Inkjet Nozzle Threshold Detection via Multi-Row Test Charts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for detecting defective printing nozzles in inkjet printing machines are inefficient and require significant effort, as they struggle to accurately identify individual nozzles causing print defects and set appropriate thresholds for nozzle evaluation, often leading to incorrect judgments and increased print quality issues.
Innovation Solution
A method involving the printing of a multi-row nozzle test chart and an area coverage element, where every nth nozzle is active, allowing for geometric association and evaluation by a computer to allocate defects and define thresholds based on deviations, reducing the need for continuous printing and evaluation of area coverage elements during production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a nozzle test chart with every nth nozzle is printed to enable individual nozzle testing, then nozzle identification capability is improved, but the complexity of the testing system and the number of test charts required increases
Solution Approach 1:
The nozzle test chart is divided into multiple rows, where each row contains test patterns from a specific subset of nozzles (every nth nozzle). This segmentation allows the system to test all nozzles systematically across multiple charts while maintaining manageable complexity in each individual chart.
Solution Approach 2:
The patent introduces a row dimension to the nozzle testing approach. Instead of attempting to print all nozzles in a single chart (which would create overwhelming complexity), the system distributes nozzle testing across multiple rows, where each row represents a different nozzle subset. This dimensional approach enables comprehensive testing while reducing individual chart complexity.
2Measurement precision
If thresholds for nozzle defect detection are set to be highly sensitive to detect all potential issues, then detection accuracy is improved, but the number of false positive errors increases
Solution Approach 1:
The patent defines thresholds based on measurable parameters from the nozzle test chart, specifically the deviation of printed patterns from their expected positions and the continuity of printed lines. By establishing thresholds through these concrete parameters, the system achieves reliable defect detection while minimizing false positives through objective, quantifiable criteria.
Solution Approach 2:
The patent replaces subjective judgment of nozzle performance with automated image processing and computational analysis. By using computer-assisted evaluation of the nozzle test chart patterns, the system eliminates human bias and subjectivity in threshold setting, leading to more consistent and reliable defect detection.
3Reliability
If continuous printing and evaluation of area coverage elements is performed during production to monitor nozzle performance, then real-time quality control is improved, but productivity and printing efficiency deteriorate
Solution Approach 1:
The patent performs nozzle performance testing and threshold definition during the setup phase before actual production printing. By conducting comprehensive nozzle evaluation in advance using the nozzle test chart, the system establishes baseline performance data and detection thresholds before production begins, eliminating the need for continuous monitoring during printing operations.
Solution Approach 2:
The patent extracts nozzle testing functionality from the continuous production process. By separating the nozzle performance evaluation into a distinct setup phase using dedicated nozzle test charts, the system removes the burden of continuous monitoring during production, thereby maintaining high printing efficiency while still achieving reliable quality control through preliminary testing.
4Measurement precision
If high-resolution image sensors are used to accurately allocate defects to specific nozzles, then nozzle allocation precision is improved, but the cost and complexity of the recording system increases
Solution Approach 1:
The patent uses a simplified nozzle test chart that creates distinct, identifiable patterns for each nozzle subset. These test patterns serve as copies or representations of nozzle performance that can be easily captured by standard image sensors. The test chart designs specific geometric patterns (vertical lines, dots) that are uniquely attributable to specific nozzles, enabling accurate identification without requiring high-resolution imaging.
Solution Approach 2:
The patent applies different test pattern designs to different regions of the nozzle test chart corresponding to different nozzle subsets. Each region contains patterns specifically optimized for testing particular nozzles, allowing the system to achieve high allocation precision for each local region using standard imaging capabilities rather than requiring uniformly high-resolution imaging across the entire system.
Data Source
AI summary
A method detects defective printing nozzles in an inkjet printing machine having a computer. The method includes printing a multi-row nozzle test chart for detection purposes, the test chart contains a number of horizontal rows of equidistant vertical lines printed periodically and disposed underneath one another. Wherein in every row of the nozzle test chart periodically only those respective printing nozzles of the print head contribute to the first element of the nozzle test chart that correspond to the specified number of the horizontal rows. An area coverage element geometrically associated with the nozzle test chart is printed. Both elements are recorded by an image sensor and both elements are evaluated by the computer. Defective printing nozzles are identified by evaluating the recorded nozzle test chart by the computer. Defects are allocated in the area coverage element to the printing nozzles in the nozzle test chart by the computer.