System and Method for Controlling a Display Backlight

• US 20110279482A1
• Filed: 05/14/2010
• Published: 11/17/2011
• Est. Priority Date: 05/14/2010
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Neal, Greg
• Granted Patent: US 9,336,728 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

In one embodiment, a backlight controller for a zoned backlight display includes a processor having a brightness value output. The processor is configured to provide a brightness value for at least one brightness zone of the display based on a target brightness value for the at least one zone, a past brightness value of the at least one zone, and a brightness time response.

Claims

1. A backlight controller for a zoned backlight display, the controller comprising:

a processor comprising a brightness value output, the processor configured to provide a brightness value for at least one brightness zone of the display based on a target brightness value for the at least one zone, a past brightness value of the at least one zone and a brightness time response.

2. The backlight controller of claim 1, wherein the processor is disposed on an integrated circuit.

3. The backlight controller of claim 2, wherein the processor further comprises a lookup table comprising entries representing the brightness time response.

4. The backlight controller of claim 1, further comprising:

a zone brightness determination circuit for determining a target brightness value and the past brightness value based on input pixel data; and

a pixel scaler for scaling pixel data for pixel plane by the target brightness value.

5. The backlight controller of claim 1, further comprising an interface coupled to the brightness value output, the interface configured to provide a brightness to at least one light emitting diode (LED) of the at least one brightness zone.

6. The backlight controller of claim 1, further comprising a PWM generator coupled to the brightness value output.

7. The backlight controller of claim 1, wherein brightness time response approximates an inverse function of a time response of a pixel plane.

8. A method of operating a display comprising a pixel plane and a zoned backlight comprising a brightness zone, the method comprising:

providing a present brightness for the brightness zone based on present input pixel data;

providing a past brightness for the brightness zone based on past input pixel data;

providing a brightness time response for transitioning from the past brightness to the present brightness over a first time period; and

changing a brightness of the brightness zone according to the brightness time response over the first time period.

9. The method of claim 8, wherein the brightness time response is based on a time response of the pixel plane.

10. The method of claim 9, wherein the brightness time response approximates an inverse function of the time response of the pixel plane.

11. The method of claim 9, wherein the brightness time response comprises a time response for an increase in brightness, and a time response for a decrease in brightness.

12. The method of claim 11, wherein the time response for the increase in brightness is faster or slower than the time response for the decrease in brightness.

13. The method of claim 8, wherein changing the brightness comprises:

determining a brightness difference between the present brightness and the past brightness;

determining a present time slot;

determining a present time slot brightness value based on the brightness difference and the present time slot; and

transmitting the present time slot brightness to the brightness zone.

14. The method of claim 13, wherein determining the present time slot brightness value comprises:

providing the brightness difference and present time slot to a lookup table;

receiving an adjustment factor from the lookup table;

scaling the adjustment factor; and

adding the adjustment factor to a previous brightness value.

15. The method of claim 13, wherein transmitting the present time slot brightness comprises transmitting a control signal to at least one light emitting diode (LED) in the brightness zone.

16. The method of claim 15, further comprising sending pixel data to a portion of the pixel plane disposed in front of the brightness zone.

17. A display system comprising:

a multi-zone light emitting diode (LED) backlight disposed behind a liquid crystal display (LCD) pixel plane;

a backlight controller coupled to a brightness input of at least one zone of the multi-zone LED backlight, the backlight controller configured to provide a brightness value for the at least one zone based on a target brightness value for the at least one zone, a past brightness value for the at least one zone, and a brightness time response, wherein the backlight controller determines the target brightness value and the past brightness value based on pixel data for the at least one zone; and

a pixel plane controller coupled the LCD pixel plane.

18. The display system of claim 17, wherein the brightness time response is based on an inverse time function of the LCD pixel plane.

19. The display system of claim 18, wherein the brightness time response comprises a time response for an increase in brightness, and a time response for a decrease in brightness.

20. The display system of claim 19, wherein the time response for the increase in brightness is faster than the time response for the decrease in brightness.