| 摘要 |
PURPOSE:To obtain high picture quality and to obtain a clean environment by consuming and collecting toner in a developing device to a photosensitive body when the toner quantity of the developing device becomes equal to or under a prescribed quantity. CONSTITUTION:A controller CPU is switched to show tank's emptiness based on a signal from a pressure sensor 16 when the toner residual quantity in a developing tank 10 becomes equal to or under the prescribed quantity. Then, when an image forming action is finished, a driving motor M, an electrostatic charger 2, a transfer charger 5 or the like are turned off. However, continuously the motor M is driven again after the lapse of specified time. At this time, the charger 2 is turned on. In spite of it, since developing bias is held to be in a non-impressing state, the electric charge of prescribed potential is imparted on the surface of the photosensitive body 1 passing through an exposure part X1 and the toner supplied to the body 1 is scraped and collected by a cleaning device 6 in a cleaning part X6. Thus, when the toner in the tank 10 is consumed, the toner of prescribed grain size is replenished. As the result, the stability of an image and the reliability of a copying machine are improved. |
