Magnetic Sensor Crosstalk Correction via Orthogonal AC Fields
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Solution Overview
Problem
Magnetic sensors often experience unwanted crosstalk, particularly due to mechanical stress, which affects their accuracy in measuring specific magnetic field components, and this issue is not adequately addressed by existing technologies.
Innovation Solution
The implementation of an AC-magnetic field generator that applies orthogonal magnetic field components at specific frequencies to magnetic sensors, allowing for the determination of sensitivity and correction of crosstalk through demodulation and filtering, enabling precise measurement of magnetic field components even in the presence of crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is designed to detect a specific magnetic field component (e.g., By), then the sensitivity to the primary direction (Syy) is improved, but unwanted crosstalk sensitivity to orthogonal directions (Syx, Syz) occurs due to mechanical stress and other factors
Solution Approach 1:
The patent applies periodic magnetic field components at known frequencies to deliberately induce crosstalk signals, then uses demodulation to extract and measure the crosstalk sensitivities. This converts the harmful crosstalk effect into a useful measurement signal that can be used to correct the primary measurement, thereby transforming the harmful factor into a benefit.
Solution Approach 2:
The patent changes the operating parameters by applying AC magnetic fields at specific frequencies rather than DC fields. This frequency-based approach allows the system to distinguish between primary signal and crosstalk components through spectral separation, enabling independent measurement and correction of crosstalk sensitivities.
2Measurement precision
If AC-magnetic field generators are added to apply periodic magnetic field components for crosstalk measurement, then crosstalk sensitivity determination is improved, but device complexity increases
Solution Approach 1:
The patent makes the magnetic field generators multi-functional: they serve both to apply the primary magnetic field for normal sensing operation and to apply periodic test fields for crosstalk measurement. This eliminates the need for separate dedicated test equipment, reducing overall system complexity while maintaining measurement precision.
Solution Approach 2:
The patent merges the crosstalk measurement function with the primary sensing function by using the same magnetic field generators and sensor for both purposes. The demodulator also serves dual functions by processing both primary signal and crosstalk-induced signals, thereby reducing the number of separate components needed.
3Measurement precision
If periodic magnetic field components are applied at given frequencies, then crosstalk-induced signals can be separated from primary signals through demodulation, but the frequency range available for primary signal detection is reduced
Solution Approach 1:
The patent uses periodic magnetic field components at specific frequencies to induce crosstalk signals. By applying these periodic test signals and using demodulation at the same frequencies, the system can extract crosstalk sensitivities without continuously occupying the frequency band, allowing primary signals to use the full frequency range during normal operation.
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 effectively improves the accuracy of magnetic field component sensing by isolating and correcting for crosstalk, ensuring reliable detection of main magnetic field components even under conditions of mechanical stress or other crosstalk-inducing factors.
Implementation Method 1
at least one AC-magnetic field generator (102, 103) that applies at least one periodic magnetic field component (Bx', By') at a given frequency (fx, fy) to the magnetic sensor (101)
Implementation Method 2
at least one demodulator (207, 209) that uses the given frequency (fx, fz) to determine a sensitivity (Syx, Syz) of the sensing element (204) respective to the at least one additional magnetic field component
Implementation Method 3
a vertical Hall effect device may be aligned in x-direction, i.e. the contacts are spaced apart in x-direction. Such device can be used to detect the y-component By of the magnetic field
Implementation Method 4
any magneto-resistive (MR) sensor may be used. Such MR sensor may comprise at least one of the following: an AMR (Anisotropic MR) sensor, a GMR (Giant MR) sensor, a TMR (Tunneling MR) sensor
Data Source
AI summary
A sensing element is provided including a magnetic sensor that detects a first magnetic field component, at least one AC-magnetic field generator that applies at least one additional magnetic field component at a given frequency to the magnetic sensor, where the first magnetic field component and the at least one additional magnetic field component are orthogonal to each other, and at least one demodulator using the given frequency to determine a sensitivity of the sensing element respective to the at least one additional magnetic field component. Also, several methods of operating such sensing element are provided.