Piezoelectric Actuator Electrode Segmentation for Stress Balancing
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Solution Overview
Problem
Existing piezoelectric actuators in inkjet heads face challenges in achieving precise control over liquid droplet discharge due to unintended stress and strain, leading to inaccuracies in bending deformation and displacement of piezoelectric elements.
Innovation Solution
The proposed piezoelectric actuator design includes a common electrode and individual electrodes with insulating layers, where the common electrode is positioned near the neutral plane, and the individual electrodes are arranged to overlap and connect electrically, reducing stress and strain by balancing expansion and contraction across the actuator's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a piezoelectric actuator uses a simple electrode structure with one common electrode and one individual electrode per piezoelectric element, then the device complexity is reduced and manufacturing is easier, but unintended stress and strain occur leading to inaccurate bending deformation and displacement
Solution Approach 1:
The electrode structure is segmented into multiple components: a common electrode, individual electrodes for each piezoelectric element, and return electrodes. This segmentation allows independent control and stress balancing for each piezoelectric element, eliminating unintended stress and strain while maintaining manufacturing feasibility through systematic construction
Solution Approach 2:
The patent applies different electrode configurations to different regions of the piezoelectric actuator. Each piezoelectric element has its own individual electrodes and return electrodes positioned specifically to balance stress and strain locally, ensuring accurate bending deformation without the unintended stress that plagues simpler designs
2Device complexity
If the piezoelectric actuator uses asymmetric electrode arrangement, then the structure is simpler to manufacture, but stress and strain are not balanced leading to inaccurate displacement control
Solution Approach 1:
The patent employs asymmetric electrode arrangement where individual electrodes and return electrodes are positioned at different locations relative to each piezoelectric element. This asymmetric configuration is specifically designed to balance stress and strain distribution, achieving reliable and accurate displacement control while maintaining reasonable device complexity
Solution Approach 2:
The return electrodes function as counterweights that balance the stress and strain generated by the individual electrodes. By positioning return electrodes opposite to individual electrodes and applying appropriate potentials, the system counteracts unintended stress and strain, ensuring reliable bending deformation and displacement control
3Ease of manufacture
If the common electrode is positioned far from the neutral plane, then the structural design is simpler, but the bending deformation accuracy decreases due to increased unintended stress and strain
Solution Approach 1:
The patent positions the common electrode near the neutral plane and establishes equipotential regions through the return electrodes. This configuration minimizes stress and strain variations across the piezoelectric elements, ensuring accurate bending deformation and displacement measurement while maintaining straightforward structural design
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 accuracy of liquid droplet discharge by stabilizing pressure in pressurizing chambers and reducing unintended bending, resulting in more precise control over droplet formation and placement.
Implementation Method 1
portions of the piezoelectric layer that are provided between the common electrode and the individual electrodes expand or contract in directions along the piezoelectric layer
Data Source
AI summary
A piezoelectric actuator includes a common electrode on a piezoelectric layer at a first side adjacent to a first surface and extends over a plurality of piezoelectric elements. A plurality of first individual electrodes is on the piezoelectric layer at a second side adjacent to a second surface. Each of the plurality of first individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and are not electrically connected together. A first insulating layer is on the common electrode at the first side and extends over the plurality of piezoelectric elements. A plurality of second individual electrodes is on the first insulating layer at the first side. Each of the plurality of second individual electrodes is at a piezoelectric element of the plurality of piezoelectric elements, and overlap centers of the plurality of first individual electrodes. The plurality of second individual electrodes are electrically connected together.