Magnetostrictive MR Sensor Biasing on Inclined Surfaces

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Solution Overview

Problem

Existing magnetic sensors fail to apply a bias magnetic field to magnetoresistive elements on an inclined surface, resulting in insufficient bias magnetic field strength due to reduced volume, which affects the sensitivity and accuracy of magnetic field detection.

Innovation Solution

A magnetic sensor design incorporating a ferromagnetic portion and an antiferromagnetic portion in exchange coupling, with a support member configured to apply compressive stress, enhancing the bias magnetic field strength on magnetoresistive elements disposed on an inclined surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a magnetic field generator is formed on an inclined surface to detect magnetic fields perpendicular to the substrate, then the sensor can detect perpendicular magnetic field components, but the volume of the magnetic field generator is reduced resulting in insufficient bias magnetic field strength

Engineering Contradiction:

Improvedetection capability for perpendicular magnetic field componentsVSAvoidvolume of magnetic field generator

Core Design Contradiction:

Adaptability or versatilityVSVolume of stationary object

Solution Approach 1:

The patent changes the physical parameters of the magnetic field generator by introducing stress application mechanisms and using materials with positive magnetostriction constants. This allows the generator to produce sufficient bias magnetic field strength despite the reduced volume caused by the inclined surface configuration, thereby maintaining detection capability for perpendicular magnetic field components.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures in the magnetic field generator, combining materials with specific magnetostriction properties. This composite approach enables the generator to achieve the required magnetic field strength with a compact design that can be accommodated on the inclined surface, resolving the contradiction between volume reduction and field strength requirements.

Inventive Principle:

Principle #40Composite materials

2Strength

If the volume of the magnetic field generator is increased to enhance bias magnetic field strength, then the bias magnetic field strength is improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvebias magnetic field strengthVSAvoidstructural complexity of magnetic field generator

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Instead of increasing volume, the patent changes other parameters such as applying mechanical stress and selecting materials with positive magnetostriction constants. This approach enhances the bias magnetic field strength through parameter optimization rather than simple volume increase, thereby avoiding excessive device complexity and manufacturing difficulty.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If magnetoresistive elements are disposed on an inclined surface to detect perpendicular magnetic fields, then the sensitivity to perpendicular magnetic field components is improved, but the bias magnetic field strength becomes insufficient affecting detection accuracy

Engineering Contradiction:

Improvesensitivity to perpendicular magnetic field componentsVSAvoidbias magnetic field strength

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The patent applies parameter changes by introducing stress control mechanisms and using materials with specific magnetostriction properties. This enables the magnetic field generator to compensate for the reduced bias field strength caused by the inclined surface configuration, thereby maintaining both the sensitivity to perpendicular magnetic field components and sufficient bias magnetic field strength for accurate detection.

Inventive Principle:

Principle #35Parameter changes

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 increases the bias magnetic field strength, improving the sensitivity and accuracy of magnetic field detection, particularly for components perpendicular to the substrate surface.

Implementation Method 1

an antiferromagnetic portion that is formed of an antiferromagnetic material and is in exchange coupling with the ferromagnetic portion

Methodology Applied

Scientific EffectExchange coupling:

Implementation Method 2

a ferromagnetic portion that is formed of a ferromagnetic material having a positive magnetostriction constant

Methodology Applied

Scientific EffectMagnetostriction: Magnetostriction

Data Source

PatentUS20250377418A1Magnetic sensor and manufacturing method thereof

Publication Date: 2025.12.11 TDK CORP

AI summary

A magnetic sensor includes an insulating layer, and an MR element and a magnetic field generator that are disposed on the insulating layer. The magnetic field generator includes a ferromagnetic portion that is formed of a ferromagnetic material having a positive magnetostriction constant, and an antiferromagnetic portion that is formed of an antiferromagnetic material and is in exchange coupling with the ferromagnetic portion. The MR element and the magnetic field generator are arranged along a first direction. The insulating layer and the magnetic field generator are configured such that, when a compressive stress in a second direction is applied to the insulating layer, a compressive stress in a third direction that is orthogonal to the first direction and that intersects the second direction is applied to the magnetic field generator.