Web Printing System Dimensional Change Compensation

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Solution Overview

Problem

Web shrinkage caused by high temperatures in moving web printing systems leads to misregistration of images printed by different printheads, resulting in visual noise due to dimensional changes in the web material.

Innovation Solution

A method and system that measure cross-process dimensional changes in the web and adjust the operation of web printing system components, such as temperature settings of rollers, to compensate for shrinkage and maintain image registration by pre-shrinking the web before printing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If high temperatures are applied to the web in the printing system, then ink reception on the web surface is optimized, but web shrinkage occurs causing misregistration of images

Engineering Contradiction:

Improveweb surface temperatureVSAvoidimage registration accuracy

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-heating the web in a web pre-heater before the web reaches the marking stations. This preliminary heating stabilizes the web dimensions and reduces subsequent shrinkage during printing, thereby preventing misregistration while still allowing optimal ink reception at the marking stations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes temperature parameters by introducing a separate pre-heating zone with controlled temperature settings before the main printing area. This allows the web to be heated to a stable temperature range that prevents shrinkage during printing, while the marking stations can operate at their optimal temperature for ink reception without causing excessive shrinkage.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If web temperature is stabilized to prevent shrinkage, then image registration accuracy is maintained, but ink reception on web surface may be suboptimal

Engineering Contradiction:

Improveimage registration accuracyVSAvoidweb surface temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent segments the heating process into two distinct zones: a web pre-heater zone for stabilizing web dimensions and a marking station zone for optimal ink reception. This segmentation allows each zone to operate at different temperature levels appropriate for its specific function, resolving the contradiction between preventing shrinkage and optimizing ink reception.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The web pre-heater performs preliminary heating action before the web reaches the marking stations. This preliminary action stabilizes the web temperature and dimensions in advance, allowing the marking stations to then apply heat for optimal ink reception without causing significant shrinkage that would affect registration accuracy.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If web dimensions are monitored and adjusted in real-time, then misregistration is prevented, but system complexity increases

Engineering Contradiction:

Improveimage registration accuracyVSAvoiddimensional change compensation system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical dimensional adjustment systems with a thermal field-based solution. Instead of using mechanical devices to physically adjust web dimensions in real-time, the system uses controlled heating fields in the web pre-heater to prevent shrinkage from occurring in the first place, thereby maintaining registration accuracy without requiring complex real-time mechanical adjustment mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system effectively prevents misregistration by stabilizing web dimensions, ensuring accurate placement of ink droplets and reducing visual noise in the printed images.

Implementation Method 1

The pre-heater roller 22 is heated to a temperature that transfers sufficient heat to the media material for optimal ink reception on the web surface as it passes the marking stations 26

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Leveling roller 34 modifies the temperature of the web and reduces any temperature differences between inked and non-inked portions of the web

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

After the temperature leveling, the ink is heated by heater 44 before the printed web enters the spreader 38

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

The spreader 38 applies pressure to the ejected ink on the surface of the web to smooth the roughly semicircular ink drops on the surface of the web and to encourage ink fill with the different colors

Methodology Applied

Scientific EffectPressure: Pressure Increase

Data Source

PatentUS8376516B2System and method for operating a web printing system to compensate for dimensional changes in the web

Publication Date: 2013.02.19 GENESEE VALLEY INNOVATIONS LLC

AI summary

A method enables changes in the operation of a web printing system in response to web dimensional changes being detected. The method includes identifying a cross-process dimensional change in a web moving through a printing system, comparing the identified cross-process dimensional change to a predetermined threshold, and changing operation of a component in the web printing system in response to the cross-process dimensional change exceeding the predetermined threshold.