Magnetic Field Sensor Shield Structure for Stray Field Suppression
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Solution Overview
Problem
Magnetic field sensor systems face challenges in accurately measuring out-of-plane magnetic fields due to interference from in-plane stray magnetic fields, which affect sensitivity and linearity, leading to compromised detection quality.
Innovation Solution
The integration of magnetic field shield structures fully encircling magnetic sense elements to suppress in-plane stray fields while redirecting out-of-plane magnetic fields for detection, utilizing geometric configurations and high permeability materials to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensor systems are used to measure magnetic fields, then speed and direction sensing capabilities are provided, but magnetic interference fields (stray magnetic fields) along sensing axes change sensitivity and linearity range, negatively affecting detection quality
Solution Approach 1:
A magnetic shield structure is introduced as an intermediary element between the magnetic sense element and the external environment. This shield redirects stray magnetic fields away from the sensing element while allowing the desired measurement magnetic field to reach the sensor, thereby improving detection quality without sacrificing sensitivity
Solution Approach 2:
The magnetic field sensing function is segmented into distinct components: the magnetic sense element for detection and the magnetic shield structure for field management. This segmentation allows the shield to selectively manage different magnetic field components (stray vs. measurement fields) independently, resolving the contradiction between precision and interference
2Measurement precision
If a magnetic shield structure is added to suppress stray magnetic fields, then detection quality improves, but device complexity increases
Solution Approach 1:
The magnetic shield structure is integrated with the magnetic sense element to form a unified sensor assembly. The shield is positioned adjacent to and围绕着 the sensing element, creating a combined structure that achieves field suppression without requiring separate complex shielding systems, thus limiting the increase in device complexity
3Object-affected harmful factors
If the magnetic shield structure fully encircles the magnetic sense element, then stray field suppression is enhanced, but the sensing element becomes more constrained
Solution Approach 1:
The magnetic shield structure is designed with spatially varying properties: it fully encircles the magnetic sense element in directions where stray field suppression is most needed (lateral directions), while maintaining openness or reduced constraint in the direction of the desired measurement field (vertical direction). This local differentiation allows the shield to suppress harmful fields without constraining the sensing capability
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 cancels homogeneous magnetic interference, improving the quality of magnetic field detection and enabling precise rotation angle sensing by isolating the desired magnetic field components.
Implementation Method 1
The structure is also configured to redirect an external magnetic field from a third axis, perpendicular to a surface of the substrate, into the first axis to be sensed as the measurement magnetic field by the magnetic sense element
Implementation Method 2
the structure being configured to suppress stray magnetic fields along a first axis and a second axis, wherein the first and second axes are parallel to a surface of the substrate and perpendicular to one another
Data Source
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AI summary
A magnetic field sensor includes a magnetic sense element and a shield structure formed on a substrate. The shield structure fully encircles the magnetic sense element for suppressing stray magnetic fields along a first axis and a second axis, both of which are parallel to a surface of the substrate and perpendicular to one another. A magnetic field is oriented along a third axis perpendicular to the surface of the substrate, and the magnetic sense element is configured to sense a magnetic field along the first axis. A magnetic field deflection element, formed on the substrate proximate the magnetic sense element, redirects the magnetic field from the third axis into the first axis to be sensed as a measurement magnetic field by the magnetic sense element. At least two magnetic field sensors, each fully encircled by a shield structure, form a gradient unit for determining a magnetic field gradient.