Meandering Magnetoresistive Sensor for Geomagnetic Detection
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Solution Overview
Problem
Magnetic sensors using magnetoresistive effect elements face issues with excessive length in the sensitivity axis direction, leading to increased thickness and decreased linearity of resistance change in response to external magnetic fields, particularly when detecting geomagnetic fields.
Innovation Solution
The magnetic sensor design includes connected-element bodies with intermediate and outer permanent magnet layers, arranged in a meandering shape to reduce element length and provide a uniform bias magnetic field, while maintaining high element resistance, and incorporates a fixed resistance element to equalize temperature coefficients and reduce parasitic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the magnetoresistive effect element is formed with a long length to increase element resistance, then power consumption is reduced, but the thickness in the sensitivity axis direction is excessively increased
Solution Approach 1:
The magnetoresistive effect element is configured to extend primarily in the width direction rather than the length direction (sensitivity axis direction). This dimensional reorientation allows the element to achieve sufficient resistance without increasing thickness, thereby resolving the contradiction between power consumption reduction and thickness control.
2Use of energy by moving object
If the element units are formed with a large length in the element-length direction, then element resistance is increased, but the bias magnetic field from permanent magnet layers does not effectively act around the center of element units causing hysteresis
Solution Approach 1:
The element units are configured to extend in the width direction rather than the element-length direction, with permanent magnet layers positioned on both sides in the width direction. This dimensional change ensures the bias magnetic field effectively acts on the center of element units, preventing hysteresis while maintaining sufficient resistance.
Solution Approach 2:
Permanent magnet layers are strategically positioned on both sides of the element units in the width direction to provide localized bias magnetic fields. This local quality enhancement ensures effective magnetic field distribution across the element units, improving linearity while maintaining resistance characteristics.
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 decreases the sensor's height, improves linearity of resistance change to external magnetic fields, and maintains high element resistance, enhancing the precision and efficiency of geomagnetic field detection.
Implementation Method 1
a magnetoresistive effect element, wherein the magnetoresistive effect element includes a plurality of connected-element bodies arranged so as to be adjacent to one another in an element-width direction with a space therebetween
Implementation Method 2
an outer permanent magnet layer disposed at ends of the connected-element bodies in a longitudinal direction, the ends of the connected-element bodies being electrically connected to each other with the outer permanent magnet layer therebetween
Data Source
AI summary
A magnetic sensor including a magnetoresistive effect element has the following structure. Element units each having an element width W1 and an element length L1 perpendicular to the element width W1 and producing a magnetoresistive effect in which electrical resistance changes in response to an external magnetic field are arranged in an element-length direction with a space therebetween. An intermediate permanent magnet layer is disposed in the space, and the element units are connected to each other with the intermediate permanent magnet layer therebetween to form a connected-element body. A plurality of the connected-element bodies are arranged so as to be adjacent to one another in an element-width direction with a space therebetween, the ends of the connected-element bodies are connected to each other with an outer permanent magnet layer therebetween to form a magnetoresistive effect element having a meandering shape.