| 摘要 |
PURPOSE:To solve the deficiency of the quantity of light in the peripheral part by providing a previous history exposure means and making the photoreceptor sensitivity during image exposure higher in both end parts than in the central part. CONSTITUTION:Optical systems including a photoreceptor 1 having previous history effect, a high illumination eraser 2, a charger 3 for previous history charging, a lamp 4 for previous history exposure, a charger 5, and a projecting lens 6 are successively arranged in the rotating direction of the photoreceptor 1 A slit 10 which is changed in slit width of both end parts is provided between the lamp 4 and the photoreceptor 1. A slit shape which is the slit 10 narrower in width the nearer the two end parts when the exposure of the lamp 4 is above the exposure P shown in the figure and is the one wider in width the nearer the two end parts conversely when below the exposure P is used for said slit 10. |
