Piezoelectric Substrate Electrode Protrusion for Adhesive Isolation
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Solution Overview
Problem
The existing liquid discharge heads face issues with adhesive influence on piezoelectric actuator substrates, leading to variations in displacement characteristics and discharge performance, which can result in inconsistent liquid discharge.
Innovation Solution
A piezoelectric substrate design where the outer peripheral part of the second electrode prevents adhesive reach to the first electrode, with electrical connection made by a protrusion, reducing susceptibility to adhesive influence and allowing for downsizing of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the piezoelectric actuator substrate is connected to the flow channel member with adhesive, then the connection is established, but the adhesive may reach the displacement element and cause variations in displacement characteristics and discharge performance
Solution Approach 1:
The patent introduces an intermediary structure (protrusion from the second electrode) between the adhesive connection zone and the first electrode/displacement element. This protrusion acts as a physical barrier that prevents adhesive from reaching the sensitive displacement element while still allowing electrical connection through the protrusion itself, thus resolving the contradiction between establishing adhesive connection and preventing adhesive contamination.
Solution Approach 2:
The second electrode is segmented into a body portion and a protrusion portion. The protrusion portion extends toward the first electrode to establish electrical connection while the main body of the second electrode maintains distance from the displacement element. This segmentation allows the electrode to serve multiple functions: electrical conduction, adhesive anchoring, and protective barrier formation.
2Object-affected harmful factors
If the piezoelectric substrate is made larger to accommodate electrodes and prevent adhesive reach, then adhesive influence is reduced, but the substrate size increases
Solution Approach 1:
Instead of increasing the substrate area (2D expansion) to prevent adhesive reach, the patent uses the protrusion extending in the vertical dimension (Z-axis) toward the first electrode. This three-dimensional approach allows the second electrode to reach the first electrode for electrical connection while maintaining horizontal distance from the displacement element, thus preventing adhesive influence without increasing substrate footprint.
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
This design enhances the stability of the piezoelectric substrate, minimizing the impact of adhesive on discharge characteristics and enabling more precise and consistent liquid discharge, facilitating improved performance and reduced substrate size.
Implementation Method 1
Upon application of a voltage to between the first electrode and the second electrode, the piezoelectric ceramic layer is deformed to pressurize a liquid in the pressurizing chambers
Data Source
Figure 1(a)~1(b)
Figure 2~2a
Figure 3
AI summary
The present invention aims at providing a piezoelectric substrate that is less susceptible to the influence of adhesive after being subjected to connection, as well as an assembly, a liquid discharge head, and a recording device, each of which uses the piezoelectric substrate. The piezoelectric substrate of the present invention is a flat plate shaped piezoelectric substrate 21 including a piezoelectric ceramic layer 21b, a plurality of first electrodes 25, a second electrode 28, and a third electrode. The second electrode 28 includes an outer peripheral part 28a disposed so as to surround the entirety of the first electrodes 25, and a protrusion 28b extending from the outer peripheral part 28a toward the inside of the outer peripheral part 28a when the piezoelectric substrate 21 is viewed from above. The second electrode 28 and the third electrode 24 are electrically connected to each other at the protrusion 28b. The outer peripheral part is used for an electrical connection with the outside.