Web Press Cross-Web Expansion Compensation
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Solution Overview
Problem
Inkjet printing in web presses faces issues with media expansion and shrinkage, leading to cross-web color misalignment and front-to-back misregistration, which affect the quality and accuracy of printed text and images, especially in duplex printing systems where precise dimensions are required.
Innovation Solution
A web press system that measures cross-web expansion and shrinkage dynamically using sensors and a controller to adjust printing parameters in real-time, ensuring accurate alignment and dimensionality of printed content without interrupting the printing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inkjet printing is performed on moving web media, then printing productivity is improved, but cross-web color misalignment occurs due to media expansion and shrinkage
Solution Approach 1:
The system performs preliminary measurement of media expansion and shrinkage using sensors before the actual printing process. Based on these measurements, the controller pre-calculates and applies compensation values to the printing positions, ensuring that even if the media expands or shrinks during printing, the colors will align correctly. This preliminary action resolves the contradiction by preparing correction data in advance while maintaining high printing speed.
Solution Approach 2:
The system implements a feedback mechanism where sensors continuously monitor the media web for expansion and shrinkage during the printing process. The controller receives this real-time feedback and dynamically adjusts the printing positions of subsequent colors to compensate for detected media dimensional changes. This closed-loop feedback system maintains color alignment precision without sacrificing printing productivity.
2Productivity
If inkjet printing is performed on moving web media, then printing productivity is improved, but front-to-back misregistration occurs due to media dimensional changes
Solution Approach 1:
The system measures media expansion and shrinkage characteristics in advance using sensors positioned along the web path. The controller uses these preliminary measurements to establish compensation profiles that account for front-to-back dimensional changes. This allows the system to maintain accurate dimensional precision while operating at high printing speeds without interruption.
Solution Approach 2:
The system employs continuous feedback monitoring of media dimensional changes in the front-to-back direction during printing. The controller adjusts printing parameters in real-time based on sensor feedback, compensating for media expansion or shrinkage that occurs as the web moves through the printing system. This ensures consistent dimensional accuracy while maintaining high productivity.
3Manufacturing precision
If media expansion and shrinkage are measured and compensation is applied dynamically, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical adjustment mechanisms with an electronic control system. Instead of using mechanical devices to physically adjust printing positions based on media expansion, the system uses sensors to detect dimensional changes and electronically modifies printing parameters through a controller. This substitution of mechanical systems with electronic control reduces overall device complexity while maintaining high manufacturing precision.
Solution Approach 2:
The system achieves compensation for media expansion and shrinkage by dynamically changing printing parameters (such as droplet ejection timing and position) rather than physically adjusting the printing mechanism. The controller modifies digital printing data in real-time based on sensor measurements, allowing precise compensation through parameter adjustment rather than mechanical intervention, thereby reducing system complexity.
4Manufacturing precision
If dynamic measurement and compensation system is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system replaces complex mechanical measurement and compensation mechanisms with electronic sensors and digital control. Instead of using mechanical devices to measure and physically compensate for dimensional changes, the system uses optical or other non-contact sensors to detect media expansion and shrinkage, then electronically adjusts printing parameters through a controller. This electronic approach reduces mechanical complexity while maintaining high dimensional accuracy.
Solution Approach 2:
The system implements a feedback control loop where sensors continuously monitor media dimensional changes and the controller automatically adjusts printing parameters in response. This automated feedback mechanism eliminates the need for complex manual measurement and adjustment systems, reducing overall device complexity while maintaining precise dimensional control throughout the printing process.
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 reduces cross-web color misalignment and front-to-back misregistration, maintaining high print quality and accuracy, and reduces downtime and paper waste by dynamically adapting to media changes during the printing process.
Implementation Method 1
When ink is deposited on media, the media expands in the cross-web direction
Implementation Method 2
When the printing fluid and media are dried, the media shrinks in the cross-web direction
Data Source
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AI summary
A web press system including a first printbar, a first sensor, a second printbar, a second sensor, and a controller. The first printbar prints first user content on a first side of a web of media. The first sensor senses a pattern on the web of media and provides first sensor data as the first printbar prints the first user content. A second printbar prints second user content on the first side of the web of media. The second sensor senses the pattern on the web of media and provides second sensor data as the second printbar prints the second user content. The controller determines an amount of expansion of the web of media in a direction perpendicular to a web advanced direction based on the first sensor data and the second sensor data and modifies printing performed by the second printbar based on the amount of expansion.