Importance

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Abstract

Apparatus for guiding a strip traveling along a selected path, which apparatus comprises a primary strip position correcting mechanism, such as a payout reel or steering roll that engages a strip at a first location for changing the position of the strip as the strip moves along from the first position to a remote control point. The strip correcting mechanism includes a primary control loop with an actuator for changing the strip position and a feedback control loop that compares the actual strip position with an adjustable reference value to control the position of the moving strip. An edge sensor at the remote control point on the strip path creates an output error signal generally proportional to the deviation of the strip edge at the remote control point from a preselected edge position. This error signal is used for periodically changing the reference value of the position correcting mechanism in the primary loop in accordance with the output error. The apparatus employs the concept of creating a series of counting bursts each having a count pulse, the number of which is determined by a given frequency component and a selected duration component. At least one of these components defining the count pulses of each counting bursts is varied in accordance with the magnitude of the output error signal so the reference value of the primary loop is changed by the output error signal.

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First Claim