NFC Card Protection in Wireless Charging Systems
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Solution Overview
Problem
New wireless charging standards with higher power output can destroy NFC cards due to strong magnetic fields, and existing solutions require integrating NFC functions into wireless charging stations, which is not always feasible.
Innovation Solution
A device with a magnetic field detection circuit and an NFC-card detection circuit that measures the magnetic field and adjusts the transmitted power based on the presence and type of NFC cards, using a wire loop tuned to 13.56 MHz to induce and measure an AC voltage, and a microcontroller to limit power if the magnetic field exceeds safety limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wireless charging power is increased to meet new standards, then charging speed and power output are improved, but magnetic field intensity increases to a level that can destroy NFC cards
Solution Approach 1:
The patent implements a feedback mechanism where the NFC reader continuously monitors the magnetic field environment and detects NFC card presence. Based on this feedback, the system dynamically adjusts the wireless charging power to maintain magnetic field intensity below the threshold that would destroy NFC cards, thus resolving the contradiction between high power output and NFC card safety
Solution Approach 2:
The system transitions from static wireless charging power levels to dynamic power adjustment. The NFC reader modulates the charging power in real-time based on detected NFC card presence and type, allowing the system to operate at high power when NFC cards are absent while automatically reducing power when NFC cards are detected, thereby resolving the power-intensity contradiction
2Reliability
If NFC detection function is integrated into wireless charging station, then NFC card destruction can be prevented, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the wireless charging station's NFC reader serve dual functions: it both enables wireless charging communication and detects NFC card presence to prevent destruction. By making the NFC reader multi-functional, the system achieves NFC card protection without adding separate detection hardware, thus resolving the contradiction between reliability improvement and device complexity
Solution Approach 2:
The NFC reader within the wireless charging station performs self-detection of NFC cards and automatically adjusts charging parameters to protect detected NFC cards. This self-service capability eliminates the need for external detection devices or manual intervention, achieving reliable NFC card protection while maintaining simple station architecture
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
Effectively prevents NFC card damage during wireless charging by dynamically adjusting the charging power to maintain magnetic fields within safe limits for different NFC card standards, ensuring safe operation without the need for integrated NFC functions in the charging station.
Implementation Method 1
a wire loop (single or multiple loops) tuned with a parallel capacitor at 13.56 MHz {which is the operating frequency of the NFC cards). The wire loop may be placed above the transmitting coil of the wireless charger, in which the magnetic field generated by the charger. This will induce an AC voltage.
Implementation Method 2
The AC voltage will be then rectified with a Schottky Diode - also known as hot carrier diode - or a bridge of diodes
Data Source
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AI summary
The present invention relates to a device (100) for preventing NFC card destruction during wireless charging operations, the device (100) comprising: a magnetic field detection circuit (10), which is configured to measure an intensity of a magnetic field (H) generated by a wireless charging system; a NFC-card detection circuit (20) which is configured to detect a presence of a NFC card; and a charging control circuit (30), which is configured to limit a transmitted power of the wireless charging system during wireless charging operations based on a maximum permitted field, wherein the maximum permitted field is related to the detected presence of the NFC card.