MEMS Mirror Support Structure for Stable Rotation Under Stress

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Solution Overview

Problem

Existing MEMS devices face instability in rotation due to mechanical stress, thermal stress, and external vibrations, leading to deteriorated frequency characteristics and inaccurate control of the mirror's oscillation.

Innovation Solution

A movable device configuration with a support structure that includes a connecting portion connected to the stationary support in a direction intersecting with the axis of rotation, acting as a buffer to absorb mechanical stress and prevent changes in static or dynamic characteristics, ensuring stable rotation of the mirror.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the mirror is directly supported by a rigid structure, then the structural strength is improved, but the rotation stability deteriorates due to mechanical stress and external vibrations

Engineering Contradiction:

Improvestructural strengthVSAvoidrotation stability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

A connecting portion is introduced as an intermediary element between the support and the stationary support. This connecting portion acts as a buffer that absorbs mechanical stress and external vibrations, preventing them from being transmitted to the mirror's rotation system, thereby maintaining rotation stability while still providing structural support.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The connecting portion is designed with specific geometric parameters (length, cross-sectional area, material properties) that allow it to exhibit appropriate stiffness and damping characteristics. By optimizing these parameters, the structure can simultaneously provide sufficient strength support while maintaining rotation stability through controlled stress absorption.

Inventive Principle:

Principle #35Parameter changes

2Strength

If the support structure is made more rigid to reduce vibrations, then the structural strength is improved, but the frequency characteristics deteriorate due to stress transmission

Engineering Contradiction:

Improvestructural strengthVSAvoidfrequency characteristics

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The connecting portion serves as a mediator that decouples the rigid support structure from the mirror assembly. It allows the support to be rigid for strength while the connecting portion itself absorbs vibrations and stress, preventing transmission to the mirror and preserving frequency characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The connecting portion is designed with flexible characteristics through its geometry and material selection, allowing it to deform elastically under stress and vibration. This flexibility enables it to absorb mechanical energy while the overall structure maintains sufficient strength, preserving the mirror's frequency characteristics.

Inventive Principle:

Principle #30Flexible shells and thin films

3Device complexity

If the mirror is directly connected to the stationary support, then the device complexity is reduced, but the rotation stability deteriorates under mechanical stress

Engineering Contradiction:

Improvestructural complexityVSAvoidrotation stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The connecting portion is a relatively simple structural element that can be integrated into existing support designs. While it adds one component to the system, its function as a stress-absorbing buffer significantly improves rotation stability, making it a worthwhile addition that maintains overall structural simplicity while solving the stability problem.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration maintains stable rotation of the mirror by reducing the transmission of mechanical stress and external vibrations, maintaining consistent frequency characteristics and oscillation accuracy even under varying conditions.

Implementation Method 1

The first piezoelectric actuator actuates the torsion bar to causes the mirror to oscillate about a first axis extending along the axis of the torsion bar using piezoelectric actuation

Methodology Applied

Scientific EffectPiezoelectric actuation: Piezoelectric Effect

Implementation Method 2

Methodology Applied

Scientific EffectMechanical stress absorption: Damping

Implementation Method 3

a torsion bar coupling the mirror to the first support

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS12554123B2Movable device, image projection apparatus, laser headlamp, head-mounted display, distance measurement device, and mobile object

Publication Date: 2026.02.17 RICOH CO LTD

AI summary

A movable device includes a movable portion; a drive unit having one end connected to the movable portion to rotate the movable portion; a support supporting the drive unit; a connecting portion having one end connected to the support to support the support; and a stationary support to which the other end of the connecting portion is connected.