Magnetoresistive Sensor Geometry for Perpendicular Field Detection

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Solution Overview

Problem

Existing magnetic sensors face issues with detection accuracy due to variations in magnetic field strength and direction, particularly when the magnetic field direction is perpendicular to the sensor's sensitivity, leading to reduced sensitivity or zero sensitivity components.

Innovation Solution

A magnetic sensor system utilizing magnetoresistive elements with first and second planes intersecting at a dihedral angle other than 90°, allowing detection of magnetic fields with directions changing within a variable range, including components both parallel and perpendicular to the second plane, by using a substrate with oblique slopes to support the magnetoresistive elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnetoresistive element is configured to have sensitivity to a magnetic field in a direction parallel to the substrate surface, then it can detect magnetic fields changing within a plane parallel to the substrate surface, but it cannot detect magnetic fields containing a component perpendicular to the substrate surface

Engineering Contradiction:

Improvedetection accuracyVSAvoiddetection direction range

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent introduces a slope structure that tilts the magnetoresistive element relative to the substrate surface, adding a vertical dimension to the detection capability. This allows the element to detect magnetic field components in both the horizontal plane and the vertical direction, transforming a two-dimensional detection limitation into a three-dimensional detection capability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If a soft magnetic body is used to convert magnetic field direction, then detection of perpendicular magnetic field components becomes possible, but detection accuracy drops due to unnecessary magnetic fields and magnetic hysteresis characteristics

Engineering Contradiction:

Improvemagnetic field detection capabilityVSAvoiddetection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent removes the soft magnetic body from the system and replaces it with a geometric slope structure. This extraction eliminates the harmful magnetic hysteresis and unnecessary magnetic fields generated by the soft magnetic body, while preserving the essential function of directing magnetic field components to the sensitive axis of the magnetoresistive element.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the magnetic-based solution (soft magnetic body for field redirection) with a mechanical/geometric solution (slope structure). This substitution uses physical geometry rather than magnetic properties to achieve the same functional outcome, avoiding the drawbacks of magnetic hysteresis and field distortion.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the magnetic field direction is perpendicular to the sensor's sensitivity direction, then the sensor cannot detect the magnetic field, but changing the sensor orientation may compromise its sensitivity to the primary magnetic field component

Engineering Contradiction:

Improvemagnetic field direction detectionVSAvoidsensitivity

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies the slope structure locally at the position of the magnetoresistive element, creating a localized geometric transformation that redirects only the relevant magnetic field components to the sensor's sensitive axis, while maintaining the sensor's original orientation and sensitivity characteristics.

Inventive Principle:

Principle #3Local quality

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 system maintains detection accuracy by ensuring the in-plane component strength remains non-zero, generating a detection value corresponding to the magnetic field direction changes, even outside the predetermined plane, thereby enhancing overall detection precision.

Implementation Method 1

a spin-valve magnetoresistive element provided on a substrate... The spin-valve magnetoresistive element includes a magnetization pinned layer having a magnetization whose direction is fixed, a free layer having a magnetization whose direction is variable depending on the direction of an applied magnetic field

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS20250258253A1Magnetic sensor and magnetic sensor system

Publication Date: 2025.08.14 TDK CORP

AI summary

At a reference position within a first plane, a magnetic field to be detected has a first direction that changes within the first plane. A magnetic sensor includes an MR element. The MR element includes a magnetic layer having first magnetization that can change in direction within a second plane. The first plane and the second plane intersect at a dihedral angle α other than 90°. The magnetic field to be detected can be divided into an in-plane component parallel to the second plane and a perpendicular component perpendicular to the second plane. The in-plane component has a second direction that changes with a change in the first direction. The direction of the first magnetization changes with a change in the second direction. A detection value depends on the direction of the first magnetization.