Method for automatically-adjusting web media tension

Abstract

A method for automatically adjusting a level of tension in web media being transported in a roll-fed web media transport system, comprising: receiving web media from a source roller, feeding the web media through an S-shaped media path in an automatically-adjusting tensioning mechanism where the web media is wrapped around curved surfaces on first and second tensioning shoes, and pulling the web media through the automatically-adjusting tensioning mechanism using a feed mechanism. The tensioning mechanism includes: a bracket assembly mounted to a frame which is adapted to freely pivot around a pivot axis. A pivot angle of the bracket assembly automatically adjusts in response to differences in a coefficient of friction between the web media and the tensioning shoes such that the tension in the web media has a reduced level of variability relative to configurations where the bracket assembly is held in a fixed position.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Reference is made to commonly assigned, co-pending U.S. patent application Ser. No. ______ (Docket K001036), entitled: “Automatically-adjusting web media tensioning mechanism”, by Turner et al., which is incorporated herein by reference.FIELD OF THE INVENTION[0002]This invention generally relates to a digital printing system for web media, and more particularly to a method for automatically adjusting a level of tension responsive to changes in characteristics of the web media.BACKGROUND OF THE INVENTION[0003]Continuous web printing allows economical, high-speed, high-volume print reproduction. In this type of printing, a continuous web of paper or other print media material is fed past one or more printing subsystems that form images by applying one or more colorants onto the print media surface. With this type of printing system, finely controlled dots of ink are rapidly and accurately propelled from the printhead onto the surface of a m...

AI Technical Summary

Benefits of technology

[0016]This invention has the advantage that it provides adequate pre-tensioning of the web media independent of the frictional characteristics of the web media without the need for manual reconfiguration.

[0017]It has the additional advantage that the tensioning mechanism automatically and passively adjusts to correct for variations in the friction coefficient in real time during a printing process.

[0018]It has the further advantage that the tensioning mechanism is more robust and less prone to human errors that may be introduced with prior art tensioning mechanisms that require manual reconfiguration.

Problems solved by technology

Variability in ink or other liquid amounts and types or variability in drying times can cause print media stiffness and tension characteristics to vary dynamically for different types of print media, contributing to the overall complexity of print media handling and print media dot registration.

Such manual adjustments can be time-consuming, and can be prone to operator error.

Therefore it is incompatible with applications where tension needs to be added to a slack web media.

This configuration provides a controlled amount of tension throughout a closed belt, but cannot be used to add tension to a slack web media.

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