Polymer Magnetic Shielding Layer for Wireless Antenna Eddy Current Suppression
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Solution Overview
Problem
Incorporating ferrite magnetic shielding layers into electronic devices is challenging due to size constraints and surface roughness issues, which can disrupt antenna operation and affect the smoothness of overlapping structures.
Innovation Solution
A polymer magnetic shielding layer with ferrite particles embedded in a polymer matrix is used, which provides effective magnetic shielding while minimizing thickness and surface roughness, and can be combined with a polymer-binder-free ferrite layer for enhanced magnetic permeability and reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a ferrite layer is used for magnetic shielding, then magnetic shielding effectiveness is improved, but the size of the electronic device increases
Solution Approach 1:
The patent uses a composite structure consisting of a polymer-binder-free ferrite layer combined with a polymer ferrite layer. The polymer-binder-free ferrite layer provides high magnetic permeability for effective magnetic shielding, while the polymer ferrite layer acts as a buffer to protect the display from surface irregularities. This composite material approach achieves effective magnetic shielding while maintaining a compact form factor suitable for portable electronic devices.
2Object-affected harmful factors
If a polymer-binder-free ferrite layer is used, then magnetic permeability is improved, but surface roughness increases
Solution Approach 1:
The patent introduces a polymer ferrite layer as an intermediary buffer layer between the polymer-binder-free ferrite layer and the display. The polymer ferrite layer has a smooth surface that protects the display from surface irregularities, particles, and roughness generated by the polymer-binder-free ferrite layer, while still providing magnetic shielding functionality. This intermediary layer resolves the conflict between achieving high magnetic permeability and maintaining surface smoothness.
3Volume of moving object
If ferrite layer thickness is reduced, then device size is minimized, but magnetic shielding effectiveness decreases
Solution Approach 1:
The patent employs a composite magnetic shielding structure with two distinct layers: a polymer-binder-free ferrite layer that provides high magnetic permeability and effective magnetic shielding in a thin profile, and a polymer ferrite layer that provides additional shielding while protecting the display. This composite approach achieves effective magnetic shielding with minimized total thickness, resolving the contradiction between thinness and shielding effectiveness.
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 effectively prevents eddy currents and surface defects, ensuring smooth operation of antennas and maintaining the appearance of the display by using a polymer ferrite layer as a buffer between the polymer-binder-free ferrite layer and the display, thereby minimizing the overall thickness of the magnetic shielding layer.
Implementation Method 1
Magnetic shielding layers can be incorporated into wireless electronic devices to prevent conductive electronic device structures from disrupting antenna operation. For example, a ferrite layer that serves as a magnetic shielding layer can be interposed between an antenna and a metal structure in an electronic device to prevent disruptive eddy currents from being produced in the metal structure during operation of the antenna.
Implementation Method 2
The polymer-binder-free ferrite layer (or other polymer-binder free magnetic shielding layer) may have a larger magnetic permeability than the polymer ferrite layer (or other polymer magnetic shielding layer) and may therefore help minimize the thickness of the magnetic shielding layer.
Data Source
AI summary
An electronic device may have a housing, electrical components, and other electronic device structures. A display may be mounted in the housing. The display may have a transparent display cover layer and a display layer such as an organic light-emitting diode display layer that is mounted to the underside of the transparent display cover layer. A flexible printed circuit with metal traces may be mounted under the organic light-emitting diode display layer. The metal traces may form coils for a near-field communications inductive loop antenna. A magnetic shielding layer may be interposed between the housing and the flexible printed circuit. The magnetic shielding layer may include a polymer magnetic shielding layer having magnetic material particles embedded in a polymer matrix. The magnetic shielding layer may also have a polymer-binder-free magnetic shielding layer.