Accuweb, Inc

James Martyn

Raymond A Buisker

Erich T Ziemann

The edge of a web of material is inserted in a gap in a detector head between an ultrasonic blockage transmitter and an ultrasonic blockage receiver such that the magnitude of the pulse of sound from the transmitter that is received by the receiver is related to the portion of the web that blocks the beam of sound and thereby the position of the edge of the web. A compensation transmitter and compensation receiver are mounted proximate to the blockage transmitter and blockage receiver and transmit similar sound signals across the gap but are unoccluded by the web. The output of the compensation receiver is detected and used to normalize the values of the signal received from the blockage receiver to compensate for the effect of transient changes in ambient conditions. The apparatus includes a controller with a microprocessor which receives the electrical pulses from the two receivers, determines the peak values of the pulses, averages pulse peak values to provide averaged values which reduce the effect of spurious signal variations, and normalizes the value of the blockage receiver signal with the compensation receiver signal to provide an error correcting output signal which can be used to bring the position of the web back to a desired position. A plurality of detectors can be operated by a single microprocessor using multiplexing techniques.

Ultrasonic web edge detection method and apparatus

The edge of a web of material is inserted into a gap in a detector head between an ultrasonic blockage transmitter and an ultrasonic blockage receiver such that the magnitude of the pulse of sound from the transmitter that is received by the receiver is related to the portion of the web that blocks the beam of sound and thereby the position of the edge of the web. The ultrasonic frequency of each pulse is preferably very high to provide a narrow beam. The second half of the electronic drive pulse to the transmitter is preferably 180.degree. out of phase with the first half of the pulse to reduce excessive ringing of the transmitter. A compensation transmitter and compensation receiver, which are mounted proximate to the blockage transmitter and the blockage receiver, transmit similar sound signals across the gap but are unoccluded by the web. The apparatus includes a controller with a microprocessor which:

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Madison, WI, United States of America

James Martyn