| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce occurrence of a reverse transfer of toner onto the photoreceptor at an exit of a primary transfer nip while suppressing occurrence of nonuniformity of image density depending on an image area ratio on a photoreceptor. <P>SOLUTION: At a primary transfer nip for magenta (M) where a photoreceptor 2M is brought into contact with an intermediate transfer belt 21, a primary transfer nip for cyan (C) where a photoreceptor 2C is brought into contact with the belt, and a primary transfer nip for black (Bk) where a photoreceptor 2Bk is brought into contact with the belt, a target value of a primary transfer current is individually reduced in response to an increase in the average image area ratio if the average image area ratio on the photoreceptor is within a general limit of 5-95%, and the target value corresponding to an average image area ratio being lower than 5% is determined to be smaller than the value for the average image area ratio of 5-95%. <P>COPYRIGHT: (C)2012,JPO&INPIT |
