| 摘要 |
PURPOSE: To prevent the cleaning achievement rate from being reduced and to prevent an uneven transfer from being caused by alternately impressing bias having polarity the same as and reverse to that at the time of transferring on a transfer means at the time of cleaning the transfer means. CONSTITUTION: This device is provided with a means for forming an image consisting of superposed toner of two or more colors on an image carrier, and a transfer material is allowed to pass between the image carrier having the toner image and the transfer means while keeping them in a press-contact state so as to electrostatically collectively transfer the toner image on the transfer material altogether. Thereafter, cleaning is performed in a state where the transfer means is brought into press-contact with the image carrier. At the time of cleaning the transfer means, for example, a transfer roller, the bias having the polarity the same as and reverse to that at the time of transferring is alternately impressed on the transfer means. Development, whether the transfer roller is pressed or not, and whether the transfer bias is impressed or not are shown in the figure. In this case, a transfer current is +20μA, forward bias is +8μA, and reverse bias is -1.2kV. |
