| 摘要 |
PROBLEM TO BE SOLVED: To provide a transfer unit capable of stably obtaining a high quality image without changing transfer conditions in a monochrome mode and in a color mode. SOLUTION: The transfer unit includes: an intermediate transfer belt 1; a plurality of photoreceptor drums (image carriers) 2a to 2d; and a plurality of transfer rollers 3a to 3d disposed in contact with the corresponding photoreceptor drums 2a to 2d via a transfer belt 4. The transfer unit can select the color mode in which toner images in their respective colors are transferred to the transfer belt 4 or the monochrome mode in which a monochrome toner image is transferred to the transfer belt 4. In the monochrome mode, the transfer unit separates the transfer belt 4 and transfer rollers 3a to 3c from the color photoreceptor drums 2a to 2c. In the transfer unit, a movable roller 10 is disposed on the internal circumference of the transfer belt 4. In monochrome mode, the movable roller 10 is moved and pressed against the transfer belt 4, so that the angle of a transfer nip between the intermediate transfer belt 4 and monochrome photoreceptor 2d in the monochrome mode is equal to that in the color mode. COPYRIGHT: (C)2009,JPO&INPIT
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