Hall Sensor Magnet Assembly for Large-Stroke Linear Sensing
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Solution Overview
Problem
Existing position sensing units in compact digital cameras, such as those in smartphones, struggle to support large lens strokes and achieve sufficiently steep slopes, limiting their ability to focus on short object-to-image distances and accommodate large zoom factors.
Innovation Solution
A position sensing unit comprising a magnetic assembly with multiple magnets having distinct polarizations and a magnetic flux measuring device, allowing for a stroke length of 1 mm to 100 mm with a minimum L/D ratio greater than 10, and achieving slopes greater than 10 mT/mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional magnet assembly with two rectangular magnets is used, then the slope S is sufficiently steep, but the linear range L/D is relatively small
Solution Approach 1:
The magnet assembly is divided into multiple rectangular magnets (at least three) with different polarizations arranged in specific patterns. This segmentation allows the magnetic field to be distributed in a way that simultaneously achieves steep slope and extended linear range, resolving the contradiction between measurement precision and stroke length
Solution Approach 2:
Different regions of the magnet assembly have different magnetic polarizations tailored to specific functional requirements. The first, second, and third rectangular magnets have different polarizations optimized for their local positions, creating a magnetic field distribution that maintains steep slope in critical regions while extending the overall linear range
2Length of moving object
If a single rectangular magnet is used, then the linear range L/D can be relatively large, but the slope S is not sufficiently steep
Solution Approach 1:
The single magnet is replaced by multiple segmented magnets with different polarizations. This segmentation enables the system to achieve both large linear range (through extended magnet arrangement) and sufficiently steep slope (through optimized polarization distribution across segments)
Solution Approach 2:
The magnet assembly uses composite magnetic structures with different polarization orientations. By combining multiple magnets with different magnetic polarizations, the system achieves a composite magnetic field that simultaneously provides extended linear range and maintains the required slope threshold
3Volume of moving object
If the magnet assembly moves within a small stroke, then the device remains compact, but it cannot support large zoom factors or macro photography
Solution Approach 1:
The magnet assembly is designed to move dynamically within an extended linear range while maintaining compact overall device dimensions. The optimized magnetic field distribution allows the system to accommodate large stroke movements (for zoom and macro functions) without proportionally increasing the device volume
Solution Approach 2:
The system changes magnetic field parameters (through multiple magnets with different polarizations) to enable extended stroke capability. This allows the device to achieve large zoom factors and macro photography functionality without requiring a proportional increase in overall device size
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 enables stable and precise position sensing over large strokes, supporting advanced camera functionalities like telephoto and macro photography with high zoom factors and object-to-image magnifications.
Implementation Method 1
MA 102 causes a magnetic field 108 in its surroundings
Implementation Method 2
a magnetic flux measuring device (MFMD) for example a Hall sensor
Data Source
AI summary
Position sensing units, comprising a magnetic assembly (MA) having a width W measured along a first direction and a height H measured along a second direction and including at least three magnets having respective magnetic polarizations that define along the first direction at least a left MA domain, a middle MA domain and a right MA domain, wherein the magnetic polarizations of each MA domain are different, and a magnetic flux measuring device (MFMD) for measuring a magnetic flux B, wherein the MA moves relative to the MFMD along the first direction within a stroke L that fulfils 1 mm≤L≤100 mm, stroke L beginning at a first point x0 and ending at a final point xmax, and wherein a minimum value Dmin of an orthogonal distance D, measured along the second direction between a particular MA domain and the MFMD, fulfills L/Dmin>10.