(19)
(11) EP 0 448 032 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
19.11.1992 Bulletin 1992/47

(43) Date of publication A2:
25.09.1991 Bulletin 1991/39

(21) Application number: 91104222.4

(22) Date of filing: 19.03.1991
(51) International Patent Classification (IPC)5: G09G 3/36
(84) Designated Contracting States:
AT BE CH DE DK ES FR GB GR IT LI LU NL SE

(30) Priority: 20.03.1990 JP 70511/90
15.03.1991 JP 74205/91

(71) Applicant: CANON KABUSHIKI KAISHA
Tokyo (JP)

(72) Inventors:
  • Inaba, Yutaka, c/o Canon Kabushiki Kaisha
    Ohta-ku, Tokyo (JP)
  • Kurematsu, Katsumi, c/o Canon Kabushiki Kaisha
    Ohta-ku, Tokyo (JP)
  • Kaneko, Shuzo, c/o Canon Kabushiki Kaisha
    Ohta-ku, Tokyo (JP)

(74) Representative: Bühling, Gerhard, Dipl.-Chem. et al
Patentanwaltsbüro Tiedtke-BÀ¼hling-Kinne & Partner Bavariaring 4
80336 München
80336 München (DE)


(56) References cited: : 
   
       


    (54) Method of driving ferroelectric liquid crystal element and ferroelectric liquid crystal display


    (57) A method of driving a liquid crystal display element in which a switching element is provided for each of pixel electrodes arranged in a matrix manner and a ferroelectric liquid crystal is sandwiched between the pixel electrodes and a counter electrode includes the steps of applying a reset voltage for resetting the entire pixel to a first stable state of the ferroelectric liquid crystal across the pixel electrode and the counter electrode, partially transiting the pixel to a second stable state by a tone signal voltage having a pole opposite to that of the reset voltage, and reversing the pole of the reset voltage every predetermined period. Assuming that a state reverse ratio of the ferroelectric liquid crystal is T(V)% when the tone signal voltage is V, a tone signal voltage V₁ after negative resetting and a corresponding tone signal voltage -V₂ after positive resetting satisfy the following relation:






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