Magnetic Sensor With Offset Magnetoresistive Element

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Solution Overview

Problem

Magnetic sensors for closed loop control face challenges in further reducing size and cost while effectively canceling environmental magnetic fields, as existing designs integrate multiple components into a single chip, limiting miniaturization and cost reduction.

Innovation Solution

A magnetic sensor design that incorporates a magnetoresistive effect element and a magnetic member on separate wiring layers, with the magnetic member serving both magnetism collection and cancel coil functions, reducing the number of circuit elements and allowing for smaller and more cost-effective devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the cancel coil, magnetoresistive effect element and magnetic member are integrated into one sensor chip, then the entire size is reduced, but further size and cost reduction is still required

Engineering Contradiction:

Improvesensor chip sizeVSAvoidnumber of circuit elements

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The magnetic member is designed to perform dual functions: it serves as both a magnetism collection element and a cancel coil. By making the magnetic member itself conductive and capable of carrying feedback current, the patent eliminates the need for a separate cancel coil, thereby reducing the number of circuit elements while maintaining the ability to cancel environmental magnetic fields.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the cancel coil function with the magnetic member by making the magnetic member conductive. This combination integrates two previously separate components (magnetic member and cancel coil) into a single element, reducing both the number of components and the overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If the magnetoresistive effect element is disposed offset with respect to the center position of the magnetic member, then detection sensitivity is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvedetection sensitivityVSAvoidpositioning accuracy

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent deliberately employs asymmetric positioning of the magnetoresistive effect element relative to the magnetic member. The element is placed at an offset position rather than at the center, creating an asymmetric configuration that enhances detection sensitivity by optimizing the magnetic flux distribution through the element.

Inventive Principle:

Principle #4Asymmetry

3Measurement precision

If the length of the magnetic member in the first direction is increased to be equal to or larger than the magnetoresistive effect element, then detection sensitivity is improved, but device area increases

Engineering Contradiction:

Improvedetection sensitivityVSAvoiddevice area

Core Design Contradiction:

Measurement precisionVSArea of moving object

Solution Approach 1:

The patent optimizes the dimensional parameters of the magnetic member, specifically setting its length in the first direction to be equal to or larger than that of the magnetoresistive effect element. This parameter adjustment ensures that the magnetic member can effectively collect and guide magnetic flux across the entire area of the sensing element, improving detection sensitivity.

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

This design achieves reduced size and cost by integrating functions, enhancing detection sensitivity and enabling closed loop control with improved magnetic flux handling, while maintaining high sensitivity and efficiency.

Implementation Method 1

a first magnetoresistive effect element electrically connected between the first and second terminals and extending in a first direction

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Implementation Method 2

magnetic flux to be detected is collected by the first magnetic member

Methodology Applied

Scientific EffectMagnetic flux collection: Magnetic Field

Implementation Method 3

making current flow in the cancel coil in response to a change in the resistance value of the magnetoresistive effect element

Methodology Applied

Scientific EffectElectromagnetic field generation: Electromagnet

Data Source

PatentUS11022660B2Magnetic sensor including a magnetic member offset from a magnetoresistive effect element

Publication Date: 2021.06.01 TDK CORP

AI summary

The size and cost of a magnetic sensor suitable for closed loop control is reduced. A magnetic sensor includes a magnetoresistive effect element that is electrically connected between terminals and extends in the x-direction and a magnetic member that is electrically connected between the terminals and extends in the x-direction along the magnetoresistive effect element. The magnetoresistive effect element is disposed offset with respect to the center position of the magnetic member in the y-direction. Magnetic flux to be detected is collected by a magnetic member and current is made to flow in the magnetic member in accordance with the resistance value of the magnetoresistive effect element, achieving closed loop control. The magnetic member functions both as a magnetism collection function and as a cancel coil, which reduces the number of elements required, and which also achieves a reduction in size and cost.