Lens Driving Device Magnetic Sensitivity Enhancement
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Solution Overview
Problem
Conventional lens driving devices with a common magnet scheme for auto-focusing (AF) and optical image stabilization (OIS) suffer from asymmetry in coil lengths, leading to a yawing effect that disrupts displacement sensing and requires improved magnetic sensitivity for precise AF and OIS functions.
Innovation Solution
A VCA-based lens driving device with an improved OIS coil structure and magnetic enhancement using a set of magnets and a magnetic enhancement device, either embedded or distributed within the bottom frame, to enhance magnetic sensitivity and stabilize the lens assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a common magnet scheme is used for AF and OIS coils, then the lens driving device becomes compact, but magnetic sensitivity is insufficient for precise AF and OIS functions
Solution Approach 1:
The patent divides the magnet arrangement into two separate magnet sets: one dedicated to the AF coil and another dedicated to the OIS coils. This segmentation allows each magnet set to be optimized for its specific function, improving magnetic sensitivity for both AF and OIS operations while maintaining a compact overall structure through the shared lens barrel integration.
Solution Approach 2:
The patent implements local quality optimization by positioning magnets at specific locations relative to each coil type. The AF magnets are arranged to concentrate flux on the AF coil, while OIS magnets are positioned to concentrate flux on the OIS coils. This localized magnetic field concentration enhances the magnetic sensitivity and driving efficiency for each function independently.
2Volume of moving object
If OIS coils are formed with different lengths or asymmetric configuration, then the device can be compact, but a yawing effect occurs that disrupts displacement sensing
Solution Approach 1:
The patent intentionally introduces asymmetric magnetic pieces with different magnetic strengths on opposite sides of the OIS coil assembly. This controlled asymmetry generates a compensating yawing moment that counteracts the unwanted yawing effect caused by asymmetric coil configurations, thereby maintaining accurate displacement sensing while allowing compact coil design.
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring the asymmetric magnetic pieces to generate counter-yawing forces before the yawing effect disrupts operation. This proactive compensation mechanism prevents displacement sensing errors by continuously balancing the yawing moments throughout the lens assembly's operation range.
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 enables precise auto-focusing and optical image stabilization by concentrating magnetic flux, reducing power consumption, and improving the accuracy of displacement sensing, thereby stabilizing the lens assembly effectively.
Implementation Method 1
The magnetic enhancement device is used to enhance the magnetic sensitivity of the OIS coil structure
Implementation Method 2
a set of optical image stabilization (OIS) coils disposed on a plane having a normal direction perpendicular to the optical axis
Implementation Method 3
at least one magnetic induction element for sensing a magnet signal induced by a displacement of the magnets
Data Source
AI summary
A lens driving device is based on a Voice Coil Actuator (VCA) structure and provides the auto-focusing and optical image stabilization (OIS) functions. These two functions can be realized by a common magnet scheme, or a separate magnet scheme. Also, the present invention provides an improved structure for the lens driving device to enhance the function of OIS thereof. By arranging a magnetic enhancement device below the OIS coils in the lens driving device, the magnetic driving force of the OIS coils and magnetic induction of the Hall sensors, if present, can be enhanced, and the magnetic sensitivity thereof may be also improved.