MEMS Mirror Rear Surface Beam Coupling for Size Reduction

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Solution Overview

Problem

The existing optical scanning apparatuses, such as those disclosed in Japanese Patent Laying-Open No. 2003-270555, face challenges in reducing the size while maintaining the required reflective mirror area, leading to increased device size due to the connection of the inner torsion bar to the outer peripheral edge of the inner movable plate.

Innovation Solution

A MEMS mirror device is designed with a frame body, an inner movable member, a first beam, a reflective mirror member, and a coupling member, where the first beam is coupled to the inner movable member at the rear surface of the reflective mirror member, allowing for a larger reflective surface area without increasing the size of the inner movable member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If the inner torsion bar is connected to the outer peripheral edge of the inner movable plate to ensure the area of the reflective mirror, then the reflective surface area is sufficient, but the device size increases

Engineering Contradiction:

Improvereflective surface areaVSAvoiddevice size

Core Design Contradiction:

Area of moving objectVSVolume of moving object

Solution Approach 1:

The patent connects the first beam to the rear surface of the reflective mirror member instead of the outer peripheral edge, utilizing the third dimension (depth/thickness) to resolve the spatial conflict between reflective area and device size

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of connecting the support beam to the outer edge of the movable plate as in conventional designs, the patent inverts the connection approach by attaching it to the rear surface of the mirror member, achieving size reduction while maintaining functional area

Inventive Principle:

Principle #13The other way round (Inversion)

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 enables a reduction in the overall size of the MEMS mirror device while ensuring the necessary reflective surface area, allowing for efficient optical scanning with suppressed hard spring effects and low power consumption.

Implementation Method 1

The first beam couples the inner movable member rotatably to the frame body

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The reflective mirror member has a reflective surface

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS12038574B2MEMS mirror device and method of manufacturing the same

Publication Date: 2024.07.16 MITSUBISHI ELECTRIC CORP

AI summary

A MEMS mirror device includes a frame body (an outer movable frame body), an inner movable member, a first beam, a reflective mirror member, and a coupling member. The inner movable member is disposed inside the frame body. The first beam couples the inner movable member rotatably to the frame body. The reflective mirror member has a reflective surface and a rear surface. The coupling member couples the reflective mirror member and the inner movable member. The first beam is coupled to the inner movable member at the rear surface of the reflective mirror member. The MEMS mirror device may be reduced in size.