Magnetic Proximity Sensor Inversion for Sensitivity
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Solution Overview
Problem
Existing magnetic proximity sensors face challenges with high baseline magnetic flux and electronic noise, leading to unreliable detection of ferromagnetic objects, especially when the sensor design requires folding of Hall sensor leads and proximity to the target, which reduces magnet strength and increases dimensions, and is influenced by remnant magnetization.
Innovation Solution
The magnetic proximity sensor design positions the Hall sensor on the side of the magnet assembly, away from the target, allowing for efficient magnetic field distribution and reduced influence from remnant magnetization, with the Hall sensor placed between 2.15 and 2.4 mm from the second pole face to achieve sensitivity greater than 100% of the bias without the need for folded leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Hall sensor is positioned close to the target surface, then the sensitivity is improved, but the baseline magnetic flux and electronic noise increase leading to unreliable detection
Solution Approach 1:
The patent inverts the conventional sensor arrangement by positioning the Hall sensor on the opposite side of the magnet from the target. Instead of placing the sensor close to the target surface, the magnet is positioned between the target and the sensor, with the sensor located on the far side of the magnet. This inversion allows the sensor to detect changes in magnetic flux caused by the target's proximity while maintaining a fixed, optimized distance from the magnet, thereby achieving high sensitivity without the baseline noise problems associated with close proximity positioning.
2Measurement precision
If the Hall sensor leads are folded to position the sensor close to the target, then the sensitivity is improved, but the magnet strength is reduced and sensor dimensions increase
Solution Approach 1:
The patent eliminates the need for folded leads by inverting the sensor arrangement. The Hall sensor is positioned on the far side of the magnet from the target, allowing straight lead connections while maintaining optimal magnetic field interaction. This inversion resolves the contradiction by achieving sensitivity through the magnetic flux changes caused by target proximity rather than through physical proximity of the sensor to the target, thereby preserving magnet strength and avoiding increased sensor dimensions.
3Measurement precision
If the sensor is positioned close to the target, then the detection capability is improved, but the sensor is influenced by remnant magnetization
Solution Approach 1:
The patent introduces the magnet as an intermediary element between the target and the Hall sensor. The magnet serves as a mediator that converts the target's proximity effects into measurable magnetic flux changes at the sensor location. By positioning the magnet between the target and sensor, the system detects target proximity through magnetic field modulation rather than direct sensor-target interaction, thereby eliminating the harmful influence of remnant magnetization on sensor performance.
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 sensitivity and reliability by maintaining strong magnetic field distribution close to the target while minimizing the impact of remnant magnetization and reducing sensor size, allowing for effective detection of ferromagnetic objects with improved signal processing.
Implementation Method 1
a magnetic field sensor such as a Hall sensor element
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
Magnetic proximity sensor, comprising a magnetic sensor element (5), and a magnet assembly (6, 7) having a first pole surface and a second pole surface, wherein the first pole surface of the magnet assembly (6, 7) is positioned adjacent to a sensor target surface of the magnetic proximity sensor, and the sensor element (5) is positioned at a first distance (t) from the second pole surface of the magnet assembly (6, 7) remote from the sensor target surface.