System for detecting double sheets output by printing machine comprises ball mounted in recess under front stop which is rotated by double sheet so that sensor produces signal

摘要

The system for detecting double sheets (6) output by a printing machine comprises a detector positioned near a front edge stop (14). A ball or roller is mounted in a recess under the stop, the distance between the underside of the stop and top of the ball being 1.5 times the thickness of a single sheet. When a double sheet is fed through, it rotates the ball and the sensor produces a signal.