Patent ID: 6744415
Filing Date: 2004-06-01
Classification: G09G

Abstract:
A system for actuating a liquid crystal display (LCD), comprising:a matrix of liquid crystal pixels in a liquid crystal display (LCD); a first digital-to-analog converter (DAC) having an output with a course step resolution; and a second DAC having an output with a fine step resolution, wherein the first and second DAC outputs are combined to apply pixel charging voltages to the matrix of liquid crystal pixels, the pixel charging voltages being representative of a video signal, the first DAC output has a first plurality of voltage ranges and the second DAC output has a second plurality of voltage ranges, wherein the second plurality of voltage ranges are within the first plurality of voltage ranges and have smaller voltage range increments than the voltage range increments of the first plurality of voltage ranges, and the first and second DACs each comprise a first network having a plurality of resistors coupled in series and a plurality of switches coupled in parallel with each resistor, a second network having a plurality of resistors coupled in series and a plurality of switches coupled in parallel with each resistor, a third network having a plurality of resistors coupled in series and a plurality of switches coupled in parallel with each resistor, switching means to couple said first network with either said second network or said third network in series between a power supply, a current source coupled in series with said first network, and control means for controlling said switches.