Hollow Magnetic Field Deflector for MI Sensor
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Solution Overview
Problem
Conventional magnetic detection devices using MI elements are limited in size reduction and accuracy due to their structural constraints, particularly in detecting three-dimensional magnetic fields, as they require multiple MI elements for each axis component, leading to increased size and complexity.
Innovation Solution
The magnetic detection device employs a hollow shell structure for the magnetic field deflector made of soft magnetic material, which reduces the volume of soft magnetic material used and enhances followability to varying magnetic fields, allowing a single MI element to detect orthogonal magnetic field components with improved accuracy and reduced production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple MI elements are provided for each component of the magnetic vector to detect three-dimensional magnetic fields, then detection accuracy is improved, but device size and thickness increase
Solution Approach 1:
A single MI element is designed to detect magnetic field components in multiple directions (X, Y, and Z axes) by utilizing the magneto-impedance effect and strategic positioning, eliminating the need for separate MI elements for each axis while maintaining comprehensive three-dimensional magnetic field detection capability
Solution Approach 2:
Multiple detection functions for different magnetic field components are merged into a single MI element through careful structural design and positioning, allowing one element to perform the work of what would traditionally require three separate elements, thereby reducing device size and component count
2Volume of moving object
If a solid magnetic field deflector of soft magnetic material is used to enable Z-axis detection without a Z-axis MI element, then device size is reduced, but followability to varying magnetic fields deteriorates
Solution Approach 1:
The magnetic field deflector is designed as a hollow shell structure rather than a solid block, creating a lighter, more responsive component that can quickly adapt to changing magnetic field conditions while maintaining the space-saving benefits of reduced material volume
Solution Approach 2:
The structural parameters of the magnetic field deflector are changed from solid to hollow shell configuration, fundamentally altering its magnetic response characteristics to achieve both compact size and high followability to varying magnetic fields
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 enables a significant reduction in size and production cost while maintaining high accuracy and sensitivity, allowing for more efficient detection of magnetic field components in multiple directions with a single MI element, thereby enhancing the overall performance and productivity of the magnetic detection device.
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
indirectly measuring the variation of amount of magnetic flux generated in the magneto-sensitive wire, which causes the MI effect, via a detection coil (pickup coil) wound around the magneto-sensitive wire
Implementation Method 3
The magnetic field deflector deflects an external magnetic field around the magneto-sensitive wire. The magnetic field deflector comprises a core part composed of a nonmagnetic material and a shell part composed of a soft magnetic material
Data Source
AI summary
A magnetic detection device that is reduced in size and thickness, but also accurate, includes a substrate and an element disposed on the substrate and including a magneto-sensitive wire sensing an external magnetic field component in an extending direction and a detection coil looping around the magneto-sensitive wire. The magnetic detection device further includes a magnetic field deflector deflecting an external magnetic field around the magneto-sensitive wire, and having a nonmagnetic material core part and a soft magnetic material shell part covering an outer side of at least part of the core part. The magnetic field deflector has a hollow, rather than solid, structure of soft magnetic material. The soft magnetic material volume is therefore significantly smaller, and the hysteresis caused in the magnetic field deflector is remarkably reduced. With the magnetic detection device, the magnetic field component orthogonal to the substrate is also detected with higher accuracy.