| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming a satisfactory image even in a high humidity environment at a low cost. SOLUTION: The image forming apparatus includes a photoreceptor belt 1, an intermediate transfer belt 10 moving while being in contact with the photoreceptor belt 1 at a transfer position, a primary transfer bias roller 11, and a secondary transfer unit 20 transferring toner images formed on the intermediate transfer belt 10 together onto a transfer sheet 25, wherein the closest distance between the surface of the primary transfer bias roller 1 and the surface of the photoreceptor belt 1 is set to be larger than the thickness of the intermediate transfer belt 10, the secondary transfer unit 20 is composed of a secondary transfer counter roller 12 to be in contact with the back face of the intermediate transfer belt 10 and a secondary transfer roller 21 to be in contact with the back face of the transfer sheet 25, and a secondary transfer bias is applied to the secondary transfer counter roller. The apparatus further includes a secondary bias control means that controls the secondary transfer bias so that a constant current flowing into the secondary transfer roller becomes constant. COPYRIGHT: (C)2009,JPO&INPIT
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