| 摘要 |
PURPOSE:To reduce variance in an output level after correction between sensors by using a data equivalent to the photoelectric conversion of an optical sensor when an object to be read is uniform and is of halftone as a correction reference data. CONSTITUTION:After a reference white original is set, and the switches 4 and 7 are connected to a setting mode, a low voltage is impressed on an optical sensor part 1 from a sensor power source (normal voltage, low voltage) 5. Thereby, a photoelectric conversion output equivalent to an output at a time when an original of halftone is read is inputted to a correction data generation circuit 8, and is stored at a storage part 10 as the correction reference data. Next, an original 2 to be inputted is set, and the switches 4 and 7 are connected a read mode, then an ordinary voltage is impressed on the sensor part 1. In this way, the bit of picture information of the original 2 is read, and the photoelectric conversion output is inputted to a correction circuit 9 through the switch 7. The circuit 9 corrects an inputted photoelectric conversion output using the correction reference data stored at the storage part 10, and outputs it as an electrical signal corresponding to exactly the bit of picture information of the original 2.
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