Magnetic Sensor Device With Orthogonal Field Converter And Shield
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Solution Overview
Problem
Magnetic sensors face reduced sensitivity and noise in detecting magnetic fields due to horizontal magnetic field components interfering with the perpendicular field component detection, which is converted by a soft magnetic material.
Innovation Solution
A magnetic sensor device with a magnetic field converter that orthogonalizes the input magnetic field and a magnetic shield to block external magnetic fields, using a configuration of magnetic field converters and detectors with magnetoresistive effect elements to suppress unwanted magnetic field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a soft magnetic material is used to convert the perpendicular magnetic field component into a parallel component for detection, then the magnetic field can be detected by the magnetoresistive effect element, but horizontal magnetic field components also interfere with the detection, generating noise and reducing sensitivity
Solution Approach 1:
A magnetic shield is introduced as an intermediary element between the magnetoresistive effect element and the external magnetic field sources. This magnetic shield selectively blocks horizontal magnetic field components from reaching the sensor, while allowing the converted vertical magnetic field components to pass through to the magnetoresistive effect element for accurate detection.
Solution Approach 2:
The harmful horizontal magnetic field components are extracted and blocked separately from the useful vertical magnetic field components. The magnetic shield is configured to specifically remove the interfering horizontal components while preserving the converted vertical components that contain the actual position information.
2Reliability
If the magnetic sensor uses a spin-valve-type magnetoresistive effect element with sensitivity to parallel magnetic fields, then it can detect converted magnetic field components, but it also detects unwanted horizontal magnetic field components, reducing sensitivity
Solution Approach 1:
The magnetic shield serves as a mediator that filters the magnetic field components before they reach the magnetoresistive effect element. It allows the useful converted vertical magnetic field components to pass through while blocking the harmful horizontal components, thereby improving both detection reliability and sensitivity.
Solution Approach 2:
The magnetic shield is positioned locally around the magnetoresistive effect element to provide targeted protection. The shield's geometry and material properties are optimized to create a localized magnetic field environment that preserves vertical components while eliminating horizontal interference at the sensor location.
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 solution enhances detection accuracy by minimizing the impact of unwanted magnetic field components, thereby improving sensitivity and reducing noise in magnetic field detection.
Implementation Method 1
a soft magnetic material is provided between the magnet and the magnetoresistive effect element. This soft magnetic material converts the perpendicular magnetic field component in a direction perpendicular to the substrate surface, of the components of the magnetic field generated by the magnet, into a magnetic field component that is parallel to the substrate surface
Implementation Method 2
a spin-valve-type magnetoresistive effect element (GMR element, TMR element or the like) in which resistance changes in accordance with change in the external magnetic field
Implementation Method 3
A magnetic shield that blocks an external magnetic field along the second direction is provided
Data Source
AI summary
A magnetic sensor device includes a magnetic field converter that receives an input magnetic field input along a first direction and outputs an output magnetic field along a second direction, which is orthogonal to the first direction. A magnetic field detector is provided at a position where the output magnetic field can be applied. A magnetic shield that blocks an external magnetic field along the second direction. is provided. The magnetic field converter has a shape in which the length in a third direction, which is orthogonal to both the first direction and the second direction, is longer than the length in the second direction, when viewed along the first direction. The magnetic shield is provided at a position overlapping with the magnetic field converter and the magnetic field detector, when viewed along the first direction.