| 摘要 |
<P>PROBLEM TO BE SOLVED: To clean sufficiently a transfer roller. Ž<P>SOLUTION: When the number of prints, a driving time or a toner adhesion amount becomes a cleaning starting value or more during a non-transcription time, the circumferential speed of a secondary transfer roller 32 is changed relative to the circumferential speed of an intermediate transfer belt 16, to thereby clean the secondary transfer roller 32. Thus, sufficient cleaning of the transfer roller can be performed in comparison with the case where each circumferential speed of an image carrier and the transfer roller is changed to the period of transfer operation in the state where the relative circumferential speed is kept approximately constant. In this case, cleaning is performed by accelerating the circumferential speed of the secondary transfer roller 32 with respect to the circumferential speed of the intermediate transfer belt 16, and then cleaning is performed by reducing the circumferential speed of the secondary transfer roller 32 with respect to the circumferential speed of the intermediate transfer belt 16. Thus, residual toner on both sides of more upstream side and downstream side in the rotation direction than a secondary transfer position 30 of the secondary transfer roller 32 is cleaned, and the whole secondary transfer roller 32 is cleaned. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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