Liquid Ejection Head Groove Design for Thermal Stress Relief
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Solution Overview
Problem
Existing liquid ejection heads face issues with thermal stress between the substrate and ejection port plate due to differing linear expansion coefficients, leading to peeling, and foreign objects adhering to the nozzle surface causing clogging and faulty ejections, as seen in known side shooter type liquid ejection heads.
Innovation Solution
A liquid ejection head design featuring an ejection port plate with a groove surrounding the ejection ports, having an inner lateral surface with alternate projections and recesses forming saw-edged ridges and furrows for corrugation, and an outer lateral surface that is flat, which reduces thermal stress and foreign object adhesion, while a wiping member ensures efficient removal of foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ejection port plate is made with a uniform thickness, then the manufacturing precision is improved, but the thermal stress between the substrate and ejection port plate increases causing peeling
Solution Approach 1:
The ejection port plate is designed with non-uniform thickness, where the thickness varies in different regions. Specifically, the thickness is smaller in regions corresponding to ejection ports and larger in other regions. This local variation in thickness allows different parts of the plate to expand and contract at different rates during thermal cycles, reducing thermal stress concentration and preventing peeling from the substrate while maintaining manufacturing feasibility.
2Reliability
If the groove has corrugated side wall surfaces with saw edged ridges and furrows, then the thermal stress is alleviated, but foreign objects are caught between the surfaces making removal difficult
Solution Approach 1:
The groove is designed with different surface characteristics in different regions. The inner lateral surface has corrugated structures with saw-edged ridges and furrows to alleviate thermal stress, while the outer lateral surface is made flat to prevent foreign object accumulation. This local differentiation of surface quality allows the groove to simultaneously provide thermal stress relief and facilitate easy cleaning by wiping members.
3Object-affected harmful factors
If the outer lateral surface of the groove is formed flat, then foreign object adhesion is reduced, but the thermal stress relief capability may be compromised
Solution Approach 1:
The groove structure is segmented into different functional regions: the inner lateral surface with corrugated patterns for thermal stress relief, the outer lateral surface with flat configuration for foreign object resistance, and the bottom surface with specific curvature for fluid flow optimization. This segmentation allows each region to be optimized for its specific function without compromising the others, achieving both thermal stress alleviation and foreign object removal efficiency.
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 effectively alleviates thermal stress, prevents peeling of the ejection port plate, and ensures high foreign object removal efficiency, maintaining excellent recording performance by minimizing ink ball formation and preventing color mixing.
Implementation Method 1
the groove surrounds the region where the ejection ports are formed and has an inner lateral surface that is arranged adjacent to that region and has a plurality of projections and recesses arranged alternately and continuously (for corrugation) so as to produce saw edged ridges and furrows
Implementation Method 2
a plurality of ejection energy generating elements arranged in rows to generate energy necessary for ejecting liquid
Data Source
AI summary
A liquid ejection head includes a substrate that carries thereon a plurality of ejection energy generating elements arranged in rows to generate energy necessary for ejecting liquid and an ejection port plate that is laid on the substrate and has a plurality of ejection ports formed therein and arranged vis-a-vis the respective ejection energy generating elements. The ejection port plate has a groove, or an oblong recess, formed on the surface thereof where the plurality of ejection ports are formed such that the groove surrounds the region where the ejection ports are formed and has a corrugated inner lateral surface and a flat outer lateral surface arranged oppositely relative to the inner lateral surface.