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Method and apparatus for dynamically and adjustably generating active matrix liquid crystal display gray level voltages

  • US 5,489,918 A
  • Filed: 03/03/1993
  • Issued: 02/06/1996
  • Est. Priority Date: 06/14/1991
  • Status: Expired due to Fees
First Claim
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1. An apparatus to generate an adjustable voltage waveform of a constant, repeating period from which actual gray scale levels for LCD pixels, which can differ from original gray scale instructions for the LCD pixels, are selected by an active matrix LCD, the apparatus allowing LCD special effects and compensation for LCD viewing and performance problems comprising:

  • an active matrix LCD including a plurality of pixels each having an adjustable transmissivity proportional to a voltage potential applied across the pixel, the transmissivity varying from T-max to T-min which correlates with voltage potentials V-max to V-min, the transmissivity range being called actual gray scale, the transmissivity of an individual pixel being called actual gray scale level for the pixel, at least one LCD driver including an electrical device to set a voltage potential from one Of the adjustable voltage waveforms across each pixel, and a driver device for presenting original gray scale instructions for each pixel for a given time to the LCD display;

    a display controller of the type including a data device to present data to the driver device of the LCD, the data representing the original gray scale instructions as to gray scale for individual pixels, a voltage generating means for generating the adjustable voltage waveforms separate from the data, each having a repeating constant period, and each containing a plurality of voltage potentials between V-max and V-min from which the voltage potential across each pixel can be selected, and a timing control including a timing device to correlate presentation of the data and the repeating, constant periods of the voltage waveforms to each driver of the LCD; and

    adjustment circuitry added to the display controller, including a modification device to operate upon the adjustable voltage waveforms and alter at least portions of some of the adjustable voltage waveforms without altering the original gray scale instructions in the corresponding data, to alter voltage potential across selected pixels of the LCD from that instructed by the original gray scale instructions;

    wherein the adjustment circuitry includes a digital to analog converter, and a digital means carrying instructions to alter the repeating voltage waveform;

    wherein the digital means includes an information storage means for storing predetermined values for altering the repeating voltage waveform;

    wherein the information storage means includes predetermined values based on viewing angle for the LCD.

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