| 摘要 |
PURPOSE:To prevent a faulty image caused by rotational fluctuation by restraining the uneven rotation of an image carrier when a transfer medium rushes in by separating the image carrier from a pressure roll, and separating a press-contact part when the image is not formed by using a driving source for the image carrier. CONSTITUTION:An arm 136 rotatably supporting the pressure roll 5 is freely rocked with center at a rotary shaft 139, and the roll 5 is allowed to press- contact to a dielectric drum 1 functioning as the image carrier by a spring 137. Furthermore, a ratchet 140 keeping the roll 5 from press-contacting to the drum 1 by engaging with the arm 136 is provided at the tip of the arm 136. Before the image is formed on the drum 1, the roll 5 is moved by the driving force of the drum 1, so that a transfer nip part 16 is separated. In synchronization with timing that the transfer medium 6 advances into the transfer nip part 16 between the drum 1 and the roll 5, the separation of the transfer nip part 16 between the drum 1 and the roll 5 is released by the ratchet 140. |
