HDR DISPLAYS AND CONTROL SYSTEMS THEREFOR

• US 20090085929A1
• Filed: 10/13/2008
• Published: 04/02/2009
• Est. Priority Date: 02/27/2001
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Seetzen, Helge, Stuerzlinger, Wolfgang, Ward, Greg, Whitehead, Lorne
• Granted Patent: US 7,731,367 B2
• Time in Patent Office: Days
• US Class Current: 345/617
• 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 controller, comprising:

a processing device configured to,

produce first control signals intended to control individually controllable elements of a backlight of a display device, wherein the first control signals are based on image data defining a desired image and comprise data that, when applied to the backlight, cause the backlight to project a pattern of light which approximates the desired image, and

produce second control signals intended to control individually controllable elements of a transmissive pixel array panel of the display device;

wherein;

the second control signals are based on the image data defining the desired image and comprises data that, when applied to the panel, cause the transmissive pixel array to modulate the pattern of light so as to reduce differences between the pattern of light and the desired image, and

the second control signals include compensation of artifacts due to pixel size differences between the backlight and the transmissive pixel array.

2. The controller according to claim 1, wherein the processing device is further configured to determine intensities of the pattern of light and use the determined intensities in production of the second control signals.

3. The controller according to claim 2, wherein the intensities are determined where the pattern of light would be incident on the panel during use of the controller in a display device.

4. The controller according to claim 1, wherein local dimming that results from the backlight projected pattern of light is enabled by the individual control of the backlight elements.

5. The controller according to claim 4, wherein the local dimming improves dynamic contrast ratio of an image displayed by the panel when illuminated by the backlight.

6. The controller according to claim 4, wherein a content of the first control signals include values to energize the individually controllable elements of the backlight so as to project light onto the individually controllable elements of the transmissive pixel array panel in a manner characterized by a spread function having a full width at half-maximum in the range of 0.3×

d2 to 3×

d2, where d2 is a center-to-center spacing of the individually controllable elements of the backlight.

7. The controller according to claim 4, wherein:

the first control signals comprise backlight control in steps of intensity;

the second control signals comprise transmissive pixel array control in steps of transmissivity; and

a number of steps of intensity is less than a number of steps of transmissivity.

8. A controller configured to,

produce signals capable of locally dimming a backlight having a plurality of pixels comprising color sub-pixels and controlling transmissivity of a display panel,

wherein,

the signals are produced from at least an image signal,

the local dimming is enabled by providing, in the signals, a plurality of backlight brightness control levels configured to control each of a plurality of individually controllable elements of the backlight,

the transmissivity control of the panel is enabled by providing, in the signals, a plurality of transmissivity control levels configured to control each of a plurality individually controllable transmissivity elements of the panel, and

the transmissivity control of the panel is based on a backlight spread function comprising a full width at half maximum in a range of 0.3×

d2 to 3×

d2 where d2 is a center-to-center spacing of individually controllable elements of the backlight.

9. The controller according to claim 8, wherein the color sub-pixels comprise the colors red, green, and blue.

10. The controller according to claim 8, wherein the controller is part of a display comprising an array of lights and a Liquid Crystal Display (LCD), the signals enabling the local dimming are coupled to the array of lights, and the signals enabling the transmissivity control are coupled to the LCD.

11. The controller according to claim 8, wherein at least one of the signals is produced utilizing a pre-processing of the image signal.

12. The controller according to claim 11, wherein the signals are produced utilizing a pre-processing of the image signal.

13. The controller according to claim 8, wherein the backlight brightness control levels are a function of the desired image contained in the image signal.

14. The controller according to claim 8, wherein the backlight brightness control levels are a function of the desired image contained in the image signal and comprise a low resolution version of the image contained in the image signal.

15. The controller according to claim 8, wherein the backlight brightness control levels comprise values to energize the individually controllable elements of the backlight so as to project light onto the individually controllable elements of the transmissive pixel array panel.

