| 摘要 |
PURPOSE:To prevent the consumption of developer in an image blank part and to share the power source of an electrifier with other devices when parts other than an image part are developed by supplying developing bias voltage with the reverse polarity of the developer to a developer holding member or turning off the developing bias voltage at the time of developing other than the image part. CONSTITUTION:At the time of developing the image blank part, developing isn't performed even when electric charges are supplied onto a photosensitive body 4 of the image blank part by electrification by supplying DC voltage with the reverse polarity of toner from a developing bias electrode 42 to a developing roller 35 or turning off a developing bias power source 42. Therefore, even when the electrifier 7 is always turned on, the consumption of the toner in the image blank part can be prevented. Thus, the power source 41 of the electrifier 7 can be shared with, for example, the power source of an electrifier 15 for transferring. It isn't necessary to always project light on the photosensitive body with always an exposure lamp turned on, therefore, especially at the time of consecutive copying, etc., deterioration and fatigue can be prevented caused by a rise in temperature in a device or by the light of the photosensitive body. |
