Camera Module Coil-Sensor Layout for Accurate OIS Feedback
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Solution Overview
Problem
Existing voice coil motor (VCM) technology is difficult to apply to subminiature, low-power camera modules, particularly in miniaturized and multifunctional cameras for mobile devices, necessitating improved performance for autofocusing and optical image stabilization.
Innovation Solution
A camera module design incorporating a stationary part with a magnet, a movable part with a first circuit board, a coil facing the magnet, and a position sensor positioned to avoid overlap with the coil, utilizing an elastic support member to ensure accurate OIS feedback operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position sensor is disposed close to the magnet for accurate OIS feedback, then measurement precision is improved, but the coil and position sensor may overlap causing mechanical interference
Solution Approach 1:
The spacer introduces a new spatial dimension (vertical separation) to resolve the horizontal overlap conflict. By positioning the position sensor above the spacer and the coil below the spacer, the design achieves three-dimensional spatial separation that eliminates mechanical interference while preserving the close proximity needed for accurate magnetic field detection and OIS feedback.
Solution Approach 2:
The spacer acts as an intermediary component that mediates the spatial relationship between the coil and position sensor. This intermediate element provides the necessary physical separation and structural support, enabling both components to maintain their optimal positions without direct contact or interference.
2Volume of moving object
If the camera module is miniaturized to reduce size, then volume is reduced, but it becomes difficult to apply existing VCM technology and maintain OIS performance
Solution Approach 1:
The design employs a nested arrangement where the position sensor is positioned above the spacer, the coil is below the spacer, and the magnet is at the bottom, creating a compact vertical stack. This nested doll-like structure allows multiple functional components to be arranged in three-dimensional space within a minimized footprint, enabling miniaturization while maintaining OIS functionality.
Solution Approach 2:
By transitioning from a planar two-dimensional layout to a three-dimensional vertical arrangement, the design achieves miniaturization. The spacer enables vertical stacking of components (sensor-spacer-coil-magnet), utilizing the third dimension to reduce the horizontal footprint while preserving component functionality and OIS performance.
3Power
If the coil and position sensor are positioned to face each other for electromagnetic interaction, then OIS drive capability is improved, but mechanical interference and manufacturing complexity increase
Solution Approach 1:
The spacer serves as a precision-engineered intermediary that pre-establishes the correct spacing and alignment between the coil and position sensor. By incorporating alignment features and precise dimensional tolerances in the spacer, the design reduces manufacturing complexity compared to directly aligning the coil and sensor, while maintaining optimal electromagnetic interaction for OIS drive capability.
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
Enables reliable and accurate optical image stabilization (OIS) feedback, enhancing autofocus performance and reducing mechanical interference in miniaturized camera modules.
Implementation Method 1
the movable part is moved in a direction perpendicular to an optical-axis direction by the interaction between the magnet and the coil
Implementation Method 2
a position sensor disposed on the first circuit board... such that at least a portion thereof is disposed in the hole of the spacer and overlaps the magnet in an optical-axis direction
Data Source
AI summary
A camera module including a stationary part including a magnet, a movable part having a first circuit board disposed so as to be spaced apart from the stationary part, a holder disposed on the first circuit board, a coil disposed on the holder so as to face the magnet, and a position sensor disposed on the first circuit board so as to face the magnet. A support member is coupled both to the stationary part and to the movable part. The movable part is configured to be moved in a direction perpendicular to an optical-axis direction by the interaction between the magnet and the coil, and the coil does not overlap the position sensor in the direction perpendicular to the optical-axis direction.