APPARATUS FOR AND METHOD OF CONTROLLING THE PERFORATION OF PAPER BY ELECTRICAL DISCHARGES

摘要

A method of and apparatus for controlling apparatus for perforating strips of paper by disruptive spark discharges. The perforate strip passes between two chambers, each of which has an opening facing the strip. Waves transmitted by a transmitter disposed in one of the chambers pass through these openings. The other chamber contains two receivers. The waves which have passed through the perforations are incident on one of the receivers. The waves which have passed through the imperforate area of the paper are incident on the other receiver. The perforating apparatus is controlled in dependence on the difference between the actual and desired values of the difference between the output signals of the two receivers.