| 摘要 |
PROBLEM TO BE SOLVED: To form an image of high quality by discriminating the cause of the increase of a surface stain toner on a photoreceptor and by executing an optimum countermeasure corresponding to each cause. SOLUTION: A self-diagnostic part 14 of a surface stain toner evaluation control part 10 judges whether the cause of the increase of a surface stain toner is the increase of a reverse or a weakly charged toner or the increase of a nonelectrostatic sticking force between a photoreceptor and the toner, from the quantities of a positive polarity component toner and a negative polarity component toner which are stuck to the photoreceptor, when the surface stain toner on the photoreceptor is increased. A surface staining countermeasure processing part 15 controls the charge quantity of the toner in a developing unit, when the cause of the increase of the surface stain toner is the increase of the reversely or weakly charged toner and improves the releasability of the surface of the photoreceptor, when the cause of the increase of the surface stain toner is the increase of the nonelectrostaic sticking force between the photoreceptor and the toner. |
