Magnetoresistive Sensor Layout for Stress-Resistant Field Detection
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Solution Overview
Problem
Existing magnetic sensor devices face challenges in maintaining detection accuracy due to stress and temperature variations, particularly when mounted on substrates with symmetrical stress distribution, which can lead to errors in detection signals.
Innovation Solution
The magnetic sensor device incorporates a unique layout of magnetoresistive elements with specific magnetization directions and a support structure that deviates the center of gravity of the element layout area from the reference plane, reducing the influence of applied stress and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic sensor is mounted on the substrate so that the center of gravity of the sensor matches that of the substrate, then the influence of stress is reduced, but this mounting approach is not always feasible due to the presence of other components like terminals
Solution Approach 1:
The patent introduces an asymmetric offset between the center of gravity of the magnetoresistive element layout area and the center of gravity of the reference plane. This asymmetric arrangement creates a moment that counteracts the stress-induced errors, allowing the sensor to maintain high detection accuracy even when mounted in positions that do not align with the substrate's center of gravity, thus providing mounting flexibility.
2Reliability
If stress is generated in the substrate due to external force or temperature, then the stress distribution is symmetrical about the center of gravity, but mounting the sensor away from the center allows exploitation of this symmetry to reduce stress influence
Solution Approach 1:
The patent converts the harmful effect of stress-induced resistance changes into a beneficial effect by deliberately offsetting the sensor's center of gravity. The offset creates a mechanical moment that exploits the symmetrical stress distribution to produce compensating resistance changes in the magnetoresistive elements, thereby converting stress from a source of error into a mechanism for error cancellation.
3Measurement precision
If multiple magnetoresistive elements are used to detect magnetic field components, then detection accuracy is improved, but the layout area and complexity increase
Solution Approach 1:
The patent merges multiple magnetoresistive elements into a compact layout where elements are arranged in a grid pattern with controlled offsets. The elements share common connection points and are integrated into a unified circuit structure, reducing the overall device complexity while maintaining the capability to detect multiple magnetic field components with high accuracy.
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 design effectively reduces the impact of stress and temperature variations, enhancing the accuracy and reliability of magnetic field detection in various applications.
Implementation Method 1
Each of the plurality of magnetoresistive elements includes a magnetization pinned layer having magnetization whose direction is fixed, a free layer having magnetization whose direction is variable depending on the target magnetic field
Data Source
AI summary
A magnetic sensor device includes at least one magnetic sensor and a support. A center of gravity of an element layout area of the at least one magnetic sensor is deviated from a center of gravity of a reference plane of the support. The at least one magnetic sensor includes four auxiliary resistor sections constituted by a plurality of magnetoresistive elements. The element layout area includes first to fourth areas for laying out the four auxiliary resistor sections, respectively. Two of the first to fourth areas are arranged so that at least parts of the respective two areas sandwich a reference axis therebetween, and other two of the first to fourth areas are arranged so that at least parts of the respective other two areas sandwich the reference axis therebetween.