Inkjet Test Pattern Formation for Nozzle Blind-Spot Detection
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Solution Overview
Problem
Existing recording devices, such as inkjet printers, face challenges in detecting defective nozzles due to the possibility of missed detection when defective nozzles are positioned at the same location or adjacent to gaps in the nozzle array, particularly in vertical array heads with color changes, leading to incomplete detection of ejection failures.
Innovation Solution
A recording device and method that forms a test pattern by shifting individual patterns in the sub scanning direction and arranging them in the main scanning direction through controlled liquid ejection from sequential nozzle groups, ensuring overlapping detection of defective nozzles by forming multiple pattern groups in the main scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test pattern is printed with pattern groups arranged in the main scanning direction using conventional nozzle rows, then the inspection process is simple, but defective nozzles at the same position or adjacent to gaps cannot be detected
Solution Approach 1:
The patent introduces a second dimension by forming pattern groups in the sub-scanning direction in addition to the main scanning direction. This creates a two-dimensional test pattern where pattern groups are arranged both along the main scanning direction and in the sub-scanning direction, enabling detection of defective nozzles that would otherwise be masked by gaps or positioned at the same location.
Solution Approach 2:
The patent segments the nozzle rows into first nozzle rows and second nozzle rows, with each row containing multiple nozzles arranged in the sub-scanning direction. This segmentation allows the formation of multiple pattern groups from different nozzle rows, creating overlapping patterns that improve detection reliability for defective nozzles.
2Reliability
If only one pattern group is formed per nozzle row, then the test pattern formation is fast, but the detection reliability is insufficient due to potential missed detections
Solution Approach 1:
The patent performs preliminary actions by forming multiple pattern groups from different nozzle rows before final inspection. The first pattern groups are formed from first nozzle rows and second pattern groups are formed from second nozzle rows, creating overlapping patterns that ensure comprehensive coverage and detection reliability.
Solution Approach 2:
The patent merges multiple pattern groups formed from different nozzle rows into a single test pattern. The first pattern groups and second pattern groups are combined such that they overlap in the sub-scanning direction, creating a comprehensive inspection pattern that maintains high detection reliability while forming all patterns in one pass.
3Measurement precision
If pattern groups are formed without sub-scanning movement, then the process is simple, but overlapping patterns cannot be formed to eliminate detection blind spots
Solution Approach 1:
The patent introduces dynamic sub-scanning movement during the test pattern formation process. The recording head performs sub-scanning movement to form pattern groups at different positions in the sub-scanning direction, creating overlapping patterns that eliminate detection blind spots and improve measurement precision for defective nozzle position detection.
Data Source
AI summary
A test pattern includes a plurality of individual patterns along a main scanning direction by liquid ejection from each of a plurality of first nozzles. The individual patterns adjacent to each other in a sub scanning direction are located at positions shifted from each other in the main scanning direction. The plurality of first nozzles include a first sequential nozzle group that is sequential in the sub scanning direction and a second sequential nozzle group that is sequential in the sub scanning direction. The test pattern includes a first pattern group derived from liquid ejection from the first sequential nozzle group and a second pattern group derived from liquid ejection from the second sequential nozzle group. The control unit performs control to form the test pattern in which at least the first pattern group and the second pattern group are arranged in the main scanning direction by performing sub scanning between formation of the first pattern group and formation of the second pattern group.