| 摘要 |
PROBLEM TO BE SOLVED: To exclude a range in which accurate position cannot be decided due to slip and a range in which a detection level of an optical sensor is unstable, in detecting double feed at the same position in sheets of paper.SOLUTION: A conveyance pulse of a frequency proportional to the rotation speed of a drive motor for paper feeding and for driving a conveyance roller pair after the paper has passed an optical sensor 6, is generated. A light receiving level of the optical sensor from the front end to the rear end of the paper 1 is sequentially recorded in each memory element of a memory element row, for each pulse. A double feed detection position is determined from among rank positions between a rank that decreases from the front end by the number obtained by adding a margin to the number of pulses including slip from the front end of the paper passing the optical sensor to reaching the conveyance roller pair, and a rank that goes back from the rear end by the number obtained by adding a margin to the number of pulses from the rear end of the paper departing from a paper feed means to reaching the optical sensor. |
