NFC Modulation Detection in Wireless Charging to Protect Passive Devices
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Solution Overview
Problem
Existing wireless charging devices risk damaging passive NFC devices due to excessive power transfer, as they cannot distinguish between passive and active NFC devices based on modulation characteristics, leading to unintended charging and potential device damage.
Innovation Solution
A wireless charging device with a detection unit that analyzes modulation characteristics of NFC signals to differentiate between passive and active NFC devices, controlling the charging unit to prevent or reduce power transfer to passive devices, thereby avoiding damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging unit transfers power to all NFC devices without distinction, then active NFC devices can be charged efficiently, but passive NFC devices may be damaged due to excessive power transfer
Solution Approach 1:
The system performs preliminary detection of modulation characteristics before initiating power transfer. By analyzing the NFC signal modulation in advance, the system identifies whether the external device is passive or active, and only then decides whether to enable charging. This preliminary action prevents power transfer to passive devices that cannot be charged, eliminating the harmful effect while preserving charging efficiency for active devices.
2Object-affected harmful factors
If the charging unit implements device type detection and control, then passive NFC devices are protected from damage, but the system complexity increases
Solution Approach 1:
The system uses feedback from the NFC communication process itself to determine device type. The modulation characteristics of the NFC signal provide natural feedback that indicates whether the external device is passive or active. This feedback mechanism is integrated into the existing NFC protocol, allowing the system to protect passive devices without adding separate complex detection hardware or protocols.
Solution Approach 2:
The external device's own NFC signal modulation characteristics serve as the identification marker. Passive devices naturally exhibit different modulation behavior compared to active devices during NFC communication. The system leverages this self-expressed characteristic without requiring the external device to provide additional identification information or undergo separate authentication processes.
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 damage to passive NFC devices by accurately identifying their presence through modulation analysis, ensuring safe operation and efficient charging of active devices.
Implementation Method 1
a charging unit configured to charge an external device by wirelessly transferring power to the external device... the charging unit comprises a low frequency (LF) transmitter configured to transfer power to the external device
Implementation Method 2
Near field communication (NFC) is an established technology for proximity communication... a primary device may generate a radio frequency (RF) field at a frequency of 13.56 MHz to power a secondary device
Data Source
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AI summary
In accordance with a first aspect of the present disclosure, a wireless charging device is provided, comprising: a charging unit configured to charge an external device by wirelessly transferring power to said external device; a detection unit configured to detect whether the external device is a passive near field communication (NFC) device or an active NFC device by analyzing a modulation characteristic of an NFC signal received by the external device; a controller configured to control the charging unit in dependence on an output of the detection unit, wherein said output indicates whether the external device is a passive NFC device or an active NFC device. In accordance with a second aspect of the present disclosure, a corresponding method of operating a wireless charging device is conceived.