Method, system and apparatus for power saving backlight

• US 8,687,028 B2
• Filed: 03/05/2013
• Issued: 04/01/2014
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Chihao Xu
• Original Assignee: Chihao Xu
• Inventors: Albrecht, Marc, Xu, Chihao, Karrenbauer, Andreas
• Primary Examiner(s): LEE, NICHOLAS J
• Application Number:
  US13/785,935
• Publication Number:
  US 20130278641A1
• Time in Patent Office: 392 Days
• Field of Search: None
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/08 Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127

Abstract

A method, apparatus, and system for displaying an image on a liquid crystal display (LCD). The method, apparatus, and system can include condensing a plurality of pixel gray values to a concentrated pixel, the concentrated pixel assigned to a geometric position on a display and described by at least one of a plurality of parameters and gray value; forming the concentrated pixels to a condensed image; resolving a light spread function of a first LED in substantially the same resolution as the condensed image; calculating a backlight needed based on the condensed image; and optimizing a value of a plurality of LEDs by considering the contribution of the plurality of LEDs on the concentrated pixel, wherein light spread functions of the LEDs are used.

Claims

1. A method of lighting a liquid crystal display, comprising:

condensing a plurality of pixel gray values to a concentrated pixel, the concentrated pixel assigned to a geometric position on a display and described by at least one of a plurality of parameters and gray value;

forming the concentrated pixels to a condensed image;

resolving a light spread function of a first LED in substantially the same resolution as the condensed image;

calculating a backlight needed based on the condensed image;

optimizing a value of a plurality of LEDs by considering the contribution of the plurality of LEDs on the concentrated pixel, wherein light spread functions of the LEDs are used; and

wherein a resolution of the condensed image is higher than the number of LEDs.

2. The method of lighting a liquid crystal display of claim 1, wherein a segment to be condensed is a rectangle array containing a plurality of pixels.

3. The method of lighting a liquid crystal display of claim 1, wherein at least one dimension of a plurality of condensed segments on a display is a binary round number.

4. The method of lighting a liquid crystal display of claim 1, wherein a filter function is applied for condensing pixel gray values.

5. The method of lighting a liquid crystal display of claim 1, further comprising utilizing a plurality of condensing functions in one local dimming processing unit.

6. The method of lighting a liquid crystal display of claim 1, further comprising assigning a plurality of concentrated pixels to an individual LED.

7. The method of lighting a liquid crystal display of claim 1, further comprising storing the condensed image in a memory of the local dimming processing unit.

8. The method of lighting a liquid crystal display of claim 7, further comprising performing iterations for calculating LED values and reading the stored, condensed image stored at least one time within a frame period.

9. The method of lighting a liquid crystal display of claim 1, further designating a start value for the plurality of LEDs without consideration of contribution of other LEDs in the plurality of LEDs and using a decrease approach to determine final LED values of the plurality of LEDs by considering the contribution of a number of LEDs on the backlight behind concentrated pixels.

10. The method of lighting a liquid crystal display of claim 9, further comprising using further iteration approaches that vary LED values by one of an increase approach, a decrease approach or a combination of an increase approach and a decrease approach to substantially fill the backlight requirement given by the condensed image.

11. The method of lighting a liquid crystal display of claim 1, further comprising successively increasing a gray value of a concentrated pixel to a 100% value for the concentrated pixel during the iterations.

12. The method of lighting a liquid crystal display of claim 1, further comprising scanning the concentrated pixels in dependence on their positions.

13. The method of lighting a liquid crystal display of claim 1, wherein an arrangement of the LED backlight is edge-lit.

14. The method of lighting a liquid crystal display of claim 1, wherein the light spread function considers characteristics of at least one of a one-dimensional structure of an LED bar, reflection stripes on edges of a panel of the display and imperfect properties of light guide.

15. The method of lighting a liquid crystal display of claim 1, wherein the light spread functions are stored in a memory.

16. A liquid crystal display module, comprising:

a liquid crystal display with a plurality of pixels to display an image;

a backlight with a plurality of LEDs; and

a processor that condenses a plurality of pixel gray values to a concentrated pixel, assigns the concentrated pixel assigned to a geometric position on a display described by at least one of a plurality of parameters and gray value, forms the concentrated pixels to a condensed image, resolves a light spread function of a first LED in substantially the same resolution as the condensed image, calculates a backlight needed based on the condensed image, and optimizes a value of a plurality of LEDs by considering the contribution of the plurality of LEDs on the concentrated pixel, wherein light spread functions of the LEDs are used, and wherein the resolution of the condensed image is higher than the number of LEDs.

17. The lighting a liquid crystal display of claim 16, wherein the processor further designates a start value for the plurality of LEDs without consideration of contribution of other LEDs in the plurality of LEDs and uses a decrease approach to determine final LED values of the plurality of LEDs by considering the contribution of a number of LEDs on the backlight behind concentrated pixels.

18. The liquid crystal display of claim 16, wherein the processor uses further iteration approaches that vary LED values by one of an increase approach, a decrease approach or a combination of an increase approach and a decrease approach to substantially fill the backlight requirement given by the condensed image.

19. A system for producing an image with a liquid crystal display, comprising:

a plurality of pixels that display an image on a liquid crystal display;

a backlight having a plurality of LEDs that light the liquid crystal pixels;

a processing unit with an access to the image data to be displayed; and

an LED driver circuit which receives LED control signals from the processing unit that condenses a plurality of pixel gray values to a concentrated pixel, assigns the concentrated pixel assigned to a geometric position on a display described by at least one of a plurality of parameters and gray value, forms the concentrated pixels to a condensed image, resolves a light spread function of a first LED in substantially the same resolution as the condensed image, calculates a backlight needed based on the condensed image, and optimizes a value of a plurality of LEDs by considering the contribution of the plurality of LEDs on the concentrated pixel, wherein light spread functions of the LEDs are used, and wherein the resolution of the condensed image is higher than the number of LEDs.

20. The lighting a liquid crystal display of claim 19, wherein the processor further designates a start value for the plurality of LEDs without consideration of contribution of other LEDs in the plurality of LEDs and uses a decrease approach to determine final LED values of the plurality of LEDs by considering the contribution of a number of LEDs on the backlight behind concentrated pixels.