XMR Sensor Position Detection Using Magnetostrictive Wave Conductors

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Solution Overview

Problem

Existing position sensors based on the runtime measurement principle for mechano-elastic density waves have limitations due to low sensitivity and high background noise, particularly when using bare XMR sensor microchips without shielding, leading to unreliable and large detector coils.

Innovation Solution

The use of XMR sensors configured as microchips, positioned close to or directly on the magneto-elastic wave conductor, often with additional bias magnets and shielding, to enhance signal quality and reduce noise, along with techniques like constant fraction discrimination to improve measurement precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If detector coils are used for detecting mechano-elastic density waves, then the sensor can detect position, but the sensitivity is low and background noise is high

Engineering Contradiction:

Improvedetection reliabilityVSAvoidsignal sensitivity

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional detector coil (electromagnetic system) with an XMR sensor that utilizes magnetoresistive effect. This substitution transitions from a mechanical/electromagnetic detection system to a magnetic field-based detection system, achieving higher sensitivity and lower noise levels while maintaining position detection capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from electromagnetic induction (coil-based) to magnetoresistive effect (XMR sensor-based). By utilizing the magnetoresistive effect where resistance changes in response to magnetic field variations, the system achieves improved signal-to-noise ratio and detection precision.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If detector coils are used without shielding, then the device complexity is reduced, but background noise increases and reliability decreases

Engineering Contradiction:

Improvedetector structure complexityVSAvoiddetection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The XMR sensor inherently provides magnetic field detection capability with built-in noise rejection properties. The magnetoresistive effect used in XMR sensors naturally filters out certain types of electromagnetic interference, reducing or eliminating the need for additional shielding structures while maintaining high detection reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If XMR sensors are positioned close to the wave conductor to improve signal quality, then measurement precision improves, but the sensor may be more susceptible to interference

Engineering Contradiction:

Improvesignal qualityVSAvoidinterference susceptibility

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The XMR sensor's magnetoresistive detection mechanism provides inherent immunity to certain types of interference. The sensor responds specifically to magnetic field changes caused by the mechano-elastic waves while being less susceptible to electromagnetic interference, allowing close positioning without compromising reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses the magnetic field as an intermediary between the mechano-elastic waves and the XMR sensor. The magnetostrictive wave conductor converts mechanical waves into magnetic field variations, which the XMR sensor then detects. This intermediary mechanism isolates the sensor from direct mechanical and electromagnetic interference while maintaining signal fidelity.

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

This configuration improves the sensitivity and reliability of position sensing by reducing background noise and enhancing signal quality, allowing for more precise detection of mechano-elastic density waves.

Implementation Method 1

Based on the Wiedemann effect, a power impulse fed into the wave conductor when superimposed with an external magnetic field laterally oriented relative to the magnetostrictive wave conductor

Methodology Applied

Scientific EffectWiedemann effect: Wiedemann Effect

Implementation Method 2

The Villary band or the wave conductor for this purpose is made from a material with a maximum change of magnetic permeability Δμr, e.g. from nickel or a nickel alloy

Methodology Applied

Scientific EffectMagnetostriction: Magnetostriction

Implementation Method 3

XMR sensors, thus thin layer sensors which change their resistances as a function of magnetic flux strength and orientation react directly to a change of the magnetic field strength (H) and its direction

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS9816843B2Magnetorestrictive position sensor according to the propagation time principle having a magnetorestrictive detector unit for mechanical-elastic density waves

Publication Date: 2017.11.14 ASM AUTOMATION SENSORIK MESSTECHN GMBH

AI summary

Instead of tapping a mechano-elastic desnity wave (MEDW) from a wave conductor or a Villary band through a detector coil, a changing field strength H is captured by a XMR sensor which is positioned on a wave conductor or proximal to the wave conductor or on a Villary band or proximal to the Villary band.