Meandering Vibrating Beam Electrode Extraction for Stress Relief
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Solution Overview
Problem
Conventional meandering-shape piezoelectric actuators face stress migration and disconnection issues due to large stresses applied at the midpoint and curvature changing points of the vibrating beam, leading to inefficient displacement and potential electrode disconnection.
Innovation Solution
The design incorporates non-existence regions for the upper electrode at specific points on the vibrating beam, such as midpoints and curvature changing points, and alternates the placement of piezoelectric films to reduce torsional and bending stresses, thereby preventing stress migration and maintaining electrode integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the piezoelectric actuator is applied to the entire vibrating beam including midpoint and curvature changing points, then the displacement efficiency is improved, but stress migration and electrode disconnection occur due to large stresses at these critical points
Solution Approach 1:
The patent extracts the piezoelectric actuator from the critical regions (midpoint and curvature changing points) where high stress occurs. By removing the piezoelectric film and upper electrode from these specific locations while maintaining them in other regions, the design prevents stress migration and electrode disconnection while preserving displacement efficiency in the less-stressed areas.
Solution Approach 2:
The patent applies local quality by creating non-uniform distribution of piezoelectric actuators along the vibrating beam. Different regions have different configurations: some regions have complete piezoelectric actuators, while critical regions have removed piezoelectric films or electrodes. This localized differentiation optimizes both displacement efficiency and electrode integrity by matching the actuator presence to the stress distribution pattern.
2Strength
If the piezoelectric film is provided continuously across the vibrating beam, then the structural integrity is improved, but stress concentration and electrode disconnection occur at midpoint and curvature changing points
Solution Approach 1:
The patent removes the piezoelectric film from critical stress regions (midpoint and curvature changing points) to eliminate the source of stress concentration. This extraction prevents the harmful effect of stress buildup while maintaining the structural integrity of the vibrating beam through the remaining piezoelectric actuators in less-stressed regions.
Solution Approach 2:
The patent implements local quality by creating spatially varying piezoelectric film distribution. The film is present in regions where it provides beneficial actuation without causing harmful stress concentration, and absent from regions where it would create stress problems. This localized approach optimizes the balance between structural integrity and stress management.
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 enhances the displacement efficiency of the vibrating element while preventing electrode disconnection, allowing for larger displacements without stress-induced failures, suitable for applications like optical reflection elements.
Implementation Method 1
a piezoelectric film 20, which is provided on the lower electrode 19
Data Source
AI summary
A vibrating element having a meandering shape includes a vibrating beam and a piezoelectric actuator provided on the vibrating beam. The vibrating beam has a meandering-shape substantially formed into the plurality of continuous turned-down shapes. The vibrating beam includes the plurality of turned-down units and the plurality of coupling units coupled to the turned-down units, and the coupling units and the turned-down units are alternately disposed. The piezoelectric actuator includes a lower electrode provided on the vibrating beam, a piezoelectric film provided on the lower electrode, and an upper electrode provided on the piezoelectric film. A non-existence region where the piezoelectric film does not exist is provided in at least one of a neighborhood of a midpoint of an inner circumference of each of the turned-down units and a neighborhood of a curvature changing point in which a curvature of the inner circumference of each of the turned-down shapes changes.