Use of a plurality of light sensors to regulate a direct-firing backlight for a display

• US 20060049781A1
• Filed: 09/07/2004
• Published: 03/09/2006
• Est. Priority Date: 09/07/2004
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Lim, Len-Li Kevin, Jaffar, Rizal, Lee, Joon-Chok
• Granted Patent: US 7,474,294 B2
• Time in Patent Office: Days
• US Class Current: 315/312
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• 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
• CPC Class Codes: H05B 45/22 using optical feedback

Abstract

A direct-firing backlight for a display is designed with a plurality of light emitting regions. Each of a plurality of light sensors is positioned to sense light produced by a corresponding one of the light emitting regions. A control system is operatively associated with the light sensors and light emitting regions. The control system receives information from the light sensors and, in response thereto, regulates light emitted from regions of a display. The regions of the display correspond to the light emitting regions of the direct-firing backlight. Various configurations of such a direct-firing backlight, and related methods, are also disclosed.

Claims

1. Apparatus, comprising:

a direct-firing backlight for a display, said direct-firing backlight having a plurality of light emitting regions;

a plurality of light sensors, each of which is positioned to sense light produced by at least one of said light emitting regions; and

a control system, operatively associated with said light sensors and light emitting regions, to receive information from said light sensors and, in response thereto, regulate light emitted from regions of a display, said regions of the display corresponding to said light emitting regions of the direct-firing backlight.

2. The apparatus of claim 1, wherein the light emitting regions comprise light emitting diodes.

3. The apparatus of claim 1, wherein the light emitting regions comprise, red, green and blue light emitting diodes.

4. The apparatus of claim 1 wherein the light emitting regions are arranged in a matrix of M columns and N rows.

5. The apparatus of claim 4, wherein the number of said light sensors equals the number of said light emitting regions.

6. The apparatus of claim 4, wherein the light sensors are spaced substantially equidistant from one another.

7. The apparatus of claim 1, wherein the light sensors provide light brightness information to the control system.

8. The apparatus of claim 1, wherein the light sensors provide light brightness and chrominance information to the control system.

9. The apparatus of claim 1, wherein the light sensors are calorimetric sensors, and wherein the information the light sensors provide to the control system is related to Commission Internationale de l'"'"'É

clairage (CIE) tristimulus values.

10. The apparatus of claim 1, wherein the control system regulates light emitted from regions of a display by comparing information received from the light sensors to at least one reference value and, in response thereto, regulating the light intensity of each light emitting region.

11. The apparatus of claim 10, wherein the control system initiates said comparisons and regulations on a periodic basis during normal operation of said direct-firing backlight.

12. The apparatus of claim 1, wherein the control system regulates light emitted from regions of a display by comparing information received from the light sensors to at least one reference value and, in response thereto, regulating the intensity and chromaticity of each light emitting region.

13. The apparatus of claim 12, wherein the at least one reference value comprises Commission Internationale de l'"'"'É

clairage (CIE) tristimulus values.

14. The apparatus of claim 12, wherein the light emitting regions comprise, red, green and blue light emitting diodes (LEDs);

and wherein the control system regulates chromaticity of a given light emitting region by regulating the drive signals of the different-colored LEDs of the given light emitting region.

15. The apparatus of claim 12, wherein the control system initiates said comparisons and regulations on a periodic basis during normal operation of said direct-firing backlight.

16. The apparatus of claim 1, wherein the control system regulates light emitted from regions of a display by comparing information received from the light sensors to at least one reference value and, in response thereto, outputting required video signal adjustments for said display.

17. The apparatus of claim 16, wherein the control system initiates said comparisons and regulation on a periodic basis during normal operation of said direct-firing backlight.

18. The apparatus of claim 1, further comprising one or more light guides, positioned in front of said light emitting regions to disperse light to said display and said light sensors.

19. The apparatus of claim 1, further comprising the display, the display being a liquid crystal display (LCD).

20. A method, comprising:

dividing a direct-firing backlight for a display into a plurality of independently controllable light emitting regions;

measuring the light emitted from each of said light emitting regions;

comparing the light emitted from each of said light emitting regions to at least one reference value; and

in response to said comparisons, independently regulating the light emitted from each light emitting region.