Piezoelectric Sensor Shear Stress Detection
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Solution Overview
Problem
Existing piezoelectric sensors that detect bending require additional measuring devices and correction circuits, leading to reduced detection efficiency due to noise from the pyroelectric effect and complexity in measurement.
Innovation Solution
A piezoelectric sensor with a unique structural configuration, including a piezoelectric body with first and second detecting electrodes on one surface and a third electrode on the other, oriented such that the polarization axis is parallel to the lengthwise direction, allowing for distortion detection based on shear stress without the need for correction circuits, enhancing sensitivity and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bimorph structure with upper and lower piezoelectric layers is used to detect bending, then the sensor can measure distortion, but additional measuring devices and correction circuits are required which deteriorate detection efficiency
Solution Approach 1:
The patent extracts and eliminates the correction circuit component from the detection system. By using a single piezoelectric layer with specifically positioned electrodes instead of a bimorph structure, the need for complex correction circuits that cancel pyroelectric noise is removed, thereby improving detection efficiency while maintaining distortion detection capability
Solution Approach 2:
The patent segments the electrode configuration into three distinct electrodes (first, second, and third electrodes) positioned at specific locations on the piezoelectric layer. This segmentation allows selective measurement of stress components and enables distortion detection without requiring additional correction circuits, thus reducing device complexity
2Reliability
If a bimorph structure with correction circuit is used, then charge cancellation due to pyroelectric effect is achieved, but the measurement system becomes more complex
Solution Approach 1:
The patent implements a self-service approach where the three-electrode configuration on the single piezoelectric layer inherently provides noise rejection capability. The specific electrode positioning allows the system to self-differentiate between pyroelectric noise and actual stress signals, eliminating the need for external correction circuits while maintaining reliability
Solution Approach 2:
The patent replaces the electrical correction circuit system with a structural electrode configuration solution. Instead of using active electronic correction, the mechanical positioning of electrodes and the resulting electrical field distribution passively achieve noise rejection, thereby reducing device complexity
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 sensor effectively detects distortion with improved sensitivity and accuracy by eliminating the need for correction circuits and minimizing noise from the pyroelectric effect, while maintaining a reduced component count and improved structural strength.
Implementation Method 1
the distortion of the detection object is detected based on electric output corresponding to shear stress applied to the piezoelectric body
Data Source
AI summary
A piezoelectric sensor is fixed to a detection object and detects distortion of the detection object includes first and second principal surfaces, and extends in the lengthwise direction. The piezoelectric sensor includes a piezoelectric body whose polarization axis extends in a direction parallel or substantially parallel to the lengthwise direction, and first and second detecting electrodes that are provided on a surface of the piezoelectric body and that extend in a direction parallel or substantially parallel to the lengthwise direction. Distortion of the detection object is detected based on electric output corresponding to shear stress of the piezoelectric body.