Mirror Drive Device Coil Positioning for Compact Magnetic Field
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Solution Overview
Problem
The existing mirror drive devices face challenges in reducing size while maintaining a strong magnetic field on the drive coil, particularly when the drive coil is positioned on the surface opposite to the mirror, due to increased distance between the permanent magnets and the drive coil, leading to insufficient magnetic field strength and larger device size for electrical connections.
Innovation Solution
The mirror drive device incorporates a support part with a frame-like shape, a movable part with a base member and a mirror, and a circuit board positioned between the support part and the magnetic body, allowing the drive coil to be connected to the circuit board via a lead-out conductor, ensuring a strong magnetic field and reducing the device's size by utilizing the circuit board as both an electrical connector and a spacer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the drive coil is disposed in the back surface of the movable part, then the mirror can be formed with a large size and a flat mirror can be formed, but the distance between the permanent magnets and the drive coil increases, resulting in insufficient magnetic field strength
Solution Approach 1:
The patent repositions the drive coil from the front surface to the back surface of the movable part, utilizing the third dimension (depth/thickness) of the movable part structure. This allows the mirror to be formed with large size on the front surface while placing the drive coil on the back surface where it can be closer to the permanent magnets, thus resolving the contradiction between mirror size and magnetic field strength.
2Force
If a single permanent magnet is disposed to overlap the support part and the movable part, then the permanent magnet becomes close to the drive coil, but the device size increases due to electrical connection requirements
Solution Approach 1:
The patent merges the electrical connection function with the structural support function by integrating the electrode directly into the support part structure. The electrode is disposed at the support part's surface facing the magnetic body, eliminating the need for separate wire bonding regions and reducing the overall device volume while maintaining strong magnetic field coupling.
3Reliability
If the drive coil is connected to the circuit board via lead-out conductor, then electrical connection is achieved, but the device size increases due to additional connection space requirements
Solution Approach 1:
The patent combines the electrical connection path within the support part structure itself, eliminating the need for external wire bonding spaces. The electrode at the support part surface provides direct electrical connection to the circuit board, integrating the connection function into the existing structural volume and minimizing additional space requirements.
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 configuration allows for a reduction in the mirror drive device's size while maintaining a sufficient magnetic field on the drive coil, enabling efficient electrical connection and minimizing stress on the movable part, thus enhancing the device's performance and compactness.
Implementation Method 1
When current flows through the drive coil, a Lorentz force is generated in the drive coil by an interaction with a magnetic field generated in the periphery of the movable part by the pair of permanent magnets
Data Source
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AI summary
In a case where a drive coil is disposed in a surface of a movable part, the surface being opposite to a mirror, a reduction in size is achieved while a magnetic field exerted on the drive coil is secured. A mirror drive device 1 includes a support part 20, a movable part 22, a permanent magnet 10 which forms a magnetic field in the periphery of the movable part 22, and a circuit board 12 which is disposed between the support part 20 and the permanent magnet 10 in a facing direction of a pair of principal surfaces of the movable part 22 so as to cause the movable part 22 to be positioned at an inside of the circuit board 12 when viewed in the facing direction. The movable part 22 includes a mirror disposition portion 36, a mirror 48 disposed at a principal surface 36b side, and a drive coil 46 disposed at the principal surface 36a side so as to face the permanent magnet 10. The support part 20 includes a base portion 24 connected to a connection member 38 and a reinforcing portion 26 which extends from the base portion 24 toward a side away from the permanent magnet 10 and the circuit board 12. The drive coil 46 is connected to electrodes 56a to 56d by lead-out conductors 42a to 42d.