RFID Antenna Resonance Circuit for Microwave Ignition Resistance
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Solution Overview
Problem
RFID tags attached to food products can ignite when exposed to electromagnetic waves from microwave ovens due to overheating and overcurrent issues, posing a fire risk.
Innovation Solution
A wireless communication device design featuring a loop pattern with specific electrode configurations and resonance circuits that manage electromagnetic waves, preventing high voltage from being applied to the RFIC and reducing heat generation, including a capacitive impedance matching circuit to mitigate discharge risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional RFID tag with metal antenna pattern is used, then wireless communication function is achieved, but ignition risk occurs when exposed to microwave oven electromagnetic waves
Solution Approach 1:
The patent changes the electrical parameters of the antenna by introducing a series capacitor to modify the impedance characteristics. This transforms the antenna's response to electromagnetic waves, creating a resonant circuit that prevents excessive current flow and voltage buildup when exposed to microwave frequencies, thereby eliminating ignition risk while preserving communication functionality
Solution Approach 2:
The capacitor serves as an intermediary element inserted into the antenna circuit. It mediates the interaction between the metal antenna pattern and the electromagnetic waves by providing capacitive reactance that counteracts the inductive reactance of the metal trace, preventing resonant overcurrent conditions that would lead to ignition
2Reliability
If flame-retardant material is used as base material, then ignition spread is limited, but continuous discharge in metal portion can still cause re-ignition
Solution Approach 1:
The patent applies preliminary action by pre-configuring the antenna circuit with a series capacitor before exposure to electromagnetic waves. This preliminary circuit modification ensures that when microwave energy is applied, the capacitive reactance immediately limits current flow and prevents the continuous discharge conditions that would otherwise occur in the metal antenna trace
Solution Approach 2:
The capacitor fundamentally changes the electrical parameters of the antenna circuit, transforming it from a purely inductive structure vulnerable to overcurrent to an LC resonant circuit with controlled impedance. This parameter change ensures that even with flame-retardant base material, the metal portion cannot generate sufficient heat through continuous discharge to cause re-ignition
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 solution effectively suppresses ignition and ensures data communication integrity even when exposed to microwave oven frequencies, preventing damage to the RFID tag and maintaining product safety.
Implementation Method 1
a loop pattern having the first electrode and the second electrode as both ends; an antenna pattern connected to the loop pattern
Implementation Method 2
an RFIC having a capacitive impedance at a second frequency higher than the first frequency
Implementation Method 3
the second current path has an inductive impedance at a second frequency
Data Source
AI summary
A wireless communication device is provided for transmitting and receiving a high-frequency signal having a first frequency for communication is disclosed. The device includes a loop pattern having a first electrode and a second electrode as both ends, an antenna pattern, a third electrode capacitively coupled to the first electrode, and a fourth electrode capacitively coupled to the second electrode. The device includes an RFIC having a capacitive impedance at a second frequency higher than the first frequency, and a first current path and a second current path connected in parallel with each other between the third electrode and the fourth electrode. The RFIC is included in the first current path and the second current path has an inductive impedance at a second frequency.