Magnetic Sensor Isotropy via Segmented Magnetoresistive Elements
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Solution Overview
Problem
Existing magnetic sensors do not adequately improve the isotropy of magnetic field detection, as they lack effective designs that reduce anisotropy in magnetoresistive elements, leading to variations in output when the external magnetic field is zero due to residual magnetization.
Innovation Solution
A magnetic sensor design featuring a bridge circuit with two types of magnetoresistive elements, where the second magnetoresistive elements have unit patterns arranged along an imaginary circle or polygon with bent and folded back shapes, reducing anisotropy by varying the current direction across horizontal directions, and minimizing linear extending portions to prevent significant resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistive elements are arranged in conventional patterns (spiral, circular, or zigzag), then the device structure is simple and easy to manufacture, but the isotropy of magnetic field detection is insufficient
Solution Approach 1:
The second magnetoresistive element is divided into multiple unit patterns (e.g., four unit patterns arranged along an imaginary circle). Each unit pattern contains bent portions and folded back shapes that are independently configured. This segmentation allows each unit to contribute differently to magnetic field detection from various directions, improving overall isotropy while maintaining manufacturability through modular design.
Solution Approach 2:
The unit patterns are arranged along an imaginary circle or polygon, creating a circular/spheroidal configuration rather than linear or rectangular arrangements. The bent portions within each unit pattern also follow curved geometries. This circular arrangement ensures uniform distribution of sensing directions, enhancing isotropy of magnetic field detection from all horizontal directions.
2Measurement precision
If linear extending portions are present in unit patterns, then the magnetoresistive element structure is simpler, but residual magnetization effects increase and sensitivity decreases
Solution Approach 1:
The unit patterns are designed to substantially lack linear extending portions, featuring instead bent portions with curved geometries and folded back shapes. This curved configuration prevents the formation of preferred magnetization directions that would occur in linear structures, thereby reducing residual magnetization effects and improving sensitivity to magnetic fields from various directions.
Solution Approach 2:
The folded back shapes and bent portions create asymmetric geometries within each unit pattern, avoiding symmetric linear extensions that would create anisotropic magnetization. This asymmetric design ensures more uniform magnetic field sensing characteristics across different directions while minimizing residual magnetization effects.
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 enhances the isotropy of magnetic field detection, reduces variations in output when the external magnetic field is zero, and minimizes the effects of residual magnetization, thereby improving the overall accuracy and reliability of magnetic field sensing.
Implementation Method 1
a magnetic sensor includes a plurality of magnetoresistive elements that are electrically connected to each other and define a bridge circuit
Data Source
AI summary
A magnetic sensor includes first magnetoresistive elements and second magnetoresistive elements. The rates of change of resistance of the first magnetoresistive elements are higher than the rates of change of resistance of the second magnetoresistive elements. The second magnetoresistive elements each include a plurality of unit patterns that are arranged along an imaginary circle or an imaginary polygon in plan view and the unit patterns each include a plurality of bent portions and a folded back shape. The plurality of unit patterns are connected to each other in a direction that encloses a region around the center of the imaginary circle or imaginary polygon.