Magnetic Field Detection Device Modulation Coil Noise Reduction
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Solution Overview
Problem
Current magnetic field detection devices face limitations in achieving high detection resolution due to interference from 1/f noise and the inability to accurately measure weak magnetic fields.
Innovation Solution
A magnetic field detection device incorporating a modulation coil that applies an alternating current magnetic field orthogonal to the sensitivity axis of magnetic field detection elements, combined with a demodulator featuring a high-pass filter, phase detection circuit, and analog-to-digital conversion, effectively modulates sensitivity and removes 1/f noise to enhance detection resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a giant magneto-resistive effect element is used for magnetic field detection, then detection resolution is improved, but 1/f noise interference increases and weak magnetic field measurement accuracy deteriorates
Solution Approach 1:
The patent applies a periodic alternating current magnetic field with frequency f to the magnetic field detection element. This periodic excitation modulates the output signal to frequency f, allowing the use of narrowband filtering at frequency f to reject 1/f noise while preserving the measurement signal, thereby resolving the contradiction between detection resolution and noise interference
Solution Approach 2:
The patent changes the operating parameters by applying an alternating current magnetic field at a specific frequency f rather than using direct current. This parameter change transforms the detection mechanism to operate in a frequency domain where 1/f noise can be effectively filtered out, improving weak magnetic field measurement accuracy while maintaining detection resolution
2Measurement precision
If conventional magnetic field detection methods are used, then device structure is simple, but detection resolution and weak magnetic field measurement capability are insufficient
Solution Approach 1:
The patent applies a preliminary alternating current magnetic field to the magnetic field detection element before actual measurement. This preliminary periodic excitation prepares the system by establishing a known frequency reference, enabling subsequent synchronous detection and filtering operations that achieve high detection resolution without requiring overly complex device architecture
Solution Approach 2:
The patent replaces complex mechanical or structural magnetic field concentration methods with an electromagnetic approach using alternating current excitation and frequency-domain signal processing. This substitution achieves high detection resolution through electrical signal manipulation rather than mechanical system complexity
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 solution enables high-accuracy detection of weak magnetic fields with reduced noise interference, achieving higher reproducibility and signal-to-noise ratio compared to existing technologies.
Implementation Method 1
a modulation coil configured to apply, to the magnetic field detection element, an alternating current magnetic field
Implementation Method 2
a magnetic field detection element having a sensitivity axis in a first direction
Data Source
AI summary
A magnetic field detection device includes a magnetic field detection element, a modulation coil, and a demodulator. The magnetic field detection element has a sensitivity axis in a first direction. The modulation coil is configured to apply, to the magnetic field detection element, an alternating current magnetic field having a first frequency and a component in a second direction, the second direction being orthogonal to the first direction. The demodulator is configured to demodulate an output signal having the first frequency and outputted from the magnetic field detection element, and detect, on a basis of an amplitude of the output signal, an intensity of a measurement magnetic field to be received by the magnetic field detection element.