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Gray level addressing for LCDs

  • US 5,861,869 A
  • Filed: 05/19/1995
  • Issued: 01/19/1999
  • Est. Priority Date: 05/14/1992
  • Status: Expired due to Term
First Claim
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1. A method for addressing a display in which multiple overlapping first and second electrodes positioned on opposite sides of an rms-responding material define an array of pixels that display information in more than two gray levels, each pixel having in a frame period a desired gray level that is represented by a pixel information element having a value between a lower limit and an upper limit, the pixels characterized by optical states that depend on values of rms voltages established across the pixels, the method comprising:

  • applying first signals to cause selections of corresponding first electrodes during characteristic time intervals of the frame period, at least some of the first signals causing selections of said corresponding first electrodes during more than one of the characteristic time intervals of the frame period;

    generating second signals of changing magnitudes and applying them to corresponding second electrodes during plural time intervals, at least some of which correspond to the characteristic time intervals, of the frame period, the magnitude of each of the second signals during at least some of the characteristic time intervals being chosen from more than two available voltage levels and dependent upon pixel information element values of pixels defined by said corresponding second electrode and selected first electrodes and the magnitude of each of said second signals during at least one time interval when no first electrode is selected, a non-select period, being chosen to produce over a frame period an optical response such that the second signals applied to different ones of the second electrodes during a frame period produce a uniform brightness of pixels that are defined by different ones of the second electrodes and that have the same pixel information element values.

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