Autofocus Lens Actuator Magnet Layout to Reduce Field Interference
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Solution Overview
Problem
Existing lens moving apparatuses face challenges in securing adequate AF driving force while minimizing magnetic field interference with adjacent components.
Innovation Solution
A lens moving apparatus design featuring a housing, bobbin, coil, magnet, and yoke configuration with specific recesses and asymmetrical placement to reduce magnetic interference, ensuring stable AF performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the magnet is positioned centrally to maximize AF driving force, then the autofocus driving capability is improved, but magnetic field interference with adjacent lens moving apparatus increases
Solution Approach 1:
The magnet is intentionally positioned asymmetrically with its center line offset from the baseline by a distance K (0 < K ≤ 0.5mm). This asymmetric positioning shifts the magnet away from the center, reducing magnetic field interference with adjacent lens moving apparatus while maintaining sufficient overlap with the coil to preserve adequate AF driving force.
2Force
If the magnet and coil overlap area is increased to enhance driving force, then the AF driving capability is improved, but the magnetic field interference with surrounding components worsens
Solution Approach 1:
The coil is designed with non-uniform winding density, having a first winding density in a first region and a second winding density in a second region. This local variation in winding density allows optimization of the magnetic field distribution, ensuring sufficient driving force where needed while reducing magnetic field strength in regions where interference with adjacent components is a concern.
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 design secures AF driving force and reduces magnetic field interference, enhancing the operational stability and accuracy of autofocus operations.
Implementation Method 1
a coil disposed at the bobbin, a magnet disposed at the side portion of the housing
Data Source
AI summary
An embodiment comprises: a housing; a bobbin disposed in the housing; a coil disposed on the bobbin; a magnet disposed in a side portion of the housing, and including a first side surface facing the coil and a second side surface opposite to the first side surface; and a yoke disposed in the upper portion of the housing and overlapping the magnet in the optical axis direction, wherein: the centerline of the magnet is located on one side with reference to a reference line; a first groove adjoining one end of the first side surface of the magnet is disposed at a first end of the magnet; a second groove adjoining the other end of the first side surface of the magnet is disposed at a second end of the magnet; the reference line passes through the center of the housing and is perpendicular to the outer surface of the side portion of the housing where the magnet is disposed; and the centerline of the magnet is a straight line passing through the center between the first end and the second end of the magnet and perpendicular to the first side surface of the magnet.