| 摘要 |
PROBLEM TO BE SOLVED: To prevent read out image data from deteriorating by correcting an error occurring in read out data due to variation in the quantity of illumination light which occurs during stoppage of intermittent operation with high accuracy. SOLUTION: Immediately after a buffer memory of read out data becomes near full state and read out operation is interrupted, a CPU 45 on an SCU 7 begins operation for detecting variation in the quantity of light. The peak detecting section of a shading ASIC 34 detects peak of read out value at a specified position on a read out document and performs similar detecting operation immediately before resuming the read out operation. Variation in the quantity of light occurring during interruption of read out operation is represented by the ratio of both peak values, reference set voltage of an A/DC 33 is regulated by a D/AC 44 based on the ratio value and the output is corrected such that the variation has no effect. Problem of prior art that it is susceptible to noise and a reference reflector having uniform reflection characteristics in the subscanning direction is required is thereby eliminated.
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