| 摘要 |
PROBLEM TO BE SOLVED: To prevent soiling of an image due to, for examples, toner scatter around a toner image, which is caused by an insufficiency of transfer bias, and a transfer failure by varying the transfer bias according to the number of consecutively-passed both-sided sheets at the time of image formation. SOLUTION: A printer control part 28 consecutively forms images on the first sides of transfer sheets via a high voltage control part 17. Also, when the number of consecutively-passed both-sided sheets, with images formed consecutively on the second sides of the same transfer sheets, exceeds a specific number, the control part 28 detects increases of the temperature and resistance of a transfer roller 5 which is in contact with a photoreceptor drum 1, and it exerts constant-current control over the transfer roller 5 each time the number of sheets exceeds the specific number. A transfer bias in which a specific voltage is added to the voltage applied at this time is determined by the printer control part 28, and this transfer bias is applied to the transfer roller 5. |
