Sheet edge detector has ultrasonic transmitter-receivers at regular intervals at distance above dense support emitting ultrasonic pulses resulting in cohesive ultrasonic wavefront

摘要

The detector has ultrasonic transmitter-receivers (4) arranged at regular intervals at a distance above dense support (2). In transmission mode, the transmitter-receivers transmit ultrasonic pulses resulting in summation in a cohesive ultrasonic wavefront that propagates towards support (2). In receiving mode the receivers receive pulses reflected from support (2), sheet (6) and/or sheet edge.