| 摘要 |
PURPOSE:To prevent forming of a black border by making a shading member movable back and forth by a wire stretched at an angle not parallel to the direction of scanning of a photosensitive body in a projecting light path. CONSTITUTION:When a light quantity sensor 36 in which photodetecting elements are arranged in a line parallel to a slit detects, light quantity near the slit 14 in the state of exposure and outputs a boundary detection signal that indicates position of largely different light receiving quantity existing in the direction of axial line of a photosensitive drum 15, a motor 32 rotates in the direction to wind a wire 18, and moves a shading sheet 17 to a position where light receiving quantity is largely different existing in the direction of axial line of the photosensitive drum 15, and then locks the shaft of an hourglass reel 13 by a brake 33 to prevent winding of the sheet 17 by a reel 30. Then, mirrors 12, 13 are returned in the direction of arrow mark W, and copying operation iis performed. Thus, the cause of a black border on a copied image can be eliminated. |
