Lens Driver Bobbin Projection for Precise Sensor Magnet Positioning
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Solution Overview
Problem
Existing camera modules face challenges in miniaturization and performance enhancement, particularly in subminiature, low-power applications, where voice coil motors (VCM) are difficult to apply, and there are issues with board assembly and sensor positioning due to blanking jig-induced breakage, burrs, and tilting during mounting on BGA.
Innovation Solution
A lens moving apparatus with a housing featuring corner magnets and a bobbin with a projection for the sensing magnet, which increases coupling force and reduces magnetic field interference, and includes a circuit board with a position sensor to improve assembly and reduce processing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing magnet is disposed close to the position sensor to improve detection precision, then measurement precision is improved, but magnetic field interference between the sensing magnet and drive magnets increases
Solution Approach 1:
The sensing magnet is positioned in a projection of the bobbin that extends toward the position sensor, utilizing three-dimensional spatial arrangement to achieve close proximity for improved detection precision while maintaining separation from the drive magnets at corner portions to avoid magnetic field interference
2Volume of moving object
If the bobbin and sensing magnet are miniaturized to reduce camera module size, then volume of moving object is reduced, but coupling force between bobbin and sensing magnet decreases
Solution Approach 1:
The sensing magnet is positioned in a projection of the bobbin, concentrating the magnetic coupling in a specific localized region. This projection structure optimizes the local magnetic field distribution and coupling efficiency, allowing strong coupling force despite miniaturization of the overall camera module
3Productivity
If boards are supplied in array state and blanked to improve productivity, then productivity is improved, but board and sensor breakage occurs due to blanking jig
Solution Approach 1:
The circuit board is designed with a groove that receives the projection of the bobbin before final assembly. This preliminary structural arrangement ensures proper positioning and prevents breakage during the blanking process by providing structural support and correct alignment
4Ease of operation
If the board is inserted into pocket and assembled to improve ease of operation, then ease of operation is improved, but assembly difficulty arises due to burrs and misalignment
Solution Approach 1:
The groove in the circuit board acts as an intermediary structure that receives the projection of the bobbin. This intermediate feature guides proper alignment and accommodates burrs, facilitating easy insertion of the board into the pocket while ensuring correct positioning during assembly
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 enhances coupling force between the bobbin and sensing magnet, minimizes board and sensor breakage, and improves assembly ease by positioning the board correctly, even with burrs, and reduces magnetic field interference, leading to improved productivity and accuracy in camera module assembly.
Implementation Method 1
a coil disposed at the bobbin so as to face the magnet
Implementation Method 2
a sensing magnet disposed at the bobbin so as to face the position sensor
Data Source
AI summary
An embodiment comprises: a housing comprising a first corner part and a second corner part opposite to the first corner part; a bobbin disposed in the housing; a magnet comprising a first magnet disposed in the first corner part of the housing and a second magnet disposed in the second corner part of the housing; a coil disposed on the bobbin and opposite to the magnet; a circuit board disposed on one surface of the housing and including a position sensor; and a sensing magnet disposed in the bobbin and opposite to the position sensor, wherein a protrusion part is formed to protrude from one surface of the bobbin, opposite to one surface of the housing, toward the one surface of the housing, and the sensing magnet is at least partially placed within the protrusion part of the bobbin.