| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus obtaining a big preventive effect for image deterioration due to transfer bias voltage control by minimizing the image quality deterioration due to a difference in density in a transfer image. <P>SOLUTION: Secondary transfer bias voltage obtaining a specified transfer current is outputted to a secondary transfer outside roller 42 from a power source 14 immediately before recording paper P is proceeded to a nip in a secondary transfer part N2 in the image forming apparatus. A control part 15 retains a transfer voltage table defining the length in a back edge region for which voltage is lowered according to a type of the recording material and distinction between both sides printing and one side printing and the amount of lowered voltage. The control part 15 detects the type of the recording medium and the distinction between both sides printing and the one side printing set by a user, sets a point for starting lowering of the secondary transfer voltage and then a final lowered voltage amount is obtained at the back edge by gradually lowering the secondary transfer bias voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT |
