| 摘要 |
PURPOSE:To eliminate a fog, or picture dissipation due to a potential change in a photosensitive drum, by correcting a bias voltage between a photosensitive body and a developing electrode from the developing density of the second patch having a low original density. CONSTITUTION:A toner density control by a control circuit 15 is performed so that the latent image of a patch 3 is developed under a reference bias voltage, and a toner supplying quantity to a toner supplying device is controlled based on the density detected level of a patch image at a point P. At such a time, the control circuit 15 performs the same development and density detection for the latent image of a patch 3A as those for the patch 3, and corrects the potential change of the photosensitive body against the low original density from a developing density detecting signal by the patch 3A, by a bias voltage control. Thereby, the fog or the image dissipation caused by the potential change at the low potential part of the photosensitive body can be eliminated. |
