| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device with a magnetic type toner concentration sensor without the fluctuation of output characteristic depending on the magnetized state of the magnetic type toner concentration sensor. SOLUTION: The toner concentration of developer is measured in a fixed state, that means, a state where the core of the magnetic type toner concentration sensor 10 is magnetized or a state where it is not magnetized. Therefore, the device is provided with a means for regulating the stop position of a magnet for cleaning 34 at a standstill time to either a magnetizing position or a non- magnetizing position, or an electromagnet is used as the magnet for cleaning and the application of a current is turned off at the standstill time, or another coil is provided in the sensor 10 and magnetization or demagnetization is positively performed. |
