Tandem printing system with fine paper-position correction
AssigneeHewlett-Packard Indigo B.V.
InventorsAron Shmaiser, Daniel Sagi, Lior Lewintz
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Abstract
A tandem printer with a mechanism for fine substrate-position correction, comprising: a first printing station; a second printing station; a rotatable element, rotating at a given rotation rate, that receives the substrate after printing thereon by the first printing station and transfer the substrate toward the second printing station; a sensor which measure the position of an edge of the substrate during its transfer from the first printing station to the second printing station; and a controller, which applies a corrective step change in angular position of the rotatable element responsive to the measurements of the sensor, without changing the general rotation rate of the rotatable element.
Claims27
A tandem printer with a mechanism for fine substrate-position correction, comprising:
- a fit printing station;
- a second printing station;
- a transfer system which transfers the substrate from the first printing station to the second printing station, comprising:
- a rotatable element, rotating at a given rotation rate, that receives the substrate after printing thereon by the first printing station and transfers the substrate toward the second printing station;
- a sensor which measures the position of an edge of the substrate during its transfer from the first printing station to the second printing station;
- a flexible strip, traveling at a given rate and providing motion to the rotatable element, wherein a corrective step displacement of the flexible strip induces a corrective step change in angular position of the rotatable element;
- a controller, which applies a corrective step change in angular position of the rotatable element responsive to the measurements of the sensor, without changing the general rotation rate of the rotatable element via a step displacement of the flexible strip;
- and
- two pulleys, situated along the flexible strip;
- one upstream and one downstream of the rotatable element, said pulleys pressing into the flexible strip at a first point and a second point, respectively, wherein when pressure of one pulley is partially released, the other pulley takes up the thus produced slack, providing a corrective step displacement of the flexible strip.
A method of applying a fine positional correction to a substrate on a tandem printer, comprising:
- printing on a substrate by a first printing station;
- transferring the substrate from the first printing station toward a second printing station, comprising:
- mounting the substrate on a rotatable element of a substrate-transfer system;
- and
- moving the substrate by rotating the rotatable element at a given rotation rate;
- measuring the angular position of an edge of the substrate on the rotatable element;
- and
- applying a step angular displacement to the rotatable element, responsive to the measurement, without changing the rotation rate of the rotatable element,
- wherein rotating the rotatable element at a given rotation rate comprises rotating the rotatable element by a flexible strip;
- wherein applying the step angular displacement to the rotatable element comprises applying a step displacement to the flexible strip, comprising either a positive and negative step displacement to the flexible strip, thus inducing a clockwise and a counterclockwise step angular displacements to the rotatable element;
- and
- applying the positive step displacement to the flexible strip comprises:
- releasing flexible strip slack upstream of the rotatable element;
- and
- taking up flexible strip slack downstream of the rotatable element;
- and
- wherein applying the negative step displacement to the flexible strip comprises:
- releasing flexible strip slack downstream of the rotatable element;
- and
- taking up flexible strip slack upstream of the rotatable element.
Dependencies are inferred from the claim text.