| 摘要 |
PURPOSE:To eliminate the contamination of a surface potential sensor and to detect a surface potential accurately, and prevent deterioration in picture quality by providing a pump below a form conveyance part, and pressing the pump when the conveyance part is opened and closed and blowing internal air to the surface potential sensor. CONSTITUTION:The bellows type pump 16 is provided under the form conveyance part 7. Then when the conveyance part 7 is opened or closed around a support shaft 7a, the pump 16 is pressed to blow the internal air to the opening part 13' of the surface potential sensor 13. Therefore, dust on the surface potential sensor 13 is removed and the surface potential of a photosensitive body is detected accurately. A specific high-voltage power source is controlled according to the detected potential. Consequently, the surface potential is controlled to an invariably constant potential and dererioratioi in picture quality is prevented. |
