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Reduced power displays

  • US 9,373,287 B2
  • Filed: 07/21/2010
  • Issued: 06/21/2016
  • Est. Priority Date: 07/23/2009
  • Status: Active Grant
First Claim
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1. A backlight for a display, the backlight comprising:

  • a plurality of groups of light emitters, each group comprising at least one light emitter;

    a power supply, the power supply configured to supply power to the groups of light emitters; and

    one or more controllers, the controllers configured to receive a new set of image data to render upon the display and control brightness levels of the light emitters within the groups by applying pulse width modulation (PWM) driving signals to each light emitter, each PWM driving signals having an initial period, a duty cycle proportional to the brightness level, and a phase offset that varies between the groups;

    wherein the brightness levels depend upon the received new image data and wherein the brightness levels of at least two light emitters are independently controllable;

    wherein the duration of a first PWM cycle of the PWM driving signals for the new image is controllable to be different from the duration of subsequent PWM cycles for the new image;

    wherein the duration of the first and subsequent PWM cycles are derived from image data so as to illuminate a primary modulator with a low resolution version of an image represented by the image data; and

    further wherein the total power of the backlight is configured to be ramped up from zero to a desired value for the first PWM cycle and fluctuate for subsequent PWM cycles for the new image to be displayed.

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