Inertial Sensor Protrusion Design for Seesaw Swing Control

Solution Overview

Problem

Existing inertial sensors face mechanical failure due to excessive seesaw swing, which causes impact and potential breakage of the movable element and substrate, as the stoppers in current designs are not effective in controlling the swing, leading to excessive displacement and electrostatic attraction issues.

Innovation Solution

The inertial sensor incorporates protrusions on the substrate that overlap with the movable element, featuring proximal and distal protrusions to gradually absorb the swing motion, reducing impact and preventing excessive contact with detection electrodes, thus enhancing mechanical strength and accuracy by controlling the seesaw swing and minimizing electrostatic attraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the stopper is positioned farther from the swing axis to restrict excessive swing, then the swing displacement is controlled, but the impact force increases causing breakage of the movable element and substrate

Engineering Contradiction:

Improveswing displacement controlVSAvoidmovable element and substrate integrity

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The stopper is divided into two distinct parts: a first stopper positioned closer to the swing axis and a second stopper positioned farther from the swing axis. This segmentation allows the system to provide both displacement control and impact force reduction, resolving the contradiction between swing restriction and structural integrity protection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first stopper acts as a cushioning element that absorbs impact energy before the movable element can reach the second stopper. By providing this preliminary cushioning effect, the system reduces the impact force on the substrate and movable element while still maintaining effective swing displacement control

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Strength

If the stopper is positioned closer to the swing axis to reduce impact, then the movable element is protected, but the swing displacement control becomes insufficient

Engineering Contradiction:

Improvemovable element protectionVSAvoidswing displacement control

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The stopper is divided into two distinct parts: a first stopper positioned closer to the swing axis and a second stopper positioned farther from the swing axis. This segmentation allows the system to provide both displacement control and impact force reduction, resolving the contradiction between swing restriction and structural integrity protection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first stopper acts as a cushioning element that absorbs impact energy before the movable element can reach the second stopper. By providing this preliminary cushioning effect, the system reduces the impact force on the substrate and movable element while still maintaining effective swing displacement control

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If the movable element swings excessively, then the detection range is increased, but electrostatic attraction with the detection electrode causes measurement errors

Engineering Contradiction:

Improvedetection rangeVSAvoidacceleration detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The stopper structure is pre-positioned to intervene in the movable element's swing motion before excessive displacement occurs. By establishing this preliminary mechanical constraint, the system prevents the movable element from reaching positions where electrostatic attraction would cause measurement errors, while still allowing sufficient swing range for accurate detection

Inventive Principle:

Principle #10Preliminary action

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 design effectively suppresses breakage of the movable element and improves mechanical strength by staged contact with protrusions, reducing unnecessary displacement and electrostatic attraction, leading to enhanced accuracy in acceleration detection.

Implementation Method 1

the proximal protrusion and the distal protrusion come into contact with the movable element at the same time or the proximal protrusion comes into contact with the movable element and then the distal protrusion comes into contact with the movable element

Methodology Applied

Scientific EffectImpact absorption: Impact Force

Implementation Method 2

the capacitance between the first movable section and the first detection electrode and the capacitance between the second movable section and the second detection electrode change accordingly in opposite phases. The acceleration in the axis-Z direction can therefore be detected based on the changes in the capacitance

Methodology Applied

Scientific EffectCapacitance change: Capacitance

Data Source

PatentUS11460483B2Inertial sensor, electronic instrument, and vehicle

Publication Date: 2022.10.04 SEIKO EPSON CORP

AI summary

An inertial sensor includes a substrate, a movable element that swings around a swing axis; and a protrusion that overlaps with the movable element in the plan view and protrudes from the substrate toward the movable element. The protrusion includes a first protrusion and a second protrusion so located as to be farther from the swing axis than the first protrusion, and when the movable element swings relative to the substrate around the swing axis, the first protrusion and the second protrusion come into contact with the movable element at the same time or the first protrusion comes into contact with the movable element and then the second protrusion comes into contact with the movable element.