Flow-path forming member with reduced cross-section for ink jet heads
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Solution Overview
Problem
Existing liquid ejecting heads face challenges in reducing pressure loss and improving air-bubble discharge properties, particularly in ink jet type recording heads where air bubbles tend to remain in the flow path, leading to increased pressure loss and inefficient ink distribution.
Innovation Solution
A flow-path forming member with a first flow path intersecting a vertical direction and a second flow path, featuring an intersection portion with a gradually reduced cross-sectional area, which increases flow velocity and prevents air bubbles from remaining, while adjusting pressure loss variations across different flow paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flow velocity is increased to allow air bubbles to flow downstream, then air-bubble discharge properties are improved, but pressure loss increases
Solution Approach 1:
The flow path includes a curved section that smoothly transitions between horizontal and vertical flow directions. This curved geometry reduces flow separation and turbulence compared to sharp corners, allowing air bubbles to be carried downstream by the curved flow pattern while minimizing energy loss from flow detachment and recirculation zones.
Solution Approach 2:
The cross-sectional area of the flow path is varied along its length, with the vertical section having a smaller cross-sectional area than the horizontal section. This area reduction increases flow velocity in the vertical section, enhancing air bubble transport capability while the gradual transition maintains laminar flow conditions to reduce pressure loss.
2Reliability
If cross-sectional area is reduced to increase flow velocity, then air bubble discharge is improved, but pressure loss increases
Solution Approach 1:
The flow path cross-sectional area is selectively reduced only in the vertical section where air bubble transport is most critical, while the horizontal section maintains a larger area for stable liquid flow. This localized area reduction targets the specific problem of air bubble accumulation without unnecessarily increasing pressure loss throughout the entire flow path.
3Reliability
If flow path is designed to discharge air bubbles, then air-bubble discharge properties are improved, but pressure loss characteristics become unbalanced across different flow paths
Solution Approach 1:
The cross-sectional area ratio between horizontal and vertical sections is optimized to balance air bubble discharge performance with pressure loss characteristics. By carefully selecting the area reduction ratio, the design achieves effective air bubble transport while minimizing excessive pressure loss and reducing variations in pressure loss across multiple flow paths in the ink jet head.
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 solution effectively reduces pressure loss and enhances air-bubble discharge properties by increasing flow velocity and preventing air bubbles from accumulating, resulting in improved performance and efficiency of the liquid ejecting head.
Implementation Method 1
the cross-sectional area of the first flow path is gradually reduced in a plane perpendicular to the intersection direction as the first flow path extends to the second flow path... the flow velocity in the intersection portion increases
Implementation Method 2
a pressure generation chamber communicating with a nozzle opening through which ink droplets are discharged is deformed by a pressure generation unit, such as a piezoelectric element
Data Source
AI summary
A first flow path through which liquid flows in an intersection direction intersecting a vertical direction and a second flow path which is connected to the first flow path and through which liquid flows downward in the vertical direction are provided. The first flow path includes an intersection portion which has a surface intersecting the intersection direction and which allows a cross-sectional area of the first flow path to be gradually reduced in a plane perpendicular to the intersection direction as the first flow path extends to the second flow path.