Angular Magnetic Field Sensor with Orthogonal Sensing Clusters
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Solution Overview
Problem
Magnetic field sensors face interference from external magnetic fields, leading to reduced accuracy and errors in detecting rotational positions due to common mode noise.
Innovation Solution
The system employs multiple magnetic field sensing elements with orthogonal axes of sensitivity, arranged in sensing clusters, which calculate the rotational position by processing signals from these elements, using arctangent calculations and difference circuits to reject external noise, thereby reducing susceptibility to external magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic field sensor is used to detect rotational position, then rotational position can be determined, but external magnetic fields introduce common mode noise that reduces accuracy
Solution Approach 1:
The sensor system is divided into multiple sensing elements (first and second magnetic field sensing elements) with different sensitivity orientations. Each element detects magnetic field components along different axes, allowing the system to segment the measurement process and combine results to reject common mode noise from external fields.
Solution Approach 2:
The patent changes the sensitivity parameter of the sensing elements by orienting them at different angles (orthogonal orientations). The first sensing element has maximum sensitivity along a first axis while the second has maximum sensitivity along a second axis perpendicular to the first. This parameter variation allows differential measurement that eliminates external field interference.
2Measurement precision
If multiple magnetic field sensing elements with orthogonal sensitivity axes are used, then external noise is rejected and accuracy is improved, but device complexity increases
Solution Approach 1:
The sensor is segmented into multiple sensing elements with distinct sensitivity axes, where each element handles a specific component of the magnetic field measurement. This segmentation enables noise rejection through differential measurement while maintaining a relatively simple overall structure.
Solution Approach 2:
The multiple sensing elements serve dual purposes: they individually detect magnetic field components and collectively enable common mode noise rejection. The orthogonal arrangement allows the same basic sensing element design to be reused with different orientations, reducing design complexity while achieving improved accuracy.
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 configuration enhances the accuracy of rotational position detection by eliminating common mode noise from external fields, ensuring precise calculation of the target's rotational angle.
Implementation Method 1
At least one of the plurality of magnetic field sensing elements may be a Hall effect element
Implementation Method 2
At least one of the plurality of magnetic field sensing elements may be a magnetoresistance element
Data Source
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AI summary
A system for detecting a magnetic target includes a magnetic field sensor comprising two or more sensing clusters positioned on a surface of a substrate; and a magnetic target comprising at least four magnetic quadrants spaced evenly around a center point of the magnetic target. The at least four magnetic quadrants have alternating magnetic polarities. The two or more sensing clusters are positioned evenly around the axis of rotation so that each of the sensing clusters detects a magnetic field of two magnetic quadrants that have the same magnetic polarity.