| 摘要 |
PURPOSE:To moderate the accuracy of a fixed type reflecting mirror and to reduce the size of the title device by arranging three reflecting mirrors between an image formation lens and an exposing part, fixing one of them and moving other two in a prescribed direction to execute scanning exposure. CONSTITUTION:The 1st reflector 11 is fixed between the image formation lens 6 and a slit exposing plate 22 and the 2nd and 3rd reflecting mirrors 14, 15 are arranged so as to be unitedly reciprocated in the arrow A direction with 45 deg. angle formed by respective reflecting surfaces. At the time of printing under said constitution, the movable mirror 12 is receded to a position shown by a broken line and the 2nd and 3rd mirrors 14, 15 are moved to exposure starting positions in the arrow A direction and then moved in the reverse direction to execute scanning exposure on a photosensitive drum 21. Since the 1st reflecting mirror 11 is fixed, its high accuracy is not required and the size can be reduced. In addition, the size of the whole device can be reduced because of the use of the leading optical path.
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