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Matrix display device with write-in facility

  • US 5,485,177 A
  • Filed: 11/26/1991
  • Issued: 01/16/1996
  • Est. Priority Date: 12/19/1990
  • Status: Expired due to Fees
First Claim
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1. An active matrix liquid crystal display device comprising:

  • a display panel having an array of picture elements each comprising a liquid crystal display element and an associated switching means, a set of row address conductors and a set of column address conductors connected to the picture elements, drive means for applying drive signals to the set of row address conductors and to the set of column address conductors for driving the picture elements, said drive means being arranged to apply data signals to the column address conductors and a selection signal to each row address conductor individually in turn so as to operate the switching means of the picture elements associated with the selected row address conductor thereby to apply the data signals to their respective display elements, the display panel further including an array of active addressed sensing elements each comprising a photosensitive element and a switching device, wherein the sensing elements each include a charge storage means which is connected to the switching device, wherein the switching devices of each row of sensing elements are each connected to a said row address conductor and a said column address conductor and are operable by a said selection signal applied to an associated row address conductor of said set of row address conductors so as to charge the charge storage means of the sensing elements according to the level of the data signals, wherein the photosensitive element of each sensing element is connected so as to discharge the charge storage means in response to the illumination thereof, and detection means connected to the sensing elements for periodically detecting the state of charge of their respective charge storage means.

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