| 摘要 |
PROBLEM TO BE SOLVED: To change voltage applied to the rollers and blade of a developing unit, in accordance with an environmental change and the density of an image, for keeping the density of the image of a copy constant by providing a power source for feeding power to each of the supplying roller, developing roller and blade and a current limiting resistor, in a state that it is connected to the power source and one of the power-fed members. SOLUTION: The developing unit 10 is provided with paths for directly applying the voltage to the developing roller 14 and blade 15 through power sources 30a and 30b. Further, paths for feeding the power to the supplying roller 13 from the power source 30 directly and through the resistor R are arranged. Then, a switching device 37 is arranged in these two power feeding paths as well. When an environmental temp. is varied and the operational environment of a device is varied as well, the detection signal of a sensor 35 is inputted to a controller 36 and the path for directly applying the applied voltage from the power source 30 is switched to the path for applying the voltage through the resistor R, in accordance with conditions set in the controller 36. |
