A sensor system for determining the position of at least one edge of at
least one web material traveling along a predetermined path. In one
embodiment, the sensor system has at least one transmitter block having a
plurality of transmitters capable of selectively transmitting ultrasonic
signals and at least one receiver block having a plurality of receivers
capable of generating receiver output signals in response to the
receivers receiving at least a portion of the ultrasonic signals
transmitted by the at least one transmitter block. The receiver block is
spaced a distance from the transmitter block so as to define a sensor
field of view therebetween whereby at least a portion of the at least one
web material traveling along a predetermined travel path interferes with
at least a portion of the ultrasonic signals transmitted by the at least
one transmitter block. The receiver output signals generated by the at
least one receiver block is indicative of the position of the web of
material as the same is moved along the travel path between the
transmitter block and the receiver block. In an alternative embodiment,
the functions of the at least one transmitter block and the at least one
receiver block are performed essentially equivalently by at least one
transceiver block and at least one reflector.