| 摘要 |
PURPOSE:To obtain a reader of long original with high accuracy by storing an actual measured value from a reference position formed on a board up to each photodetector to each photodetector, applying operational processing between the said actual measuring value and a preset setting value to obtain a correcting value. CONSTITUTION:Ater all photodetectors 21, 22,..., 2n-1, 2n are mounted on a board 3, the first position mark on the board is taken as a reference position S, the interval from the said reference position S to the alignment mark 5 of each element is measured actually and actually measured values L0, L1, L2... Ln-1 obtained in this way are stored permanently in a storage section 6 of each photodetector respectively. On the other hand, each set value from the reference position S up to the position mark at each set interval is outputted vai a counter circuit (not shown) and the operation is processed with the actually measured value read from the storage section 6. That is, the result of operation obtained by subtracting the set value from the actually measured value is used as a correction value, it is stored in the 2nd storage section 6' and a received data is expanded or contracted in response to the correction value.
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