Angular Velocity Sensor Crosstalk Noise Reduction

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Solution Overview

Problem

Existing angular velocity sensors suffer from crosstalk noise due to the proximity of drive and monitor electrodes, which deteriorates monitoring accuracy.

Innovation Solution

The design includes a substrate with a movable body connected by a connection portion, allowing the movable drive electrode and detection electrode to vibrate while keeping the fixed monitor electrodes far from the drive electrodes, and utilizing differential operation between multiple fixed monitor electrodes to cancel noise and enhance accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the drive electrode and monitor electrode are disposed adjacent to each other, then the device complexity is reduced, but crosstalk noise occurs on the monitor electrode and monitoring accuracy deteriorates

Engineering Contradiction:

Improveelectrode arrangementVSAvoidmonitoring accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The harmful effect of crosstalk noise from the drive electrode is extracted and isolated by spatially separating the monitor electrode from the drive electrode. The monitor electrode is positioned on the opposite side of the movable body relative to the drive electrode, effectively removing the noise source from the monitoring zone and resolving the contradiction between simple arrangement and accurate monitoring.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If the fixed monitor electrode is disposed far from the fixed drive electrode, then crosstalk noise is reduced and monitoring accuracy is improved, but the device structure becomes more complex

Engineering Contradiction:

Improvemonitoring accuracyVSAvoidelectrode configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of increasing lateral distance between electrodes, the patent utilizes the vertical dimension by positioning the monitor electrode on the opposite side of the movable body from the drive electrode. This dimensional approach achieves noise reduction while maintaining a compact overall structure, resolving the contradiction between accuracy improvement and structural complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Measurement precision

If differential operation is performed between multiple fixed monitor electrodes, then noise is canceled and monitoring accuracy is enhanced, but the device complexity increases

Engineering Contradiction:

Improvevibration monitoring accuracyVSAvoidmonitor electrode configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent converts the potentially harmful crosstalk noise into a beneficial differential signal. By positioning multiple monitor electrodes symmetrically and performing differential operation, the common-mode noise from the drive electrode is rejected, while the differential vibration signal from the movable body is amplified. This transforms the noise challenge into an accuracy enhancement, resolving the contradiction between noise rejection and system complexity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 crosstalk noise, enabling more accurate monitoring of vibrations and improving the overall monitoring accuracy of the physical quantity sensor.

Implementation Method 1

a fixed drive electrode that is fixed to the substrate, is disposed to face the movable drive electrode, and vibrates the movable body in the first direction

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 2

a fixed monitor electrode that is fixed to the substrate, is disposed to face the movable detection electrode, and detects vibration of the movable body in the first direction

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Data Source

PatentUS11561101B2Physical quantity sensor, inertia measurement device, vehicle positioning device, electronic apparatus, and vehicle

Publication Date: 2023.01.24 SEIKO EPSON CORP

AI summary

A physical quantity sensor includes a substrate, a movable body that includes a movable drive electrode, a movable detection electrode, and a connection portion for connecting the movable drive electrode and the movable detection electrode and is allowed to vibrate along a first axis with respect to the substrate, a fixed drive electrode that is fixed to the substrate, is disposed to face the movable drive electrode, and vibrates the movable body along the first axis, and a fixed monitor electrode that is fixed to the substrate, is disposed to face the movable detection electrode and detects vibration of the movable body along the first axis.