| 摘要 |
<p>PURPOSE:To aim at the stabilization of double-feed detection at the time of a variation in temperature and surroundings, by detecting the occurrence of double feeding with a difference between the mean value of data conformed to mechanical displacement of each roller and the setting value at a time when both sheet bodies of No.n and No.n-1 are conveyed by the roller. CONSTITUTION:When paper of the second downward is fed, an output voltage Vout of a differential amplifier 5 is measured in the same way as the first one, finding the sampling mean value VmDATA2, and it is compared with the mean value VmDATA1 of the first paper, thus double feeding is discriminated. That is to say, when related to a formula I, it is discriminated that the second paper is double fed. And, threshold value TH2 is set in advance as in a formula II. In case of No.n paper, when it satisfies a formula III, it is discriminated that the No.n paper is double fed. Thus, as to the conveyed paper of the second paper downward, it is compared with just before the latest data, so that even if input of the amplifier 5 is slowly offset by a temperature variation, a portion of the offset voltage can be offset.</p> |