16. The controller according to claim 8, wherein:

the backlight brightness control levels comprise backlight control in steps of intensity;

the transmissivity control levels comprise transmissive pixel array control in steps of transmissivity; and

a number of steps of intensity in the backlight brightness control levels is less than a number of steps of transmissivity in the transmissivity control levels.

17. A controller, comprising:

a processing device having an input capable of receiving an image signal and configured to produce a local dimming signal and a transmissive panel control signal;

wherein;

the local dimming signal comprises control levels for a plurality of individually controllable backlights,

the control levels are determined as a function of a desired image contained in the image signal,

at least one of the local dimming signal and transmissive panel control signal are produced on-the-fly, and

the transmissive panel control signal comprises a signal configured to place the transmissive panel in a state that reduces differences between light produced by the plurality of individually-controllable backlights and the desired image including mitigation of at least one artifact due to a difference in resolution between the backlights and the panel.

18. The controller according to claim 17, wherein the function of the desired image comprises a low resolution version of the desired image.

19. The controller according to claim 17, wherein the transmissive panel control signal is produced with at least one artifact reduction algorithm.

20. The controller according to claim 19, wherein the artifact reduction algorithm comprises an algorithm that reduces artifacts that would result from the combination of a lower resolution backlight having pixels common to a plurality of

pixels of a higher-resolution transmissive panel.

21. The controller according to claim 19, wherein the artifact reduction algorithm comprises an algorithm that sets the control levels to provide an approximation of the desired image by determining an average of desired luminance values for image areas corresponding to each pixel of the transmissive panel.

22. The controller according to claim 21, wherein the controller sets the transmissive panel control signal after determining the average.

23. The controller according to claim 22, wherein the average comprises a weighted average of the desired luminance values.

24. A method, comprising the steps of:

receiving image data defining a desired image;

preparing first control signals comprising local dimming signals based on the image data, the first control signals configured to control individually controllable elements of a backlight of a display device in a manner that, if applied to the backlight, cause the backlight to project a pattern of light that is locally dimmed and which comprises a low resolution version of the desired image, and

preparing second control signals based on the image data, the second control signals configured to control individually controllable elements of a transmissive pixel array panel of the display device, the second control signals comprising data that, if applied to the transmissive pixel array panel, cause the transmissive pixel array panel to modulate the pattern of light so as to reduce differences between the pattern of light and the desired image and account for at least one artifact caused by differences in pixel sizes between the backlight and the transmissive panel.

25. The method according to claim 24, further comprising the step of determining intensities of the pattern of light and using the determined intensities in preparation of the second control signals.

26. The method according to claim 25, further comprising the step of determining the intensities at a point where the pattern of light would be incident on the panel during use of the controller in the display device.

27. The method according to claim 24, wherein local dimming that results from the backlight projected pattern of light is enabled by individual control of the backlight elements in the display device as asserted by the local dimming signals.

28. The method according to claim 27, wherein the step of preparing first control signals comprising local dimming signals comprises preparing values to energize the individually controllable elements of the backlight so as to project light onto the individually controllable elements of the transmissive pixel array panel in a manner characterized by a spread function having a full width at half-maximum in the range of 0.3×

d2 to 3×

d2, where d2 is a center-to-center spacing of the individually controllable elements of the backlight.

29. The method according to claim 27, wherein:

the step of preparing first control signals comprising local dimming signals comprises the step of determining backlight control values in steps of intensity;

the step of preparing second control signals comprises determining transmissive pixel array control values in steps of transmissivity; and

a number of steps of intensity for the backlight control values is less than a number of steps of transmissivity for the transmissive pixel array control values.

30. The method according to claim 24, wherein the steps of preparing first and second control signals are embodied in a form suitable for use by a computer.

31. The method according to claim 28, wherein the steps of the method are embodied in a form suitable for use in a display device controller.