| 摘要 |
PROBLEM TO BE SOLVED: To provide a duplicate feed detection device capable of detecting the lapping of sheet from the transmitted light quantity through the sheet even when the sheet which is not constant in concentration by an image formed thereon is used. SOLUTION: Stacked sheets are separated at a specified timing and carried by a sheet feeding means 4, and the transmitted light quantity is measured at a plurality of positions along the carrying direction on the sheets by a transmitted light quantity measuring means 8 comprising a light-flooding part 81 and a light-receiving part 82 which are provided across a carrying path of the sheet. A duplicate feed detection device measures the reference sheet in advance, a plurality of transmitted light quantities are stored as the reference values in relation to the positions on the sheet, and the value of the stored transmitted light quantity is compared with the measured value of the transmitted light quantity for each position on the sheet. The duplicate feed of the sheets is discriminated based on the result of comparison of a comparing means.
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