| 摘要 |
PURPOSE:To obtain a toner concentration switching method wherein image quality with corresponding to toner concentration after it is switched is obtained also in image density or staining when the toner concentration is switched. CONSTITUTION:In the case of switching the toner supply control of a developing device 4, the electrostatic charging potential of a photosensitive body (drum) 1 and exposure by an exposing lamp 10 are spuriously switched at the same time so that a potential gamma may be nearly equal to developing gamma by the toner concentration after it is switched. By switching the electrostatic charging potential, the desired image density is rapidly controlled without actuating a developing unit and a toner supplying unit at the time of switching by a switch, and the staining and deterioration such as poor reproducibility at a low potential part are corrected to be within an appropriate range by switching the exposure. |
