| 摘要 |
PURPOSE:To change over a developing device with simple constitution by rotating an image holding body in cleaning condition at the time of changing over from one side developing device to other developing device. CONSTITUTION:When change over is executed from the first developing device 23 from the second developing device 24, and even if the developing device 23 located backward in the rotating direction of a photosensitive drum 2 is separated from the drum 2, the toner of the developing device 23 is stuck on the drum 2 over the section theta1 from contacting positions (a) and (b) of developing devices 23 and 24 to a cleaning position (c). In such condition, when the developing device 24 located forward is contacted in the rotating direction of the drum 2, the toner of the developing device 23 is mixed into the developing device 24. Then, over the distance of a section theta2 or above from the contacting position (a) of the developing device 23 to the contacting point (b) of the developing device 24, clearances S3 and S4 are formed between the magnet roller and the drum 2 of developing devices 23 and 24, the drum 2 is rotated in the cleaning condition and the mixing of the toner is prevented. Consequently, since changeover can be executed without using the positive reverse rotatable driving motor, and the supply of the toner can be stopped without turning the magnet roller, the device can be made simple constructively. |
