| 摘要 |
PURPOSE:To obtain a stable output independently of the size of a read area by detecting automatically the size of an original of a picture to be read, extracting only the read area from a detection signal. CONSTITUTION:In energizing a key 21 with an original 13 of size A, a size command section 20 closes entirely switches 181-183 and only a switch 18 is closed by the key 21 with the size B. When laser beam scans the area F1 from the line L sequentially, then the signal is subject to photoelectric conversion 16 via an optical fiber element 15, a detection signal is amplied (17), the switch is conducted selectively by the key selection depending on the size and the analog signal is summed (19) and outputted. Through the constitution, the signal in response to the contrast of the original 13 is obtained without being affected by a stray light due to scattered light and the operability is obtained.
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