Multi-feed judging device, image forming apparatus, multi-feed judging method and multi-feed judging program

摘要

A multi-feed judging device includes a transporting unit that holds a recording medium between a driving roller and a driven roller, which is driven by the driving roller, and transports the recording medium by rotating the driving roller; a detecting unit that detects a position of the driven roller; a calculating unit that calculates a thickness of the recording medium based on positions of the driven roller when the recording medium is transported and when the recording medium is not transported; a reference value updating unit that updates a reference value of the thickness by using the calculated thickness; a judging unit that judges, using the reference value, whether recording media, which are transported after the reference value was updated, are transported while overlapping each other or not. The calculating unit calculates the thickness when the position is within a predetermined range.

主权项

1. A multi-feed judging device comprising:
a transporting unit that holds a recording medium between a driving roller and a driven roller, which is driven by the driving roller, and transports the recording medium by rotating the driving roller; a detecting unit that detects a position of the driven roller; a calculating unit that calculates a thickness of the recording medium based on a position of the driven roller when the recording medium is transported and a position of the driven roller when the recording medium is not transported; a reference value updating unit that updates a reference value of the thickness by using the calculated thickness; and a judging unit that judges, using the reference value updated by the reference value updating unit, whether recording media, which are transported after the reference value was updated, are transported while overlapping each other or not, wherein: the calculating unit calculates the thickness by using the position detected by the detecting unit, when the position detected by the detecting unit is within a set range, and the reference value updating unit updates a reference value for each kind of recording media, and resets the reference value when at least one of opening or closing a feeding device, powering off the multi-feed judging device, and switching to an energy saving mode.