(19)
(11) EP 0 525 616 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
27.04.1994 Bulletin 1994/17

(43) Date of publication A2:
03.02.1993 Bulletin 1993/05

(21) Application number: 92112537.3

(22) Date of filing: 22.07.1992
(51) International Patent Classification (IPC)5: G03G 15/02, G03G 15/00, G03G 21/00
(84) Designated Contracting States:
DE FR GB

(30) Priority: 23.07.1991 JP 182594/91

(71) Applicant: SHARP KABUSHIKI KAISHA
Osaka 545 (JP)

(72) Inventors:
  • Kido, Eiichi
    Yamatotakada-shi, Nara 635 (JP)
  • Yui, Yuhi
    Mie 518-04 (JP)

(74) Representative: TER MEER - MÜLLER - STEINMEISTER & PARTNER 
Mauerkircherstrasse 45
81679 München
81679 München (DE)


(56) References cited: : 
   
       


    (54) Charging device


    (57) A charging device having a counter (11) for outputting an information signal indicating the number of copies produced as a detection signal indicating a change in the thicknes (T3) of a photosensitive layer (1c), and a microcomputer (12) for correcting the voltage to be applied to a charging roller (7) by a variable DC power source (10). When a detection signal from the counter (11) is input into the microcomputer (12), it corrects the voltage so as to approximate the surface potential of a photoreceptor drum to a set value. With this arrangement, the surface potential (Vc) of the photoreceptor drum (1) is kept uniform, and therefore it is possible to produce copies of good quality constantly.






    Search report