(19)
(11) EP 0 641 655 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
22.11.1995 Bulletin 1995/47

(43) Date of publication A2:
08.03.1995 Bulletin 1995/10

(21) Application number: 94306488.1

(22) Date of filing: 02.09.1994
(51) International Patent Classification (IPC)6: B41J 2/05
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 03.09.1993 JP 219786/93

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

(72) Inventors:
  • Imanaka, Yoshiyuki
    Ohta-ku, Tokyo (JP)
  • Furukawa, Tatsuo
    Ohta-ku, Tokyo (JP)
  • Hayasaki, Kimiyuki
    Ohta-ku, Tokyo (JP)
  • Maru, Hiroyuki
    Ohta-ku, Tokyo (JP)
  • Izumida, Masaaki
    Ohta-ku, Tokyo (JP)

(74) Representative: Beresford, Keith Denis Lewis et al
BERESFORD & Co. 2-5 Warwick Court High Holborn
London WC1R 5DJ
London WC1R 5DJ (GB)


(56) References cited: : 
   
       


    (54) Noise prevention in an ink jet printhead


    (57) The present invention is directed to resolve the noise problem with the ink in an ink jet head without changing the substrate manufacturing process for the ink jet head, that is, increasing the cost on the manufacture, and without needs of disposing a noise countermeasure component on the side of the printer main device, or making the design change for the countermeasure. The present invention is characterized in that to prevent malfunction from arising by the noise, a hysteresis circuit 101 to provide different input data threshold values upon rising and falling is provided on an input portion of the signal for a drive control logic system such as a drive input signal for a shift register 404 and a latch circuit 403 on the same substrate as that of the heating elements 401, the driver 402 and the drive control logic circuit, utilizing a diffusion layer constituting a driver 402.






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