| 摘要 |
PROBLEM TO BE SOLVED: To effectively remove toner on a transfer belt, without having to add a new member and to restrain damage given to the transfer belt in the midst of cleaning to the minimum. SOLUTION: By applying a bias, having both positive and negative polarities to transfer bias power sources 23 for 2nd and 3rd colors among the transfer bias power sources 23 of respective transfer rollers 4, the toner on the transfer belt 14 is transferred reversely to a photosensitive drum 1 and removed. Then, the image-forming device is provided with a 1st cleaning mode, in which the circumferential speed of the belt 14 is nearly equal to that of the drum 1 and a 2nd cleaning mode, in which the difference of the circumferential speed between them is 10%, and the 1st cleaning mode is carried out in the case of estimating that toner amount on the belt 14 is a minute amount and the 2nd cleaning mode is carried out when the toner amount on the belt 14 is expected to be large. |
