the light source that are positioned outside a perimeter of the light-modulating panel and behind the light modulating panel.

20. The display controller according to claim 19, wherein the light pattern projected onto the light modulating panel comprises light re-directed from the light source to the light modulating panel.

21. The display controller according to claim 20, wherein the light pattern projected onto the light modulating panel results from re-direction of the light from the light-emitters of the light source via reflection and diffusion.

22. The display controller according to claim 19 wherein the controller is configured to determine the light intensities at the pixels of the light-modulating panel by estimating intensities of light emitted from the light emitters of the light source at the pixels of the light-modulating panel.

23. The display controller according to claim 22 wherein the controller is configured to determine the driving values for the separately-controllable light-emitting elements of the light source by determining averages or weighted averages of the desired luminance values for image areas corresponding to different ones of the light emitting elements of the light source layer.

24. The display controller according to claim 19 wherein the controller is configured to estimate an approximate intensity of light from the light emitting elements of the light source and to use the estimate to control light transmission values for the pixels of the light-modulating panel.

25. A display comprising:

a light modulating panel comprising a plurality of pixels, the pixels individually controllable to vary transmission of light through the panel at locations corresponding to the pixels;

a light source arranged relative to the light modulating panel, the light source comprising controllable light-emitting elements located behind the light modulating panel and outside a perimeter of the light modulating panel;

an optical system comprising one or more optical elements which cooperate to deliver light from the light-emitting elements of the light source to the light modulating panel, the one or more optical elements operative to reflect and diffuse light from the light-emitting elements of the light source such that light from the plurality of light-emitting elements of the light source is redirected and spread out to illuminate the pixels of the light modulating panel with light having an intensity that is non-uniform across the light-modulating panel;

a controller connectable to receive image data, the image data specifying a desired image, the desired image having a desired luminance corresponding to each of the pixels of the light-modulating panel, the controller configured and connected to control light output of the light-emitting elements of the light source such that the light that non-uniformly illuminates the light-modulating panel approximates the desired image by providing a variation in light intensity with position on the light-modulating panel according to the image data, the controller further configured and connected to control light transmission of the pixels of the panel such that the resulting displayed image approaches the desired image specified by the image data.

26. The display according to claim 25, wherein the optical system is configured to redirect light from the light source that is mainly emitted in a direction parallel to a plane of the light modulating panel to a direction mainly perpendicular to the plane of the light modulating panel.

27. The display according to claim 25, wherein the optical system is configured to redirect light from the light source that is mainly emitted next to the light modulating panel to a direction mainly into the light modulating panel.

28. The display according to claim 25, wherein the optical system is configured to carry light from the light source that is emitted adjacent an edge of the light modulating panel across the panel to illuminate pixels in a central area of the light emitting panel.