Linear Printhead Cross-Track Error Correction via Image Resampling

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Solution Overview

Problem

Digital printing systems with linear printheads face cross-track alignment errors due to manufacturing variations, leading to objectionable color channel misalignment, which existing methods struggle to correct without complex and costly fixtures.

Innovation Solution

A method involving the creation of a test target with alignment marks, capturing its printed image, analyzing the positions to determine cross-track position errors, and applying a correction function to resample image lines, thereby reducing cross-track position errors in printed images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If complex and costly fixtures are used to correct cross-track position errors, then manufacturing precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvecross-track alignment precisionVSAvoidcomplexity of correction system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical correction fixtures with a software-based image processing system. The DFE captures an image of the test target, processes the image data to detect alignment mark positions, and computes correction values algorithmically. This substitution of mechanical systems with computational methods resolves the contradiction by achieving high precision without increasing device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a digital copy (image) of the test target instead of physical measurement fixtures. By capturing an image of the printed test target and analyzing it through software, the system avoids the need for complex physical measurement and correction fixtures, thereby reducing device complexity while maintaining manufacturing precision.

Inventive Principle:

Principle #26Copying

2Manufacturing precision

If complex and costly fixtures are used to correct cross-track position errors, then manufacturing precision is improved, but cost increases

Engineering Contradiction:

Improvecross-track alignment precisionVSAvoidcost of correction system

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive mechanical correction fixtures with a software-based image processing system implemented in the DFE. This substitution eliminates the need for costly hardware components while achieving the same or better precision through computational algorithms, directly addressing the cost issue.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a consumable test target that is printed once and then discarded after serving its calibration purpose. This disposable approach eliminates the need for expensive, durable correction fixtures, significantly reducing the cost of the correction system while maintaining manufacturing precision.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If a simple calibration process is used, then ease of operation is improved, but measurement precision may worsen

Engineering Contradiction:

Improvesimplicity of calibration processVSAvoidposition error measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system performs self-calibration by automatically capturing an image of the test target, processing the image data, detecting alignment mark positions, and computing correction values without requiring external measurement equipment or complex user intervention. This self-service approach maintains simplicity while achieving high measurement precision through automated image processing algorithms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses feedback from the captured image to automatically adjust and determine correction values. By analyzing the actual positions of alignment marks in the printed test target and comparing them to expected positions, the system generates precise correction data, maintaining both ease of operation and measurement precision.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10885405B2Correcting cross-track errors in a linear printhead

Publication Date: 2021.01.05 EASTMAN KODAK CO

AI summary

A method for correcting cross-track position errors in a digital printing system having a linear printhead includes printing a test target including a plurality of alignment marks. A data processing system is used to automatically analyze a captured image of the printed test target to determine a measured position for each of the alignment marks. The measured positions for the alignment marks is compared to reference positions to determine measured cross-track position errors. A cross-track position correction function is determined responsive to the measured position errors, wherein the cross-track position correction function specifies cross-track position corrections to be applied as a function of cross-track position. A corrected digital image is determined by resampling the image lines of a digital image responsive to the cross-track position correction function.