| 摘要 |
PURPOSE:To easily detect a process unit being unmounted at low cost by connecting the input terminal of a control part to a position of specific voltage level and deciding whether or not the process unit is mounted from the voltage level at the input terminal of the control part. CONSTITUTION:When the process unit 3 is not mounted in a device main body 1, the voltage level at the input terminal 25a of the control part 25 is VCC or VSS. When the unit 3 is mounted in the main body 1, on the other hand, the output of a sensor 65 is connected to the input terminal of the control part 25 through connectors 38 and 34. Then the sensor 65 facing a developing device 6 detects the toner concentration of the developer passing right before it, i.e. the rate of the amount of toner to the total amount of carriers and toner in case of a two-component developer and outputs a voltage of certain level because there are carriers in a normal use state. There is a difference between the potential levels at the input terminal 25a of the control part 25 when the unit is mounted and not mounted, and when the voltage at the input terminal 25a deviates from the voltage level in the normal use state, it is decided that the unit 3 is not mounted.
|
