Magnetic Sensor Shielding for Perpendicular Field Interference
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Solution Overview
Problem
Magnetic sensors with magnetic field conversion elements struggle to effectively shield against external magnetic fields perpendicular to the sensor substrate, leading to errors in detection signals and reduced sensitivity.
Innovation Solution
The magnetic sensor system includes a magnetic field converter with yokes made of soft magnetic material, a magnetic field detector with magnetoresistive elements, and a plurality of shields separated from each other, all formed of soft magnetic material, to convert and detect magnetic fields while shielding against unwanted field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field conversion elements are used to detect magnetic fields perpendicular to the substrate, then sensitivity to perpendicular magnetic fields is improved, but shielding against unwanted parallel magnetic field components deteriorates
Solution Approach 1:
The shield is divided into multiple segments (first shield, second shield, third shield) arranged at different positions and orientations. Each segment provides localized shielding in specific directions, collectively achieving comprehensive shielding against parallel magnetic field components while maintaining detection sensitivity to perpendicular fields.
Solution Approach 2:
The shielding structure extends into the vertical dimension with shields positioned at different heights above the substrate. The first shield is positioned at a first height, the second shield at a second height, and the third shield at a third height, creating three-dimensional shielding coverage that blocks parallel magnetic field components from reaching the detection element.
2Object-affected harmful factors
If shields are added to block parallel magnetic field components, then shielding effectiveness is improved, but device complexity increases
Solution Approach 1:
Each shield segment serves multiple functions: the first shield provides shielding in one direction, the second shield provides shielding in another direction, and the third shield provides additional shielding coverage. This multi-functional arrangement achieves comprehensive shielding with a moderate number of components, balancing effectiveness and complexity.
Solution Approach 2:
The shields are arranged in a nested configuration where the first shield, second shield, and third shield are positioned at different heights and orientations, creating a layered shielding structure. This nested arrangement maximizes shielding effectiveness while minimizing the number of components needed compared to a solid enclosure.
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 configuration enhances the shielding effectiveness, preventing errors in detection signals and maintaining sensitivity even when the input magnetic field contains components perpendicular to the intended detection direction.
Implementation Method 1
a system including a magnetic sensor may be intended to detect a magnetic field in a direction perpendicular to the surface of a substrate by using a magnetoresistive element provided on the substrate. Magnetic sensors including one or more magnetic field conversion elements formed of a soft magnetic material are known to serve such a purpose.
Implementation Method 2
The spin-valve magnetoresistive element includes a magnetization pinned layer having a magnetization whose direction is fixed, a free layer having a magnetization whose direction is variable depending on the direction of an applied magnetic field
Data Source
AI summary
A magnetic sensor includes a magnetic field converter, a magnetic field detector, and a plurality of shields aligned in a Y direction. The magnetic field converter includes a plurality of yokes. Each yoke has a shape elongated in the Y direction, and is configured to receive an input magnetic field component in a direction parallel to a Z direction and to output an output magnetic field component in a direction parallel to an X direction. The magnetic field detector includes a plurality of trains of elements. Each train of elements includes a plurality of MR elements that are aligned in the Y direction along one yoke and connected in series. Each shield has such a shape that its maximum dimension in the Y direction is smaller than its maximum dimension in the X direction.