| 摘要 |
PURPOSE:To prevent the reproducibility of high picture quality from deteriorating by providing a shutter member which open a light collection part during original size detection and closes it during original lighting. CONSTITUTION:When a copy is taken, an original O is placed on a table 9 at a specific position and a cover 10 is closed. Then the closure is detected by a detecting means to turn on a lamp 11 for a certain time and also turns on a plunger 26. A slit 20 is opened to irradiate the front end of the original with luminous flux from the lamp 11 and a photosensor 21 detects the level of reflected light corresponding to the size of the original O to decide the size of the original. Then, when a copying operation start signal is inputted, the plunger 26 is turned off, the shutter 22 is returned by an elastic member 25 to its closure position shown by a broken line, and an optical scanning system begins to scan. Thus, the slit 20 is closed when image exposure is started after the original size is detected, and the luminous flux from the lamp 11 illuminates only an exposure position of the original. Consequently, the picture quality is prevented securely from deteriorating.
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