| 摘要 |
PROBLEM TO BE SOLVED: To improve the life of an image carrier while maintaining the productivity, and suppress the generation of color shift.SOLUTION: For the sheet interval that is between image formation on a first surface of a sheet and image formation on a second surface of a sheet in a color double-sided mode, a system control part 101 stops the developing operation of all developing device 84 once, while keeping a primary transfer bias ON for all transfer rollers 85. That is, the system control part 101 makes a secondary transfer bias ON at a time point t32 as well as sequentially making OFF exposure by scanning type optical devices 50 for Y, M, C and Bk, and simultaneously makes all the developing devices 84 OFF at a time point t36 while keeping the secondary transfer bias ON. Accordingly, fogging toner is in the state of being present at primary transfer nip parts T of Y, M, C and Bk until the primary transfer of Bk is finished, and the friction coefficient is a low value of μ2. |
