Inkjet Stitch Gap Calibration for Cross-Track Error Correction
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Solution Overview
Problem
Existing methods for aligning image data in multi-printhead printers fail to adequately account for density-dependent stitching characteristics, leading to visible artifacts at the boundaries between printheads.
Innovation Solution
A method involving the application of test image print data with predefined boundary patterns and reference features to determine an aim stitch gap that minimizes the visibility of stitching boundaries, using digitized image analysis to correct for cross-track alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing alignment methods are used in multi-printhead printers, then the printing process can be completed, but visible artifacts appear at the boundaries between printheads due to misalignment in cross-track and in-track directions
Solution Approach 1:
The patent applies preliminary action by performing alignment calibration using test patterns before actual printing. Test patterns with known geometric features are printed and analyzed to determine misalignment conditions, allowing correction values to be pre-calculated and stored. During production printing, these pre-determined correction values are applied to compensate for misalignment, eliminating visible artifacts at printhead boundaries.
Solution Approach 2:
The patent implements feedback by analyzing the printed test patterns to detect actual misalignment between printheads. The system measures deviations in test pattern features and uses this feedback information to calculate correction values. These correction values are then applied to subsequent printing operations, creating a closed-loop system that continuously ensures alignment precision and eliminates artifacts.
2Measurement precision
If test patterns with multiple density levels are printed to determine aim stitch gap, then accurate stitching correction can be achieved, but the calibration process becomes more complex
Solution Approach 1:
The patent applies local quality by analyzing different regions of the test pattern with different density levels separately. Each density level (e.g., low density, medium density, high density) is evaluated to determine its specific aim stitch gap, as misalignment characteristics vary with density. This localized analysis allows the system to capture density-dependent alignment behavior while maintaining a systematic calibration process through structured analysis of uniform density regions.
3Manufacturing precision
If the aim stitch gap is determined using uniform density regions, then density-dependent stitching characteristics are captured, but the analysis requires digitizing and processing test images
Solution Approach 1:
The patent applies copying by creating a digital representation (digitized copy) of the printed test pattern for analysis. Instead of directly measuring physical alignments, the system captures an image of the printed test pattern and analyzes the digital copy to determine stitch gap and misalignment. This copying approach simplifies the measurement process while maintaining precision, as digital image analysis is more straightforward than direct physical measurement of printed features.
Data Source
AI summary
Cross-track stitch errors in an inkjet printer are reduced by printing test patterns for a plurality of stitch gaps. A first test pattern portion to be printed with a first jetting module includes a uniform region on a left side of a stitching boundary having a predefined boundary pattern, and a first reference feature within the first uniform density region spaced apart from and parallel to the stitching boundary. A second test pattern portion to be printed with a second jetting module includes a uniform region on a right side of the stitching boundary, and a second reference feature within the second uniform density region spaced apart from and parallel to the stitching boundary. Wherein the first and second test pattern portions are spaced apart by the predefined stitch gap. The printed test pattern is analyzed to determine an aim stitch gap that minimizes a visibility of the stitch boundary.