Actuator Coil Segmentation for Magnetic Fog Noise Reduction
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Solution Overview
Problem
Magnetic fog noise interferes with the precision of position control in camera modules, particularly when using magnetic position detection devices, due to the proximity of drive coils and position detection elements, limiting configuration freedom and increasing noise levels.
Innovation Solution
The actuator design features a dual coil structure with an inner and outer coil, where the magnetic fields produced by each coil counteract each other near the position detection element, allowing for optimal placement and reducing magnetic fog noise by adjusting the turn ratio and current distribution between the coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position detection element is configured near a drive coil to enable position detection, then position detection capability is improved, but magnetic fog noise increases and position control precision deteriorates
Solution Approach 1:
The drive coil is divided into multiple independent coil sections (first coil section, second coil section, third coil section, fourth coil section) arranged around the position detection element. Each section can be independently controlled to generate magnetic fields that counteract each other, creating a low-noise zone near the position detection element while maintaining driving capability.
Solution Approach 2:
Different regions of the coil structure are assigned different functions: the outer coil sections (first and fourth) provide primary driving force, while the inner coil sections (second and third) are optimized to minimize magnetic interference with the position detection element. The coil sections adjacent to the position detection element are designed with specific turn ratios and current distributions to create local magnetic field cancellation.
2Power
If the coil is configured close to the position detection element to improve actuation efficiency, then driving capability is improved, but magnetic flux from the coil enters the position detection element causing noise
Solution Approach 1:
The coil is segmented into four distinct sections that can be independently controlled. This allows the outer sections to provide strong driving magnetic fields while the inner sections generate counteracting fields to protect the position detection element from magnetic flux interference.
Solution Approach 2:
The magnetic flux that would normally interfere with the position detection element is converted into a beneficial effect by using the inner coil sections to generate opposing magnetic fields. The harmful magnetic interference is transformed into a controlled magnetic counterbalance that actually protects the detection element while maintaining actuation efficiency.
3Device complexity
If a single coil configuration is used to simplify the structure, then device complexity is reduced, but configuration freedom is limited and noise reduction capability is insufficient
Solution Approach 1:
The coil is divided into four independently controllable sections arranged around the position detection element. This segmentation provides configuration freedom to optimize the magnetic field distribution, allowing different sections to serve different functions (driving vs. noise cancellation) while maintaining a relatively simple overall structure.
Solution Approach 2:
The coil sections are designed with asymmetric characteristics relative to the position detection element, with different turn ratios and current distributions for sections adjacent to versus opposite the detection element. This asymmetric configuration enables optimized noise reduction while maintaining structural simplicity.
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 significantly reduces magnetic fog noise, enabling higher precision in position control of camera lenses and improving image stabilization and focusing capabilities.
Implementation Method 1
a current I flows in a positive direction towards the Y-axis and acts with the magnetic flux density B in a positive direction of the Z-axis, and thus a Lorentz force in a positive direction of the X-axis is produced between the winding and the permanent magnet 110. F=BIL
Implementation Method 2
magnetic position detection devices, for the reasons such as: if an optical position detection device is used, there is a potential risk of forming ghost imaging due to leakage light entering a camera component
Data Source
AI summary
The present invention reduces magnetic fog noise of an actuator.An actuator is used jointly with a position detection element to locate a lens in a direction of a first axis. A coil is formed in a manner of setting a second axis perpendicular to the first axis as a length direction, and has a first side and a second side parallel to the second axis, and a third side and a fourth side parallel to the first axis. A permanent magnet produces magnetic fields perpendicular to the first axis and the second axis and being in opposite directions with respect to the first side and the second side, respectively. During use, the position detection element is configured near the third side. The coil is split into multiple parts in a width direction on at least the third side.