Flexible Web Registration via Offset Inkjet Imagers
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Solution Overview
Problem
High-speed printing systems face challenges in accurately registering printed content on flexible webs, particularly due to the elastic deformability of the substrate, which can lead to misregistration errors such as color shifts, moire, and dot gain effects.
Innovation Solution
The implementation of a printing system with individually controllable ink jet imager units offset along the process direction, combined with a position encoder and image sensors, allows for precise registration of content printed on both sides of a flexible web. This system independently controls the printing portions of each imager unit to ensure accurate alignment and minimize misregistration errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed printing is used to increase productivity, then printing speed is improved, but registration accuracy deteriorates due to elastic deformability of the substrate
Solution Approach 1:
The system dynamically adjusts the printing position of each imager unit in real-time based on feedback from position encoders and image sensors. The control system continuously monitors web position and elastic deformation, then dynamically modifies print head positioning to compensate for substrate movement and deformation during high-speed printing, maintaining registration accuracy despite speed increases
Solution Approach 2:
Position encoders and image sensors provide continuous feedback about web position and printed content alignment. The control system processes this feedback information and adjusts the printing positions of imager units accordingly, creating a closed-loop control system that maintains registration accuracy even at high printing speeds where elastic deformation occurs
2Productivity
If multiple imager units are used to print different portions of the web, then productivity is improved, but registration complexity increases
Solution Approach 1:
The printing system is divided into multiple independently controllable imager units, each responsible for printing specific portions of the web. This segmentation allows each unit to be controlled independently while maintaining overall registration through coordinated positioning, enabling high-speed printing without compromising alignment accuracy
Solution Approach 2:
Each imager unit is equipped with position encoders and the system uses image sensors to monitor printed content. The control system processes feedback from all units and coordinates their positions to maintain accurate registration across the entire web width, managing the complexity of multiple units through centralized feedback control
3Productivity
If the web is transported at high speed, then productivity is improved, but misregistration errors increase due to elastic deformability
Solution Approach 1:
The system dynamically adjusts printing positions based on real-time web position data from position encoders. During high-speed transport, the control system continuously updates the printing position commands to imager units to compensate for web elastic deformation and movement, maintaining alignment accuracy despite high transport speeds
Solution Approach 2:
Position encoders mounted on the web provide continuous feedback about web position during high-speed transport. The control system uses this feedback to calculate and apply real-time corrections to imager unit positioning, compensating for elastic deformation and maintaining registration accuracy even at high printing speeds
Data Source
AI summary
A printing system comprises a transport apparatus adapted to transport a flexible web along a process direction and first and second individually controllable ink jet imager units offset from one another along the process direction. Each of the first imager unit and the second imager unit includes a first portion operable to print on a first portion of the web and a second portion operable to print on the second portion of the web wherein each of the first portion and second portion of the first and second imager units is stationary along the process direction and the lateral direction.