Magnetic Position Detector for Long Stroke Camera Modules
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Solution Overview
Problem
Current magnetic position sensing techniques struggle to achieve high accuracy over long stroke movements in camera modules, such as smartphone periscope cameras, due to limitations in Hall sensor configurations and interference from external magnetic fields, leading to ambiguity issues and reduced working ranges.
Innovation Solution
A magnetic position detector arrangement using multiple small magnets and magnetic sensing elements positioned at optimized distances to maximize signal distinction and avoid ambiguity, with a processing unit determining displacement through unique signal combinations, allowing for precise absolute positioning over extended strokes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Hall sensor configurations are used, then the device complexity is low, but the measurement precision deteriorates over long stroke movements
Solution Approach 1:
The patent divides the sensing system into multiple discrete components: at least two magnets are positioned at different locations, and at least two magnetic sensing elements are arranged at specific distances from each other. This segmentation allows the system to distinguish between different positions along the stroke by detecting unique magnetic field patterns from multiple sources, thereby achieving high positioning accuracy over long distances without requiring a single complex sensor.
Solution Approach 2:
The patent introduces spatial dimensionality by positioning magnets and sensing elements at optimized distances from each other in three-dimensional space. The sensing elements are arranged at specific distances not only from the magnets but also from each other, creating a multi-dimensional sensing geometry. This dimensional arrangement enables the system to resolve positional ambiguity by detecting the combined magnetic field signatures from multiple perspectives, achieving long-stroke measurement precision.
2Length of moving object
If the distance between sensing elements is increased to cover longer stroke, then the stroke range is improved, but the signal distinction and measurement accuracy deteriorate
Solution Approach 1:
Instead of using a single sensing element that would require large spacing to cover long strokes, the patent segments the sensing function across multiple elements. Each sensing element detects magnetic fields from multiple magnets, and the combined signals from spaced-apart elements create a distinctive pattern for each position. This segmentation allows the system to maintain signal distinction even when elements are spaced to cover extended stroke ranges.
Solution Approach 2:
The patent creates a composite sensing system by combining outputs from multiple magnetic sensing elements into a unified position measurement. The processing unit integrates signals from multiple sensors that are positioned at optimized distances, effectively creating a composite measurement that maintains high signal distinction across the entire stroke range. This composite approach allows the system to achieve both long stroke coverage and high measurement precision simultaneously.
3Measurement precision
If multiple magnets and sensing elements are used to improve accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent segments both the magnetic field sources (multiple magnets) and the detection system (multiple sensing elements) into discrete, modular units. This segmentation allows for flexible configuration where the number and arrangement of magnets and sensors can be optimized for specific applications. The segmented architecture achieves high positioning accuracy through multiple independent measurement points while maintaining manageable device complexity through modular design.
Solution Approach 2:
The patent creates a universal positioning system where multiple magnets and sensing elements serve dual purposes: each magnet contributes to the magnetic field pattern for position detection, and each sensing element participates in detecting fields from multiple magnets. This multi-functionality means that adding components increases both the measurement capability and the coverage range simultaneously, achieving high positioning accuracy without proportionally increasing overall system complexity.
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
This solution enables accurate absolute positioning of lens elements with high precision (0.1% accuracy) over long strokes, such as 4-15mm, by minimizing ambiguity points and enhancing signal separation, thus improving zoom quality in smartphone cameras.
Implementation Method 1
at least two magnetic sensing elements Hj positioned on the first structural element 1 at a mutual sensor distance d along the first axis A, at least two magnets Mi positioned on the second structural element 2 at a mutual magnet distance a along the first axis A
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
Magnetic position detector arrangement for measuring a displacement along a first axis (A), having a first structural element (1) and a second structural element (2) moveable with respect to each other along the first axis (A), and positioned at a mutual distance (h) perpendicular to the first axis (A). At least two magnetic sensing elements (Hj) are positioned on the first structural element (1) at a mutual sensor distance (d) along the first axis (A). At least two magnets (Mi) are positioned on the second structural element (2) at a mutual magnet distance (a) along the first axis (A). A processing unit (5) is connected to the at least two magnetic sensing elements (Hj), and arranged to determine the displacement along the first axis (A) using sensor signals (Sj) from the at least two magnetic sensing elements (Hj).