NFC Electric Field Detection for LPCD Wake-Up Communication

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Solution Overview

Problem

Terminal devices in low power detection card (LPCD) mode face difficulty in exiting this mode due to insufficient antenna coupling or weak electric field changes, leading to challenges in normal communication.

Innovation Solution

An NFC electric field detection system with an NFC antenna and detection control module that receives a first radio frequency signal to detect the LPCD mode and sends a second radio frequency signal to excite the terminal device for normal communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the terminal device works in LPCD mode to reduce power consumption, then battery life is extended, but the ability to detect and communicate with NFC devices deteriorates due to insufficient antenna coupling and weak electric field changes

Engineering Contradiction:

Improvepower consumptionVSAvoidNFC communication reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a detection control module as an intermediary component that actively manages the transition between LPCD mode and normal communication mode. This module monitors electric field changes and antenna coupling status, then triggers mode switching when NFC communication is detected, thereby mediating between power savings and communication reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically switches between two operational states: LPCD mode for power saving and normal communication mode for reliable NFC interaction. The detection control module continuously monitors system state and transitions modes based on detected NFC signals, making the system adaptive rather than static

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If the terminal device works in LPCD mode, then power consumption is reduced, but the coupling area of the antenna becomes insufficient for normal NFC communication

Engineering Contradiction:

Improvepower consumptionVSAvoidantenna coupling area

Core Design Contradiction:

Use of energy by moving objectVSArea of stationary object

Solution Approach 1:

The detection control module performs preliminary detection of NFC devices while in LPCD mode by monitoring electric field changes. When an NFC device is detected, the system proactively switches to normal communication mode before actual communication is attempted, ensuring adequate antenna coupling area is available when needed

Inventive Principle:

Principle #10Preliminary action

3Duration of action of stationary object

If the terminal device works in LPCD mode, then battery life is extended, but electric field changes become too weak to trigger normal communication mode

Engineering Contradiction:

Improvebattery lifeVSAvoidelectric field change detection

Core Design Contradiction:

Duration of action of stationary objectVSDifficulty of detecting and measuring

Solution Approach 1:

The detection control module implements a feedback mechanism that continuously monitors electric field changes and uses this information to determine when to exit LPCD mode. The module compares detected field changes against thresholds and triggers mode switching based on this feedback, making detection reliable even with weak signals

Inventive Principle:

Principle #23Feedback

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 system effectively wakes up terminal devices from LPCD mode, ensuring normal communication and improving communication efficiency by using a second radio frequency signal to excite the device.

Implementation Method 1

the NFC antenna is configured to: when the terminal device transmits an NFC signal, sense field strength of the NFC radio frequency field to form an electrical signal corresponding to the field strength

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the NFC coil is configured to sense a radio frequency signal

Methodology Applied

Scientific EffectElectromagnetic radiation detection:

Implementation Method 3

the noise filtering terminal is configured to filter out a noise signal of the radio frequency signal sensed on the NFC coil

Methodology Applied

Scientific EffectNoise filtering: Filter (electronic)

Data Source

PatentEP4601202A1NFC electric field detection systems and methods, and NFC devices

Publication Date: 2025.08.13 ADVANCED NOVA TECH (SINGAPORE) HLDG PTE LTD

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AI summary

This specification provides an NFC electric field detection system and method, and an NFC device. The NFC electric field detection system in this specification includes an NFC antenna and a detection control circuit. The near field communication NFC antenna is configured to: in a case that an NFC radio frequency field of a terminal device is sensed, receive a first radio frequency signal transmitted by the terminal device; and the detection control module is configured to detect, according to the first radio frequency signal, that the terminal device is in a low power detection card LPCD mode; and in a case that abnormal communication is performed with the terminal device, send, to the terminal device by using the NFC antenna, a second radio frequency signal used to excite the terminal device, so as to communicate with the terminal device.