Patent Number: 6,253,048

Title: Contact charging device

Abstract: When electrostatic capacity C.sub.f [F/m.sup.2 ] per unit area of an elastic member when an ac voltage of an arbitrary frequency f [Hz] is applied is given by C.sub.f =C.sub.1k.multidot.(f/1000).sup.-a, using electrostatic capacity C.sub.1k [F/m.sup.2 ] per unit area when an ac voltage of 1 kHz is applied and using a rate of change a, electrostatic capacity C of a micro-region of an elastic member per unit area is substituted with C.sub.f per each frequency component which forms a voltage of a rectangular pulse equivalent to a voltage applied to a charge system. Then, the elastic member is made of such a material that the rate of change a falls within a range of a .ltoreq.-0.1544.multidot.log(C.sub.1k /C.sub.0) +0.0307, and further, within a range of a .ltoreq.-0.146.multidot.log(C.sub.1k /C.sub.0) -0.0688. Consequently, it is possible to provide a contact charging device which incorporates conditions for improving charge uniformity, which are obtained by taking frequency characteristics of the electrostatic capacity into consideration.

Inventors: Kido; Eiichi (Yamatokoriyama, JP), Ishii; Hiroshi (Osaka, JP)

Assignee: Sharp Kabushiki Kaisha

International Classification: G03G 15/02 (20060101); G03G 015/02 ()

Expiration Date: 06/26/2018