| 摘要 |
PURPOSE:To eliminate the crest of a subdeveloping device and to prevent the deterioration of an image such as a white stain by detecting that the subdeveloping device is replaced, provisionally causing the subdeveloping device to forcibly act on a photosensitive drum, and again separating it. CONSTITUTION:When the subdeveloping device 3 is replaced, a detection switch 17 detects the effect. Prior to copying, forcibly the subdeveloping device 3 is provisionally made close to the photosensitive drum 1, that is, acts on it, and then separated again. Thus the angular crest of a developer formed on the developing roller 3c of the subdeveloping device 3 can be eliminated, and the escape of charges on the photosensitvie drum 1 through the crest of the subdeveloping device 3 can be reduced, prior to developing a selected colored image or a black one even if the subdeveloping device 3 is far away from the photosensitive drum 1. Moreover the deterioration of the image such as a white stain can be prevented.
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