Magnetic Sheet with Local Permeability for Compass Noise
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Solution Overview
Problem
In electronic devices, the close proximity of magnetic body members to electronic compasses due to miniaturization and multifunctionalization constraints leads to increased direction errors caused by magnetic noise, and existing solutions with powdered magnetic materials are costly and offer limited detection sensitivity.
Innovation Solution
A magnetic sheet comprising a thin sheet-shaped Fe-based metal magnetic body with an AC relative magnetic permeability of 220-770 at 500 kHz, held on a resin film with an adhesive layer, allowing for flexibility and reduced direction errors when used with electronic compasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the magnetic body member is disposed close to the electronic compass due to miniaturization constraints, then the device size is reduced, but the direction error of the electronic compass increases
Solution Approach 1:
The magnetic body member is designed with non-uniform magnetic permeability distribution, having a first region with lower magnetic permeability (30-150) and a second region with higher magnetic permeability (200-500). This local quality variation allows the magnetic body to provide shielding function in specific areas while minimizing interference with the electronic compass, resolving the contradiction between compact size and measurement accuracy.
Solution Approach 2:
The patent changes the magnetic permeability parameter of the magnetic body member by using materials with different permeability values in different regions. The first region uses material with lower permeability to reduce magnetic noise, while the second region uses material with higher permeability for effective magnetic shielding, thus maintaining both compact size and compass accuracy.
2Measurement precision
If a magnetic body member with low magnetic permeability is used to reduce direction error, then the electronic compass accuracy is improved, but the magnetic shielding function is weakened
Solution Approach 1:
The magnetic body member is divided into functional regions: a first region with lower magnetic permeability (30-150) that reduces magnetic noise for improved compass accuracy, and a second region with higher magnetic permeability (200-500) that provides effective magnetic shielding. This spatial differentiation of material properties simultaneously achieves both improved measurement precision and maintained shielding reliability.
Solution Approach 2:
The magnetic body member is constructed as a composite structure combining materials with different magnetic permeability characteristics. The first region uses low-permeability material to minimize interference, while the second region uses high-permeability material for shielding, creating a composite magnetic body that fulfills both competing requirements.
3Adaptability or versatility
If powdered magnetic material is used to create the magnetic body member, then the manufacturing flexibility is improved, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent adopts a resin-based magnetic body member that can be molded into various shapes directly, replacing the expensive and complex process of powderizing, dispersing, and forming amorphous metal powders. This approach uses readily available resin materials with embedded magnetic particles, significantly simplifying the manufacturing process while maintaining flexibility in design.
Solution Approach 2:
The invention extracts and eliminates the complex powder processing steps (powderizing, dispersing, forming) from the manufacturing process. By using a resin-based composite material that can be directly molded, the patent removes the intermediate processing stages required for powder metalurgy, reducing both cost and process complexity while retaining manufacturing flexibility.
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 magnetic sheet effectively suppresses direction errors in electronic compasses, providing more accurate direction information while maintaining flexibility and reducing manufacturing complexity.
Implementation Method 1
the thin sheet-shaped magnetic body has an AC relative magnetic permeability μr of 220 or more and 770 or less at a frequency of 500 kHz
Implementation Method 2
The thin sheet-shaped magnetic body is held on the resin film with an adhesive layer sandwiched between the thin sheet-shaped magnetic body and the resin film
Implementation Method 3
Position information is obtained by an electromotive force generated in the coil group 340 according to the principle of electromagnetic induction
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
Provided is a thin sheet-shaped magnetic body holding on a resin film with an adhesive layer sandwiched between the thin sheet-shaped magnetic body and the resin film, wherein the thin sheet-shaped magnetic body is made from an Fe-based metal magnetic material, has a thickness of 15 µm to 35 µm and has an AC relative magnetic permeability µr of 220 or more and 770 or less at a frequency of 500 kHz.