VCM Lens Module Position Sensing for Temperature-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, especially in small-scale, low-power devices like smartphones, which are prone to shocks and vibrations.
Innovation Solution
A lens moving apparatus with a bobbin, housing, and position sensors that utilize a combination of magnets and coils to stabilize the magnetic field intensity and compensate for temperature-induced focal length variations, while also incorporating elastic members to absorb shocks and prevent terminal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voice coil motor (VCM) is used in a camera module, then auto-focusing function is achieved, but the magnetic field intensity varies with temperature causing unreliable operation
Solution Approach 1:
The patent implements a feedback mechanism where a position sensor detects the actual position of the lens assembly and feeds this information back to a controller. The controller adjusts the driving signals to the voice coil motor based on the detected position and temperature conditions, creating a closed-loop control system that compensates for temperature-induced magnetic field variations and maintains reliable auto-focusing operation.
Solution Approach 2:
The patent changes operational parameters by introducing temperature compensation algorithms that adjust the driving current or voltage to the voice coil motor based on detected temperature conditions. This parameter adjustment compensates for the temperature-dependent variations in magnetic field intensity, allowing the system to maintain consistent auto-focusing performance across different temperature ranges.
2Volume of moving object
If the camera module is made small-scale for smartphones, then portability is improved, but the module becomes prone to shocks and vibrations
Solution Approach 1:
The patent incorporates damping structures and shock-absorbing materials within the camera module assembly before shocks occur. These pre-installed cushioning elements are designed to absorb and dissipate impact energy and vibration forces, protecting the sensitive lens and sensor components from damage during normal smartphone operation including drops and vibrations.
Solution Approach 2:
The patent introduces intermediary damping structures and shock-absorbing elements that act as mediators between the external shock sources and the internal sensitive components. These intermediary elements absorb and attenuate the harmful effects of shocks and vibrations before they can reach and damage the lens assembly and image sensor.
3Object-affected harmful factors
If terminals are made flexible to absorb shocks, then shock resistance is improved, but terminal strength decreases
Solution Approach 1:
The patent employs composite material structures for the terminal components, combining materials with different mechanical properties. The terminal assembly integrates rigid structural elements for strength with flexible damping materials for shock absorption, creating a composite structure that simultaneously achieves both high strength and excellent shock resistance without compromising either property.
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 reliability of auto-focusing by stabilizing magnetic field intensity and automatically compensating for temperature-induced focal length changes, while also protecting terminal components from damage and vibrations.
Implementation Method 1
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
Implementation Method 3
upper and lower elastic members each coupled to both the bobbin and the housing
Data Source
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.