Magnetic Position Sensing for Linear Lens Detection Signals

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Solution Overview

Problem

Existing position detection devices using magnetic sensors face issues where the detection signal varies nonlinearly due to nonlinear variations in the direction of the target magnetic field, necessitating complex signal correction.

Innovation Solution

A position detection device with a magnetic field generator that generates a target magnetic field whose direction varies nonlinearly relative to object position, coupled with a magnetic sensor that ensures the detection signal varies linearly by using magnetoresistive elements with specific magnetization configurations, allowing for linear variation of the detection signal despite nonlinear changes in the target magnetic field direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnetic sensor detects a target magnetic field whose direction varies nonlinearly with object position, then the detection signal varies nonlinearly, but this requires complex signal correction processing

Engineering Contradiction:

Improveposition detection accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the magnetization direction of the pinned layer from a fixed orientation to one that is tilted at a specific angle relative to the reference direction. This parameter change in the magnetic sensor's internal structure transforms the detection characteristics, enabling linear output signals even when the target magnetic field direction varies nonlinearly with object position, thereby eliminating the need for complex signal correction

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite magnetic sensor structure combining a pinned layer with specific magnetization orientation and a free layer that responds to the target magnetic field. This composite configuration at the material/structural level creates a detection system where the combined magnetic properties produce linear signal variation, resolving the contradiction between measurement precision and processing complexity

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If the direction of the target magnetic field varies nonlinearly relative to object position, then the detection signal becomes nonlinear, but linearization requires additional correction mechanisms

Engineering Contradiction:

Improvesignal processing simplicityVSAvoiddetection signal linearity

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

By changing the magnetization direction parameter of the pinned layer to a tilted orientation at a predetermined angle, the patent achieves linear detection signal output without requiring additional correction mechanisms. This single parameter modification in the sensor structure simultaneously improves ease of operation and maintains measurement precision

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If magnetoresistive elements are configured with specific magnetization directions, then the detection signal can vary linearly despite nonlinear target magnetic field variations, but this requires precise control of magnetization orientation

Engineering Contradiction:

Improvedetection signal linearityVSAvoidmagnetization orientation control

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent specifies a particular angle range for the pinned layer magnetization direction (45 degrees relative to the reference direction), providing a clear manufacturing target. This well-defined parameter specification enables precise control during fabrication while achieving the desired linear detection signal output, balancing manufacturing precision requirements with measurement accuracy

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

Enables linear variation of the detection signal relative to object position changes, even when the target magnetic field direction varies nonlinearly, simplifying signal processing and improving accuracy in applications like autofocus mechanisms.

Implementation Method 1

a magnetic sensor that detects the target magnetic field and generates a detection signal corresponding to the direction of the target magnetic field

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS12571656B2Position detection device, camera module, and rotary actuator

Publication Date: 2026.03.10 TDK CORP

AI summary

A position detection device includes a magnetic field generator and a magnetic sensor. The magnetic field generator is configured so that a mode of variation of a direction of a target magnetic field relative to variations in a position of a lens is such that the direction of the target magnetic field varies nonlinearly relative to the variations in the position of the lens. The magnetic sensor is configured so that a mode of variation of a detection signal relative to variations in the direction of the target magnetic field is such that the detection signal varies nonlinearly relative to the variations in the direction of the target magnetic field.