Actuator with Multiple Beam Structure for Stress Distribution

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Solution Overview

Problem

The existing optical scanning devices face challenges in miniaturization and stress concentration during tilting operations, leading to potential fracture issues due to high internal stresses in silicon components, particularly when subjected to torsional and bending vibrations.

Innovation Solution

The proposed actuator design incorporates a pair of supporting beams and movable frames with a multiple beam structure connection parts that convert bending vibration into torsional vibration, distributing stress evenly and preventing concentration on specific parts, allowing for stable operation and miniaturization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the first spring part and second spring parts are used to vibrate the reflector mirror part, then the optical scanning function is achieved, but the internal stresses concentrate on these spring parts causing high risk of silicon fracture

Engineering Contradiction:

Improverisk of silicon fractureVSAvoidinternal stress concentration

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The invention divides the single spring part structure into multiple spring parts (first spring part and second spring parts). The second spring parts are arranged in parallel and connect the movable frame to the fixed frame, distributing the stress that would otherwise concentrate on a single spring part. This segmentation reduces the internal stress on each individual spring part and lowers the risk of silicon fracture during high-speed tilting operations.

Inventive Principle:

Principle #1Segmentation

2Stress or pressure

If the first spring part is extended to reduce torsion per unit length, then stress concentration is reduced, but the actuator size increases making miniaturization difficult

Engineering Contradiction:

Improvetorsion per unit lengthVSAvoidactuator size

Core Design Contradiction:

Stress or pressureVSVolume of moving object

Solution Approach 1:

Instead of extending the spring part in the longitudinal direction (one dimension) to reduce torsion, the invention introduces a transverse dimension by arranging multiple second spring parts side by side. This dimensional transition allows stress distribution without increasing the actuator's length, enabling miniaturization while maintaining low stress levels.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention combines multiple second spring parts in parallel to achieve the stress distribution effect. By merging several shorter spring parts together, the structure achieves the same stress-reduction benefit as a single long spring part would provide, but without the increased size penalty.

Inventive Principle:

Principle #5Merging (Combining)

3Stability of the object's composition

If the second spring parts are fixed to the fixed frame part, then structural stability is achieved, but all torsional and bending stresses concentrate on the spring parts during tilting operation

Engineering Contradiction:

Improvestructural stabilityVSAvoidstress concentration on spring parts

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The structure is segmented into multiple load-bearing elements (first spring part and multiple second spring parts) that are all fixed to the fixed frame. This segmentation distributes the stress path across multiple connections, maintaining structural stability while preventing stress concentration on any single spring part.

Inventive Principle:

Principle #1Segmentation

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 design effectively distributes internal stresses, preventing fracture and enabling stable operation while allowing for miniaturization of the actuator, as demonstrated by reduced maximum internal stress levels below the fracture threshold during high-speed tilting drives.

Implementation Method 1

connection parts arranged to connect the movable frames and end portions of the supporting beams by a multiple beam structure, convert the bending vibration into torsional vibration, and transmit the torsional vibration to the supporting beams

Methodology Applied

Scientific EffectVibration conversion:

Implementation Method 2

drive source arranged to apply bending vibration to the movable frames

Methodology Applied

Scientific EffectBending vibration:

Data Source

PatentUS8681404B2Actuator and optical scanning device using actuator

Publication Date: 2014.03.25 MITSUMI ELECTRIC CO LTD

AI summary

An actuator includes: a pair of supporting beams to support an object from both sides thereof in a direction parallel to an axis of rotation; a pair of movable beams to sandwich the object and the pair of supporting beams from both sides in a direction perpendicular to the axis of rotation; a plurality of beams to sandwich the pair of movable frames from both sides thereof in the direction perpendicular to the axis of rotation and support the object; a resonant drive source to apply bending vibration to the pair of movable frames and drive the object around the axis of rotation when a resonant drive operation is performed; and a non-resonant drive source to apply bending vibration to the plurality of beams and tilt and drive the object around a second axis of rotation perpendicular to the axis of rotation when a non-resonant drive operation is performed.