Liquid Ejection Head Channel Cross-Section for Bubble Removal
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Solution Overview
Problem
Lengthening the ejection orifice row in liquid ejection heads leads to increased stagnation of air bubbles at the outlet, causing ejection failures due to the enlarged angle and wall surface length of the flow path, which necessitates frequent suction operations and increased waste ink, thereby reducing the benefit of wider liquid ejection range.
Innovation Solution
The design includes a support member with a first and second flow path, where the channels are aligned in the arrangement direction of the ejection orifices, with at least one channel having a cross-section that increases from upstream to downstream, reducing the angle of the wall surface with respect to the flow direction, facilitating air bubble movement to the inlet and preventing stagnation at the outlet, thus reducing ejection failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the ejection orifice row is lengthened to eject liquid over a wider range, then the liquid ejection range is improved, but air bubbles stagnate more at the outlet end, causing ejection failures
Solution Approach 1:
The flow path is divided into multiple segments with different cross-sectional characteristics. The upstream portion has a smaller cross-section that decreases toward the outlet, while the downstream portion has a larger cross-section that increases toward the outlet. This segmentation allows different regions to perform different functions: the upstream segment promotes air bubble movement toward the inlet, while the downstream segment ensures adequate liquid flow supply to the lengthened ejection orifice row.
Solution Approach 2:
Different portions of the flow path are given different local qualities in terms of cross-sectional area. The upstream flow path has a smaller cross-sectional area with a specific angle configuration, while the downstream flow path has a larger cross-sectional area. This local differentiation optimizes each region for its specific function: air bubble removal upstream and liquid supply downstream.
2Quantity of substance
If the outlet of the flow path is enlarged in the arrangement direction to accommodate a longer supply port, then the liquid supply capacity is improved, but the wall surface length and angle increase, causing air bubble stagnation
Solution Approach 1:
The flow path cross-section is segmented into upstream and downstream portions with different area characteristics. The upstream portion maintains a smaller cross-section with a controlled angle to facilitate air bubble movement, while the downstream portion enlarges the cross-section to provide adequate liquid supply capacity to the extended ejection orifice row.
Solution Approach 2:
Instead of uniformly enlarging the outlet to increase liquid supply capacity (which causes air bubble stagnation), the invention inverts the approach by creating a flow path where the cross-sectional area varies along the flow direction. The upstream smaller cross-section promotes air bubble movement against the flow, while the downstream larger cross-section ensures sufficient liquid supply.
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
This configuration effectively suppresses ejection failures by allowing air bubbles to move easily to the inlet without stagnating at the outlet, reducing the frequency of suction operations, minimizing waste ink, and maintaining efficient liquid supply to the ejection orifices, even when the ejection orifice row is lengthened, thereby achieving a wider ejection range without increased manufacturing costs.
Implementation Method 1
a cross section that intersects with a flow direction of a liquid increases from an upstream side to a downstream side... reducing the angle of the wall surface with respect to the flow direction... facilitating air bubble movement to the inlet
Data Source
AI summary
A liquid ejection head includes an element substrate and a support member. The element substrate includes an ejection orifice row, and a supply port. The support member includes a first flow path for supplying a liquid from a liquid supply source to the supply port. The first flow path includes a plurality of channels for supplying liquid to the supply port. At least one of the plurality of channels has a shape in which a cross section that intersects with a flow direction Y of the liquid increases from an upstream side to a downstream side with respect to the direction in which the liquid is supplied.