| 摘要 |
PURPOSE:To obtain a stable image by impressing at least three kinds of previously set voltages on the grid of a scorotron so that the assumed value of the surface potential of a photosensitive body can be obtained, and controlling an image forming condition based on the assumed value. CONSTITUTION:A primary electrostatic charger 2 is provided close to the photosensitive body 1 and the scorotron therein is connected to a primary high voltage power source 3, and also a bias power source 4 which impresses the voltage on the grid of the scorotron is installed. The surface potential of the photosensitive body 1 is detected by a potential sensor 7 and development is executed by a developing device 5. And at least three kinds of previously set voltages are impressed on the grid and the assumed value of each surface potential of the photosensitive body 1 by the minimum exposure and the maximum exposure at the time when optional voltage is impressed on the grid is obtained based on each surface potential of the photosensitive body 1 by the minimum exposure and the maximum exposure. And at the time of forming the image, the condition of the exposure, etc., is controlled by a controller 9 based on the assumed value. Then, the fog of the image can be removed and the image can be favorably formed because the condition is controlled based on the assumed value of the electrification quantity near to real one. |
