| 摘要 |
PURPOSE:To restrain the fluctuation of the fluidity of developer based on environmental or secular change, and the fluctuation of nip width caused by mechanical error, etc., between drum/sleeve and to form a high-quality image over a long term by constituting a device so that the carrying speed of a developer carrier can be controlled in accordance with the detected value of the inflow current of developing bias. CONSTITUTION:A control circuit 48 detects a detected current from a current sensor 43 based on a counter value, and performs the variable control of a developing sleeve driving motor 47 through a motor driving circuit 46 so that the detected current may be always a specified value. The variable control is performed based on algorithm stored in a memory 49. Every time the counter value attains 100, the developing current in the case of non-image is detected by using the sensor 43, and the variable control of the driving motor 47 for a developing sleeve 30 is performed through the driving circuit 46 so that the detected current may be always the specified value. Thus, the nip width is controlled to be about specified value at which the highest-quality image is obtained. |
