Piezoelectric Element Stacked Sheets 90-Degree Axis
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Solution Overview
Problem
Piezoelectric sheets made of polymers with chiral molecules tend to tear easily, especially when used in uniaxial or biaxial stretching, which limits their application in devices like speakers and actuators due to high stress and susceptibility to tearing.
Innovation Solution
A piezoelectric element comprising multiple stacked sheets with different stretching axes, where at least one sheet's axis forms an angle of 90 degrees with another, and an insulating layer is used to electrically isolate electrodes, enhancing the laminate's strength and allowing for increased electric field intensity without raising applied voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniaxial or biaxial stretching is applied to piezoelectric sheets to achieve high piezoelectricity, then piezoelectric constant is improved, but the sheets become prone to tearing due to high stress
Solution Approach 1:
The patent uses a composite structure consisting of multiple piezoelectric sheets stacked together with their stretching axes oriented in different directions (e.g., alternating between X-axis and Y-axis directions). This composite arrangement allows the sheets to share and distribute mechanical stress, preventing any single sheet from bearing excessive load that would cause tearing, while collectively maintaining high piezoelectric response.
Solution Approach 2:
The patent transitions from using single piezoelectric sheets to a multi-layer stacked structure where sheets are arranged in the thickness direction with alternating stretching axis orientations. This dimensional arrangement in the stacking direction allows stress to be distributed across multiple layers and directions, preventing concentration of stress in any single plane and thereby reducing tearing tendency.
2Strength
If multiple stacked sheets with different stretching axes are used, then resistance to tearing is improved, but device complexity increases
Solution Approach 1:
The patent systematically varies the stretching axis orientation parameter of adjacent sheets (e.g., alternating between 0° and 90° directions) to achieve stress distribution. This parameter variation follows a simple periodic pattern that is easy to implement during manufacturing, avoiding complex random orientations while still achieving the stress-distribution benefit.
Solution Approach 2:
The patent uses sheets with identical material composition and physical properties, differing only in the orientation of their stretching axes. This homogeneity in material properties simplifies manufacturing processes, as the same base material and processing steps can be used for all sheets, with only the stretching direction needing to be alternated.
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 significantly reduces the tendency to tear, increases the amplitude of deformation, and enhances the strain forces and displacement of the piezoelectric sheets, while maintaining transparency and stability, making them suitable for applications like transparent speakers.
Implementation Method 1
a piezoelectric sheet made of a polymer, which exhibits piezoelectricity when it is stretched
Data Source
AI summary
A piezoelectric element including a plurality of stacked piezoelectric sheets, wherein the stretching axis of a first piezoelectric sheet and the stretching axis of a second piezoelectric sheet of the plurality of piezoelectric sheets are oriented in different directions from each other. Preferably, the stretching axis of the first piezoelectric sheet and the stretching axis of the second piezoelectric sheet are intersected at an angle of 90 degrees.