| 摘要 |
PURPOSE:To prevent the unevenness in the brightness of a copying image from fluctuating at every changing of magnification by disposing a light shielding means having a middle stop aperture shape along the moving direction of lenses in proximity to the lens face and changing the aperture shape according to the change in the magnification. CONSTITUTION:The projected images of the parts (a), (b), (c) of an original 1 placed on an orginal plate 5 are formed as electrostatic latent images on a photosensitive drum 4 by lens systems 2, 3 moving along rails 9. At this time, differences in illuminances on the drum 4 are produced depending on the magnitudes of the inclination theta of main rays. A light shielding means 11 having an aperture 10 of a middle stop is provided in the position proximate to the faces of the lens systems 2, 3 on the original 1 side, and the width of the aperture 10 gradually decreases from the end part to the central part and gradually increases from the central part to the other end part with respect to the moving directions of the lens systems 2, 3. With such constitution, image exposure is made on the drum 4 while substantially uniform quantity of light is being maintained in spite of a change in the angle theta. |
