Shielding Film Structure for Wireless Charging EMI Filtering
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Solution Overview
Problem
Current wireless charging technologies face challenges in improving charging rates while minimizing electromagnetic radiation and maintaining safety, as conventional shielding methods either block or attenuate electromagnetic energy, affecting both user safety and regulatory compliance.
Innovation Solution
A shielding film with a conductive and insulating part structure that differentially responds to high-frequency and low-frequency electromagnetic fields by forming eddy currents, effectively absorbing high-frequency signals while allowing low-frequency signals to pass through, thereby enhancing charging efficiency and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If output power of the wireless charger is increased to improve charging rate, then charging rate is improved, but electromagnetic radiation increases reducing safety
Solution Approach 1:
The shielding film changes its electromagnetic properties based on frequency parameters. For high-frequency electromagnetic fields (harmful radiation), the conductive structure generates strong eddy currents that create opposing magnetic fields to cancel and shield the radiation. For low-frequency electromagnetic fields (useful charging signals), the insulating parts allow the magnetic field lines to pass through with minimal attenuation, enabling the charging signal to penetrate while blocking the harmful high-frequency radiation.
Solution Approach 2:
The shielding film uses a composite structure combining conductive parts (metal particles, conductive polymer, or conductive coating) and insulating parts (dielectric material) in an alternating pattern. This composite design enables differential response to electromagnetic fields of different frequencies: the conductive portions generate eddy currents to shield high-frequency radiation, while the insulating portions maintain magnetic field penetration for low-frequency charging signals.
2Object-affected harmful factors
If conventional electromagnetic shielding technology is used to block electromagnetic radiation, then electromagnetic radiation is blocked, but transmission of electromagnetic field energy for charging is affected
Solution Approach 1:
The shielding film applies different local properties to different regions: conductive parts are positioned to generate eddy currents for shielding high-frequency radiation, while insulating parts are positioned to allow low-frequency magnetic field lines to pass through. This local differentiation enables simultaneous shielding of harmful radiation and transmission of useful charging energy through different regions of the same film.
Solution Approach 2:
The film's electromagnetic response parameters change based on the frequency of the incident electromagnetic field. At high frequencies, the conductive structure dominates and generates strong eddy currents for shielding. At low frequencies, the insulating structure dominates and allows magnetic field penetration. This frequency-dependent parameter change enables selective shielding without blocking charging signals.
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 shielding film effectively filters high-frequency electromagnetic fields, preventing interference and radiation, while allowing low-frequency signals to be transmitted, thus improving charging rates and ensuring user safety and regulatory compliance.
Implementation Method 1
By using an eddy current loss effect, the shielding film provided in this embodiment of this application can effectively absorb and shield a high-frequency electromagnetic field
Implementation Method 2
Under the influence of a magnetic field of a second electromagnetic field, a second eddy current is formed in the first film layer, and a loop of the second eddy current passes through the first insulating part, so that current intensity of the second eddy current can be reduced
Data Source
AI summary
A shielding film includes a first film layer. The first film layer includes a first conductive part and a first insulating part, and the first insulating part penetrates the first conductive part in a thickness direction of the first film layer. Under electromagnetic influence of a first electromagnetic field, a first eddy current is formed in the first film layer, and a loop of the first eddy current is located in the first conductive part, so that the first eddy current has relatively high current intensity. Under electromagnetic influence of a second electromagnetic field, a second eddy current is formed in the first film layer, and a loop of the second eddy current passes through the first insulating part, so that current intensity of the second eddy current can be reduced.