Inkjet Nozzle Detection via Grid Chart Width Analysis
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Solution Overview
Problem
Conventional methods for determining missing nozzles in high-resolution inkjet printing heads are inefficient in in-line mode, requiring high-resolution cameras and slowing down the printing process, leading to potential inaccuracies in nozzle detection.
Innovation Solution
A nozzle operating situation checking method that prints a grid-shaped testing chart while transporting the printing medium, extracts grid boxes through image processing, derives a standard width, and detects missing nozzles by comparing box widths with a corrected standard width, allowing accurate determination even with low-resolution cameras during in-line inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-resolution camera is used to determine missing nozzles in high-resolution printing heads, then measurement precision is improved, but productivity deteriorates because the process becomes too slow for in-line mode
Solution Approach 1:
The testing chart is segmented into a grid pattern with multiple line segments printed by different nozzles. Instead of requiring each nozzle to print a complete linear pattern, the grid structure allows partial patterns to be combined and evaluated collectively, enabling accurate missing nozzle detection with lower resolution cameras during continuous transport
Solution Approach 2:
The invention transitions from one-dimensional linear pattern evaluation to two-dimensional grid pattern evaluation. By printing line segments in both transverse and transport directions forming a grid, the system can detect missing nozzles through spatial analysis of the grid structure, achieving accurate detection without requiring high-resolution cameras that would slow down in-line inspection
2Productivity
If a low-resolution camera is used to maintain high inspection speed in in-line mode, then productivity is improved, but measurement precision deteriorates making accurate nozzle determination impossible
Solution Approach 1:
The testing chart divides the evaluation into multiple line segments across a grid structure. Each segment is printed by specific nozzles, and the collective pattern of segments allows low-resolution cameras to capture sufficient information for accurate missing nozzle detection without requiring high spatial resolution
Solution Approach 2:
The invention changes the evaluation parameter from requiring high spatial resolution of complete linear patterns to evaluating the spatial distribution and connectivity of grid line segments. This parameter change enables low-resolution cameras to achieve accurate nozzle detection by analyzing the grid structure rather than requiring detailed linear patterns
Data Source
AI summary
A nozzle operating situation checking method for inkjet printing apparatus which perform printing by dispensing ink droplets from a printing head having a plurality of nozzles arranged in a transverse direction of a printing medium. The method includes the following steps: a step of printing a testing chart; a step of reading the testing chart downstream of the printing head; a step of extracting grid boxes; a step of deriving a standard width from width sizes; a step of detecting a box having a width size equal to or larger than a corrected standard width by comparing the width sizes of the respective boxes with the corrected standard width; and a step of determining that a missing nozzle exists upon detection of the box having a width size equal to or larger than the corrected standard width.