MOTION-BLUR COMPENSATION IN BACKLIT DISPLAYS

• US 20070146257A1
• Filed: 12/08/2006
• Published: 06/28/2007
• Est. Priority Date: 03/13/2002
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: University of British Columbia
• Inventors: Seetzen, Helge, Stuerzlinger, Wolfgang, Whitehead, Lorne, Ward, Gregory
• Granted Patent: US 8,059,110 B2
• Time in Patent Office: Days
• US Class Current: 345/84
• 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 screen which incorporates a light modulator. The screen may be a front projection screen or a rear-projection screen. The screen is illuminated with light from a light source comprising an array of controllable light-emitters. The controllable-emitters and 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 method for operating a display comprising a spatially-modulatable backlight illuminating a spatial light modulator, the method comprising:

controlling the spatially-modulatable backlight and the spatial light modulator according to image data to display an image;

periodically refreshing the spatial light modulator;

while refreshing the spatial light modulator, reducing an intensity of the spatially-modulatable backlight; and

,

overdriving the spatially-modulatable backlight at a time when the spatial light modulator is not being refreshed.

2. A method according to claim 1 comprising overdriving the spatially-modulatable backlight in alternation with reducing the intensity of the spatially-modulatable backlight.

3. A method according to claim 1 comprising overdriving the spatially-modulatable backlight by an amount selected to compensate for the reduction in intensity of the spatially-modulatable backlight while the spatial light modulator is being refreshed, such that a viewer perceives a desired brightness.

4. A method according to claim 1 wherein reducing the intensity of the spatially-modulatable backlight comprises dimming the spatially-modulatable backlight.

5. A method according to claim 1 wherein reducing the intensity of the spatially-modulatable backlight comprises turning off the spatially-modulatable backlight.

6. A method according to claim 1 wherein:

the spatially-modulatable backlight comprises a plurality of individually-controllable light sources;

refreshing the spatial light modulator is performed by sequentially refreshing a plurality of sections of the spatial light modulator;

a group of one or more of the individually-controllable light sources corresponds to each of the sections; and

the method comprises, while refreshing one of the sections, reducing an intensity of one of the groups of individually-controllable light sources that corresponds to the section being refreshed.

7. A method according to claim 6 comprising overdriving the individually-controllable light sources of the one of the groups at a time when the corresponding section is not being refreshed.

8. A method according to claim 6 wherein one section comprises a row of elements of the spatial light modulator and the group of individually-controllable light sources that corresponds to the one section comprises a row in an array of the individually-controllable light sources.

9. A method according to claim 6 wherein reducing the intensity of the one of the groups comprises turning off individually-controllable light sources belonging to the group.

10. A method according to claim 6 comprising time multiplexing the operation of the individually-controllable light sources and synchronizing the time multiplexing to the refreshing of the spatial light modulator.

11. A method according to claim 1 wherein the spatial light modulator comprises a liquid crystal display panel and the spatially-modulatable backlight comprises an array of light-emitting diodes.

12. An electronic display comprising:

a spatial light modulator;

a spatially-modulatable backlight illuminating the spatial light modulator; and

a controller configured to;

control the spatially-modulatable backlight and the spatial light modulator according to image data to display an image;

periodically refresh the spatial light modulator; and

,

in alternation, dim and overdrive the spatially-modulatable backlight, wherein dimming the spatially-modulatable backlight coincides with refreshing the spatial light modulator.

13. A display according to claim 12 wherein the spatially-modulatable backlight comprises a plurality of individually-controllable light sources.

14. A display according to claim 13 wherein the individually-controllable light sources comprise light-emitting diodes.

15. A display according to claim 14 wherein the spatial light modulator comprises a liquid crystal display panel.

16. A display according to claim 13 wherein:

the spatial light modulator comprises a plurality of sections that are refreshed in sequence;

a group of one or more of the individually-controllable light sources corresponds to each of the sections; and

the controller is configured to sequentially dim groups of the individually-controllable light sources that correspond to the sections in synchronization with the sections being refreshed.

17. A display according to claim 16 wherein the sections comprise rows of elements of the spatial light modulator and the groups of individually-controllable light sources that correspond to the sections comprise rows in the array of the individually-controllable light sources.

18. A display according to claim 13 wherein the controller is configured to overdrive one of the groups in a period when the section corresponding to the one of the groups is not being refreshed.

19. A display according to claim 13 wherein the operation of the individually-controllable light sources is time multiplexed and the time multiplexing is synchronized to the refreshing of the spatial light modulator.