Patent ID: 8044899

Claim:
A method of controlling a backlight apparatus for a display device, the backlight apparatus comprising a plurality of LEDs, the control method comprising: controlling one or more photo-sensors for measuring at least one of brightness or color of one or more LEDs; receiving a source of video signals, each video signal including a plurality of video frames, each video frame having a video frame time period T; subdividing the video frame time period T of each video frame into at least three sub-periods, the first sub-period being background measurement period during which one or more photo-sensors measure the background light, the second sub-period being an LED calibration period during which one or more photo-sensors measure one or more LED groups, and the third sub-period being an operation period during which the photo-sensors are switched off and LEDs are switched on for displaying the video frame, wherein each LED group comprises at least one LED and at least one LED group measured during the second sub-period of one video frame T is different from an LED group measured during a second sub-period of a subsequent video frame T; the second sub-period is further subdivided into time slots t 1 to t n where n is the number of LED groups to be calibrated during the second sub-period an LED to be calibrated is switched either on or off for a time period of duration t and the photo-sensor to measure a target LED group is switched on for a time period τ during a corresponding time slot t, the time period τ being less than the time period t; transmitting the LED measurement to a processing unit; and adjusting the driving conditions of the measured LED to control at least one of a desired brightness or a desired color based on the photo-sensor measurement.