Linear Magnetometer Bridge Using Offset Magnetic Fields
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Solution Overview
Problem
Magnetoresistance elements often exhibit non-linear responses to magnetic fields, making it challenging to construct magnetometers with linear magnetic field trajectories, particularly when the axes of sensitivity are not aligned with the sensor's orientation.
Innovation Solution
A bridge configuration using nonlinear magnetoresistance elements, such as GMR or TMR elements, is designed to achieve a linear response by determining specific reference angles for the elements, ensuring the output is linear over a range of horizontal magnetic field values, even when the axes of sensitivity are not centered about zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistance elements are used in a bridge configuration, then the device can sense magnetic fields, but the response is non-linear making it difficult to achieve linear magnetic field trajectories
Solution Approach 1:
The patent changes the operating parameters of the magnetoresistance elements by introducing offset magnetic fields that shift the operating point away from the non-linear region. By adjusting the reference angles and applying offset fields, the system operates in a region where the magnetoresistance elements exhibit more linear behavior, thereby achieving linear magnetic field trajectories despite the inherent non-linearity of the elements.
Solution Approach 2:
The patent introduces offset magnetic fields as intermediary elements that mediate between the input magnetic field and the output signal. These offset fields compensate for the non-linear response of the magnetoresistance elements by pre-biasing the operating point, effectively linearizing the overall transfer characteristic of the bridge circuit.
2Adaptability or versatility
If the axis of maximum sensitivity is not aligned with the sensor orientation, then the sensor can detect magnetic fields in different directions, but the response becomes non-linear
Solution Approach 1:
The patent changes the operating parameters by introducing offset magnetic fields that compensate for misalignment between the sensitivity axis and sensor orientation. By adjusting the reference angles and offset field strength, the system maintains linear response even when the magnetoresistance elements are not perfectly aligned with the desired sensing direction.
Solution Approach 2:
The patent employs asymmetric bridge configurations where the four magnetoresistance elements have different reference angles (e.g., 0°, 45°, 90°, 135°). This asymmetric arrangement allows the system to handle magnetic fields in multiple directions while maintaining linearity through the specific combination of offset fields and reference angle configurations.
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 the construction of linear magnetometers with a linear response to magnetic field trajectories, effectively addressing the non-linearity issues in existing magnetoresistance elements, allowing for accurate sensing across a range of horizontal magnetic fields.
Implementation Method 1
a first magnetoresistance element having a first reference angle, a second magnetoresistance element in series with the first magnetoresistance element and having a second reference angle
Data Source
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AI summary
In one aspect, a bridge includes a first magnetoresistance element having a first reference angle, a second magnetoresistance element in series with the first magnetoresistance element and having a second reference angle, a third magnetoresistance element in parallel with the first magnetoresistance element and having the first reference angle and a fourth magnetoresistance element in series with the third magnetoresistance element and having the second reference angle. An output of the bridge has a linear response over a range of horizontal magnetic field values not centered about a zero value and a reference angle indicates an angle the magnetoresistance element is most sensitive to changes in a magnetic field.