Liquid Ejection Head Electroosmotic Flow Circulation
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Solution Overview
Problem
In liquid ejection heads, the evaporation of volatile components from the ejection orifice leads to liquid thickening, increasing viscosity and causing ejection failures, especially when the pause time is long, and existing solutions require large arrangement spaces, making it difficult to arrange ejection orifices densely.
Innovation Solution
A liquid ejection head design featuring an ejection orifice array with energy-generating elements, through ports, and electrodes that generate an electroosmotic flow to reduce liquid thickening and allow for high-density orifice arrangement by creating a linear liquid flow path with alternating current electroosmotic flow, preventing ink concentration and maintaining fluidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential pressure system or conventional liquid circulation method is used, then liquid can be circulated in the head, but the liquid flow path becomes long and requires large arrangement space
Solution Approach 1:
The patent transitions from conventional long linear flow paths to a compact three-dimensional arrangement where multiple flow paths are stacked vertically. The liquid supply ports and discharge ports are positioned at different heights, creating vertical flow paths that significantly reduce the horizontal arrangement space while maintaining effective liquid circulation throughout the ejection head.
Solution Approach 2:
The patent implements a nested structure where multiple liquid flow paths are arranged in overlapping vertical layers. The liquid supply ports and discharge ports are positioned to create interconnected flow paths that nest within each other spatially, allowing multiple circulation paths to occupy minimal horizontal space while maintaining functional independence.
2Reliability
If the liquid flow path is lengthened to improve circulation, then liquid can be refreshed, but the arrangement space increases and ejection orifices cannot be arranged densely
Solution Approach 1:
The patent utilizes vertical stacking of flow paths to reduce horizontal space requirements. By arranging liquid supply ports and discharge ports at different vertical levels with short horizontal distances, the system achieves effective liquid refreshment while maintaining high ejection orifice density in the horizontal plane.
Solution Approach 2:
The patent divides the liquid circulation system into multiple independent vertical flow path segments, each with its own supply and discharge ports. This segmentation allows parallel liquid refreshment across multiple zones simultaneously, achieving comprehensive liquid renewal without requiring a single long flow path that would reduce orifice density.
3Duration of action of moving object
If pause time after ejection is extended, then ejection cycle can be completed, but liquid thickening becomes remarkable and ejection failure occurs
Solution Approach 1:
The patent implements preliminary liquid circulation that continuously moves liquid through the flow paths during idle periods. The liquid supply ports and discharge ports maintain a persistent flow that prevents liquid stagnation and thickening even when ejection cycles are paused, ensuring the liquid remains in an ejectable state regardless of pause duration.
Solution Approach 2:
The patent maintains continuous liquid circulation through the vertically stacked flow paths during both active ejection and pause periods. The electroosmotic flow mechanism ensures uninterrupted liquid movement that continuously refreshes the liquid at ejection orifices, preventing thickening and maintaining ejection reliability throughout extended pause times.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The electroosmotic flow effectively reduces ink thickening, enabling the arrangement of ejection orifices in a high-density configuration, improving ejection accuracy and reducing the size of the recording element while maintaining ink freshness and preventing color unevenness.
Implementation Method 1
electrodes arranged in each of the plurality of liquid flow paths, and for generating an electroosmotic flow in the liquid
Data Source
AI summary
A liquid ejection head is provided with an ejection orifice array having multiple ejection orifices in order to eject a liquid; multiple energy-generating elements for generating energy in order to eject the liquid; a substrate provided with the energy-generating elements; a through-port array having multiple through-ports penetrating the substrate; multiple linear liquid flow paths positioned between the through-port array and the ejection orifice array and connected to respective ejection orifices of the ejection orifice array and respective through-ports of the through-port array; and first and second electrodes arranged in each of the multiple liquid flow paths for generating an electroosmotic flow in the liquid.