Lens Moving Assembly With Integrated Position Sensing for Stable Autofocus
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Solution Overview
Problem
Conventional Voice Coil Motor (VCM) technology is difficult to apply to subminiature camera modules due to challenges in miniaturization, handshake prevention, and accurate focusing, especially in small electronic devices like smartphones, where camera modules are prone to shocks and require complex configurations.
Innovation Solution
A lens moving apparatus with a bobbin, first and second coils, magnets, position sensors, and elastic members that allow for miniaturization and low-cost assembly, while ensuring accurate focusing and handshake prevention by electromagnetic interaction and sensor feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If VCM technology is applied to subminiature camera modules, then focusing function is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines the VCM actuator and position sensor into an integrated assembly where the sensor is mounted directly on the bobbin structure. This merging reduces the number of separate components and simplifies the overall device complexity while maintaining the automated focusing function.
Solution Approach 2:
The bobbin structure serves multiple functions: it acts as the mounting platform for the coil, supports the position sensor, provides magnetic shielding, and serves as part of the mechanical actuation system. This multi-functionality reduces the need for additional separate components.
2Reliability
If handshake prevention device is added to camera module, then reliability is improved, but device complexity increases
Solution Approach 1:
The handshake prevention sensor is integrated into the same bobbin structure that houses the focusing sensor and VCM components. By merging multiple sensing functions into a single integrated platform, the patent reduces configuration complexity while maintaining reliability through comprehensive vibration and position monitoring.
3Measurement precision
If position sensor is placed near first coil, then measurement precision is improved, but harmful magnetic field interference increases
Solution Approach 1:
The patent introduces a magnetic shield (typically made of ferrite or other magnetic shielding material) positioned between the first coil and the position sensor. This intermediary element redirects or contains the magnetic field lines, allowing the sensor to accurately detect position while protecting it from harmful high-frequency magnetic interference generated by the coil during operation.
4Volume of moving object
If camera module is miniaturized, then productivity and adaptability are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent integrates multiple components (VCM coil, position sensor, magnetic shield, and mounting structures) into a single integrated bobbin assembly. This merging approach reduces the number of separate parts that need to be assembled, thereby lowering cumulative assembly errors and making miniaturization more achievable while maintaining manufacturing precision.
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 apparatus enables miniaturization, reduces costs, and enhances the fixing ability of the bobbin and sensor board, preventing handshake-induced malfunctions and ensuring precise focusing in subminiature camera modules.
Implementation Method 1
a second magnet disposed so as to be opposite to the first coil, the second magnet being configured to move the bobbin in a direction parallel to an optical axis via electromagnetic interaction with the first coil
Implementation Method 2
a first position sensor disposed on the outer circumferential surface of the bobbin and spaced apart from the first coil, a first magnet disposed so as to be opposite to the first position sensor
Data Source
AI summary
An embodiment includes a bobbin provided at an outer circumferential surface thereof with a first coil, a first position sensor disposed on the outer circumferential surface of the bobbin and spaced apart from the first coil, a first magnet disposed so as to be opposite to the first position sensor, a second magnet disposed so as to be opposite to the first coil, the second magnet being configured to move the bobbin in a direction parallel to an optical axis via electromagnetic interaction with the first coil, a housing configured to support the first magnet and the second magnet; and upper and lower elastic members coupled to the bobbin and the housing, wherein the first position sensor is moved along with the bobbin.