Piezoelectric Element With Inactive Region And Through Hole Conductor
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Solution Overview
Problem
Existing piezoelectric actuators face limitations in maximizing displacement due to uneven binding forces and mechanical strength issues, particularly in HDD suspension systems, where the difference in binding forces between the active and inactive regions of the piezoelectric element leads to suppressed deformation and reduced displacement transmission.
Innovation Solution
The piezoelectric element design includes a piezoelectric body with active and inactive regions, where the first main surface is actively displaced, and the second main surface is supported with a higher binding force, utilizing a first through hole conductor for enhanced mechanical strength at the end portion, and optional additional electrodes and conductors to improve conductivity and reduce conduction failures during firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the first main surface side is supported by a supporting member with a larger binding force, then the mechanical strength is improved, but the bending deformation is suppressed and the displacement amount is reduced
Solution Approach 1:
The patent applies local quality by creating an inactive region at the second main surface side of the piezoelectric body where no electric field is applied. This inactive region has different mechanical properties (higher rigidity) compared to the active region, allowing the supported surface to maintain mechanical strength while the free surface can undergo larger displacement. The inactive region acts as a rigid support layer that prevents excessive bending while the active region generates the driving displacement.
2Productivity
If the piezoelectric element is designed with active and inactive regions, then the displacement transmission is improved, but the device complexity increases
Solution Approach 1:
The patent segments the piezoelectric body into two distinct regions: an active region where electric field is applied and generates displacement, and an inactive region where no electric field is applied and provides mechanical support. This segmentation allows each region to perform its specific function optimally - the active region maximizes displacement generation while the inactive region provides structural stability and improves displacement transmission to the supporting member.
3Length of moving object
If the interval between the third electrode and the first main surface is increased, then the displacement amount is improved, but the mechanical strength at the end portion is reduced
Solution Approach 1:
The patent uses a composite structure at the end portion by placing a through-hole conductor (made of rigid material such as metal) within the piezoelectric body. This through-hole conductor reinforces the end portion, providing mechanical strength to compensate for the reduced support when the third electrode is positioned closer to the first main surface. The composite structure combines the piezoelectric material with the rigid conductor to achieve both displacement optimization and mechanical reinforcement.
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 effectively suppresses bending deformations caused by binding force differences, allowing for increased displacement transmission to the supporting member, thereby enhancing the displacement amount and mechanical strength, while minimizing conduction failures.
Implementation Method 1
a piezoelectric body 41, a first electrode 42, a second electrode 43, a third electrode 44... The piezoelectric body includes first and second main surfaces 41a and 41b having rectangular shapes and opposing each other... The active region includes a region from the first electrode to the third electrode
Data Source
AI summary
A piezoelectric element includes a piezoelectric body, a first electrode, a second electrode, a third electrode, and a first through hole conductor. The piezoelectric body includes first and second main surfaces opposing each other, and first and second end surfaces opposing each other. The first electrode is disposed on the first main surface. The second electrode is disposed apart from the first electrode on the first main surface. The third electrode is disposed in the piezoelectric body to oppose the first electrode. The first through hole conductor is connected to the second and third electrodes. The piezoelectric body includes an active region and an inactive region. The active region includes a region from the first electrode to the third electrode. The inactive region includes a region from the third electrode to the second main surface.