Hall Sensor Layout for Position Anomaly Detection Under Magnetic Interference
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Solution Overview
Problem
Existing position sensors fail to detect anomalies in multiple movement ranges of a moving body, particularly when both sensors are influenced by an external magnetic field or when an anomaly occurs only in one sensor, leading to incorrect detection.
Innovation Solution
A position sensor configuration using two Hall ICs offset in the magnetic field direction and intersecting direction on a substrate, with amplifiers setting detection values to have a preset relation, allowing for anomaly detection by comparing voltage outputs from both sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two sensors are used to detect positions in multiple movement ranges, then the detection range is improved, but the reliability of anomaly detection deteriorates when both sensors are influenced by external magnetic fields simultaneously
Solution Approach 1:
The patent applies local quality by creating intentional asymmetry in the sensor configuration. The first and second sensors are positioned at different locations with different magnetic flux density characteristics. This means each sensor experiences a different local magnetic environment, so when an external magnetic field interferes, the sensors are affected differently. This local differentiation enables reliable anomaly detection through comparison, while maintaining wide detection range coverage.
2Adaptability or versatility
If sensors are arranged to detect the same signal for redundancy, then the detection coverage is improved, but the ability to detect sensor anomalies deteriorates when anomalies occur in specific sensors
Solution Approach 1:
The patent implements asymmetry by deliberately positioning the first sensor and second sensor at different locations where they experience different magnetic flux densities. Rather than symmetric placement that would make sensors interchangeable, the asymmetric arrangement ensures each sensor has a unique detection characteristic. This allows the system to detect which specific sensor is malfunctioning by comparing their outputs, while both sensors continue to contribute to comprehensive detection coverage.
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 accurate detection of anomalies in the sensor system across various rotation ranges, even under external magnetic field interference, ensuring reliable operation of the position sensor.
Implementation Method 1
a first Hall IC 21 and a second Hall IC 22 that detect directions of magnetic flux generated by the magnet 10
Data Source
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AI summary
A position sensor of the present invention includes: a magnet that moves together with a moving body; a magnetic sensor that detects a magnetic flux generated by the magnet; and a detector that detects an anomaly of the magnetic sensor based on a detection value detected by the magnetic sensor. The magnetic sensor is set so as to detect the detection value taking a value on a locus preset in accordance with a position of the moving body, and the locus is set so that a change rate of the detection value corresponding to change of the position of the moving body differs for each of a plurality of sections set within a movement range of the moving body. The detector detects the anomaly of the magnetic sensor based on a relation between the detection value and a comparison value that is a value corresponding to the locus.