Piezoelectric Element with Segmented Polarizing Region
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Solution Overview
Problem
The variation in displacement of piezoelectric elements is caused by their shape, which is influenced by the firing process of ceramic materials, leading to inconsistent distortion and bending, resulting in varied displacement outcomes.
Innovation Solution
A piezoelectric element design with a polarizing region on one main surface and a non-polarizing region on the opposing surface, where the polarizing region is thicker than the non-polarizing region, controlling the shape by bending and minimizing displacement variation, and a piezoelectric actuator with a supporting member using adhesive resin to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a piezoelectric element is formed through a firing process of piezoelectric ceramic material, then the piezoelectric element can be manufactured, but the piezoelectric element may be distorted or bent with variation between elements
Solution Approach 1:
The piezoelectric body is divided into two distinct regions: a polarizing region and a non-polarizing region. This segmentation allows each region to have different thicknesses and functional properties, with the polarizing region being thicker to accommodate distortion while the non-polarizing region maintains shape precision, thereby resolving the contradiction between manufacturability and shape uniformity.
Solution Approach 2:
Different regions of the piezoelectric body are given different local qualities: the polarizing region has greater thickness and contains distortion from the firing process, while the non-polarizing region has controlled thickness and maintains uniform shape. This local differentiation allows the element to be manufactured through firing while achieving consistent displacement characteristics.
2Manufacturing precision
If the piezoelectric element has a uniform shape, then displacement can be controlled consistently, but the firing process causes distortion and bending that varies between elements
Solution Approach 1:
The distortion and bending caused by the firing process, which would normally be harmful to shape uniformity, are converted into a benefit by intentionally designing the polarizing region to be thicker and contain this distortion. This allows the firing process to proceed easily while the resulting distortion is localized and controlled, ultimately achieving consistent displacement across elements.
Solution Approach 2:
The thickness parameter is changed between different regions of the piezoelectric body. The polarizing region is designed with greater thickness to accommodate firing-induced distortion, while the non-polarizing region maintains a controlled thickness for shape precision. This parameter variation allows both easy manufacturing through firing and consistent displacement control.
3Manufacturing precision
If the polarizing region is thicker than the non-polarizing region, then the piezoelectric element has a bent shape that suppresses displacement variation, but the element thickness is increased
Solution Approach 1:
The piezoelectric body is segmented into regions with different thicknesses, allowing the polarizing region to be thicker for distortion accommodation while the overall element thickness is optimized for the specific application. This segmentation enables displacement uniformity without requiring uniform increase in overall thickness.
Solution Approach 2:
The thickness is optimized locally rather than uniformly throughout the element. The polarizing region has greater thickness where distortion occurs, while other regions maintain appropriate thickness for functionality. This local quality approach achieves displacement uniformity without unnecessarily increasing the overall element thickness.
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 design achieves consistent displacement suppression, ensuring uniformity in piezoelectric element shape and displacement, improving the actuator's performance by maintaining a bent shape and increasing the adhesive area between the external electrode and the supporting member.
Implementation Method 1
a piezoelectric body 41, an external electrode 42 disposed on a first main surface 41a of the piezoelectric body 41, an internal electrode 44 disposed in the piezoelectric body 41 to oppose the external electrode 42
Data Source
AI summary
A piezoelectric element includes a piezoelectric body, an external electrode, and an internal electrode. The piezoelectric body includes first and second main surfaces opposing each other. The external electrode is disposed on the first main surface and has a first polarity. The internal electrode is disposed in the piezoelectric body to oppose the external electrode in a direction in which the first main surface and the second main surface oppose each other and has a second polarity different from the first polarity. A region from the internal electrode to the external electrode in the piezoelectric body is a polarizing region, and a region from the internal electrode to the second main surface in the piezoelectric body is a non-polarizing region.