Piezoelectric Pressure Sensor Bridge Circuit for Linearity
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Solution Overview
Problem
Existing pressure sensors with piezoelectric elements face challenges in achieving high accuracy and minimizing higher-order nonlinear components in their output due to the distribution of stress on the diaphragm, which affects the measurement precision and sensitivity.
Innovation Solution
A pressure sensor design that includes a diaphragm with four piezoelectric element areas disposed in the maximum deflection area, where the first and second piezoelectric element areas are connected in series via an output terminal, and the third and fourth areas are connected via a grounding terminal, forming a full bridge circuit. This configuration ensures that stress from diaphragm distortion is evenly distributed across the piezoelectric elements, reducing higher-order nonlinear components and maximizing output voltage without altering the diaphragm's overall configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric elements are disposed in areas with high stress concentration, then measurement sensitivity is improved, but higher-order nonlinear components increase
Solution Approach 1:
The patent applies local quality by selectively positioning piezoelectric elements in specific regions of the diaphragm where the stress distribution characteristics optimize both sensitivity and linearity. Rather than uniform distribution, the elements are placed in areas with appropriate stress concentration while avoiding regions that generate excessive nonlinear components, thus achieving localized optimization of measurement quality.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the positional parameters of piezoelectric elements on the diaphragm surface. By varying the coordinates and distribution pattern of the piezoelectric elements, the system optimizes the balance between stress utilization (for sensitivity) and stress distribution uniformity (for linearity), thereby resolving the contradiction between sensitivity and nonlinear distortion.
2Power
If piezoelectric elements are concentrated in high-stress areas, then output voltage increases, but measurement accuracy deteriorates due to nonlinear components
Solution Approach 1:
The patent applies local quality by selectively positioning piezoelectric elements in specific regions of the diaphragm where the stress distribution characteristics optimize both sensitivity and linearity. Rather than uniform distribution, the elements are placed in areas with appropriate stress concentration while avoiding regions that generate excessive nonlinear components, thus achieving localized optimization of measurement quality.
Solution Approach 2:
The patent employs asymmetry in the strategic placement of piezoelectric elements to achieve balanced stress utilization. By using asymmetric positioning patterns rather than symmetric uniform distribution, the system maximizes output voltage from high-stress regions while compensating for nonlinear effects through carefully designed asymmetric element placement.
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 enhances the accuracy and sensitivity of pressure measurements by reducing higher-order nonlinear components, resulting in improved output voltage and measurement precision, as demonstrated by reduced deviations from first- and second-order approximations in the pressure sensor's output.
Implementation Method 1
a plurality of piezoelectric element areas which change in resistance according to distortion of the diaphragm
Data Source
AI summary
A pressure sensor includes a diaphragm on a silicon substrate and a plurality of piezoelectric element areas that change in resistance according the distortion of the diaphragm. The plurality of piezoelectric element areas of the pressure sensor include a first piezoelectric element area, a second piezoelectric element area, a third piezoelectric element area, and a fourth piezoelectric element area. The diaphragm has a maximum deflection area whose stress becomes 80% or more of a maximum stress when distorted by a predetermined pressure. The first piezoelectric element area, the second piezoelectric element area, the third piezoelectric element area, and the fourth piezoelectric element area are disposed in the maximum deflection area.