| 摘要 |
PROBLEM TO BE SOLVED: To restrain discharge in a primary transfer area and to reduce transfer dust, which is caused by the discharge during belt transfer, by properly selecting a transfer bias voltage according to the detected potential-information of an image carrier. SOLUTION: A control system is composed of a potential sensor 13 as a photoreceptor potential detection means, a belt transfer power source 35, and a belt transfer electric-field control means 36. The potential sensor 13 detects the potential information of the surface of the photoreceptive drum 9, (photoreceptor potential), and outputs the information to the belt transfer electric-field control means 36. The belt transfer power source 35 applies a transfer bias voltage of a specific level to a transfer bias roller 20a. Based on the photoreceptor potential detected by the potential sensor 13, the belt transfer electric-field control means 36 sets a transfer bias voltage which causes no discharge on the side of the entrance of a transfer nip and, at this bias value, it controls the belt transfer power source 35. |
