(19)
(11) EP 0 488 516 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
28.10.1992 Bulletin 1992/44

(43) Date of publication A2:
03.06.1992 Bulletin 1992/23

(21) Application number: 91309733.3

(22) Date of filing: 22.10.1991
(51) International Patent Classification (IPC)5: G09G 3/36
(84) Designated Contracting States:
DE FR GB

(30) Priority: 28.11.1990 JP 323432/90

(71) Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
Armonk, NY 10504 (US)

(72) Inventors:
  • Sadahiro, Terazawa
    Sagamihara-shi, Kanagawa-ken (JP)
  • Hidefumi, Yamaguchi
    Fujisawa-shi, Kanagawa-ken (JP)

(74) Representative: Burt, Roger James, Dr. et al
IBM United Kingdom Limited Intellectual Property Department Hursley Park
Winchester Hampshire SO21 2JN
Winchester Hampshire SO21 2JN (GB)


(56) References cited: : 
   
       


    (54) Method and apparatus for displaying gray-scale levels


    (57) A liquid crystal matrix display has plural picture elements (PELs) arranged in an X-Y matrix. Each PEL includes a thin film transistor (TFT) and a display electrode. Data lines are formed in the X direction and gate lines in the Y direction. To display one of eight gray-scale levels for each PEL, one of eight voltage levels is selectively applied to the data line. The voltage levels are applied through a combination of switches which operate under the control of a selector which translates a three bit address into the selection of one or more switches. By this means the number of voltage sources and switches to operate a cell is less than the number of gray-scale values.






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