| 摘要 |
PURPOSE: To reduce futile toner consumption by avoiding an optimal bias control in an unnecessary case. CONSTITUTION: This device is provided with a bias control means 7 that controls a bias voltage impressed on a developing means and transfer means based on the image forming condition, a measuring means 24 that measures off-time of the power supply during power-on-time, a control decision means 22 that permits the bias control means 7 to execute the bias control when the measured power-off-time exceeds a specified time and does not permit the same to execute the bias control when the power-off-time does not exceed the specified time, and a storing means 21 that stores the process conditions just prior to switching off of power. The control decision means 22 decides further in response to switching on the power, whether or not the contents of the process conditions prior to the power switch off are abnormal, and permits the bias control means to execute the bias control regardless of the power-off-time in the case of an abnormality. |
