Optical Mirror Module With Halbach Magnet Stress Isolation
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Solution Overview
Problem
The planar-type actuator described in Patent Literature 1 experiences unintentional inclination due to stress from thermal expansion of the magnetic field generation means, which is held by a holding plate, potentially affecting the device substrate and movable part.
Innovation Solution
An optical module utilizing a Halbach array of magnets, where the magnet part is held by a package with a Halbach structure and a relaxation layer to prevent stress transmission to the mirror unit, and a restriction part to restrict movement, ensuring the magnet part is integrally held and the mirror unit is supported on the upper surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the magnetic field generation means is firmly held by attaching a holding plate using an adhesive, then the magnetic field generation means is securely fixed, but stress due to thermal expansion acts on the device substrate and movable part causing unintentional inclination
Solution Approach 1:
A relaxation layer is introduced as an intermediary between the magnetic field generation means and the device substrate. This layer mediates the thermal expansion stress by providing a compliant interface that absorbs expansion forces, preventing stress transmission to the device substrate and movable part while maintaining secure fixation of the magnetic field generation means
Solution Approach 2:
The holding structure transitions from rigid adhesive bonding to a compliant relaxation layer with different mechanical properties. The relaxation layer has lower modulus of elasticity compared to the holding plate, allowing it to deform and absorb thermal expansion stresses, thereby changing the stress transmission parameters from the magnetic field generation means
2Power
If magnets in a Halbach array are used as magnetic field generation means, then a strong magnetic field is generated, but complicated stress acts on members in contact with the magnets due to varying thermal expansion directions
Solution Approach 1:
The relaxation layer serves as a stress-absorbing intermediary between the Halbach array magnets and the holding plate. Since magnets in a Halbach array have varying magnetization directions that cause complicated thermal expansion stresses, the relaxation layer's compliant properties allow it to absorb these multi-directional stresses without transmitting them to the holding plate or device substrate
Solution Approach 2:
The holding structure employs a composite design combining a rigid holding plate for secure mounting with a compliant relaxation layer for stress absorption. This composite structure allows the rigid component to provide mechanical support while the compliant component handles thermal expansion stresses, enabling the use of high-performance Halbach array magnets
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 solution effectively curbs the inclination of the mirror unit by managing stress from thermal expansion, ensuring reliable operation and reducing power consumption.
Implementation Method 1
a magnet part having upper and bottom surfaces and a side surface extending from the upper surface to the bottom surface and configured to generate a magnetic field acting on the movable mirror part
Implementation Method 2
A relaxation layer for relaxing stress from the magnet part is provided between the upper surface and the mirror unit
Implementation Method 3
The magnet part has a Halbach structure including a first magnet applied with a force in a first direction toward the bottom surface from the upper surface and a second magnet applied with a force in a second direction toward the upper surface from the bottom surface
Data Source
AI summary
An optical module includes a mirror unit configured to have a movable mirror part, a magnet part configured to have upper and bottom surfaces and a side surface and generate a magnetic field acting on the movable mirror part, and a holding member configured to hold the magnet part. The magnet part has a Halbach structure including a first magnet having a force to act in a first direction and a second magnet having a force to act in a second direction. The holding member integrally holds the magnet part against a force acting on the first magnet in the first direction and a force acting on the second magnet in the second direction. The mirror unit is supported on the upper surface by the holding member. A relaxation layer for relaxing stress from the magnet part is provided between the upper surface and the mirror unit.