| 摘要 |
PURPOSE:To keep almost constant the image densities of plural copies obtained successively, by gradually lowering the charging quantity of a photoreceptor depending on corona charging in accordance with repeating of the copying process in successive copying of plural sheets. CONSTITUTION:Photoreceptor 1 is formed into a cylinder, rotatable in the arrow direction, and surrounded with chargers 2, 3, optical exposure system 4, developing devices 5, 6, etc. arranged in the rotation direction around its circumference. Both the photoconductive layers of receptor 1 are corona-charged to polarities reverse to each other, and quantity of the first charging is set to a high value so as to obtain a sufficient image density in single sheet copying. In the case of successive copying on plural sheets, said charging quantity is gradually lowered in accordance with the progress of successive copying so as to keep copy image density almost constant. |
