| 摘要 |
PURPOSE:To use a magnetic sensor even in an electrophotographic device, where reversal development of one copy per two rotations is performed, to stabilize the toner concentration by turning off the output of the magnetic sensor, which detects the toner concentration of a magnetic brush developing device, at the time of reversal development process. CONSTITUTION:The output of a magnetic sensor 6 which detects the toner concentration of a magnetic brush developing device 2 is turned off at the time of reversal development process. It is preferable that the output of the magnetic sensor 6 is turned off in response to the switching timing of a bias voltage at the time of reversal development process, and it is preferable that the output is turned on in response to the switching timing of the bias voltage at the time of cleaning process. While the output of the magnetic sensor 6 is turned off, the toner is not replenished at all or is replenished based on the detection value just before turning-off of the output of the magnetic sensor 6. Thus, the output of the magnetic sensor is prevented from being disturbed to stabilize the toner concentration. |
