Inkjet Printing Pathfinder Correction for Positional Errors
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Solution Overview
Problem
Inkjet printing systems face inherent positioning errors due to inaccuracies in robotic positioning and variations in printhead orientation and object dimensions, making accurate printing challenging without costly calibration.
Innovation Solution
A method involving the use of 'pathfinder' dot patterns printed in a preliminary pass, analyzed to calculate corrections, which are then applied in a subsequent full printing pass to compensate for positioning errors, ensuring accurate alignment and registration of dot patterns on surfaces with known tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If system calibration is used to correct positioning errors, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by printing test dot patterns (pathfinders) before the actual printing process. These pre-printed patterns serve as reference markers that enable subsequent measurement and correction of positioning errors without requiring complex real-time calibration systems during production printing.
Solution Approach 2:
The patent uses copying by creating duplicate reference dot patterns at known positions and geometric relationships. By printing these identical reference patterns multiple times across different swathes, the system can compare actual printed positions against the known reference positions to calculate and correct positioning errors.
2Productivity
If robotic positioning systems are used to move printhead and substrate, then productivity is improved, but positioning accuracy deteriorates due to inherent errors
Solution Approach 1:
The patent implements feedback by using machine vision systems to capture images of the pre-printed pathfinder dot patterns, calculate actual positioning deviations from expected positions, and use this feedback information to correct subsequent printing operations. This closed-loop feedback mechanism compensates for robotic positioning errors while maintaining high productivity.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting printing parameters based on measured positioning errors. The system calculates correction values from the analyzed dot patterns and modifies printing data parameters (such as dot positions and timing) to compensate for identified positioning deviations, thereby maintaining accuracy despite robotic motion variations.
3Manufacturing precision
If high resolution printing is achieved on nominal surfaces, then manufacturing precision is improved, but adaptability to surfaces with varying dimensions deteriorates
Solution Approach 1:
The patent uses preliminary action by printing adaptive reference dot patterns that are specifically designed to account for surface variations. These pathfinder patterns are printed first on the actual object surface (not just a nominal model), allowing the system to measure and adapt to the real surface geometry and dimensional variations before performing high-resolution printing.
Solution Approach 2:
The patent applies dynamics by making the printing system adaptive and flexible rather than static. The system dynamically adjusts printing parameters based on real-time measurements of the actual object surface and printed dot patterns, enabling it to accommodate variations in object dimensions and curvature while maintaining high printing resolution.
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
This approach effectively corrects print position errors, enabling accurate printing on objects with curved surfaces and varying dimensions by applying necessary adjustments to the printing data, thereby improving printing resolution and registration.
Implementation Method 1
The image processing module is configured to analyze the relative positions of the printed dots in the printed second swathe data, and to identify groups of dots which comprise the at least one dot pattern.
Data Source
AI summary
A method of controlling a system including a printhead for printing an image on at least one surface, wherein the at least one surface differs in shape from a nominal surface by a known tolerance, and wherein the printhead and the at least one surface move relative to each other along a predetermined print path comprising at least one swathe. Small dot patterns (referred to as “pathfinders”) are printed on a surface of the object in a preliminary printing pass, then the printed dot patterns are analyzed, for example with a machine vision system. The necessary corrections may then be calculated from this analysis and applied to a subsequent full printing pass.