| 摘要 |
PROBLEM TO BE SOLVED: To provide a contact type charging device whose service life is made as long as possible despite its lightweight, flexible, double-structured roller type. SOLUTION: An initializing charging roller 16 comprises a core metal 54, a conductive foamed body 55 whose center is pierced with the core metal, a semiconductive adhesive 56 applied to the whole peripheral surface of the foamed body by spraying with a sprayer 58 in such a way that the adhesive is made thin at both ends of the foamed body in its axis direction and thick at a central part, and a tubular conductive resin body 57 bonded entirely to the adhesive. The electric resistance of the conductive foamed body 55 is≤9×10<SP>-5</SP>Ω, the surface electric resistance of the conductive resin body 57 is in the range of 1×10<SP>-5</SP>-9×10<SP>-5</SP>Ω/sq, a product hardness of the whole is ASKER-F90°or less, and superposed bias voltage applied to a photoreceptor drum 16 is DC-600(V) and AC1,650(Vp-p)/1.3 kHz. Under the above charging condition, nearly uniform charging performance can be ensured at the initially set voltage even in the brand-new state and even after deposition of toner and dirt. COPYRIGHT: (C)2005,JPO&NCIPI
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