| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a tension applying device that suppresses curling habit of a belt and applies a predetermined tension to a belt member during the drive of the belt without increasing load on a drive motor during the drive, and to provide a belt unit and an image forming apparatus. <P>SOLUTION: When the operation of the device is stopped, a second coil spring 33 formed from a shape memory alloy is stretched by the pressing force of a first coil spring 31 and the weight of an arm member 32, pressing force applied to the tension roller 20 decreases and consequently the intermediate transfer belt 22 slackens. When the device is driven, the heat source 45a of a fixing device 45 generates heat and the second coil spring 33 is heated, the second coil spring 33 returns to its original shape and pulls up the arm member 32, thereby applying predetermined tension to the intermediate transfer belt 22. <P>COPYRIGHT: (C)2011,JPO&INPIT |
