Differential Magnetic Sensor Sensitivity Equalization
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Solution Overview
Problem
Conventional differential type magnetic sensors face challenges in accurately measuring local weak magnetic fields due to sensitivity differences between magneto-impedance elements, leading to residual background magnetic field components that obscure the signal of interest, particularly in environments with significant background noise like geomagnetism or industrial settings.
Innovation Solution
Incorporating a signal adjusting means to equalize the detection sensitivities of magneto-impedance sensors by adjusting the driving current and signal processing gains, ensuring that the magnetic field signal voltages from both sensors are of the same level when exposed to equal external magnetic field intensities, thereby canceling out common background magnetic field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two magneto-impedance sensors are used for differential measurement to eliminate background magnetic field components, then the ability to detect local weak magnetic fields is improved, but sensitivity differences between the two sensors cause residual background magnetic field components to remain
Solution Approach 1:
The patent applies preliminary action by adjusting the detection sensitivities of the two magneto-impedance sensors before the differential measurement is performed. A sensitivity adjustment unit equalizes the sensitivities of both sensors in advance, ensuring that when the differential operation is performed, the background magnetic field components are completely eliminated. This preliminary sensitivity equalization prevents residual background noise from affecting the measurement of local weak magnetic fields.
2Measurement precision
If the detection sensitivities of two magneto-impedance sensors are made equal through strict production control, then measurement precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by introducing adjustable sensitivity parameters through the sensitivity adjustment unit. Instead of requiring strict control of manufacturing parameters to achieve equal sensitivities, the system allows post-manufacturing adjustment of sensitivity parameters. This converts a manufacturing precision problem into a programmable parameter adjustment problem, significantly reducing production complexity while maintaining high measurement precision.
Solution Approach 2:
The sensitivity adjustment unit acts as an intermediary between the two magneto-impedance sensors and the differential operation unit. It mediates the sensitivity differences by equalizing the output signals from both sensors before they undergo differential processing. This intermediary component simplifies the overall system by handling sensitivity matching electronically rather than requiring complex manufacturing controls.
3Measurement precision
If signal processing is performed to equalize sensitivity differences, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The sensitivity adjustment unit is designed with multi-functionality, serving both as a sensitivity equalization device and as part of the overall signal processing chain. By integrating the sensitivity adjustment function into a unified processing unit, the patent avoids adding separate complex signal processing subsystems. The same unit that adjusts sensitivity also prepares signals for differential operation, reducing overall device complexity while maintaining high measurement 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 approach allows for precise detection of local weak magnetic fields by minimizing the impact of background noise, enhancing the sensitivity and accuracy of the magnetic sensor without the need for costly and time-consuming production processes to match sensor sensitivities.
Implementation Method 1
the magneto-impedance sensor uses, as a magneto-sensitive body, an amorphous wire or a thin film body and thereby can constitute a magneto-impedance element... a pulse current or a high-frequency current is supplied to the magneto-sensitive body such as the amorphous wire so as to realize about a magneto-impedance effect in the amorphous wire
Data Source
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AI summary
(Subject) To provide a differential magnetic sensor capable of accurate magnetic detection of a local weak magnetic field even when there is a difference in detection sensitivity of a plurality of magnetic sensors used as a differential type magnetic sensor. (Means for solving) The differential type magnetic sensor comprises a driving circuit 2 for outputting driving currents, two magnetic detecting means E10, E20 including two magneto-impedance elements comprising two magneto-sensitive bodies which are disposed at two distant points and wherein the magnetic field signal voltages are generated in response to two external magnetic fields intensities around the two magneto-sensitive bodies to which the driving currents are applied and a differential operating means 5 for operating a difference signal voltage between the two magnetic field signal voltages output from the magnetic detecting means and for outputting the difference signal voltage between the two external magnetic field intensities, and further comprises a signal adjusting means which is interposed between the driving circuit 2 and the differential operating means and adjust the two magnetic field signal voltages output based on the two magneto-sensitive bodies having different detection sensitivities such that the detection sensitivities of the two magnetic detection means are considered to be roughly the same as each other.