Dual-Sided Security Marker With Segmented Cavities

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Solution Overview

Problem

Dual resonator security markers with resonators in a single cavity suffer from reduced amplitude and frequency coupling, leading to suboptimal system performance, and are prone to crushing due to increased thickness.

Innovation Solution

Placing two resonators in separate cavities within the marker housing, with each resonator biased by the same bias element, reduces coupling and loading, allowing for increased amplitude and detection of a beat frequency, resulting in improved performance and reduced material usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two resonators are placed in a single cavity, then the marker produces resonant signal, but the amplitude is reduced by about 65% compared to dual resonator markers and frequency coupling occurs

Engineering Contradiction:
Improvesystem performanceVSAvoidcavity structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The single cavity structure is divided into two separate cavities, with one resonator placed in each cavity. This segmentation eliminates frequency coupling between resonators and allows each resonator to operate independently, achieving full amplitude output while maintaining a compact marker structure.

Inventive Principle:
Principle #1Segmentation

2Length of moving object

If resonator width and thickness are reduced, then the marker width and thickness are reduced, but the output amplitude decreases proportionally

Engineering Contradiction:
Improvemarker widthVSAvoidoutput amplitude
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

Instead of reducing the dimensions of a single resonator, the invention uses two separate resonators in separate cavities. Each resonator can be optimized at standard dimensions for maximum amplitude, while the overall marker width is controlled by the lateral spacing of the two cavities rather than the width of individual resonators.

Inventive Principle:
Principle #1Segmentation

3Length of stationary object

If two resonators are placed close together, then the marker thickness is reduced, but crushing resistance decreases

Engineering Contradiction:
Improvemarker thicknessVSAvoidcrushing resistance
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

The invention distributes two resonators laterally across separate cavities rather than stacking them vertically. This dimensional redistribution maintains a thin profile while improving crushing resistance by spreading the structure's load-bearing capacity across a wider area, reducing stress concentration points.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Reliability

If resonators are equally spaced from the same bias element, then coupling is reduced and beat frequency is detected, but the bias element placement becomes more critical

Engineering Contradiction:
Improvedetection performanceVSAvoidbias element positioning
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The bias element is positioned equidistantly between two separate cavities, each containing one resonator. This symmetric segmentation creates two equal magnetic circuit paths, reducing coupling between resonators and enabling beat frequency detection. The segmented cavity structure provides natural positioning references that simplify bias element placement tolerances.

Inventive Principle:
Principle #1Segmentation

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 achieves approximately twice the output amplitude of single resonator markers while maintaining equivalent system performance, with reduced thickness and increased resistance to crushing, and enables detection of a beat frequency for enhanced system performance.

Implementation Method 1

a bias magnet is disposed within the housing adjacent to one or more magnetoelastic resonator

Methodology Applied
Scientific EffectMagnetoelastic resonance: Magnetoelastic Effects

Implementation Method 2

the security tag or marker produces a resonant signal with a particular amplitude that is detectable by the monitoring system

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 3

the first and second resonators are biased by the same bias element to oscillate at a frequency of a received transmit burst

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3635698B1Dual-sided security marker
Publication Date: 2021.04.21 SENSORMATIC ELECTRONICS CORP
  • EP3635698B1 patent drawingFigure 1
  • EP3635698B1 patent drawingFigure 2
  • EP3635698B1 patent drawingFigure 3

AI summary

Systems and methods for making a marker. The methods comprise: obtaining a marker housing having first and second cavities formed therein; disposing a first resonator in the first cavity and a second resonator in a second cavity; and placing a bias element at a location on or in the marker so that the first and second resonators are (a) equally spaced apart from the same bias element and (b) biased by the same bias element when the marker is in use to oscillate at a frequency of a received transmit burst.