| 摘要 |
PROBLEM TO BE SOLVED: To control a bias voltage applied in an image forming process and (or) a developing process and to prevent overplating, that is, the erroneous development of a non-image forming area by applying a bias potential selected according to a background charge potential region to a second developing device. SOLUTION: The bias voltage applied to a first developing device 24 is strictly defined to control the development of a background and an image. The developing bias of the next developing device 34 is increased to prevent the overplating and for maintaining development processing for the corresponding color image, the increase of a voltage for forming a related image is required as well. For instance, the developing bias applied to the developing device 24 is lower than that applied to the developing device 34. The developing bias for a fixed developing device is selected and controlled to be substantially equal to or a little higher than a background voltage produced by the cycle of development, reelectrification and the formation of the image. |
