| 摘要 |
PROBLEM TO BE SOLVED: To provide a long-life image forming apparatus that prevents energization deterioration of a transfer belt or a secondary transfer roller. SOLUTION: The image forming apparatus includes: a secondary transfer roller (61) for holding a sheet material (P) with a transfer belt (11); a power supply (62) applying a secondary transfer bias voltage between the transfer belt (11) and the secondary transfer roller (61); an optical detection unit (10) for detecting the amount of toner external additive adhered to the surface of the transfer belt (11); and a control part (18) controlling the secondary transfer bias voltage of the power supply (62) on the basis of an output obtained from the optical detection unit (10). COPYRIGHT: (C)2011,JPO&INPIT
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