Magnetic Sensor Differential Detection via High-Permeability Link
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Solution Overview
Problem
Existing magnetic-field detecting devices face challenges in accurately isolating minute magnetic fields generated by subjects from external magnetic fields, particularly terrestrial magnetism, due to the risk of both sensors detecting the subject's magnetic field when placed close together.
Innovation Solution
A magnetic-field detecting device comprising a pair of magneto-sensors with a connecting member made of high permeability magnetic material, allowing both sensors to equally sense external magnetic fields and detect the subject's field by differential operation, with features like amorphous wire connecting members and shielding to reduce noise and enhance resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both sensors are placed close together to detect minute magnetic fields, then detection sensitivity is improved, but both sensors detect external magnetic fields equally causing inability to isolate subject's magnetic field
Solution Approach 1:
The sensor system is segmented into two functionally distinct sensors: a first sensor that detects both external and subject magnetic fields, and a second sensor that detects only external magnetic fields. This segmentation allows differential processing to isolate the subject's magnetic field while maintaining close proximity for high sensitivity detection.
Solution Approach 2:
A magnetic connecting member made of high-permeability magnetic material is introduced as an intermediary between the two sensors. This connecting member equally couples both sensors to external magnetic fields while allowing the first sensor to also detect the subject's magnetic field, enabling differential measurement to isolate the subject's field contribution.
2Loss of information
If sensors are placed far apart to avoid detecting subject's magnetic field simultaneously, then external field cancellation is improved, but detection sensitivity decreases
Solution Approach 1:
The sensor system is segmented into two functionally distinct sensors: a first sensor that detects both external and subject magnetic fields, and a second sensor that detects only external magnetic fields. This segmentation allows differential processing to isolate the subject's magnetic field while maintaining close proximity for high sensitivity detection.
Solution Approach 2:
The local quality of each sensor's detection capability is differentiated: the first sensor is positioned and configured to detect both external and subject magnetic fields, while the second sensor is configured to detect only external magnetic fields. This local differentiation enables effective differential measurement for isolating the subject's magnetic field.
3Measurement precision
If high permeability magnetic material is used for connecting member, then both sensors equally sense external magnetic fields, but noise from terrestrial magnetism increases
Solution Approach 1:
The system uses feedback through differential processing: the output of the second sensor (detecting only external fields) is subtracted from the output of the first sensor (detecting both external and subject fields). This feedback mechanism cancels out the terrestrial magnetism noise that is equally present in both sensors, leaving only the subject's magnetic field signal.
Solution Approach 2:
The terrestrial magnetism noise, which initially appears as a harmful factor, is converted into a benefit through differential measurement. Since both sensors equally sense the terrestrial magnetism through the high-permeability connecting member, subtracting their outputs cancels the noise while preserving the subject's magnetic field signal.
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 device effectively isolates and accurately detects minute magnetic fields by equally subjecting both sensors to external fields, reducing noise and improving resolution, enabling high-sensitivity detection of magnetic signals with reduced external interference.
Implementation Method 1
the connecting member being formed of a magnetic material having a relative magnetic permeability of at least 100
Implementation Method 2
respective coils for sensing changes of magnetic fluxes in the magnetism sensing portions
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Providing a magnetic-field detecting device which has a plurality of sensors the outputs of which are subjected to a differential operation, and which permits accurate detection of a magnetic field. The magnetic-field detecting device 10 is configured such that magnetism sensing portions of a pair of magneto-sensors 12 are connected in series to each other within a magnetic circuit, by a connecting member 14 which is formed of a magnetic material having a relative magnetic permeability of at least 100, a magnetic material having a relative magnetic permeability which is at least 1/100 of that of a magnetic material of the magnetism sensing portions, or the same magnetic material as the magnetism sensing portions of the sensors 12. Accordingly, both of the sensors 12 are equally subjected to an external magnetic field such as an environmental magnetic field and a magnetic background noise, and are able to detect the external magnetic field. The measuring sensor 12a is provided to detect the magnetic field generated by a subject 50, and a difference of an output of the measuring sensor 12a with respect to an output of the reference sensor 12b is obtained so as to reduce an influence of the external magnetic field, so that only the magnetic field generated by the subject 50 can be accurately detected.