Lens Position Sensing Layout for Closed-Loop Autofocus Modules
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Solution Overview
Problem
Conventional camera modules face difficulties in accurately controlling lens focal length due to the lack of a function to detect the lens position, leading to resonance issues when a shock is applied, corresponding to the resonant frequency of the elastic member.
Innovation Solution
A lens driving device is designed to perform feedback control of auto focus by detecting the lens position, with a sensing magnet and sensor part disposed at a corner to minimize magnetic field interference, allowing for the adjustment of damping force in a closed-loop system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing magnet and sensor part are disposed at a corner part, then magnetic field interference is minimized and lens position detection precision is improved, but the device structure becomes more complex
Solution Approach 1:
The sensing magnet and sensor part are disposed at a corner part of the housing rather than at the center, utilizing the spatial dimension to minimize magnetic field interference between the sensing magnet and driving magnet. This corner disposition arrangement reduces interference while maintaining detection precision.
2Force
If driving magnets are disposed at all four lateral surfaces of housing, then electromagnetic force for auto focus function is enhanced, but the device complexity increases
Solution Approach 1:
The driving magnets are disposed at all four lateral surfaces of the housing, merging multiple electromagnetic force sources to enhance the overall electromagnetic force for the auto focus function. This combination of multiple magnets provides stronger and more balanced driving force.
3Extent of automation
If lens position detection function is added, then auto focus feedback control is enabled, but the outer size of lens driving device increases
Solution Approach 1:
The sensing magnet and sensor part are disposed at a corner part of the housing rather than extending the device outward, utilizing the internal spatial arrangement to enable lens position detection without increasing the outer size of the lens driving device.
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 detection of the lens position, minimizing tilt caused by magnetic field interference, and allows for the realization of a lens position detection function without increasing the outer size of the lens driving device.
Implementation Method 1
a sensing magnet and a sensor part are disposed at a corner part
Implementation Method 2
an elastic member that couples a bobbin and a housing
Data Source
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AI summary
The present embodiment relates to a lens driving device comprising: a housing; a bobbin disposed inside the housing; a coil disposed at the bobbin; a magnet disposed in the housing and facing the coil; an elastic member coupled to the housing and the bobbin; and a damper disposed at the elastic member, wherein the elastic member comprises an outer part coupled to the housing, an inner part coupled to the bobbin, and a connection part for connecting the outer part and the inner part; and the damper is disposed at the connection part.