| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus improving drum surface polishing property while suppressing toner consumption in carrying out a refreshing mode. SOLUTION: Titanium oxide used as an external additive is preferentially moved to the photoreceptor drums 1a-1d sides and supplied to sliding friction rollers 30 while leaving toner base particles as much as possible on developing rollers 29 in the developing apparatuses 3a-3d during non-transfer to a recording medium, thus carrying out the refreshing mode for polishing the surface of the photoreceptor drums 1a-1d. As a method for moving the titanium oxide to the photoreceptor drums 1a-1d sides, the electrostatic properties of the toner base particles and titanium oxide are set to unlike poles, and bias of the same polarity as the titanium oxide is applied, or titanium oxide having electrostatic property of the same polarity as the toner base particles and smaller in electrostatic property (the amount of charge per unit weight) in comparison with the toner base particles is used, and bias smaller than normal developing bias (of the same polarity as toner and titanium oxide) is applied. COPYRIGHT: (C)2011,JPO&INPIT
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