| 摘要 |
PROBLEM TO BE SOLVED: To accurately judge the deterioration of an intermediate transfer belt and to highly precisely detect the end of its life by detecting a mechanical characteristic such as a change in the length of its periphery or a change in its tensile force, which is the factor of the deterioration of the intermediate transfer belt. SOLUTION: A spring 70 is suspended from a tension roller 64, and a position sensor 11 of an optical system, magnetic system, or the like is provided at one end of it in its axial direction. The position sensor 11 is provided with a flag which moves synchronizing with the movement of the tension roller 64, and it measures the movement of the flag optically. To the position sensor 11 a judging circuit 21 is connected for comparing an amount of measured change with a reference value, and to the judging circuit 21 a display unit 22 is connected. In the case the length of the periphery of the intermediate transfer belt 61 changes due to the slack in the belt, the position of the tension roller 64 changes and therefore the amount of change is measured by the position sensor 11. Further, the value of the measurement is compared with the specific value by the judging circuit 21. When the amount of change is above the reference value, it judges that the end of life has reached, and causes the display unit 22 to display the information. |
