Rotary Reciprocating Actuator Layout for Larger Mirror Swing

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Solution Overview

Problem

Rotary reciprocating drive actuators face challenges in increasing the size and amplitude of movable objects like mirrors due to heat generation from coils and interference between the magnet and yoke, which affects drive performance and assembly complexity.

Innovation Solution

A rotary reciprocating drive actuator design featuring a ring-shaped magnet with alternately disposed poles, a core with magnetic pole parts facing the magnet via an air gap, and a dual-bearing support system to maintain linearity and stability, allowing for increased size and amplitude of movable objects while minimizing heat transfer and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a coil is disposed on a rotating shaft in a moving coil type actuator, then the actuator can drive the rotating shaft to rotate reciprocally, but heat generated by the coil adversely affects the mirror surface condition, bonding condition, and shape

Engineering Contradiction:
Improvedrive capabilityVSAvoidcoil heat generation
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent extracts the coil from the rotating shaft and relocates it to the fixed part. The rotating shaft now carries only the magnet and mirror, eliminating the heat source from the rotating component. The coil remains stationary on the fixed part, allowing heat to be managed more effectively without directly affecting the mirror.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the stationary coil and the rotating magnet. The coil generates a magnetic field that interacts with the magnet on the rotating shaft to produce rotational force, eliminating the need for direct mechanical or thermal contact between the coil and rotating components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If current input to the coil is increased to increase mirror size and amplitude, then the drive performance improves, but heat generation from the coil increases

Engineering Contradiction:
Improvemirror sizeVSAvoidcoil heat generation
Core Design Contradiction:
Volume of moving objectVSTemperature

Solution Approach 1:

The patent replaces the conventional moving coil mechanical system with a moving magnet system. The stationary coil generates a magnetic field that interacts with the rotating magnet, creating a more efficient electromagnetic coupling that reduces resistive heating while maintaining or enhancing drive capability for larger mirrors.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Power

If a magnet and yoke are disposed in the same area on a rotating shaft, then electromagnetic interaction is achieved, but the mirror and yoke interfere with each other when the rotating shaft rotates

Engineering Contradiction:
Improveelectromagnetic interactionVSAvoidinterference between components
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent extracts the yoke from the rotating shaft and relocates it to the fixed part along with the coil. This separation eliminates the interference problem between the mirror and yoke that would occur during rotation, while the magnetic circuit is maintained through the fixed part's magnetic pole parts facing the rotating magnet.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the conventional arrangement by making the magnet the rotating component rather than having the coil and yoke rotate together. The stationary coil and yoke on the fixed part interact with the rotating magnet, reversing the traditional moving coil configuration to eliminate component interference.

Inventive Principle:
Principle #13The other way round (Inversion)

4Power

If wiring is pulled out from the rotating shaft to the fixed body side, then electrical connection is achieved, but assembling property is lowered

Engineering Contradiction:
Improveelectrical connectionVSAvoidassembling property
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The patent extracts the coil from the rotating shaft, which eliminates the need for complex wiring arrangements on the rotating component. The coil is positioned on the fixed part where wiring can be easily connected without involving rotating connections, significantly simplifying the assembly process.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enhances the size and amplitude of movable objects, stabilizes drive performance, and reduces heat-related issues, enabling efficient and reliable operation of the actuator.

Implementation Method 1

a driving part configured to rotate the rotating shaft about an axis of the rotating shaft with respect to the fixed part by utilizing electromagnetic interaction

Methodology Applied
Scientific EffectElectromagnetic interaction: Electromagnetic Induction

Implementation Method 2

a rotation angle position holding part configured to hold a rotation angle position of the rotation shaft at a neutral position by a magnetic attraction force generated between the magnet and the rotation angle position holding part

Methodology Applied
Scientific EffectMagnetic attraction force: Magnetism

Data Source

PatentEP4047798B1Rotary reciprocating drive actuator
Publication Date: 2024.12.25 MITSUMI ELECTRIC CO LTD
  • EP4047798B1 patent drawingFigure 1
  • EP4047798B1 patent drawingFigure 2
  • EP4047798B1 patent drawingFigure 3

AI summary

A rotary reciprocating drive actuator capable of increasing the size and amplitude of a movable obj ect such as a mirror, and of stabilizing the drive performance is provided. The rotary reciprocating drive actuator includes a movable part including a rotating shaft, a fixed part supporting the rotating shaft, and a driving part that includes a coil and a core disposed on the fixed part and a magnet disposed on the rotating shaft, and rotates the rotating shaft about the axis thereof with respect to the fixed part by utilizing electromagnetic interaction. The fixed part includes first and second supports disposed so as to face each other with the magnet therebetween in the axial direction. The rotating shaft is rotatably attached to the first and second supports via first and second bearings. One of the first and second bearings is a rolling bearing, and the other is a slide bearing.