Liquid Ejection Head Nozzle Drive Signal Grouping
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Solution Overview
Problem
Existing liquid ejection methods face challenges in maintaining uniform ejection rates across nozzles, leading to variations in thin film quality due to differences in nozzle usage frequencies and substrate patterns, which are difficult to compensate for with limited hardware configurations.
Innovation Solution
A method that calculates average or median ejection rates for each nozzle, classifies nozzles into groups based on these rates, and sets proper drive signal conditions for each group to ensure uniform liquid ejection, even when nozzles are used with different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drive signal is used for all nozzles, then the control system is simple, but the ejection rate varies among nozzles leading to non-uniform liquid placement
Solution Approach 1:
The patent segments the nozzles into multiple groups based on their ejection rate characteristics, and assigns different drive signal conditions to each group. This segmentation allows the system to address variation in ejection rates without requiring completely independent control for each nozzle, thus balancing complexity and precision.
Solution Approach 2:
The patent applies local quality by setting different drive signal conditions for different nozzle groups according to their specific ejection rate characteristics. Each nozzle group receives customized drive signal parameters (such as voltage level, pulse width) tailored to its performance, thereby achieving uniform ejection across all nozzles while maintaining manageable system complexity.
2Manufacturing precision
If drive signals are set up independently for each nozzle, then ejection uniformity is improved, but the hardware configuration and control requirements become excessively complex
Solution Approach 1:
The patent merges nozzles with similar ejection rate characteristics into the same group, assigning a common drive signal condition to each group. This merging approach reduces the number of distinct drive signal configurations needed, thereby simplifying hardware configuration and control requirements while still maintaining ejection uniformity across all nozzles.
Solution Approach 2:
The patent creates a universal classification system where nozzles are categorized into groups based on their ejection rate characteristics. Each group receives a standardized drive signal condition that can be applied universally to all nozzles within that group, reducing the overall complexity of the control system while achieving the goal of uniform ejection.
3Productivity
If nozzles are used with different frequencies due to substrate patterns, then coverage of the substrate is optimized, but variation in ejection rate increases
Solution Approach 1:
The patent performs preliminary classification of nozzles into groups based on their ejection rate characteristics before the actual ejection process. This preliminary action allows the system to pre-assign appropriate drive signal conditions to each nozzle group, ensuring that even when nozzles are used with different frequencies for substrate coverage, their ejection rates remain consistent through pre-configured compensation.
Data Source
AI summary
A method for setting up a condition for a drive signal in a liquid ejection head that includes a plurality of linearly-arranged nozzles and driving elements provided for each of the nozzles, includes: calculating an average value or a median value of ejection rates for each nozzle relating to a supply of the drive signal under a plurality of conditions; classifying the plurality of nozzles into a plurality of groups based on the average value or the median value of the ejection rates; calculating a proper condition for the drive signal corresponding to each group based on a statistical value of the ejection rate relating to the group; and selecting one proper condition among proper conditions corresponding to the groups so as to set the selected proper condition for each nozzle.