Disjoint Template Matching for Printhead Registration
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Solution Overview
Problem
Existing printer technologies face challenges in accurately identifying disjoint test patterns due to low contrast between ink and media, and the presence of visual noise from artifacts like paper fibers, which can lead to incorrect registration of printheads, affecting print quality and accuracy.
Innovation Solution
A method and system that utilize a disjoint template matching process, where a controller forms and identifies a test pattern with specific mark arrangements, using optical sensors to generate image data and retrieve templates from memory to accurately locate marks, even in noisy conditions, thereby improving printhead registration accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a sparse test pattern with small marks is used to reduce visibility to human observers, then the aesthetic quality and imperceptibility of the test pattern is improved, but the difficulty of detecting and measuring the marks by the controller increases due to low contrast and noise from artifacts
Solution Approach 1:
The patent divides the test pattern into multiple disjoint groups, where each group contains marks from a single marking device. This segmentation allows the controller to identify marks from each device independently using device-specific templates, improving detection accuracy even when individual marks are small and low-contrast.
Solution Approach 2:
The patent creates different mark arrangements for different marking devices, where each device produces a unique spatial pattern of marks. This local differentiation allows the controller to distinguish between marks from different devices and identify them accurately using matching templates, even when the marks themselves are small and difficult to detect.
2Difficulty of detecting and measuring
If traditional large marks are used in test patterns, then the ease of detecting and measuring marks is improved, but the aesthetic quality and imperceptibility of the test pattern deteriorates as the marks become visible to human observers
Solution Approach 1:
The test pattern is segmented into multiple disjoint groups with marks from different marking devices separated spatially. This allows the use of multiple small marks per device rather than a single large mark, maintaining detection capability through pattern recognition while reducing individual mark size and visibility.
Solution Approach 2:
The patent combines multiple small marks from the same marking device into a disjoint group that forms a recognizable spatial pattern. By merging the information from multiple small marks into a collective pattern, the system achieves detection reliability comparable to large marks while maintaining low visibility.
3Loss of substance
If disjoint test patterns with small number of drops per mark are used, then the amount of marking material consumed is reduced, but the contrast between ink and media decreases making mark identification more difficult
Solution Approach 1:
The patent segments the marking process into multiple devices, each creating a small number of marks with minimal material. The segmentation allows the system to use very small marks (few drops) per device while maintaining identification accuracy through the unique spatial patterns created by each device's specific mark arrangement.
Solution Approach 2:
The patent changes the spatial arrangement parameters of marks for each marking device, creating unique patterns that differ in position, spacing, and configuration. This parameter variation allows the controller to distinguish between devices and identify marks accurately even when the marks themselves are small and low-contrast, compensating for reduced material usage.
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
Enhances the accuracy of printhead registration by effectively distinguishing between marks and noise, ensuring precise alignment and maintaining print quality even with low-contrast inks and noisy environments.
Implementation Method 1
an optical sensor to generate scanned image data of the printed test pattern
Data Source
AI summary
A method uses a sparse test pattern to identify a spatial relationship between a printhead and an image receiving surface in a printer. The method includes operating a plurality of ejectors in the printhead to form a printed marks on the image receiving surface, generating image data of the test pattern, and applying a predetermined disjoint template to the image data to identify a location of the printed marks. The disjoint template matching process improves the accuracy of identifying the printed marks in noisy image data and for sparse test patterns.