| 摘要 |
PROBLEM TO BE SOLVED: To make excellently transferable a toner image to both sides of a transfer material by performing constant-current control to either a 2nd transfer means or a 3rd transfer means and performing constant-voltage control to the other. SOLUTION: A transfer device 14c being 1st and 2nd transfer means forms a transfer area 14b between an intermediate transfer belt 14a and a photoreceptor drum 10. DC voltage having an opposite polarity to toner is impressed on the device 14c by a constant-voltage power source EV11 so as to transfer the toner image on the drum 10 to the belt 14a or the surface or recording paper P being the transfer material. A back surface transfer device 14g being the 3rd transfer means is desirably constituted of a corona discharger. Then, it is provided to be opposed to a conductive counter ground roller grounded while putting the belt 14a in between, and the DC voltage having the opposite polarity to the toner is impressed on the device 14g by a constant- current power source EA11 so as to transfer the toner image on the belt 14a to the back surface of the recording paper P. Thus, the transfer conditions of the 2nd and the 3rd transfer means do not interfere with each other. |
