Lens Moving Module with Dual-Magnet Position Sensing for Stable Autofocus
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Solution Overview
Problem
Existing camera modules face challenges in maintaining reliable auto-focusing and preventing terminal damage due to variations in magnetic field intensity caused by temperature changes, and are prone to mechanical stress from user handling.
Innovation Solution
A lens moving apparatus with a bobbin, first and second magnets, and a position sensor that detects the sum of magnetic field intensities to compensate for temperature-induced variations and secure terminal connections, using elastic members and coils for precise movement control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnet is used for auto-focusing, then the structure is simple, but the magnetic field intensity varies with temperature causing unreliable operation
Solution Approach 1:
The single magnet is divided into two separate magnets (first magnet and second magnet) positioned at different locations. The position sensor detects the sum of magnetic field intensities from both magnets, which compensates for temperature-induced variations and maintains reliable auto-focusing operation without increasing overall system complexity.
Solution Approach 2:
A position sensor is introduced to detect the sum of magnetic field intensities from the two magnets. This feedback mechanism allows the system to monitor and compensate for temperature variations, ensuring consistent auto-focusing performance while maintaining a relatively simple structure.
2Measurement precision
If the position sensor is placed close to the coil for detection, then detection sensitivity is high, but the sensor is affected by temperature-induced magnetic field variations
Solution Approach 1:
A magnetic flux shield is introduced as an intermediary between the position sensor and the first coil. This shield blocks the magnetic flux generated by the first coil from reaching the position sensor, preventing temperature-induced variations in the coil's magnetic field from affecting sensor readings, while the sensor still accurately detects the magnetic field intensities from the two magnets.
3Strength
If rigid connections are used for terminal mounting, then structural strength is high, but cracks occur in terminals due to mechanical stress from handling
Solution Approach 1:
Elastic members are used to provide flexible, shock-absorbing connections between the terminal and the circuit board. These elastic members can deform under mechanical stress from hand shaking or drops, preventing crack formation in the terminals while maintaining secure electrical connections, thus improving both strength and reliability.
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 enhances the reliability of auto-focusing by stabilizing magnetic field intensity and prevents terminal damage through precise magnetic field detection and compensation, ensuring consistent performance and durability.
Implementation Method 1
a first coil disposed on an outer circumferential surface of a bobbin, a housing provided with first and second magnets for moving the bobbin by interaction with the first coil
Implementation Method 2
a first position sensor for detecting a sum of intensities of magnetic fields of the first and second magnets
Data Source
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AI summary
Embodiments provide a lens moving apparatus including a bobbin including a first coil disposed on an outer circumferential surface thereof, a housing provided with first and second magnets for moving the bobbin by interaction with the first coil, upper and lower elastic members each coupled to both the bobbin and the housing, and a first position sensor for detecting a sum of intensities of magnetic fields of the first and second magnets, wherein the first position sensor is disposed in a space between the first magnet and the second magnet when the bobbin is disposed at an initial position.