| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that outputs high quality image without disturbing a transfer image, even on cardboard paper or highly stiff recording material by making a small alteration to an image forming apparatus of normal type. Ž<P>SOLUTION: In the image forming apparatus, the primary transfer roller 5Y of a photoreceptor drum 1Y furthest upstream in the rotating direction of an intermediate transfer belt 9 includes a nip pressure adjustment mechanism 50 that switches primary transfer nip pressure in two steps. A tension adjustment mechanism 60 switches the biasing force of a tension roller 13 in two steps. In a mode for coping with a high stiffness recording material, the primary transfer nip pressure of the primary transfer roller 5Y is made higher than normal pressure and, at the same time, tension applied to the intermediate transfer belt 9 by the tension roller 13 is made lower than normal tension. This prevents image forming sections PM, PC, and PK from being subjected to impactive vibration caused and propagated in the intermediate transfer belt 9 when the leading end of a recording material comes into contact with the intermediate transfer belt 9. Accordingly, image failure resulting from impactive vibration is avoided. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
