RFID Tag Discharge Electrode for Microwave Safety

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Solution Overview

Problem

RFID tags attached to food items can ignite when exposed to high-frequency electromagnetic waves in microwave ovens due to energy absorption, leading to potential fires, as existing flame-retardant configurations do not adequately prevent ignition and combustion.

Innovation Solution

A wireless communication device with a base material, a conductor pattern including an antenna pattern, and a discharge auxiliary electrode positioned to lower dielectric breakdown voltage, allowing controlled discharge and cutting of the antenna pattern to prevent ignition and heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a metal antenna pattern is provided on a base material for RFID communication, then wireless communication capability is achieved, but ignition and combustion risk increases when exposed to microwave heating

Engineering Contradiction:

Improvewireless communication capabilityVSAvoidignition and combustion risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-positioning the discharge auxiliary electrode on the base material before microwave exposure occurs. This electrode is strategically placed to intercept and control discharge paths before they can cause ignition. The electrode creates a controlled discharge mechanism that prevents uncontrolled arcing and heat generation in the metal antenna pattern during microwave heating, thereby resolving the contradiction between maintaining wireless communication functionality and preventing ignition risk.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If flame-retardant base material is used to prevent combustion, then base material ignition risk is reduced, but metal antenna discharge continues to pose ignition risk

Engineering Contradiction:

Improvebase material combustion preventionVSAvoidmetal antenna discharge

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The discharge auxiliary electrode serves as an intermediary element between the metal antenna pattern and the base material. It intercepts the harmful discharge from the metal antenna and provides a controlled discharge path that dissipates energy safely. This intermediary structure prevents the discharge from directly affecting the base material, thereby resolving the contradiction between preventing base material combustion and controlling metal antenna discharge.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If high-power electromagnetic wave heating is applied to food items, then heating efficiency is improved, but RFID tag ignition risk increases due to energy absorption

Engineering Contradiction:

Improveheating efficiencyVSAvoidRFID tag ignition risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of electromagnetic wave energy absorption by the RFID tag into a beneficial controlled discharge mechanism. The discharge auxiliary electrode is designed to utilize the induced electromagnetic energy to create controlled discharges that prevent more harmful uncontrolled arcing and ignition. By transforming the harmful energy absorption into a controlled discharge process, the system maintains high heating efficiency while preventing RFID tag ignition.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 prevents ignition and combustion of RFID tags and attached products during microwave heating by efficiently managing discharges and reducing resonance currents, ensuring safe operation in high-frequency electromagnetic environments.

Implementation Method 1

a dielectric breakdown voltage between two different opposed portions is lowered on the conductor pattern

Methodology Applied

Scientific EffectDielectric breakdown: Avalanche Breakdown

Implementation Method 2

efficiently managing discharges and reducing resonance currents

Methodology Applied

Scientific EffectElectrical discharge: Electric Arc

Implementation Method 3

energy of an electromagnetic wave from the microwave oven is absorbed by the RFID tag together with the product

Methodology Applied

Scientific EffectElectromagnetic energy absorption: Absorption (EM radiation)

Implementation Method 4

heat generation and sublimation of the metal material due to an overcurrent flowing in the metal material

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 5

reducing resonance currents, ensuring safe operation in high-frequency electromagnetic environments

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS10891529B2Wireless communication device

Publication Date: 2021.01.12 MURATA MFG CO LTD

AI summary

An RFID tag is provided as a wireless communication device that transmits and receives a communication signal. The RFID tag includes a base material, a conductor pattern including an antenna pattern provided at the base material, and a discharge auxiliary electrode. The discharge auxiliary electrode is disposed at a position where the discharge auxiliary electrode overlaps or is close to the antenna pattern in planar view, and lowers a dielectric breakdown voltage between two different opposed portions on the conductor pattern. With this configuration, ignition and combustion is prevented even in a situation in which the RFID tag is subjected to high-frequency power for heating a food item while attached to the food item.