Light sensor within display

• US 8,289,248 B2
• Filed: 05/10/2007
• Issued: 10/16/2012
• Est. Priority Date: 04/05/2007
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Mobile Communications AB (Sony Group Corp.)
• Inventors: Kunkel, Lars Peter
• Primary Examiner(s): Nguyen, Simon
• Application Number:
  US11/746,694
• Publication Number:
  US 20080248837A1
• Time in Patent Office: 1,986 Days
• Field of Search: 455/566, 345/84, 345/102, 345/214, 345/698
• US Class Current: 345/84
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/144 the light being ambient light
• 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 3/3611 Control of matrices with row and column drivers

Abstract

A mobile communication device with a display may be configured to apply pulse width modulation (PWM) signals to light emitting diodes (LEDs) for providing backlighting for the display, monitor ambient light conditions during off periods of PWM signals applied to the LEDs and adjust the PWM signals based the monitored ambient light conditions.

Claims

1. A method comprising:

providing backlighting to a display;

sensing ambient light conditions during off periods of the backlighting;

where the sensed ambient light conditions are sensed by one or more light sensors;

adjusting the sensed ambient light conditions based on an image on the display; and

adjusting a brightness of the backlighting based on the adjusted sensed ambient light conditions, where the adjusted sensed ambient light conditions are different from the sensed ambient light conditions.

2. The method of claim 1, where adjusting the sensed ambient light conditions based on an image on the display further comprises:

adding or subtracting known light conditions from the sensed ambient light conditions, where the known light conditions are associated with the image on the display.

3. The method of claim 1, wherein adjusting the brightness of the backlighting further comprises:

changing a duty cycle of a pulse width modulation signal.

4. The method of claim 1, where the light sensors are located adjacent to backlighting light emitting diodes or located adjacent to a light guide.

5. The method of claim 1, where the display comprises one or more display cells, and where the adjusting the sensed ambient light conditions based on an image on the display comprises:

determining a number of the one or more display cells that are displaying images; and

in response to determining the number of the one or more display cells displaying images or parts of an image is greater than a threshold number, adjusting the sensed ambient light conditions.

6. The method of claim 1, where adjusting a brightness of the backlighting based on the adjusted sensed ambient light conditions further comprises:

accessing a look-up table that stores backlighting values and sensed ambient light condition values, where each sensed ambient light condition value is associated with at least one backlighting value; and

determining, from the look-up table, a backlighting value associated with the adjusted sensed ambient light condition value; and

adjusting a brightness of the backlighting based on the determined adjusted sensed ambient light condition value.

7. The method of claim 6,

where the backlighting values and sensed ambient light condition values form a graphical relationship,

where the backlighting values increase for sensed ambient light condition values greater than zero but less than a first threshold sensed ambient light condition value,

where the backlighting values do not increase for sensed ambient light condition values greater than the first threshold sensed ambient light condition value but less than a second threshold sensed ambient light condition value, and

where the backlighting values decrease for sensed ambient light condition values greater than the second threshold sensed ambient light condition value.

8. The method of claim 1, where the sensing ambient light conditions during off periods of the backlighting further comprises:

in response to determining the one or more light sensors are configured to sense ambient light conditions associated with one or more frequencies other than one or more frequencies associated with the backlighting, directing the backlighting away from the one or more light sensors.

9. The method of claim 1,

where the providing backlighting to a display comprises providing backlighting to the display during on periods of the backlighting, and

where the adjusting a brightness of the backlighting based on the adjusted sensed ambient light conditions comprises adjusting a duration of each off period of the backlighting based on the adjusted sensed ambient light conditions.

10. A mobile communication device comprising:

a display, the display including;

light emitting diodes for providing backlight,

light sensors for sensing light,

a display for displaying images, and

logic to;

apply pulse width modulation signals to the light emitting diodes,

monitor an intensity of light received from the light sensors during off periods of the applied pulse width modulation signals, where the monitored intensity is a pre-adjusted monitored intensity, and

adjust the monitored intensity based on a currently displayed image produced on the display, and adjust the signals based on the adjusted monitored intensity, and not based on the pre-adjusted monitored intensity.

11. The mobile communication device of claim 10, wherein the light sensors or the light emitting diodes are located adjacent to a light guide.

12. The mobile communication device of claim 11, wherein the light guide is located underneath the display.

13. The mobile communication device of claim 10, wherein adjusting the plus width modulation signals based on the adjusted monitored intensity further comprises:

changing a duty cycle of the pulse width modulation signals.

14. The mobile communication device of claim 13, wherein adjusting the plus width modulation signals based on the adjusted monitored intensity further comprises:

changing the duty cycle of the plus width modulation signals based on a stored value of the adjusted monitored intensity.

15. A method comprising:

applying pulse width modulation signals to light emitting diodes for providing backlighting for a display;

monitoring ambient light conditions, by a light sensor, during off periods of plus width modulation signals applied to the light emitting diodes;

adjusting the modulation ambient light condition based on an image on the display; and

adjusting the pulse width modulation signals based on the adjusted monitored ambient light conditions, where the adjusted monitored ambient light conditions are different from the monitored light conditions.

16. The method of claim 15, where adjusting the monitored ambient light conditions based on an image on the display further comprises:

adding or subtracting known light conditions from the monitored ambient light conditions.

17. The method of claim 16, wherein the known light conditions are associated with an image on the display.

18. The method of claim 15, where the adjusting the pulse width modulation signals based on the adjusted monitored ambient light conditions further comprises:

changing a duty cycle of the pulse width modulation signals.

19. The method of claim 18, where the adjusting the pulse width modulation signals based on the adjusted monitored ambient light conditions further comprises:

changing the duty cycle of the pulse width modulation signals based on a stored value of the adjusted monitored intensity, where the stored adjusted monitored intensity corresponds with the adjusted monitored ambient light conditions.

20. The method of claim 15, where the light sensor and the light emitting diodes are located adjacent to a light guide.