Magnetic Sensor Yoke Stabilization via Orthogonal Magnetic Bodies

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Solution Overview

Problem

Magnetic sensors with yokes face challenges in maintaining output characteristics stability under continuously changing magnetic fields, particularly due to changes in magnetization direction, leading to issues like linearity and hysteresis changes.

Innovation Solution

A magnetic sensor design incorporating a soft magnetic structure with yokes and additional magnetic bodies arranged orthogonally to the yokes, where the magnetic field strength changes with relative position, stabilizing the magnetization of yokes and preventing changes in output characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a yoke is used to convert magnetic field direction, then sensitivity to perpendicular magnetic field is improved, but output characteristic stability deteriorates under continuously changing magnetic fields

Engineering Contradiction:

Improvesensitivity to perpendicular magnetic fieldVSAvoidoutput characteristic stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies local quality by creating different magnetic field environments in different regions. A magnetic field generation unit generates a bias magnetic field in a specific direction (parallel to the substrate) to maintain stable magnetization in the yoke, while the detection element detects the perpendicular magnetic field component. This localized bias field application stabilizes the yoke's magnetization direction without affecting the detection of the perpendicular field component.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the magnetic field parameters by introducing a bias magnetic field with a specific direction (parallel to substrate) and intensity. This bias field parameter adjustment ensures that the total magnetic field acting on the yoke maintains a stable magnetization direction, preventing characteristic changes while allowing detection of perpendicular field variations.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the magnetization direction of the yoke changes under continuously changing magnetic fields, then adaptability to different field directions is improved, but linearity and hysteresis characteristics deteriorate

Engineering Contradiction:

Improveresponse to different magnetic field directionsVSAvoidlinearity and hysteresis characteristics

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent creates a localized bias magnetic field environment using the magnetic field generation unit that maintains stable magnetization in the yoke. This localized field control allows the yoke to respond to perpendicular field changes while maintaining consistent linearity and hysteresis characteristics, as the bias field compensates for directional variations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The magnetic field generation unit acts as an intermediary that introduces a bias magnetic field to mediate between the perpendicular detection field and the yoke's magnetization stability. This intermediary field ensures that the yoke maintains stable magnetization direction while still responding to the detection field, preserving linearity and hysteresis characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 stabilizes the magnetization of yokes, preventing changes in output characteristics and ensuring consistent performance under varying magnetic fields.

Implementation Method 1

The yoke converts a magnetic field in a direction perpendicular to the surface of the substrate into a magnetic field in a direction parallel to the surface of the substrate

Methodology Applied

Scientific EffectMagnetic field conversion: Magnetic Field

Implementation Method 2

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

PatentUS20250003770A1Magnetic sensor, position detection device, and lens module

Publication Date: 2025.01.02 TDK CORP

AI summary

A magnetic sensor includes a soft magnetic structure including at least one yoke, and magnetoresistive (MR) elements configured to detect a magnetic field generated by the at least one yoke, the MR elements being adjacent to the at least one yoke in a transverse direction of the at least one yoke. The soft magnetic structure further includes at least one additional magnetic body arranged next to the at least one yoke in a longitudinal direction of the at least one yoke and located off the at least one yoke in an orthogonal direction orthogonal to the longitudinal direction.