Lens Moving Assembly with Offset Hall Sensing for Autofocus
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Solution Overview
Problem
Conventional camera modules face challenges in miniaturization and accurate sensing due to complex structures and interference from multiple magnetic devices, which affect the accuracy of handshake correction and autofocusing in compact camera modules.
Innovation Solution
A lens moving apparatus with a first lens moving unit for autofocusing and a second lens moving unit for handshake correction, utilizing a bobbin, coil units, and magnets to minimize interference, and a sensor to accurately detect displacement, ensuring precise movement and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple magnetic devices are used for autofocusing and handshake correction, then the camera module achieves comprehensive lens control, but magnetic interference deteriorates sensing accuracy
Solution Approach 1:
The patent divides the magnetic field generation and sensing functions into spatially separated components. The first coil unit for autofocusing and the second coil unit for handshake correction are positioned at different locations, creating distinct magnetic field zones. This segmentation allows each sensing device to operate in its own magnetic environment, reducing cross-interference while maintaining comprehensive lens control capability.
Solution Approach 2:
The patent introduces magnetic shielding structures as intermediary elements between the magnetic devices and sensing devices. These shielding components act as mediators that redirect or contain magnetic field lines, preventing unwanted magnetic interference from reaching the Hall sensors. This allows the magnetic devices to generate strong fields for lens control while protecting the sensing accuracy.
2Volume of moving object
If the camera module is miniaturized for small electronic devices, then it becomes suitable for smartphones, but accurate sensing becomes more difficult due to limited space and increased interference
Solution Approach 1:
The patent employs a nested arrangement where the sensing device is positioned within the magnetic field generation region but at a specific depth where magnetic interference is minimized. The Hall sensor is located between the magnet and the coil units, creating a nested configuration that allows compact packaging while maintaining sensing accuracy through careful positional optimization.
Solution Approach 2:
The patent resolves spatial conflicts by utilizing the depth dimension (z-axis) to separate magnetic field generation and sensing functions. Instead of only lateral separation in the x-y plane, the design positions components at different depths along the optical axis, allowing the sensing device to operate in a magnetic field zone that is optimized for accuracy while maintaining compact overall module dimensions.
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 achieves accurate displacement detection and minimizes interference, enabling effective optical image stabilization and autofocusing in compact camera modules, suitable for small electronic devices like smartphones.
Implementation Method 1
a sensor, which is a Hall sensor, is provided at the lens barrel or at the housing, and the sensor detects the displacement of the lens barrel by sensing the magnetic force of the magnet
Implementation Method 2
a first coil unit, which interacts with the magnet with respect to the optical axis direction, is provided at the lens barrel or at the housing, and a second coil unit, which interacts with the magnet with respect to the first direction, is provided at the lens barrel or at the housing
Data Source
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AI summary
A lens moving apparatus includes a bobbin including a first coil, a first magnet facing the first coil, a housing supporting the first magnet, upper and lower elastic members coupled to the bobbin and the housing, a base spaced apart from the housing, a second coil unit, which faces the first magnet and includes a second coil, a circuit board on which the second coil unit is mounted, a plurality of support members, which support the housing such that the housing is movable in second and/or third directions and which connect at least one of the upper and lower elastic members to the circuit board, and a second sensor detecting displacement of the housing in the second and/or third directions, wherein the center of the second sensor is disposed so as not to overlap the second coil.