Importance

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Abstract

A device for providing extremely accurate tracking and control of a continuous belt or web driven by at least one roller such as a paper transport belt for an electrostatic plotter, printer or the like includes a method for cancelling out the effect of belt edge irregularities by sampling the irregularities in the edge of a belt at precise positional intervals for an initial rotation of the belt and storing the sampled values as elements in a reference array. The reference array is corrected to include an error component representative of linearly increasing measurement of error for each of said array elements due to lateral shifting of the belt. During subsequent operation, the lateral displacement of the belt is continuously scanned for each of said positional intervals with respect to a corresponding element of the array. A corrective feedback mechanism generates corrective feedback signals representative of a desired belt position for each of said positional intervals to thereby maintain the belt on an ideal axis of travel. In a paper transport system incorporating this device, a transport belt can be corrected within a fraction of a belt revolution, irrespective of direction, and paper or another recording medium can be accurately registered on repeated writing passes to within 0.0005 inches.

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First Claim