Inkjet Printhead Inspection Patterns for Discharge Failure Sorting
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Solution Overview
Problem
High-density inkjet printheads with numerous nozzles face challenges in managing nozzle states due to factors like dust, air bubbles, and ink viscosity, leading to discharge failures that can result in image defects, making it difficult to accurately sort printed products as non-defective or defective during printing operations.
Innovation Solution
A printing apparatus and method that utilize inspection patterns to determine the state of printed images, allowing for efficient sorting of products into non-defective and defective categories by reading and analyzing first and second inspection patterns printed on the media, distinguishing between no discharge failures, continuous discharge failures, and mixed states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of nozzles in the printhead is increased to achieve high-density printing, then the printing resolution and coverage are improved, but the difficulty of managing nozzle states and detecting discharge failures increases
Solution Approach 1:
The patent divides the monitoring task into segments by placing multiple inspection patterns at different positions (first inspection pattern, second inspection pattern, and additional patterns) to monitor different nozzle groups separately. This segmentation allows the system to manage and detect discharge failures in large-scale printheads by breaking down the complex monitoring task into smaller, manageable sections.
Solution Approach 2:
The patent introduces inspection patterns as intermediary elements between the nozzles and the detection system. These patterns serve as test targets that mediate the detection process, allowing indirect monitoring of nozzle discharge states through optical reading of the printed patterns, thereby simplifying the management of large numbers of nozzles.
2Manufacturing precision
If the printing operation is stopped to perform recovery when a discharge failure is detected, then the image quality is maintained, but the printing efficiency decreases
Solution Approach 1:
The patent performs preliminary detection of discharge failures by monitoring inspection patterns during the printing operation. By detecting discharge failures early and continuously, the system can identify problematic nozzles before they cause significant image quality degradation, allowing for targeted recovery actions that minimize printing interruptions.
Solution Approach 2:
The patent implements a feedback mechanism where inspection patterns are continuously read and analyzed during printing, providing real-time information about nozzle discharge states. This feedback allows the control unit to make informed decisions about when to interrupt printing for recovery, balancing image quality maintenance with printing efficiency by only stopping when necessary.
3Manufacturing precision
If all printed products are sorted as defective when a discharge failure occurs, then the product quality is ensured, but the waste of non-defective products increases
Solution Approach 1:
The patent applies local quality assessment by analyzing which specific inspection patterns show discharge failures and determining the affected regions. Based on the location and extent of discharge failures, the system selectively sorts only the affected printed products as defective, while allowing products with acceptable quality (where discharge failures did not occur or were minimal) to be classified as non-defective, thereby reducing waste.
Solution Approach 2:
The patent uses different colored inks in the inspection patterns to monitor discharge failures of different nozzle groups. By analyzing which colors are affected by discharge failures, the system can determine the extent and location of problems, enabling more accurate sorting decisions that distinguish between definitely defective products and those that may still be acceptable.
4Measurement precision
If inspection patterns are used to detect discharge failures, then the accuracy of defective product identification is improved, but the device complexity and control difficulty increase
Solution Approach 1:
The patent segments the inspection system into distinct components: inspection patterns printed by different nozzle groups, reading units positioned at specific locations, and control algorithms that analyze specific pattern regions. This segmentation makes the complex control task more manageable by dividing it into independent, modular functions that can be controlled and analyzed separately.
Data Source
AI summary
Printed products can be efficiently sorted into non-defective ones and defective ones even when a discharge failure occurs during the printing operation. Two inspection patterns for detecting discharge failure are printed before and after a plurality of images. The inspection patterns are read to determine the type of discharge failure. Printed media are sorted based on whether it is determined that there is a continuous discharge failure, whether it is determined that there is an accidental discharge failure, or whether it is determined that the discharge is normal.