| 摘要 |
PROBLEM TO BE SOLVED: To stably form an image by always keeping transfer efficiency constant even when a gap between a photoreceptor drum and a transfer roller is changed by the shake of the transfer roller and the photoreceptor drum in an image forming device having a non-contact transfer roller system. SOLUTION: A piezoelectric body 2 is made to press-contact with the peripheral surface of the transfer rover 12, and a voltage detection circuit 3 detecting voltage generated in the piezoelectric body 2 is connected to the piezoelectric body 2. A transfer bias control part 1 controls bias voltage applied to the roller 12 based on the change of an output value by the circuit 3, that is, the shake and the secular positional change of the roller 12, that is, the change of the gap between the photoreceptor drum 11 and the roller 12. Thus, the image is stably formed by always keeping the transfer efficiency constant even when the gap between the drum 11 and the roller 12 is changed by the shake and the secular positional change of the drum 11 and the roller I2. |
