| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent breakage of a surface layer and a base layer in a transfer belt so as to improve durability of the transfer belt by arranging a controlling means driving a tension adjusting means according to tension of a belt member detected by means of a tension detection means. SOLUTION: A transfer belt 18 is stretched and arranged between a driving roller 16 and a roller 17. On the driving roller 16 side of a bearing 22, a load cell 23 is fixed so that its pressure detecting face is brought into contact with the bearing 22. In this way, tension of the transfer belt 18 is converted into an electric signal so as to be transmitted to a CPU 24. If a signal representing a tension value of the transfer belt 18 is higher than a target tension value previously set in the CPU 24, a reverse rotation signal with a predetermined pulse is fed to a stepping motor 34 from a pulse generating device 38. This feedback control is repeated, and tension of the transfer belt 18 is always kept at a fixed target value.</p> |
