| 摘要 |
PURPOSE: To finish discharging operations in all the developing devices in the shortest time by selecting and driving one or more developing devices within such an extent that the load torque of a driving motor does not exceed a rating torque. CONSTITUTION: The driving motor is provided with the rating torque capable of simultaneously driving two developing devices in developing operation. At the discharging operation time in the developing device, the developing devices 11 and 12 are simultaneously driven. Developer in the developing devices 11 and 12 are carried and discharged by the outer screw 84 of a rotating agitation screw 51. The load torque of the driving motor is reduced in accordance with the discharge of the developer. After a prescribed time T2 from the start of the discharging operation in the developing devices 11 and 12, a developing device 13 is driven together. The time T2 is a time required for reducing the load torque of the driving motor by the amount of the torque for driving one developing device. Besides, after a prescribed time T3 from the start of driving the developing device 13, a developing device 14 is driven together. |
