V-Shaped Mirror Actuator Layout for Wide-Angle Low-Profile Scanning

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Solution Overview

Problem

Existing rotary reciprocating actuators for optical scanning devices face challenges in achieving a low profile while maintaining high amplitude and wide angle, and are difficult to assemble due to complex configurations like the use of four-pole magnets.

Innovation Solution

A rotary reciprocating actuator design featuring a V-shaped mirror supported by a frame part with a drive unit that includes a core assembly and a movable member with a magnet, using a two-pole magnet configuration and preload springs to stabilize the rotation, allowing for easy assembly and high amplitude scanning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the mirror size is increased to achieve high amplitude and wide angle scanning, then the scanning amplitude and angle are improved, but the product height increases making it difficult to achieve a low profile

Engineering Contradiction:
Improvescanning amplitude and angleVSAvoidproduct height
Core Design Contradiction:
Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent transitions from a conventional horizontal mirror rotation configuration to a vertical mirror rotation configuration. By rotating the mirror in the vertical direction rather than horizontally, the scanning beam achieves wide angle coverage without requiring a larger horizontal mirror size, thereby maintaining a compact product height while improving scanning adaptability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs an asymmetric V-shaped mirror design instead of a conventional flat or symmetric mirror. The V-shape configuration allows the mirror to achieve both horizontal and vertical scanning components through single-axis rotation, improving scanning amplitude and angle coverage without proportionally increasing the mirror size or product height

Inventive Principle:
Principle #4Asymmetry

2Power

If four-pole magnets are used in the drive system, then the magnetic drive capability is improved, but the assembly complexity increases reducing assemblability

Engineering Contradiction:
Improvemagnetic drive capabilityVSAvoidassembly complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex four-pole magnet configuration from the drive system, replacing it with a simpler two-pole magnet arrangement. This extraction of unnecessary complexity maintains sufficient magnetic drive capability for mirror rotation while significantly reducing assembly complexity and improving assemblability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using the conventional four-pole magnet configuration that requires precise alignment of multiple magnetic poles, the patent inverts the approach by using a two-pole configuration where the magnetic field is generated more simply. This inversion of the magnetic circuit design reduces the number of components and simplifies the assembly process while maintaining adequate drive power

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

The design achieves easy assembly, reduced height, wide angle, and high amplitude scanning with improved stability and reliability.

Implementation Method 1

a magnetic flux passing through the core body is generated by energization of the coils, causing reciprocating rotation of the movable body about an axis of the shaft portion by electromagnetic interaction between the magnetic flux and the magnet

Methodology Applied
Scientific EffectElectromagnetic interaction: Electromagnetic Induction

Data Source

PatentEP4502693B1Rotary reciprocating actuator and optical scanning device
Publication Date: 2026.04.01 MITSUMI ELECTRIC CO LTD
  • EP4502693B1 patent drawingFigure 1
  • EP4502693B1 patent drawingFigure 2
  • EP4502693B1 patent drawingFigure 3

AI summary

A rotary reciprocating actuator including: a movable member (2) including a shaft part (20) with a magnet (30) fixed on an outer periphery, wherein a V-shaped mirror (10) is held such that a ridgeline (11) of the V-shaped mirror (10) is along the shaft part (20), and the movable member (2) is supported in a rotatable manner back and forth around an axis through the shaft part (20); and a unit body (40) including a plurality of magnetic poles (420a, 420b), a coil member (50), and a magnetic member (48), the plurality of magnetic poles (420a, 420b) facing the magnet (30) and being separated from each other in a circumferential direction of the shaft part (20), the coil member (50) being configured to form, together with the magnet (30), an electromagnetic drive part configured to rotate back and forth the movable member (2), the magnetic member (48) facing the magnet (30) in the radial direction of the shaft part (20) and being disposed between the plurality of magnetic poles (420a, 420b) in the circumferential direction to bias the movable member (2) toward an initial position of back-and forth rotation by attracting the magnet (30). The electromagnetic drive part sways the V-shaped mirror (10) while maintaining an angle of the V-shaped mirror (10) by rotating back and forth the movable member (2).