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Window-dependent brightness/tint control for video digital-to-analog converters

  • US 5,638,090 A
  • Filed: 12/01/1994
  • Issued: 06/10/1997
  • Est. Priority Date: 12/01/1994
  • Status: Expired due to Term
First Claim
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1. In a visual display system that includes a display monitor that provides a visual display and a plurality of video digital-to-analog converter networks, each video digital-to-analog converter (DAC) network having an output connected to a corresponding control input of the display monitor and being responsive to a digital pixel control input signal that determines the value of a current output signal provided by said video DAC network to the control input for each pixel of the visual display, the improvement comprising, for each video DAC network, a display control circuit for controlling brightness in a selected window of the visual display, the display control circuit comprising:

  • an added DAC network that responds to an enabling control signal by providing a supplemental current output signal to the monitor control input connected to receive the current output signal from the associated video DAC network;

    an instruction storage register that stores instruction data that define the value of the supplemental current output signal;

    a logic block that responds to the instruction data provided by the instruction storage register by generating an enabling control signal that causes the added DAC network to provide the supplemental current output signal, the logic block being enabled to provide the enabling control signal by a window-dependent overdrive input signal that is synchronous to the digital pixel control input signal and that defines the selected window of the visual display.

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