Inkjet Nozzle Detection via Asymmetric Test Pattern
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Solution Overview
Problem
Inkjet printing devices face challenges in efficiently and reliably detecting impaired nozzles, which can lead to print image degradation due to contaminants and misalignment, affecting print quality.
Innovation Solution
A compact test pattern is designed with an N×M matrix of printed and non-printed matrix points, allowing for robust detection using a Convolutional Neural Network, enabling the identification of impaired nozzles by printing and analyzing sensor data from the test pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional test pattern is used for nozzle detection, then the detection process is simple, but the detection reliability is insufficient and cannot compensate for lateral offsets
Solution Approach 1:
The test pattern is segmented into multiple columns, each corresponding to a specific nozzle. Each column contains a unique sequence of printed and non-printed matrix points that serves as a fingerprint for that nozzle. This segmentation allows individual nozzle identification and impairment detection while maintaining the ability to detect lateral offsets through sequence comparison.
Solution Approach 2:
The test pattern is designed in advance with predetermined sequences of printed and non-printed matrix points for each column. These sequences are configured before printing to enable automatic detection of lateral offsets by comparing the actual printed pattern against the expected predetermined sequences, thus preparing the system for offset compensation before the actual detection occurs.
2Reliability
If the test pattern covers the entire print head width, then all nozzles can be detected, but material consumption increases
Solution Approach 1:
The test pattern uses a selective approach where not all matrix points in each column need to be printed. By strategically selecting which matrix points to print and which to leave non-printed, the system achieves sufficient detection coverage for all nozzles while minimizing ink consumption. The unique sequences are achieved through partial printing rather than complete coverage.
3Measurement precision
If the test pattern is made robust against lateral offsets, then detection accuracy improves, but the pattern design becomes more complex
Solution Approach 1:
The test pattern employs asymmetric design where each column has a unique, non-repeating sequence of printed and non-printed matrix points. This asymmetry ensures that even if a lateral offset occurs, the mismatched sequences will be easily detectable. The asymmetric patterns serve as unique identifiers that maintain detection accuracy despite positional variations.
Data Source
AI summary
A test pattern is described for detecting an impaired nozzle of an inkjet printing device. The test pattern has a matrix with matrix points. The printed matrix points in the individual columns respectively exhibit a defined spacing relative to one another in the row direction. An impaired nozzle with transverse offset can thus be particularly reliably and robustly detected.