| 摘要 |
An ultrasonic edge detector system wherein the lateral position of a moving web or sheet is monitored by projecting an ultrasonic beam from a transmitting transducer toward a receiving transducer and the web edge occludes or shadows more or less of the ultrasonic beam changing the ultrasonic energy received by the receiving transducer. Changes in output of the receiving transducer are detected as a measure of change in edge position. Accuracy in the measurement of the position of the edge is achieved by lengthening the path of acoustic energy from the transmitting transducer to the receiving transducer by positioning an acoustic reflector in said path. Reverberations are reduced by causing the angle of incidence of the ultrasonic beam to be at an angle alpha of greater than 0 degrees. A dual receiving transducer system is disclosed compensating for fluctuations in power to the edge detector system.
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