Liquid Ejecting Head Tributary Flow Path Pressure Loss Uniformity
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Solution Overview
Problem
Existing liquid ejecting heads with multiple tributary flow paths face challenges in maintaining consistent pressure losses, flow velocities, and reducing path size due to varying cross-sectional areas and bifurcation points, leading to issues with air bubble discharge and connectability.
Innovation Solution
A liquid ejecting head design featuring a mainstream flow path with tributary portions that include vertical flow paths with changing cross-sectional areas, allowing for adjusted flow path resistances and reduced pressure losses, and a common outlet-port forming member to improve connectability and reduce the radial size of the flow path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cross-sectional area of the entire flow path is changed to adjust pressure losses, then pressure loss variation is reduced, but the flow path size increases and connectability problems arise
Solution Approach 1:
The patent applies local quality by changing the cross-sectional area at specific locations rather than throughout the entire flow path. The variable cross-sectional area is implemented only in the vertical flow paths at different distances from the liquid storage unit, while other portions maintain consistent dimensions. This localized modification achieves pressure loss uniformity without unnecessarily increasing overall flow path size.
Solution Approach 2:
The flow path is segmented into different portions with different cross-sectional area characteristics. The vertical flow paths are divided into sections based on their distance from the liquid storage unit, with each section having optimized cross-sectional area. This segmentation allows independent optimization of pressure characteristics for each tributary path without affecting the entire flow path system.
2Manufacturing precision
If the cross-sectional area of the entire flow path is changed to adjust pressure losses, then pressure loss variation is reduced, but connectability of flow paths becomes problematic
Solution Approach 1:
The invention maintains standard, connectable dimensions at the outlet ports of the vertical flow paths while applying variable cross-sectional area only in the intermediate sections. This ensures that the connectability interfaces remain consistent and compatible, while the internal flow path geometry is optimized for uniform pressure distribution.
3Object-generated harmful factors
If supply pressure is extremely increased to ensure air-bubble discharge in tributary flow paths with small flow velocity, then air bubble discharge improves, but pressure loss variation increases
Solution Approach 1:
The patent addresses air bubble discharge by optimizing the cross-sectional area in vertical flow paths based on their specific distance from the liquid storage unit. Tributary paths farther away receive increased cross-sectional area to compensate for lower flow velocity and ensure adequate air bubble discharge, while closer paths maintain smaller cross-sectional areas. This localized optimization achieves uniform pressure loss without requiring extreme supply pressure increases.
4Adaptability or versatility
If the number of bifurcation portions increases to serve more heads, then more heads can be supplied, but the flow path size increases
Solution Approach 1:
The patent efficiently accommodates multiple tributary portions by optimizing the vertical dimension of the flow path geometry. The variable cross-sectional area is implemented in the vertical flow paths, utilizing the vertical dimension to achieve flow control without expanding the horizontal footprint. This allows multiple heads to be served with minimal increase in overall flow path volume.
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 design achieves reduced variation in pressure losses and flow velocities, enhances air bubble discharge properties, and minimizes the size of the flow path while ensuring uniform supply pressures across tributary portions, improving the overall performance and connectivity of the liquid ejecting head.
Implementation Method 1
the cross-sectional area changes in the middle of the vertical flow path... the distances from the liquid ejection surface to positions at which the cross-sectional areas of the vertical flow paths change are different from each other
Data Source
AI summary
A flow-path member has a flow path to supply liquid to each head main body having nozzle openings through which liquid is ejected. The flow path of the flow-path member includes a mainstream portion and a plurality of tributary portions which branch off from the mainstream portion. Each of the plurality of tributary portions includes a vertical flow path which is connected, on an outlet port side, to a manifold portion of the head main body. Furthermore, in the vertical flow path, the cross-sectional area changes in the middle thereof. In addition, in the respective vertical flow paths, positions at which the cross-sectional areas change are different from each other.