| 摘要 |
PROBLEM TO BE SOLVED: To automatically shift a mode to a cleaning mode when a cleaning roller is soiled, irrespectively of the number of printing times. SOLUTION: The device is provided with an image carrier, the cleaning roller 26 which is rotated following the rotation of the image carrier, a rotating speed detecting means for detecting the rotating speed of the cleaning roller 26, a toner quantity detecting means for detecting the quantity of the toner stuck to the cleaning roller 26 based on the fluctuation of the rotating speed and a mode switching means for switching a normal printing mode and a cleaning mode. In this case, the rotating speed of the cleaning roller 26 is detected, and the quantity of the toner stuck to the cleaning roller 26 is detected based on the fluctuation of the rotating speed. And, the normal printing mode is automatically switched to the cleaning mode based on the toner quantity, and vice versa, irrespectively of the number of printing times. |
