Abstract: A multi-feed detection device is provided with: a base; an arm rotatably supported on the base; a magnet affixed to the arm; a Hall element which is affixed to the base, and which outputs an electric signal corresponding to the strength of the magnetic field; a differentiation circuit which outputs a voltage corresponding to the differential value of the output of the Hall element; and an integration circuit which outputs a voltage corresponding to the integral value of the output of the differentiation circuit. The arm applies a force against a conveyance path by way of a spring. One or more sheets of paper conveyed on the conveyance path raise the arm, separating the magnet from the Hall element. Accordingly, the output of the integration circuit varies, and the number of sheets of paper is detected on the basis of this variation.

Abstract: A multi-feed detection device is provided with: a base; an arm rotatably supported on the base; a magnet affixed to the arm; a Hall element which is affixed to the base, and which outputs an electric signal corresponding to the strength of the magnetic field; a differentiation circuit which outputs a voltage corresponding to the differential value of the output of the Hall element; and an integration circuit which outputs a voltage corresponding to the integral value of the output of the differentiation circuit. The arm applies a force against a conveyance path by way of a spring. One or more sheets of paper conveyed on the conveyance path raise the arm, separating the magnet from the Hall element. Accordingly, the output of the integration circuit varies, and the number of sheets of paper is detected on the basis of this variation.