Liquid Ejection Head Adhesive Placement for Protective Member
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Solution Overview
Problem
Existing liquid ejection heads face issues with protective members flaking off due to adhesive failure or stress from differing coefficients of linear expansion between materials, leading to potential damage from printed media floating during continuous printing.
Innovation Solution
A liquid ejection head design featuring a protective member with openings corresponding to ejection orifice arrays, arranged adjacent to the ejection surface via an adhesive, which reduces the risk of flaking and enhances adhesion strength by strategic adhesive application between ejection orifice arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective member is bonded to the ejection surface using adhesive, then the protective member prevents damage from printed media contact, but the protective member may flake off due to adhesive failure or stress from coefficient of linear expansion differences
Solution Approach 1:
The adhesive is applied selectively in specific regions between the first and second ejection orifice arrays, rather than uniformly across the entire ejection surface. This localized adhesive application concentrates bonding strength at critical areas while reducing overall adhesive volume and potential failure points, resolving the contradiction between protective function and adhesion stability.
Solution Approach 2:
The protective member is constructed using composite material structure with a base layer and a surface layer having different properties. The base layer provides structural strength and adhesion to the ejection surface, while the surface layer offers protective functionality. This composite structure reduces stress concentration and mitigates the effect of coefficient of linear expansion differences, preventing flaking while maintaining protective function.
2Reliability
If the protective member is made of rigid material to prevent damage, then the protective function is enhanced, but the stress from coefficient of linear expansion difference causes flaking
Solution Approach 1:
The protective member uses a composite structure with a base layer providing rigidity for protective function and a surface layer with compatible thermal expansion properties. This composite material design reduces thermal stress accumulation at the interface, preventing flaking while maintaining the necessary protective rigidity.
Solution Approach 2:
The protective member's material parameters are optimized by selecting materials with coefficients of linear expansion that match or are compatible with the ejection surface material. This parameter matching reduces thermal stress differential, allowing the protective member to maintain its rigid protective function without flaking due to thermal expansion mismatch.
3Strength
If adhesive is applied in large amount to ensure strong bonding, then adhesion strength is improved, but the risk of flaking increases due to adhesive failure
Solution Approach 1:
Instead of applying adhesive uniformly across the entire ejection surface, the adhesive is concentrated in specific regions between the first and second ejection orifice arrays. This localized application creates stronger bonding at critical areas where stress concentration occurs, while reducing the total adhesive volume and potential failure points, thereby improving both adhesion strength and bonding reliability.
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 prevents damage from printed media contact and maintains the integrity of the liquid ejection head by ensuring strong adhesion between the protective member and the ejection surface, reducing the likelihood of flaking and improving the reliability of continuous printing operations.
Implementation Method 1
a protective member provided with a first opening corresponding to the first ejection orifice array and a second opening corresponding to the second ejection orifice array, wherein the protective member is arranged adjacent to the ejection surface of the printing element substrate via an adhesive arranged between the first ejection orifice array and the second ejection orifice array
Data Source
AI summary
A liquid ejection head according to the present disclosure includes: a printing element substrate including an ejection surface provided with a first ejection orifice array in which an ejection orifice configured to be capable of ejecting a liquid is arranged in plurality in an array direction and a second ejection orifice array arranged in a direction intersecting with the array direction and the first ejection orifice array; and a protective member provided with a first opening corresponding to the first ejection orifice array and a second opening corresponding to the second ejection orifice array, wherein the protective member is arranged adjacent to the ejection surface of the printing element substrate via an adhesive arranged between the first ejection orifice array and the second ejection orifice array.