US 4,572,417 AGranted

Web tracking apparatus

AssigneeEastman Kodak Company

InventorsBrian J. Joseph, Stephen C. Rumsey

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Abstract

Apparatus for controlling the alignment, in a lateral (cross-track) direction, of a web moving along a path to minimize lateral deviation between successive discrete areas of such web. The apparatus includes a steering roller for supporting the web for movement along such path. The steering roller is rotatable about an axis perpendicular to the plane of the span of the web approaching the steering roller. As the web moves along the path, the lateral position of a marginal edge of the web relative to a reference plane is sensed. When such lateral edge position is at either of two spaced predetermined locations relative to such reference plane, signals indicative of the presence of such edge at such locations are produced. The steering roller, in response to such signals, is rotated about the axis perpendicular to the plane of the span of the web approaching the steering roller to steer the web and thereby cause the lateral position of the edge of the web to progress from the predetermined location at which the edge was sensed to the other predetermined location as the web moves along its path.

Claims7

Dependent claims

Apparatus for controlling alignment, in a lateral direction, of a web moving along a path, said apparatus comprising:

at least one roller for supporting said web for movement along such path, said roller being a web steering roller mounted for rotation about an axis perpendicular to the plane of the span of said web approaching said steering roller;
means for sensing the lateral position of an edge of said web relative to a reference plane, as said web moves along such path, said sensing means producing a first signal proportional to the lateral position of said edge at or beyond a first predetermined location spaced from such reference plane and producing a second signal proportional to the lateral position of said edge at or beyond a second predetermined location spaced from such reference plane and from said first location;
and
means for rotating said steering roller about said axis in either of two opposite directions, said rotating means being responsive to said first signal to rotate said steering roller in one direction an amount proportional to said first signal to steer said web for moving said edge toward said second location, and responsive to said second signal to rotate said steering roller in the other direction an amount proportional to said second signal to steer said web for moving said edge toward said first location, whereby said edge progresses laterally substantially between said first and second locations as said web moves along such path.

1 more element

In an electrographic reproduction apparatus having a dielectric web providing successive discrete image receiving areas, and a plurality of web supporting rollers for moving such web along a path in which such image receiving areas are brought into operative relation with electrographic process stations to form related transferable images in such areas respectively and to transfer such images to a receiver member to form a composite reproduction, one of said web supporting rollers being a steering roller mounted for rotation about a caster axis, an improved means for controlling lateral alignment of said web so that lateral deviation between successive areas of such web is minimized whereby transfer of such transferable images is accomplished in accurate superimposed register, said control means comprising:

means for sensing the lateral position of an edge of such moving web relative to a reference plane, and for producing a signal corresponding to the position of said edge from such reference plane;
means, responsive to such edge position signal, for producing (i) a first signal proportional to such edge position signal when such edge is at or beyond a first position relative to said reference plane, (ii) a second signal proportional to such edge position signal when such edge is at or beyond a second position relative to said reference plane, and (iii) a third signal when such edge position signal corresponds to a position of said edge between said first and second positions;
and
a reversible servo motor coupled to said steering roller, said servo motor being responsive to said first and second signals for rotating said steering roller an amount proportional to such signals about said caster axis in directions to respectively steer the web for lateral movement of said edge from one to the other of said first and second positions as the web moves along such path, and non-responsive to said third signal whereby steering of the web is not effected while said edge is between said first and second positions.

1 more element

Dependencies are inferred from the claim text.