Magneto-resistive Sensor with Closed Flux Magnetization for Angle Error Compensation
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Solution Overview
Problem
Existing magneto-resistive sensors face challenges in accurately determining magnetic field quantities due to limitations in sensitivity and accuracy, particularly in rotational speed sensor applications, where static disturbance fields can cause angle measurement errors.
Innovation Solution
A magneto-resistive sensor device with a magnetic free layer having a spontaneously generated in-plane closed flux magnetization pattern and a magnetic reference layer with a non-closed flux magnetization pattern, combined with a circuit to detect changes in electrical parameters in response to external magnetic fields, is used to improve sensitivity and accuracy by compensating for static disturbance fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magneto-resistive sensor structures are used, then the device is simple to manufacture, but the measurement precision and sensitivity are insufficient due to static disturbance fields
Solution Approach 1:
The sensor device is divided into multiple magneto-resistive structures arranged in a bridge circuit configuration (e.g., Wheatstone bridge with four arms). Each structure contains a magnetic free layer with specific magnetization pattern, and they are positioned at different locations to detect different components of the magnetic field. This segmentation allows differential measurement that cancels out static disturbance fields while maintaining manufacturing feasibility.
Solution Approach 2:
Different regions of the sensor device have different magnetic free layers with specifically designed magnetization patterns (e.g., vortex, radial, or uniform magnetization). Each local region is optimized to respond to specific field components, enabling the device to achieve high measurement precision for magnetic field quantity determination while managing overall complexity through localized optimization.
2Measurement precision
If conventional magneto-resistive structures are used, then the device structure is simple, but the sensitivity is insufficient for accurate angle measurement
Solution Approach 1:
The sensor employs multiple magneto-resistive structures (typically four) arranged in a bridge circuit, where each structure measures a different aspect of the magnetic field. This segmentation enables differential measurement that enhances angle measurement accuracy while compensating for static disturbance fields, thereby improving both sensitivity and reliability simultaneously.
Solution Approach 2:
The bridge circuit configuration provides inherent feedback through differential measurement. By comparing the resistance changes of multiple magneto-resistive structures, the system can detect and compensate for static disturbance fields, improving angle measurement accuracy and sensitivity without requiring additional complex components.
3Measurement precision
If a single magneto-resistive structure is used, then the device complexity is low, but the ability to compensate for static disturbance fields is insufficient
Solution Approach 1:
The device uses multiple magneto-resistive structures (typically four) arranged in a bridge circuit, where each structure is positioned to detect different magnetic field components. This segmentation enables the system to differentiate between rotating magnetic fields (containing motion information) and static disturbance fields, achieving compensation while maintaining a relatively simple overall structure that can be manufactured using standard processes.
Solution Approach 2:
Each magneto-resistive structure in the bridge circuit serves multiple functions: it acts as both a sensing element for magnetic field detection and as part of the differential measurement system for disturbance compensation. This multi-functionality allows the device to achieve high measurement precision without proportionally increasing complexity, as the same structures perform both sensing and compensation roles.
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 enhances the accuracy of magnetic field quantity determination and reduces angle measurement errors caused by static disturbance fields, improving the overall performance of magneto-resistive sensors in various applications.
Implementation Method 1
A magnetic sensor device according to an embodiment comprises a magneto-resistive structure comprising a magnetic free layer configured to provide an in-plane closed flux magnetization pattern and a magnetic reference layer comprising a reference magnetization pattern, a further magneto-resistive structure comprising a further magnetic free layer with an in-plane non-closed flux magnetization pattern and a further magnetic reference layer comprising a further reference magnetization pattern, and at least one circuit to detect a change of an electrical parameter of the magneto-resistive structure and to detect a change of an electrical parameter of the further magneto-resistive structure in response to an applied external magnetic field
Data Source
AI summary
A device according to an embodiment may comprise a magneto-resistive structure comprising a magnetic free layer with a spontaneously generated in-plane closed flux magnetization pattern and a magnetic reference layer having a non-closed flux magnetization pattern.