| 摘要 |
PROBLEM TO BE SOLVED: To provide an image reader capable of holding quality of an image as high by obtaining a reference signal for shading correction at high precision irrespective of stain with time of a rear side surface member to read an original. SOLUTION: The maximum value within a range of a original passing area L2 is detected by a peak hold circuit 24 and a gain of an amplifier 32 is controlled so that the detected maximum output value of an A/D converter 11 reaches a preset target value 224. A reading signal of the original passing area L2 in the main scanning direction is detected at timing when a reference original 1a is on a rear side surface roller 14 and the reading signal (reference reflection signal) of the original passing area L2 at the time is used for calculation of initial reference data. A reading signal of a non-passing area L1 of the original is stored as a correction signal (reference reflection correction signal) of the initial reference data whenever the non-passing area L1 of the original is read.
|
