Lens Driving Module Layout for Precise Sensing in Compact VCM Cameras
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Solution Overview
Problem
Existing camera modules face challenges in miniaturization and power efficiency, particularly in applying voice coil motor (VCM) technology to subminiature, low-power camera modules. Additionally, there are issues with board assembly, such as breakage during blanking operations, burr-induced misalignment, and sensor tilting during BGA mounting.
Innovation Solution
A lens moving apparatus is designed with a housing, a bobbin, magnets, a coil, and a sensing magnet. The bobbin has a projection that houses the sensing magnet, increasing coupling force and reducing magnetic field interference. This design also addresses board assembly issues by minimizing breakage, aligning boards correctly despite burrs, and preventing sensor tilting during mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing magnet is disposed closer 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 patent positions the sensing magnet at a corner portion of the bobbin, utilizing the three-dimensional space within the housing. By placing the sensing magnet at the corner rather than directly adjacent to the position sensor on the same plane, the design achieves close proximity for accurate detection while spatial separation reduces magnetic field interference with the drive magnets located at opposite corners.
2Volume of moving object
If the bobbin size is reduced to achieve miniaturization of the camera module, then volume of moving object is reduced, but the coupling force between the bobbin and sensing magnet decreases
Solution Approach 1:
The patent concentrates the sensing magnet at a specific corner portion of the bobbin rather than distributing it across the entire bobbin surface. This localized placement creates a strong, concentrated magnetic field interaction point, maximizing the coupling force between the sensing magnet and position sensor while maintaining a compact bobbin size. The corner positioning optimizes the local magnetic coupling efficiency.
3Ease of operation
If the board is inserted into the housing pocket during assembly, then ease of operation is improved, but burrs on the board cause misalignment and assembly difficulty
Solution Approach 1:
The patent incorporates a guide groove in the housing that receives a guide protrusion on the board during assembly. This guide structure is designed in advance to accommodate and compensate for burrs on the board edges. The guide groove acts as a cushioning feature that allows the board to be inserted smoothly into the correct position despite the presence of burrs, preventing misalignment and facilitating easy 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 the coupling force between the bobbin and the sensing magnet, reduces magnetic field interference, and improves the assembly process by reducing board breakage, ensuring proper alignment, and preventing sensor tilting. This results in a more efficient and reliable camera module.
Implementation Method 1
a coil (120) disposed at the bobbin (110) so as to face the magnet (130), wherein the coil (120) is configured to generate an electromagnetic force through an electromagnetic interaction between the coil (120) and the magnet (130)
Implementation Method 2
a circuit board (190), which is disposed on one surface of the housing (140) and includes a position sensor (170), and a sensing magnet (180) disposed at the bobbin (110) so as to face the position sensor (170)
Data Source
AI summary
A lens driving assembly includes a housing having a first corner part and a second corner part opposite to the first corner part; a bobbin disposed in the housing; a magnet including 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. 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.