| 摘要 |
PURPOSE:To maintain the surface of a cylindrical glass always in a cleaned state by providing the cylindrical glass continuously or intermittently rotating at a constant speed to form a window and pressing a cleaning member into contact with its side face. CONSTITUTION:A cylindrical glass 15 serving as the window of a scanning optical system rotates at a constant speed, and since a cleaning member 20 is pressed into contact with its surface, it is maintained always in a cleaned state. Laser beams pass through the glass 15 near the central axis and fall on the part 3 of a photosensitive drum 1 to be exposed, but the member 20 located on the side of the glass 15 does not stand at all in the way of the laser beams. |
