Patent ID: 6831875
Filing Date: 2004-12-14
Classification: B65H,G01S,Y10S

Abstract:
An apparatus for ultrasonically detecting an edge of a web, comprising:a ultrasonic-wave transmitter transmitting ultrasonic-wave pulse train; a ultrasonic-wave receiver arranged in facing relation to said ultrasonic-wave transmitter, receiving said ultrasonic-wave pulse train, and converting the received ultrasonic-wave pulse train into electric signals, said web being fed between said ultrasonic-wave transmitter and said ultrasonic-wave receiver; a rectifying circuit for rectifying said electric signals; a low-pass filter circuit for smoothing output signals transmitted from said rectifying circuit; a first sample-holding circuit for sampling an output signal transmitted from said low-pass filter circuit, at first timing; a second sample-holding circuit for sampling an output signal transmitted from said low-pass filter circuit, at second timing later than said first timing; a third sample-holding circuit for sampling an output signal transmitted from said first sample-holding circuit, at said second timing; and a differentially amplifying circuit for calculating a difference between an output signal transmitted from said second sample-holding circuit and an output signal transmitted from said third sample-holding circuit.