Liquid Ejection Head Adhesion Gradient for Deformation Resistance
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Solution Overview
Problem
The existing liquid ejection heads, as disclosed in Japanese Patent Laid-Open No. 2020-131627, are prone to bonding failure due to stress propagation from a deforming support member, which can lead to peeling of the first substrate from the second substrate.
Innovation Solution
The liquid ejection head incorporates a design where the area joining the support member and the first substrate has distinct regions with varying adhesion strengths, including a high-adhesion area and a low-adhesion area, to mitigate stress propagation and improve deformation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive agent is applied between the nozzle board and the cover member to suppress liquid invasion, then liquid resistance is improved, but stress propagation from support member deformation causes bonding failure
Solution Approach 1:
The patent applies adhesive agent selectively in specific regions rather than uniformly across the entire bonding surface. The adhesive is applied in the liquid ejection direction along the bonding surface between the nozzle board and cover member, creating regions of different adhesion strength. This local differentiation allows the bonding structure to resist liquid invasion in critical areas while accommodating stress from support member deformation in other areas, thus resolving the contradiction between liquid resistance and bonding strength.
2Stability of the object's composition
If the support member is rigidly bonded to the first substrate, then structural stability is improved, but stress from deformation propagates to cause peeling between substrates
Solution Approach 1:
The patent creates a gradient adhesion structure where the adhesive agent is applied with varying coverage and strength in different regions of the bonding surface. In regions where liquid invasion needs to be blocked, strong adhesion is provided. In regions where stress relief is needed, the adhesive application is reduced or omitted, allowing the structure to flex and absorb deformation stress. This local quality differentiation enables the bonding structure to simultaneously achieve structural stability and deformation resistance.
Solution Approach 2:
The bonding surface is segmented into multiple regions with different adhesion characteristics. Rather than a uniform bonding interface, the adhesive agent is applied in discrete patterns or gradients along the liquid ejection direction. This segmentation allows different portions of the bonding interface to perform different functions: some regions provide strong mechanical coupling for structural stability, while other regions provide stress relief pathways for deformation resistance.
Data Source
AI summary
To provide a liquid ejection head whose resistance to the deformation of a support member has been improved. The liquid ejection head comprises: a first substrate having a first surface in which an ejection port configured to eject liquid is provided; a support member joined to the first surface of the first substrate and provided with an opening surrounding an area in which the ejection port in the first substrate is provided; and a second substrate joined to a second surface on the opposite side of the first surface of the first substrate. An area in which the support member and the first substrate are joined includes a first area in which adhesion strength between the support member and the first substrate is relatively high and a second area in which adhesion strength between the support member and the first substrate is relatively low.