Digital Print-Head Alignment Using Imaged Test Patterns
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Solution Overview
Problem
Digital printing presses face challenges in aligning print-heads, leading to degraded print quality due to mechanical misalignment and electrical miss-calibration, resulting in waste and reduced revenue generation.
Innovation Solution
A method and system for aligning print-heads using a print-head array with imaging sensors and processors to determine and correct vertical, horizontal, and rotational errors by printing and imaging alignment patterns, adjusting print-head positions and activation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If print-heads are mechanically aligned and electrically calibrated, then print quality is improved, but device complexity and alignment time increase
Solution Approach 1:
The system performs preliminary alignment by printing test patterns and capturing images before actual production printing. The processor determines misalignment amounts from these preliminary measurements and generates correction data, allowing the print-heads to be pre-aligned and calibrated before manufacturing or operation, thereby reducing complexity during production
Solution Approach 2:
The system uses imaging sensors to create optical copies (images) of physical alignment patterns printed by the print-heads. These digital copies are then processed to determine misalignment, replacing complex direct mechanical measurement systems with simpler optical copying and digital analysis
2Manufacturing precision
If print-heads are precisely aligned, then print quality is improved, but alignment time and productivity are reduced
Solution Approach 1:
Alignment is performed as a preliminary one-time action before production printing begins. The system captures images of alignment patterns and processes them to determine misalignment amounts, completing the precision alignment task before the productivity-critical production phase, thus minimizing impact on ongoing productivity
Solution Approach 2:
The patent replaces complex mechanical alignment systems with optical imaging and digital image processing. Instead of using mechanical sensors or physical measurement devices that would require manual intervention and time, the system uses imaging sensors to capture patterns and a processor to automatically calculate corrections, significantly reducing alignment time
3Manufacturing precision
If misalignment is detected and corrected, then print quality is improved, but waste of substrate and ink increases due to initial misalignment
Solution Approach 1:
The system performs misalignment detection and correction as a preliminary action before actual production printing. By capturing images of alignment patterns and processing them to determine misalignment amounts, the system corrects print-head positions before production begins, preventing waste of substrate and ink that would occur if printing started with misaligned print-heads
Solution Approach 2:
The system implements a feedback mechanism where imaging sensors continuously monitor the positions of alignment patterns printed by the print-heads. The processor analyzes these images to determine misalignment amounts and generates correction data that is fed back to adjust print-head positions, ensuring continuous precision and preventing waste during operation
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
Improves print quality by ensuring precise alignment of print-heads, reducing waste and enhancing revenue generation through accurate printing.
Implementation Method 1
The imager is configured to acquire an image of a printed first alignment pattern and further configured to acquire an image of a printed second alignment pattern
Data Source
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AI summary
A system for aligning print-heads in a printing-press, which includes a print-head array which includes a plurality of print-head-rows. Each print-head-row includes a plurality of print-heads and prints print a color associated with therewith. Each print-head includes an array-of-nozzles, which includes a plurality of nozzle-lines. The system includes an imager and a processor. The imager includes at least one imaging-sensor. The imager is configured to acquire an image of a printed first-alignment-pattern and further configured to acquire an image of a printed second-alignment-pattern. The processor is configured to receive the image of the first-alignment-pattern and the image of the second-alignment-pattern and to determine alignment of reference print-heads in at least a reference-row of print-heads from the image of the first-alignment-pattern. The processor is also configured to determine alignment of color print-heads in rows other than the reference-row of print-heads, relative to the reference print-heads, from the image of the second-alignment-pattern.