Light Deflector Torsion Bar Constricted Shape Rigidity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing optical scanning devices with torsion beams face issues of discontinuity in rigidity at the root portion of the torsion beam, leading to potential damage from concentrated stress when the scanning speed of light is increased.

Innovation Solution

A light deflector design featuring torsion bars with a constricted shape, where the transverse width is largest at the connections to the mirror section and frame body, and gradually decreases toward the central part, reducing rotational torque and enhancing rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If ribs are added for reinforcement in the movable plate section, then the rigidity of the center of rotation is improved, but the weight and moment of inertia of the movable plate section increase

Engineering Contradiction:

Improverigidity of center of rotationVSAvoidweight of movable plate section

Core Design Contradiction:

Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The torsion bar is designed with non-uniform cross-sectional dimensions, having larger dimensions at the connection portions and smaller dimensions at the central portion. This local variation in geometry provides enhanced rigidity at the connection points where it is most needed, while reducing weight in the central region, thereby resolving the contradiction between overall rigidity and weight reduction

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If ribs are added for reinforcement in the movable plate section, then the rigidity of the center of rotation is improved, but the moment of inertia of the movable plate section increases

Engineering Contradiction:

Improverigidity of center of rotationVSAvoidmoment of inertia of movable plate section

Core Design Contradiction:

Stability of the object's compositionVSWeight of stationary object

Solution Approach 1:

The torsion bar employs localized reinforcement at the connection portions through increased cross-sectional dimensions, providing the necessary rigidity support at critical points without adding mass throughout the entire structure. This selective reinforcement approach improves rotational stability while minimizing the increase in moment of inertia

Inventive Principle:

Principle #3Local quality

3Strength

If the transverse width of the torsion bar is increased at the central part, then the torsional strength is improved, but the rigidity of the light deflector decreases and distortion increases

Engineering Contradiction:

Improvetorsional strength of torsion barVSAvoidrigidity of light deflector

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The torsion bar is designed with larger cross-sectional dimensions at the connection portions and smaller dimensions at the central portion. This configuration concentrates the material where torsional strength is most critical (at the connections to the mirror section and frame body) while maintaining overall rigidity by reducing material in the central region, thereby preventing distortion and resolving the contradiction between torsional strength and rigidity

Inventive Principle:

Principle #3Local quality

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 constricted shape of the torsion bars in the light deflector design suppresses distortion, increases rigidity, and reduces the likelihood of damage, allowing for the creation of smaller and thinner devices while maintaining high resonance frequency and limit deflection angle characteristics.

Implementation Method 1

a piezoelectric actuator that is provided on the frame body and rotates the torsion bars around the axis in a reciprocating manner

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the torsion bar has a constricted shape in which, in the case where a connection between the torsion bar and the mirror section is defined as a first connection and a connection between the torsion bar and the frame body is defined as a second connection, a transverse width at the first connection and the second connection is the largest and the transverse width gradually decreases toward a central part in a length direction

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12332427B2Light deflector

Publication Date: 2025.06.17 STANLEY ELECTRIC CO LTD

AI summary

A light deflector 2 includes: a mirror section 9 that reflects light; a movable frame 8 provided in such a manner as to surround the mirror section 9; a pair of torsion bars 13a and 13b having one end of each torsion bar connected to the mirror section 9 and the other end thereof connected to the movable frame 8 on a Y-axis; and semi-annular piezoelectric actuators 10a and 10b that are provided on the movable frame 8 and rotate the torsion bars 13a and 13b around the Y-axis in a reciprocating manner. The torsion bars 13a and 13b each have a constricted shape in which the transverse width at both end parts is the largest and the transverse width gradually decreases toward the central part thereof in a length direction.