US 4,959,040 A · Method and apparatus for precisely positioning and stabilizing a continuous belt or web or the like

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.

Claims12

Dependent claims

An apparatus for improved tracking and control of a traveling belt or web or the like supported and driven by at least one roller means comprising:

means for establishing a reference array of belt positions relative to a position fixed with respect to an ideal axis of travel for said belt at precise positional intervals along the entire length of said belt;
control means for sensing at each positional interval the displacement of said belt from said ideal axis of travel and for providing a corrective feedback signal representative of the displacement difference between said sensed position and a corresponding element of said reference array;
tracking actuator means responsive to said corrective feedback signal for moving the angle of said roller to thereby maintain said belt in a substantially invariant position with respect to its ideal axis of travel.

An apparatus for improved tracking and control of a traveling belt or web or the like supported on a roller means comprising:

a continuous belt;
at least one roller means disposed for supporting and rotating said belt at least one complete revolution along an axis of travel;
means for calibrating said belt with respect to a locus of positions defining an ideal axis of travel at predetermined precise positional intervals for a complete revolution of said belt and for storing said calibration values as elements in a reference array;
control means for sensing the displacement of said belt at said predetermined positional intervals with respect to a corresponding reference array element and for thereby producing a corrective feedback signal representative of the desired position of said belt at each of said corresponding positional intervals;
adjusting means responsive to said corrective feedback signal for adjusting the angle of said roller means relative to said belt such that said belt is thereby maintained in a substantially invariant position with respect to said axis of travel.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for precisely positioning and stabilizing a continuous belt or web or the like

Life of this patent

Method and apparatus for precisely positioning and stabilizing a continuous belt or web or the like

Life of this patent

Abstract

Claims12