Frame-Shaped Movable Mass Sensor for Temperature Stability

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Solution Overview

Problem

Existing physical quantity sensors face challenges in maintaining superior temperature characteristics due to substrate warping caused by temperature variance, which affects the accuracy of acceleration and angular velocity detection.

Innovation Solution

The design incorporates a movable electrode structure with a frame-like mass section that encloses fixed electrode sections, allowing for reduced deformation and increased sensitivity by shortening the distance between electrodes and improving electrostatic capacity changes, while also using differential signal calculations and overlapping wiring to reduce noise and parasitic capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the movable electrode and fixed electrode are connected to substrate via multiple connecting sections, then the electrode structure is stable, but the distance between connecting sections cannot be shortened and substrate warping causes deformation

Engineering Contradiction:

Improveelectrode structure stabilityVSAvoidtemperature characteristics

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The movable mass is divided into multiple discrete masses (first movable mass, second movable mass, etc.) positioned at different locations. This segmentation allows each mass to be independently supported by connecting sections, distributing the structural stress and reducing the impact of substrate warping on any single electrode connection, thereby maintaining both stability and measurement precision

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The movable masses are positioned within the enclosed space formed by the fixed electrode structure. The fixed electrode sections form a sort of frame that encloses the movable masses, creating a nested configuration where the movable components are protected within the fixed structure, reducing deformation from substrate warping

Inventive Principle:

Principle #7Nested doll (Nesting)

2Measurement precision

If the distance between connecting sections is shortened, then temperature characteristics improve, but the electrode structure becomes more compact

Engineering Contradiction:

Improvetemperature characteristicsVSAvoidsubstrate area occupied

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The sensor design transitions from a one-dimensional linear arrangement of electrodes to a two-dimensional planar configuration. Multiple fixed electrode sections and movable masses are arranged in different spatial positions on the substrate plane, allowing short connection distances without requiring excessive linear space, thus improving temperature characteristics while managing area occupation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If the movable mass is positioned between connecting sections, then the structure is compact, but substrate warping influences the electrodes via connecting sections causing deformation

Engineering Contradiction:

Improvestructural compactnessVSAvoidelectrode deformation

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

Multiple movable masses are positioned at different locations within the fixed electrode structure. These masses act as counterweights that balance each other, reducing the net effect of substrate warping forces on any single electrode connection. The distributed positioning compensates for localized deformations through the collective stability of the entire electrode assembly

Inventive Principle:

Principle #8Anti-weight (Counterweight)

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 enhances the sensor's temperature stability and sensitivity, reducing the impact of substrate warping and improving detection accuracy and reliability.

Implementation Method 1

an elastic section which connects the movable electrode side fixed section and the movable mass section such that the movable mass section is displaceable in the first direction

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

detects a physical quantity such as acceleration and angular velocity based on electrostatic capacity between the two electrodes

Methodology Applied

Scientific EffectElectrostatic capacity: Capacitance

Data Source

PatentUS10151771B2Physical quantity sensor having a frame-shaped movable mass, electronic device, and mobile body

Publication Date: 2018.12.11 SEIKO EPSON CORP

AI summary

A physical quantity sensor includes a movable electrode side fixed section, a first fixed electrode side fixed section which has a first fixed electrode section and a second fixed electrode side fixed section which has a second fixed electrode section, a movable mass section which has a first movable electrode section that has a portion facing the first fixed electrode section and a second movable electrode section that has a portion facing the second fixed electrode section and which is formed in a shape that encloses the movable electrode side fixed section, the first fixed electrode side fixed section, and the second fixed electrode side fixed section in planar view, and an elastic section which connects the movable electrode side fixed section and the movable mass section.