Capacitive RFID Strap Testing via Dielectric Coupling

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Solution Overview

Problem

Quality testing for physical characteristics such as capacitance and resistance of RFID straps is a bottleneck in production due to the slow and potentially damaging process of using contact pins, which can become contaminated and require frequent cleaning.

Innovation Solution

A capacitive measuring system that utilizes coupling through a dielectric, including a meter, test pads, springs, and wiring, to maintain constant contact pressure and calculate RFID strap capacitance, allowing for the measurement of electrical properties without direct contact, using a multi-point coupling scheme to compensate for substrate variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contact pins are used for testing RFID strap characteristics, then direct electrical contact is achieved, but the testing process becomes slow and prone to damage due to pin movement, dragging, and contamination

Engineering Contradiction:

Improvecontact reliabilityVSAvoidtesting speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent introduces a dielectric substrate as an intermediary between the test pads and the RFID strap. This mediator allows electrical coupling to occur through the dielectric material without requiring direct contact between test pins and the strap, thereby eliminating pin dragging and contamination while maintaining reliable electrical contact for capacitance and resistance measurements

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical contact pin system with an electrical field-based measurement system. Instead of using physical pins that move and drag across the substrate, the system uses electrical fields to couple through the dielectric substrate and measure electrical characteristics, eliminating the mechanical wear and contamination problems

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If contact pins are used for testing, then electrical contact is established, but frequent cleaning and maintenance are required due to contamination

Engineering Contradiction:

Improvecontact stabilityVSAvoidmaintenance frequency

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The dielectric substrate serves as a permanent intermediary that prevents direct contact between test elements and the RFID strap. This eliminates contamination of contact surfaces, removing the need for frequent cleaning and maintenance while ensuring stable electrical contact for measurements

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system creates an electrical field copy or representation of the electrical characteristics through the dielectric substrate without requiring physical contact. This allows measurement of electrical properties (capacitance, resistance) by coupling through the dielectric, eliminating the need for direct contact and subsequent cleaning

Inventive Principle:

Principle #26Copying

3Device complexity

If conventional pin-based testing is used, then simple contact is achieved, but damage to pins or substrate surface may occur

Engineering Contradiction:

Improvetesting system simplicityVSAvoiddamage risk

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The dielectric substrate acts as a protective cushioning layer between the test pads and the RFID strap. This prior cushioning prevents direct mechanical contact that could cause damage, while still allowing electrical field coupling for measurement purposes

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The dielectric substrate serves as a protective intermediary layer that prevents direct contact between test elements and the RFID strap. This mediator eliminates the risk of mechanical damage to both pins and substrate surface while maintaining electrical coupling capability

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This method enables accurate and efficient measurement of RFID strap characteristics with improved contact reliability and reduced risk of damage, achieving measurement accuracy of around 1% of the strap capacitance without the need for frequent cleaning or maintenance.

Implementation Method 1

the coupling capacitance through the dielectric substrate may be utilized to calculate the strap capacitance

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

measuring system that utilizes coupling through a dielectric

Methodology Applied

Scientific EffectDielectric coupling: Dielectric

Data Source

PatentUS9874603B2System and method for capacitive coupling testing

Publication Date: 2018.01.23 AVERY DENNISON RETAIL INFORMATION SERVICES LLC

AI summary

A system for measuring RFID strap characteristics by coupling through a dielectric. The system can include a meter, test pads, springs, and wiring. Test pads may contact a substrate opposite of the RFID strap, and the coupling capacitance through the dielectric substrate may be utilized to calculate the strap capacitance. Similarly, other electrical properties of an RFID strap or other RFID assembly may be measured by coupling through a dielectric.