| 摘要 |
PROBLEM TO BE SOLVED: To suppress formation of groove-like scratches due to penetration of a carrier of a two-component developer into a charge nip portion between a photosensitive drum and a charging roller. SOLUTION: In an image forming apparatus using a two-component developer, when a carrier penetrates into a charge nip portion between the photosensitive drum and the charging roller, the carrier rotates in accordance with rotation of the photosensitive drum, whereby streaky grooves are formed in a surface of the charging roller to cause density unevenness. During rotation of the photosensitive drum (drum driving ON) and non-image-formation, a charging bias in which its DC component is not over a discharge threshold (charging weak bias) is applied. As a result, the carrier penetrating into the charge nip portion is electrostatically restrained and rotation is suppressed to suppress formation of streaky grooves. COPYRIGHT: (C)2006,JPO&NCIPI
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