Leaning Magnet Displacement Sensing for Long-Range Accuracy
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Solution Overview
Problem
Existing magnet displacement sensing systems are limited by the size of the magnet, which affects resolution and accuracy, especially for longer displacements, and complex magnet designs are difficult to manufacture and acquire.
Innovation Solution
A system using a magnet with magnetization direction perpendicular to its major surface, oriented at an angle to the displacement direction, allowing for sensing of long displacements with good accuracy using a differential sensor that is immune to stray fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the size of the magnet is increased to sense longer displacements, then the maximum displacement sensing range is improved, but the magnetic field spreads out causing slower variation over distance which degrades resolution and accuracy
Solution Approach 1:
The patent changes the magnetization direction parameter from longitudinal (parallel to displacement) to transverse (perpendicular to displacement). This parameter change allows the magnetic field to vary more rapidly with displacement while using a longer magnet, thereby maintaining high resolution and accuracy over extended sensing ranges.
Solution Approach 2:
The patent transitions from sensing displacement in the same dimension as magnetization (longitudinal) to sensing displacement perpendicular to the magnetization direction (transverse). This dimensional change enables the magnetic field gradient to be more sensitive to displacement while using a longer magnet structure.
2Length of moving object
If a magnet with complex multipole design is used to sense longer displacements, then the displacement sensing range is improved, but the manufacturing complexity and acquisition difficulty increase significantly
Solution Approach 1:
The patent changes the magnetization configuration from complex multipole patterns to a simple uniform transverse magnetization. This parameter simplification maintains the capability to sense long displacements while dramatically reducing manufacturing complexity and making the magnet easier to acquire.
3Reliability
If a differential sensor is used to achieve immunity against stray magnetic fields, then the sensor's immunity to stray fields is improved, but the sensor becomes more impacted by magnetic field dilution limiting practical displacement sensing to 20-30 mm
Solution Approach 1:
The patent changes the magnetization direction parameter in the differential sensor configuration from longitudinal to transverse. This parameter change creates a magnetic field configuration where the field gradient is more sensitive to displacement while maintaining the differential sensor's stray field immunity, thereby extending the practical sensing range beyond 20-30 mm.
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
Enables sensing of large displacements with high accuracy and simplicity, using easily procurable magnets and sensors that are resistant to stray fields.
Implementation Method 1
a sensor for measuring a first magnetic field component Bu along a direction u, and a second magnetic field component Bz along a direction z
Data Source
AI summary
In a first aspect, the present invention relates to a system for sensing a displacement (d) along a direction y of a magnet relative to a sensor, comprising: (i) a sensor for measuring a first magnetic field component Bu along a direction u, and a second magnetic field component Bz along a direction z, substantially orthogonal to u and y; and (ii) a magnet above the sensor in the z-direction, the magnet having a magnetization direction substantially perpendicular to a major surface of the magnet, substantially perpendicular to the z-direction and different from the y-direction.