Piezoelectric MEMS Resonator Flexure Rotation

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Solution Overview

Problem

Piezoelectric rotational MEMS resonators face challenges with non-uniform charge distribution and high spring constants due to inflexible suspender attachment, leading to reduced signal-to-noise ratios, increased energy losses, and frequency instability, which hinder the development of efficient piezoelectric rotational resonators.

Innovation Solution

The use of flexures that allow the end of the suspender attached to the inertial mass to rotate, reducing bending moment and achieving uniform charge distribution, thereby improving the linearity and reducing spring constants, allowing for more effective piezoelectric transducer operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If inflexible suspender attachment is used, then structural stability is improved, but charge distribution uniformity deteriorates and spring constant increases

Engineering Contradiction:
Improvestructural stabilityVSAvoidcharge distribution uniformity
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent applies the dynamics principle by transforming the static, inflexible suspender attachment into a dynamic, flexible connection using a flexure mechanism. The flexure allows the suspender to rotate and adapt its configuration during operation, enabling uniform charge distribution across the piezoelectric transducer while maintaining structural stability through controlled flexibility rather than rigid fixation.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If inflexible suspender attachment is used, then structural stability is improved, but energy losses increase

Engineering Contradiction:
Improvestructural stabilityVSAvoidenergy losses
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent employs the flexible shells and thin films principle by introducing a flexure component that acts as a flexible connection between the suspender and the inertial mass. This flexure reduces bending moments and allows smooth rotational motion, thereby minimizing energy dissipation through friction and deformation while preserving structural integrity during oscillation cycles.

Inventive Principle:
Principle #30Flexible shells and thin films

3Stability of the object's composition

If inflexible suspender attachment is used, then structural stability is improved, but frequency stability deteriorates

Engineering Contradiction:
Improvestructural stabilityVSAvoidfrequency stability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The dynamics principle is applied through the flexure mechanism that enables the suspender to rotate and adjust its position dynamically during operation. This dynamic adaptation ensures uniform charge distribution and consistent mechanical coupling, leading to stable resonant frequency and improved frequency stability while maintaining overall structural stability through controlled flexibility.

Inventive Principle:
Principle #15Dynamics

4Manufacturing precision

If flexures are introduced to allow rotation, then charge distribution uniformity is improved, but device complexity increases

Engineering Contradiction:
Improvecharge distribution uniformityVSAvoiddevice complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies the flexible shells and thin films principle by using a flexure component that provides the necessary rotational freedom and uniform charge distribution. The flexure is designed as a simple, elegant mechanical element that achieves the desired functionality without introducing complex mechanisms, maintaining manufacturing feasibility while improving charge distribution uniformity across the piezoelectric transducer.

Inventive Principle:
Principle #30Flexible shells and thin films

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 approach enhances signal-to-noise ratios, increases the oscillation amplitude, and maintains frequency stability, facilitating smaller device sizes and improved performance in gyroscopes and clock oscillators.

Implementation Method 1

at least one coated suspender is attached from its second attachment point to the inertial mass with a flexure

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3407491B1Piezoelectric rotational MEMS resonator
Publication Date: 2021.10.06 MURATA MFG CO LTD
  • EP3407491B1 patent drawingFigure 1~2
  • EP3407491B1 patent drawingFigure 3
  • EP3407491B1 patent drawingFigure 4

AI summary

This disclosure reveals a resonator where at least one suspended inertial mass is driven into rotational oscillation by a piezoelectric drive transducer, or where the rotational motion of at least one suspended inertial mass is sensed by a piezoelectric sense transducer. The disclosure is based on the idea of attaching suspenders to the inertial mass with at least one flexure, which allows the end of the suspender which is attached to the inertial mass to rotate in relation to the inertial mass at this attachment point when the inertial mass is in motion. The resonator may be employed in a resonator system, a clock oscillator or a gyroscope.