Ferromagnetic Shielding Layer for Decoupled NFC and Inductive Charging
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Solution Overview
Problem
Existing inductive charging and near-field communication devices face inefficiencies in inductive charging and unstable NFC communication due to magnetic coupling between charging and communication antennas, limited coverage, and sensitivity to metallic objects, leading to signal-to-noise ratio deterioration and reduced charging efficiency.
Innovation Solution
A device with a charging surface and a layer of ferromagnetic material beneath the charging antenna, where the NFC antenna is designed to surround the ferromagnetic layer with a specific permeability ratio, decoupling the charging and communication antennas to enhance magnetic field distribution and reduce impedance mismatch, thereby improving charging efficiency and stabilizing NFC communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the NFC antenna is arranged around the WPC antenna on the same printed circuit board, then the device structure is simplified, but the magnetic coupling between charging and communication antennas causes signal-to-noise ratio deterioration and unstable NFC communication
Solution Approach 1:
A ferromagnetic shielding layer is introduced between the WPC charging antenna and the NFC communication antenna to act as an intermediary element. This layer selectively guides magnetic flux at charging frequencies while blocking or redirecting magnetic interference at NFC frequencies, thereby reducing magnetic coupling and improving signal-to-noise ratio without requiring physical separation of the antennas
Solution Approach 2:
The patent utilizes frequency-dependent magnetic properties of the ferromagnetic shielding layer by selecting materials with specific permeability characteristics at different frequencies. The layer exhibits high permeability at WPC charging frequencies to guide magnetic flux, while at NFC frequencies the magnetic coupling is reduced, enabling stable communication
2Productivity
If the charging antenna is centered for optimal inductive charging alignment, then charging efficiency is improved, but the NFC antenna coverage is limited to the central area only
Solution Approach 1:
The NFC antenna is configured in a peripheral arrangement around the central WPC charging antenna, utilizing the radial dimension. This allows the NFC communication coverage to extend to the edges of the charging surface while the charging antenna remains centrally positioned for optimal charging efficiency
Solution Approach 2:
The device is segmented into two functional zones: a central charging zone with the WPC antenna for inductive charging, and a peripheral communication zone with the NFC antenna for near-field communication. This spatial segmentation allows both functions to operate optimally without interfering with each other
3Adaptability or versatility
If a second printed circuit board is added to accommodate the NFC antenna, then NFC communication is enabled, but the device thickness increases and manufacturing complexity increases
Solution Approach 1:
Both the WPC charging antenna and the NFC communication antenna are integrated onto the same printed circuit board, eliminating the need for a second PCB. The ferromagnetic shielding layer is used to manage magnetic interference, allowing dual functionality in a single-layer configuration, thereby reducing device thickness and simplifying manufacturing
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 configuration reduces energy losses, increases inductive charging efficiency, and extends NFC communication coverage uniformly around the device, ensuring stable communication during charging even with metallic objects, by optimizing the permeability of the ferromagnetic material for both low-frequency charging and high-frequency communication.
Implementation Method 1
part of the field created by said at least one communication coil passing through the layer of ferromagnetic material having a permeability comprising a real part and an imaginary part, the material of the layer of ferromagnetic material being selected so as to have a real part greater than 10 with, at the selected high frequency, a ratio between the imaginary part and the real part between 0.05 and 1
Implementation Method 2
the charging module forms a charging signal that makes it possible to channel an electric current, the strength of which varies over time, through the primary antenna. The primary antenna that is thus supplied forms a variable magnetic field.
Implementation Method 3
at least one near-field communication antenna emitting a magnetic field at a high frequency selected between 3 and 30 MHz
Data Source
AI summary
A device for high-frequency communication and for the inductive charging of an apparatus, including a charging surface, at least one charging antenna emitting a magnetic field at a low frequency and a layer of ferromagnetic material. The device includes at least one communication antenna and a printed circuit board. The communication antenna is in the form of a coil locally surrounding the layer with an axis of symmetry situated in a plane parallel to the layer. The material of the layer is selected so as to have, at high frequency, an imaginary part with sufficiently high permeability to generate leaks on a surface of the layer extending perpendicular to the layer, while at the same time maintaining, at low frequency, an imaginary part with sufficiently low permeability to allow inductive charging.