Flexible Substrate Printing Registration Compensation
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Solution Overview
Problem
High-speed printing on flexible substrates, such as plastic webs, faces challenges with misregistration errors due to substrate distortion and the spreading of water-based inks, which can lead to coalescing of ink droplets and adverse effects on image quality.
Innovation Solution
A printing system comprising two ink jet printing units that print registration marks and raster lines on a flexible substrate, with a detector calculating substrate distortion and adjusting the printing of subsequent raster lines to compensate for distortion, thereby minimizing misregistration errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-based inks are used for printing on impermeable substrates, then environmental and health concerns about VOC emissions are addressed, but ink droplets spread across the surface and coalesce, adversely affecting image quality
Solution Approach 1:
The patent changes the physical parameters of the substrate by applying a coating layer that modifies its surface properties. This coating enables water-based inks to be deposited without spreading and coalescing, while still allowing the substrate to remain impermeable. The coating parameter change resolves the contradiction by providing a surface that prevents ink droplet merging while maintaining environmental benefits of water-based inks.
2Productivity
If high-speed printing is used, then productivity is improved, but substrate distortion and ink spreading occur, leading to misregistration errors
Solution Approach 1:
The patent applies a coating layer to the substrate before printing occurs. This preliminary action prepares the substrate surface to resist ink spreading and minimize distortion during high-speed printing. By pre-treating the substrate with the coating, the system enables high-speed printing while maintaining registration accuracy, as the coating prevents the harmful effects that would otherwise occur at high speeds.
Solution Approach 2:
The coating layer acts as an intermediary between the substrate and the ink. This intermediary layer mediates the interaction by preventing direct contact between water-based ink and the impermeable substrate surface, thereby eliminating ink spreading and coalescing. The intermediary coating enables high-speed printing to proceed without causing misregistration errors.
3Reliability
If multiple layers of inks and coatings are applied to achieve proper adhesion and rub resistance, then product quality is improved, but registration between layers must be maintained, increasing process complexity
Solution Approach 1:
The patent applies a coating layer that serves multiple functions simultaneously: it provides adhesion for subsequent ink layers, delivers rub resistance, and prevents ink spreading. By making this single coating layer multi-functional, the patent reduces the need for multiple separate layers and coatings, thereby simplifying the overall process while maintaining product quality.
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 minimizes misregistration errors and maintains image quality by accurately compensating for substrate distortion and controlling ink spreading, even at high speeds.
Implementation Method 1
a detector downstream of the first printing unit that detects the first successive pair of registration marks, calculates a first magnitude of distortion of the substrate based on the detection of the first successive pair of registration marks
Implementation Method 2
water within the ink is partially absorbed by the surface of the web during a drying process
Implementation Method 3
the lack of ability of the water-based ink to penetrate or absorb into the web itself leads to individual ink droplets spreading across the surface of the web
Implementation Method 4
The system effectively minimizes misregistration errors and maintains image quality by accurately compensating for substrate distortion
Data Source
AI summary
Printing systems and methods of printing using at least first and second printing units (100a, 100b) to print on a flexible substrate (22) sense distortion of the substrate during printing and adjust the effective resolution of the second printing unit (100b) to achieve registration at least to a desired degree.