| 摘要 |
PURPOSE:To surely, simply and easily detect the image density so that an image forming condition can be controlled, by positioning a rotary mirror for executing a scan of an image, and receiving a light beam by a photodetector provided on a fixed position. CONSTITUTION:An image projecting optical path is formed by irradiating an image of a microfilm 2 being an original from the lower part. In the reader mode, a rotary mirror 1 is positioned at a position shown by a full line in the figure, and the image is turned to a fixed mirror 3, thereafter, bent by the mirror 3, and enlarged and projected to a screen A. Subsequently, in the printer mode, the mirror 1 rotates to a print start position shown by an imaginary line, and executes a scan of the image by further rotating by a prescribed angle. In such a way, the image is brought to slit projection and exposure to the surface of a photosensitive body 7 through fixed mirrors 4, 5 and 6. An image density detecting means 21 is provided on a fixed position of the extended direction side along the mirror surface 9 of a photometric position, and plural pieces of photometric elements 22 are fixed and provided on the lower face of an intermediate base 23 being alight shielding plate, by which the image density can be detected surely.
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