Magneto-Impedance Sensor With Soft Magnetic Field Converter
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Solution Overview
Problem
Conventional magnetic detection devices using MI elements are limited in size reduction due to the need for separate MI elements for each axis of the magnetic vector, restricting their miniaturization and thickness reduction, especially in the Z-axis direction.
Innovation Solution
A magnetic detection device design where a soft magnetic body is positioned between the detection coils of MI elements for X and Y axes, allowing the magnetic field direction to be changed to enable detection of the Z-axis component, thereby omitting the need for a separate MI element for the Z-axis and enhancing arrangement flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate MI elements are provided for each axis (X, Y, Z) to detect three-dimensional magnetic components, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The MI element is designed to perform multiple detection functions by detecting different magnetic field components through different operational modes. The same physical element can detect both in-plane magnetic fields (when used directly) and out-of-plane magnetic fields (when used with the magnetic body), eliminating the need for separate dedicated elements for each axis.
Solution Approach 2:
A magnetic body with specific magnetic permeability is introduced as an intermediary component between the MI element and the external magnetic field. This magnetic body converts out-of-plane magnetic field components into in-plane components that the MI element can detect, enabling the single element to measure three-dimensional magnetic fields.
2Measurement precision
If separate MI elements are provided for each axis to detect three-dimensional magnetic components, then measurement precision is improved, but the device size and thickness increase
Solution Approach 1:
The MI element serves multiple detection purposes simultaneously, detecting both X-axis and Z-axis magnetic components through different operational configurations, thereby reducing the overall device volume compared to using separate dedicated elements for each axis.
Solution Approach 2:
The magnetic body acts as a field converter that transforms three-dimensional magnetic field information into a format detectable by the planar MI element, enabling accurate Z-axis detection without requiring additional thickness for separate out-of-plane sensing elements.
3Adaptability or versatility
If a magnetic field direction changing body is added to enable Z-axis detection with existing MI elements, then adaptability is improved, but device complexity increases
Solution Approach 1:
The magnetic body is positioned strategically between the MI element and the external magnetic field to redirect out-of-plane magnetic field lines into the plane of the MI element. This simple intermediary structure enables enhanced adaptability for detecting magnetic fields in any direction without requiring complex mechanical or electronic systems.
Solution Approach 2:
The magnetic body is placed at a specific location (above or below the MI element) where it can locally modify the magnetic field distribution to achieve the desired direction-changing effect, rather than requiring a complex system-wide solution.
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 allows for a significant reduction in size and thickness of the magnetic detection device while maintaining high performance by enabling detection of all three-dimensional magnetic components with a single MI element, improving sensitivity and cost-effectiveness.
Implementation Method 1
MI elements utilize a magneto-impedance effect (referred to as an "MI effect") that, when a high frequency pulse current or the like is caused to flow through a magneto-sensitive wire such as an amorphous wire, its impedance varies in accordance with a magnetic field due to a skin effect.
Implementation Method 2
a magnetic field direction changing body composed of a soft magnetic material of which at least a part is disposed at another surface side of the substrate or in the substrate above a position that is symmetric with respect to the left-side coil part and the right-side coil part. The magnetic field direction changing body is able to change an external magnetic field component in a third axis direction to a measurement magnetic field component in the first axis direction.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4B
AI summary
An object is to provide a magnetic detection device that can be reduced in size and thickness. The magnetic detection device (1) of the present invention comprises: a substrate (S); and a first magneto-impedance element (MI element) disposed at one surface side of the substrate and comprising a first magneto-sensitive wire (W1) and a first detection coil (C1). The first magneto-sensitive wire senses an external magnetic field component in a first axis direction in which the first magneto-sensitive wire extends. The first detection coil loops around the first magneto-sensitive wire. The first detection coil according to the present invention comprises a left-side coil part (C11) and a right-side coil part (C12) that coexist along the first magneto-sensitive wire, and is provided with a magnetic field direction changing body (F1) composed of a soft magnetic material of which at least a part is disposed at another surface side of the substrate or in the substrate above an intermediate position between the left-side coil part and the right-side coil part. The magnetic field direction changing body is able to change an external magnetic field component in a third axis direction intersecting the substrate to a measurement magnetic field component in the first axis direction. The external magnetic field component in the third axis direction is able to be detected on the basis of a left-side output obtained from the left-side coil part and a right-side output obtained from the right-side coil part.