Magnetic Sensor Lattice Shielding for Vertical Field Detection
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Solution Overview
Problem
Magnetic sensors using magnetoresistive elements face challenges in accurately detecting the vertical magnetic field component due to interference from disturbance magnetic fields, which alter the sensitivity of the sensor, making it difficult to detect the earth's magnetic field with high accuracy.
Innovation Solution
A magnetic sensor design that incorporates a soft magnetic member arranged with a space between the magnetoresistive element, providing shielding against disturbance fields in both the X1-X2 and Y1-Y2 directions, and includes a current bypass electrode layer to reduce sensitivity changes, allowing for precise detection of the vertical magnetic field component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a soft magnetic material is used to convert the vertical magnetic field component into a horizontal magnetic field component, then the magnetoresistive element can detect the vertical magnetic field component, but the disturbance magnetic field from the loud speaker superimposes on the converted horizontal magnetic field component, causing sensitivity changes and reducing detection accuracy
Solution Approach 1:
The soft magnetic member is divided into a first soft magnetic portion extending in the X1-X2 direction and a second soft magnetic portion extending in the Y1-Y2 direction. This segmentation allows each portion to provide shielding in specific directions, with the first portion shielding disturbance fields from the X1-X2 direction and the second portion shielding disturbance fields from the Y1-Y2 direction (sensitivity direction), thereby reducing sensitivity changes while maintaining detection accuracy
Solution Approach 2:
A non-magnetic layer is introduced between the soft magnetic member and the magnetoresistive element, creating a non-magnetic space in the height direction. This intermediary layer prevents direct magnetic coupling while allowing the soft magnetic member to convert the vertical magnetic field component into a horizontal magnetic field component that can be detected by the magnetoresistive element, while also reducing the impact of disturbance magnetic fields
2Object-affected harmful factors
If the soft magnetic member is arranged close to the magnetoresistive element to provide effective shielding, then shielding against disturbance magnetic fields is improved, but the space for converting and providing the horizontal magnetic field component is reduced
Solution Approach 1:
The soft magnetic member and magnetoresistive element are arranged with a space in the height direction (vertical dimension), while the soft magnetic member extends in the horizontal plane (X1-X2 and Y1-Y2 directions). This dimensional arrangement allows the soft magnetic member to provide effective shielding in the horizontal directions while maintaining sufficient vertical space for magnetic field conversion and transmission to the magnetoresistive element
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 design effectively reduces sensitivity changes caused by disturbance fields, enabling high-accuracy detection of the vertical magnetic field component, even in the presence of interference, thereby improving the sensor's performance in mobile devices like cellular phones.
Implementation Method 1
a magnetoresistive element that is formed by stacking a magnetic layer and a non-magnetic layer on a substrate and that exhibits a magnetoresistive effect
Implementation Method 2
a soft magnetic member that converts a vertical magnetic field component input from the outside from a direction perpendicular to the substrate into a horizontal magnetic field component in a direction along the substrate
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A magnetic sensor (1) includes a plurality of magnetoresistive elements (S1-S4) that are formed by stacking a magnetic layer (61) and a non-magnetic layer (62) on a substrate and that exhibit a magnetoresistive effect and a soft magnetic member (3) that converts a vertical magnetic field component into a horizontal magnetic field component. The soft magnetic member is formed of a plurality of first and second soft magnetic portions (3a, 3b) respectively extending in an X1-X2 direction and a Y1-Y2 direction, combined together in the shape of a lattice. The magnetoresistive elements (S1-S4) have a sensitivity direction in the Y2 direction and include a magnetoresistive element (S1, S4) located on a Y1 side portion side of the first soft magnetic portion and a magnetoresistive element (S2, S3) located on a Y2 side portion side of the first soft magnetic portion, respectively receiving horizontal magnetic field components from the Y1 direction and Y2 direction.