| 摘要 |
PURPOSE:To detect the exchanging time of a developing device by comparing a signal value from a storage means with a signal value about toner residual in the developing device from a detection means through a comparison means. CONSTITUTION:When a new process cartridge 8 having different kind of toner is loaded in the device main body of an image forming device, an ID number is inputted and stored in a 2nd memory 25 from a microcomputer 30. At a stage where an image is formed by the cartridge 8, an initial current value which flows in an electrode 21 for detection from a developing roller 3b is converted into a voltage value through a conversion means 22 and stored in a storage area corresponding to the ID number in a 1st memory 24. The value of a ratio between a voltage value based on the initial current value and the voltage value transmitted through the electrode 21 and the means 22 from moment to moment is compared and examined by a comparison and decision means 23. When the value of the ratio attains a specified value, a warning signal is outputted to an exchanging display means 26. Thus, a developing device 3 is surely exchanged. |
