Methods and Systems for Reduced Flickering and Blur

• US 20090295706A1
• Filed: 05/29/2008
• Published: 12/03/2009
• Est. Priority Date: 05/29/2008
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Feng, Xiao-Fan
• Granted Patent: US 8,068,087 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Elements of the present invention relate to systems and methods for generating, modifying and applying backlight array driving values.

Claims

1. A method for determining a display backlight modulation process, said method comprising:

a) performing motion detection on at least a portion of a first frame of a video sequence to determine whether substantial motion occurs in said portion of said first frame;

b) performing motion detection on a corresponding portion of a second frame of said sequence to determine whether substantial motion occurs in said corresponding portion of said second frame;

c) using a first pulse-width-modulated (PWM) backlight modulation screen comprising at least one fixed-width pulse at a first width and a first spacing for said first frame;

d) if substantial motion is detected in one of said first frame and said second frame, but not the other of said first frame and said second frame, using a transition backlight modulation screen for displaying said second frame, wherein said transition backlight modulation screen comprises a pulse with a pulse width that is different than said first width.

2. A method as described in claim 1 wherein said motion detection comprises determining an average pixel level in said at least a portion of said first frame and said corresponding portion of said second frame.

3. A method as described in claim 1 wherein said motion detection comprises morphological dilation of a motion map based on an average pixel level in said at least a portion of said first frame and said corresponding portion of said second frame.

4. A method as described in claim 1 wherein said motion detection comprises performing a logical OR operation on a motion map for said first frame and a motion map for said second frame.

5. A method as described in claim 1 wherein said transition backlight modulation screen pulse width is determined by:

6. A method as described in claim 1 wherein said first PWM backlight modulation screen contains multiple pulses and said second PWM backlight modulation screen contains only one pulse.

7. A method as described in claim 1 wherein said first PWM backlight modulation screen contains only one pulse and said second PWM backlight modulation screen contains multiple pulses.

8. A method as described in claim 1 wherein said at least a portion of said first frame and said corresponding portion of said second frame correspond to a display backlight element.

9. A method for determining a display backlight modulation process, said method comprising:

a) comparing a first block of a first frame of a video sequence to a corresponding second block of a second frame of said video sequence to determine whether motion occurs in said second block;

b) incrementing a motion map variable for a pixel in said second block when said comparing results in a determination that motion occurs in said second block;

c) decrementing said motion map variable when said comparing results in a determination that motion does not occur in said second block; and

d) creating a backlight modulation screen for said second block, wherein said backlight modulation screen comprises at least one pulse with a pulse width that is dependent on said motion map variable.

10. A method as described in claim 9 wherein said comparing comprises determining an average value for pixels in said first block and said second block and determining that motion occurs when said average value for said first block differs from said average value for said second block by a threshold amount.

11. A method as described in claim 9 wherein said comparing comprises creating a motion map based on a comparison of pixel values in said first block and said second block and performing morphological dilation on said motion map.

12. A method as described in claim 9 wherein said comparing comprises creating a first motion map for said first frame and second motion map for said second frame and performing a logical OR operation on said first motion map and said second motion map to create a third motion map.

13. A method as described in claim 9 wherein said at least one pulse has a pulse width determined by:

14. A method as described in claim 9 wherein said first block and said second block correspond to a display backlight element.

15. An apparatus for determining a display backlight modulation process, said apparatus comprising:

a) a motion detector for comparing a first block of a first frame of a video sequence to a corresponding second block of a second frame of said video sequence to determine whether motion occurs in said second block;

b) a motion map manager for incrementing a motion map variable for a pixel in said second block when said comparing results in a determination that motion occurs in said second block;

c) said motion map manager also for decrementing said motion map variable when said comparing results in a determination that motion does not occur in said second block; and

d) a screen generator for creating a backlight modulation screen for said second block, wherein said backlight modulation screen comprises at least one pulse with a pulse width that is dependent on said motion map variable.

16. An apparatus as described in claim 15 wherein said comparing comprises creating a first motion map for said first frame and second motion map for said second frame and performing a logical OR operation on said first motion map and said second motion map to create a third motion map.

17. An apparatus as described in claim 15 wherein said at least one pulse has a pulse width determined by:

18. A method for determining a display backlight modulation process, said method comprising:

a) generating a display blank signal comprising a plurality of waveforms within an image frame time, said plurality of waveforms comprising a first waveform and a second waveform;

b) triggering a first backlight modulation pulse with said first waveform, wherein said first pulse has a first on time and a first off time;

c) triggering a second backlight modulation pulse with said second waveform, wherein said second pulse has a second on time and a second off time; and

d) driving a display backlight with said first pulse and said second pulse.

19. A method as described in claim 18 wherein said first on time of said first pulse is triggered by said first waveform.

20. A method as described in claim 18 wherein said first off time of said first pulse is triggered by said first waveform.

21. A method as described in claim 18 wherein said first on time of said first pulse is measured in advance of said first waveform and said off time of said first pulse coincides with said first waveform.

22. A method as described in claim 18 wherein said first on time of said first pulse coincides with said first waveform and said off time of said first pulse is measured after said first waveform.