Piezoelectric Actuator Electrode Segmentation for Strain Relief
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Solution Overview
Problem
Piezoelectric actuators in ink jet recording heads and other devices experience reduced displacement due to accumulated residual strain from repeated driving, affecting ejection characteristics such as ink droplet weight and flight speed.
Innovation Solution
A piezoelectric device with a stacked configuration of electrodes and a piezoelectric layer, where the second and third electrodes extend from the edge of the pressure chamber to the outside, and the first electrode is formed between them, allowing for deformation in both directions to reduce residual strain and maintain displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piezoelectric actuator is driven repeatedly to eject ink droplets, then the ejection function is maintained, but residual strain accumulates in the piezoelectric layer causing reduced displacement
Solution Approach 1:
The piezoelectric layer is divided into multiple regions with different electrode configurations. The first electrode is positioned only in the central region facing the pressure chamber, while the second and third electrodes extend beyond the pressure chamber boundaries. This segmentation allows different portions of the piezoelectric layer to serve different functions: the central region for ejection and the extended regions for strain relief.
Solution Approach 2:
The second and third electrodes act as intermediary elements that extend beyond the pressure chamber to provide a strain relief mechanism. These electrodes serve as a mediator between the piezoelectric layer and the external environment, allowing the layer to expand and contract without accumulating residual strain during repeated driving cycles.
2Device complexity
If the piezoelectric layer is constrained within the pressure chamber boundaries, then the structure is compact, but residual strain accumulates reducing actuator performance
Solution Approach 1:
The electrode configuration extends in the planar dimension beyond the pressure chamber boundaries. The second and third electrodes protrude laterally from the region facing the pressure chamber, utilizing the horizontal dimension to provide strain relief without increasing the vertical height or compromising the compact stacked structure of the piezoelectric actuator.
3Reliability
If the piezoelectric layer is allowed to deform freely, then residual strain is reduced, but the actuator size and complexity increase
Solution Approach 1:
The electrode configuration implements local quality by providing different electrode arrangements in different regions. The first electrode is concentrated in the central region for ejection, while the second and third electrodes extend to the periphery for strain relief. This localized differentiation optimizes both ejection performance and strain management without requiring complete redesign of the entire actuator structure.
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 configuration reduces residual strain in the piezoelectric layer, maintaining ejection characteristics and preventing deterioration in ink droplet weight and flight speed even with repeated driving.
Implementation Method 1
a piezoelectric actuator having a piezoelectric layer provided on the vibration plate. The piezoelectric actuator is driven to change the pressure of ink in the pressure chamber
Data Source
AI summary
A piezoelectric device includes a substrate on which a plurality of recesses are arranged in a first direction, a vibration plate, and a piezoelectric actuator having a first electrode, a second electrode and a third electrode, a fourth electrode, and a piezoelectric layer, in which a plurality of active portions are provided, the second electrode and the third electrode are provided from an edge of a region facing a recess to an outside of the recess, the first electrode is formed between the second electrode and the third electrode, and the fourth electrode configures a common electrode for the plurality of active portions.