Single-Crystal Disk Resonator for Low-Quadrature Gyroscopes

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Solution Overview

Problem

Piezoelectric transducers face limitations in converting mechanical energy to electrical energy due to low signal-to-noise ratio and quadrature errors in micromachined gyroscopes, which are exacerbated by non-ideal coupling between drive and sense modes.

Innovation Solution

A piezoelectric structure utilizing a single crystal with opposite magnitude piezoelectric coefficients d31 and d32, coupled with electrodes, that expands in one direction and contracts in another when an alternating electric field is applied, generating torque and displacement, thereby enhancing mechanical displacement and reducing quadrature errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional piezoelectric transducers are used, then electrical energy can be converted to mechanical energy, but the signal-to-noise ratio is low and quadrature errors occur due to non-ideal coupling between drive and sense modes

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidquadrature error

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent employs asymmetric piezoelectric coupling by utilizing different piezoelectric coefficients (d31 for drive mode, d32 for sense mode) in the single crystal resonator. This asymmetric coupling configuration enables strong coupling to the drive mode while providing immunity to quadrature errors, thereby resolving the contradiction between measurement precision and reliability in micromachined gyroscopes

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the piezoelectric coupling parameters by selecting specific crystal orientations and utilizing the unique properties of single crystal materials with opposite magnitude piezoelectric coefficients. This parameter change enables the resonator to achieve both high signal-to-noise ratio and immunity to quadrature errors simultaneously

Inventive Principle:

Principle #35Parameter changes

2Force

If piezoelectric transducers operate in conventional modes, then mechanical displacement can be generated, but the mechanical displacement is insufficient for high-performance applications

Engineering Contradiction:

Improvemechanical displacementVSAvoidcharge generated per unit mechanical energy

Core Design Contradiction:

ForceVSProductivity

Solution Approach 1:

The patent transitions from conventional in-plane vibration modes to out-of-plane vibration modes by utilizing the unique piezoelectric properties of single crystal resonators. This dimensional change enables significantly larger mechanical displacement while maintaining high charge generation efficiency, as the out-of-plane modes exploit the full piezoelectric potential of the single crystal structure

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 solution achieves significant mechanical displacement and improved signal-to-noise ratio by strongly coupling the drive mode and minimizing quadrature errors, leading to enhanced performance in piezoelectric transducers and gyroscopes.

Implementation Method 1

a single crystal having piezoelectric coefficients d31 and d32 of opposite magnitude, such that when an alternating electric field is applied in the Z direction, the piezoelectric structure expands in one of the X and Y directions and contracts in the other of the X and Y direction

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

when an alternating electric field is applied in the Z direction, the piezoelectric structure expands in one of the X and Y directions and contracts in the other of the X and Y direction, thereby generating torque resulting in displacement in the Z direction

Methodology Applied

Scientific EffectPiezoelectric coupling: Piezoelectric Effect

Data Source

PatentUS11496115B2In-plane and out-of-plane disk resonator

Publication Date: 2022.11.08 PURDUE RES FOUND

AI summary

A piezoelectric structure is disclosed which includes a single crystal having piezoelectric coefficients d31 and d32 of opposite magnitude, such that when an alternating electric field is applied in the Z direction, the piezoelectric structure expands in one of the X and Y directions and contracts in the other of the X and Y direction, a first electrode coupled to the single crystal, and a second electrode coupled to the single crystal, wherein the alternating electric field is input to the single crystal through the first and second electrodes.