(19)
(11) EP 0 466 506 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.04.1993 Bulletin 1993/16

(43) Date of publication A2:
15.01.1992 Bulletin 1992/03

(21) Application number: 91306354.1

(22) Date of filing: 12.07.1991
(51) International Patent Classification (IPC)5: G09G 3/36, G09G 3/20
(84) Designated Contracting States:
DE FR GB

(30) Priority: 13.07.1990 JP 184147/90

(71) Applicant: Citizen Watch Co. Ltd.
Shinjuku-ku Tokyo (JP)

(72) Inventor:
  • Ebihara, Heihachiro
    Tokorozawa-shi, Saitama (JP)

(74) Representative: Adams, William Gordon et al
RAWORTH, MOSS & COOK 36 Sydenham Road
Croydon Surrey CR0 2EF
Croydon Surrey CR0 2EF (GB)


(56) References cited: : 
   
       


    (54) Electrooptical display device


    (57) The present invention improves the drop of a contrast, the occurrence of cross-talk and the drop of a response speed by bringing the drive state of an electrooptical display device to theoretical values. In a display device including a display panel having common electrode groups and segment electrode groups, a common electrode drive circuit and a segment electrode drive circuit, the quantity of the current flowing through the display panel through the segment electrode drive circuit is detected by a current detection circuit consisting of a differential amplifier 101 and a resistor Ra and by a current detection circuit consisting of a differential amplifier 102 and the resistor Ra, and the common electrode drive voltage applied to the common electrode groups through the common electrode drive circuit is controlled by a differential amplifier 103 on the basis of this current detection quantity, whereby the contrast is improve, cross-talk is eliminated, and remarkable effects are obtained.






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