| 摘要 |
PURPOSE:To urge cleaning before the remarkable slip of an image forming belt occurs. CONSTITUTION:The revolving speed of a driving motor 17 for the photosensitive belt 5 is detected by an encoder 22 and the number of pulses corresponding to the revolving speed is counted by an encoder pulses counting means 23. Slits 20 are provided at regular intervals on the belt 5, and a photosensor (PC slip hole sensor) 21 detects the passage of the slits 20. Since the number of pulses corresponding to the interval between the slits is known in advance, it is compared with the number of pulses counted by the means 23 in a slip comparing and discriminating means 25. When the compared result exceeds an allowable value, a warning signal is outputted to a display device, etc., by a warning means 26. |
