System and Method for Backlight Control for An Electronic Display

• US 20090184904A1
• Filed: 01/23/2008
• Published: 07/23/2009
• Est. Priority Date: 01/23/2008
• Status: Active Grant

• Current Assignee: Polaris PowerLED Technologies, LLC (Microchip Technology Incorporated)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Vi, Klen, Chen, Sean, Santo, Hendrik, Dhayagude, Tushar, S., Dilip
• Granted Patent: US 8,217,887 B2
• Time in Patent Office: Days
• US Class Current: 345/82
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• 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 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

The present invention discloses apparatus and techniques relating to the intelligent control of a display'"'"'s backlight LED strings. The present invention provides for controlling the display intensity on a region-by-region basis and for adjusting the intensity multiple times within the duration of a frame. The present invention also provides backlight adjustment in a manner that emphasizes certain colors and deemphasizes certain colors. The present invention also provides for adjustment of the backlight based on the ambient temperature.

Claims

1. An electronic display comprising:

a plurality of strings of light emitting diodes (LEDs);

a first circuitry for controlling the luminosity of the plurality of strings of LEDs;

a plurality of pixels for displaying a plurality of image frames of a video;

a second circuitry for controlling the plurality of pixels;

the second circuitry for displaying each image frame of the plurality of image frames for a predetermined period of time; and

the first circuitry for adjusting the luminosity levels of the plurality of strings of LEDs for a plurality of times within the predetermined period of time.

2. The display of claim 1, wherein the predetermined period of time includes approximately 1/30 seconds.

3. The display of claim 1, wherein the plurality of times includes a number selected from the set of one, two, three, four, five, six, seven, eight, nine and ten.

4. The display of claim 1, further comprising:

the predetermined period of time is the period of time between two successive rising edges of pulses of the VSYNC signal.

5. The display of claim 1, further comprising:

the first circuitry configured to adjust the luminosity of the plurality of LED strings for a plurality of times between the occurrence of two successive pulses of the VSYNC signal.

6. The display of claim 1, wherein the plurality of strings of LEDs include a string of red LEDs, a string of blue LEDs and a string of green LEDs.

7. The display of claim 1, further comprising:

a first display section associated with a first set of pixels of the plurality of pixels;

a second display section associated with a second set of pixels of the plurality of pixels;

a first set of strings of the plurality of strings associated with the first section;

a second set of strings of the plurality of strings associated with the second section;

the first circuitry configured to adjust the luminosity of the first set of strings according to the portion of an image frame being displayed by the first set of pixels and to adjust the luminosity of the second set of strings according to the portion of the image frame being displayed by the second set of pixels.

8. The display of claim 1, further comprising:

an ambient light sensor coupled to the first circuitry; and

the first circuitry configured for adjusting the luminosity levels of the plurality of strings of LEDs based on the ambient lighting conditions.

9. The display of claim 8, wherein the first circuitry configured to adjusting the luminosity of a red string of LEDs to a different luminosity level from the luminosity level of a green string of LEDs.

10. The display of claim 1, wherein the display includes a liquid crystal display.

11. The display of claim 1, further comprising:

the first circuitry for causing the luminosity levels of the plurality of strings of LEDs to become zero during a raster blanking interval.

12. The display of claim 1, wherein the plurality of strings of LEDs include a combination of a string of white LEDs and one or more strings of LEDs selected from the group consisting of a string of red LEDs, a string of blue LEDs and a string of green LEDs.

13. A method for an electronic display comprising:

generating a clock signal having a frequency that is a multiple of a reference frequency; and

using the clock signal for controlling backlighting circuitry of the display.

14. The method of claim 13, wherein the reference frequency includes the frequency of the VSYNC signal.

15. The method of claim 13, controlling the backlighting circuitry of the display includes adjusting the luminosity level of a string of LEDs at the frequency of the clock signal.

16. The method of claim 15, wherein adjusting the luminosity level of the string of LEDs multiple times during the display of a single video frame.

17. The method of claim 15, wherein adjusting the luminosity of the string of LEDs based on the color of the LEDs and an ambient light condition.

18. An liquid crystal display comprising:

a plurality of strings of light emitting diodes (LEDs) including a string of red LEDs, a string of green LEDs and a string of blue LEDs;

a first circuitry for controlling the luminosity of the plurality of strings of LEDs;

a plurality of pixels for displaying a plurality of image frames of a video;

a second circuitry for controlling the plurality of pixels;

the second circuitry for displaying each image frame of the plurality of image frames for a predetermined period of time determined by the frequency of the VSYNC signal; and

the first circuitry for adjusting the luminosity levels of the plurality of strings of LEDs for a plurality of times within the predetermined period of time.

19. The display of claim 18, wherein the predetermined period of time includes approximately 1/30 seconds.

20. The display of claim 18, wherein the plurality of times includes a number selected from the set of one, two, three, four, five, six, seven, eight, nine and ten.

21. The display of claim 18, wherein the first circuitry for generating a clock signal having a frequency that is higher than the frequency of the VSYNC signal, and adjusting the luminosity levels of the strings of LEDs according to the clock signal frequency.

22. The display of claim 18, wherein the first circuitry for adjusting the luminosity of the string of red LEDs to a different luminosity level from the luminosity level of the string of blue LEDs based upon an ambient light condition.