Movable Mirror Optical Module With Halbach Magnet Stress Isolation
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Solution Overview
Problem
The planar-type actuator's magnetic field generation means, when attached to a device substrate, experiences thermal expansion stress, leading to unintentional inclination of the substrate and movable parts due to direct contact, which can cause instability in optical modules.
Innovation Solution
An optical module design incorporating a Halbach array magnet structure with a holding member that integrates and supports the magnets, utilizing a relaxation layer between the magnet and mirror unit to mitigate stress transmission and prevent inclination, while efficiently utilizing the magnetic field for reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the magnetic field generation means is firmly held by attaching to the device substrate using 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 holding plate is introduced as an intermediary component between the magnetic field generation means and the device substrate. The holding plate serves as a mediator that receives thermal expansion stress from the magnetic field generation means through its adhesive layer, preventing this stress from being transmitted to the device substrate and movable part, thereby eliminating the cause of unintentional inclination while maintaining secure fixation
Solution Approach 2:
The fixing structure is segmented into multiple independent adhesive layers: one adhesive layer bonds the magnetic field generation means to the holding plate, and another adhesive layer bonds the holding plate to the device substrate. This segmentation isolates the thermal expansion stress to the holding plate and its adhesive layers, preventing stress transmission to the device substrate while maintaining overall structural integrity
2Strength
If the magnetic field generation means is firmly held by attaching to the device substrate using adhesive, then the magnetic field generation means is securely fixed, but the adhesive layer may be damaged due to stress from thermal expansion
Solution Approach 1:
The holding plate acts as a protective intermediary that absorbs thermal expansion stress, shielding the adhesive layers from damaging forces. By concentrating stress on the holding plate's adhesive bonds rather than transmitting it through the device substrate, the reliability of the adhesive connections is maintained while preserving secure fixation
Solution Approach 2:
The holding plate structure provides beforehand cushioning against thermal expansion stress. The holding plate and its adhesive layers are positioned in advance to intercept and absorb expansion forces before they can damage the primary adhesive bond between the magnetic field generation means and the device substrate, ensuring long-term reliability
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 optical module effectively curbs the inclination of the mirror unit by managing thermal stress and optimizing magnetic field utilization, ensuring stable operation and reduced power consumption.
Implementation Method 1
a magnetic field is generated when a current flows in a drive coil of the movable part, and a Lorentz force is generated due to interaction between this magnetic field and a static magnetic field of the magnetic field generation means
Implementation Method 2
stress due to thermal expansion of the magnetic field generation means acts on the device substrate and the movable part
Implementation Method 3
A relaxation layer for relaxing stress from the magnet part is provided between the upper surface and the mirror unit
Data Source
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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.