| 摘要 |
PURPOSE:To obtain excellent high picture quality by equalizing surface potentials at positions on a photosensitive drum corresponding to the arrange ment positions of developing devices which differ in distance from a main elec trostatic charger while the primary current of the main electrostatic charger is held constant. CONSTITUTION:The quantity of exposure light from a preliminary exposing means 18 is varied according to a selection between developing means 6 and 7 which visualize a latent image formed on an image carrier 1 after an electrostatic discharging process wherein the preliminary exposing means 18 moves remaining charges on the image carrier 1 by exposing the image carrier 1 before image formation. Consequently, even if the surface potential surface detection accuracy of a potential sensor deteriorates owing to the long-period use of the device, a copy image of excellent high picture quality is obtained without being affected by the decrease in detection accuracy. |
