| 摘要 |
PURPOSE:To stabilize the image quality before and after replenishing a developer, and also, to facilitate the miniaturization of the device, by constituting the device so that the developing contrast on an image carrying body is varied for a prescribed period from immediately after having replenished a toner into a developing device. CONSTITUTION:From the number of times of outputting a toner non-existence signal from a toner sensor 18 in a developing device 17, and an integrating time, etc., the quantity of a toner in the developing device 17 is calculated by a toner quantity detecting circuit 11, and at the time point when it has become a prescribed detecting level, a toner non-existence signal 13 is outputted. On the other hand, whenever a laser 6a ON signal is outputted in an image area, the quantity of a consumed toner is calculated in a toner quantity calculating circuit 10 and supplied to a developing bias control circuit 15. Subsequently, a set value of the circuit 15 is varied by the signal 13. Also, simultaneously, by developing positively positive fog onto a photosensitive drum 28 between paper, the positive fog appearing on an image can be decreased. In such a way, by varying an image area and a non-image area on the drum 28, the image quality before and after replenishing a developer can be stabilized. |
