Dual Magnetic Sensor Layout for Noise-Resistant Position Detection

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Solution Overview

Problem

Position detection devices using magnetic sensors are prone to errors due to noise magnetic fields, leading to inaccurate lens position detection in autofocus mechanisms.

Innovation Solution

A position detection device utilizing a combination of first and second magnetic sensors, each with a specific magnetic field configuration, generates a sum of detection signals to mitigate noise interference, ensuring accurate position detection even in the presence of noise magnetic fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single magnetic sensor is used to detect lens position, then the device structure is simple, but measurement precision deteriorates due to noise magnetic field interference

Engineering Contradiction:

Improvesensor configurationVSAvoidposition detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The detection system is segmented into multiple independent magnetic sensors (first magnetic sensor and second magnetic sensor) positioned at different locations. Each sensor detects magnetic field components in different directions, and their signals are combined to achieve accurate position detection while rejecting noise magnetic fields.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces magnetic field generation units as intermediaries that create known magnetic field patterns. By comparing the detected magnetic fields with these known patterns, the system can distinguish between legitimate position-indicating fields and noise magnetic fields, thereby improving measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple magnetic sensors and field generation units are used to reject noise, then measurement precision improves, but device complexity increases

Engineering Contradiction:

Improveposition detection accuracyVSAvoidsensor and field generation structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The magnetic field generation units serve multiple functions: they generate magnetic fields for position detection, provide reference patterns for noise rejection, and enable the system to operate in various detection modes. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If magnetic field components are configured in specific directions to cancel noise, then measurement precision improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvenoise rejection capabilityVSAvoidmagnetic field alignment accuracy

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The system incorporates feedback mechanisms where the detected magnetic field signals are processed to determine lens position. The feedback loop allows the system to compensate for minor misalignments in magnetic field components, reducing the stringency of manufacturing precision requirements while maintaining noise rejection capability.

Inventive Principle:

Principle #23Feedback

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 device achieves high-accuracy position detection by minimizing noise-induced errors through the opposing magnetic field components and signal summation, maintaining precision in lens positioning.

Implementation Method 1

a first magnetic sensor configured to detect, at a first detection position in a first reference plane, a first detection-target magnetic field and to generate a first detection signal that varies in magnitude according to the direction of the first detection-target magnetic field

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

a second magnetic sensor configured to detect, at a second detection position in a second reference plane, a second detection-target magnetic field and to generate a second detection signal that varies in magnitude according to the direction of the second detection-target magnetic field

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 3

The signal generator generates the sum of the first detection signal and the second detection signal as the position detection signal

Methodology Applied

Scientific EffectSignal summation:

Data Source

PatentUS20260029252A1Module and magnetic sensor device

Publication Date: 2026.01.29 TDK CORP

AI summary

A position detection device includes a first position detector, a second position detector, and a signal generator. The first position detector includes a first magnetic field generation unit, a second magnetic field generation unit, and a first magnetic sensor. The second position detector includes a third magnetic field generation unit, a fourth magnetic field generation unit, and a second magnetic sensor. The positions of the second and fourth magnetic field generation units vary in response to variations in a detection-target position. The signal generator generates a position detection signal, which is the sum of a first detection signal generated by the first magnetic sensor and a second detection signal generated by the second magnetic sensor. Each of the first and second position detectors includes a bias magnetic field generation unit.