Electrode Geometry for Electroluminescent Pigment Excitation

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Solution Overview

Problem

Existing document checking devices for value and security documents face challenges in reliably and efficiently exciting electroluminescent pigments with reduced maximum amplitude of alternating voltage, particularly in decentralized systems like small bill validators or ATMs, due to limitations in installation space and interference issues.

Innovation Solution

A document checking device with electrodes designed to concentrate electric field lines, achieving higher flux densities in specific areas, allowing for reliable excitation of electroluminescent pigments with reduced voltage amplitude, and minimizing interference and energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrodes with uniform field distribution are used, then the installation space can be larger, but the excitation reliability of electroluminescent pigments is insufficient and high voltage amplitude (30 kV) is required

Engineering Contradiction:
Improveexcitation reliabilityVSAvoidelectrode structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The electrode is designed with non-uniform geometry (point electrode, edge configuration, or asymmetric shape) to create localized regions of high electric flux density. This concentrates the electric field where needed to reliably excite electroluminescent pigments without requiring high voltage across the entire electrode structure, thus improving excitation reliability while controlling device complexity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention transitions from considering only the two-dimensional electrode surface area to incorporating the third dimension of field distribution in space. By designing electrodes that create concentrated field lines in specific spatial regions (point sources, edge effects), the patent achieves reliable excitation in targeted areas without proportionally increasing overall device size or complexity.

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

2Reliability

If high voltage amplitude (30 kV) is applied to bridge air gaps, then electroluminescent pigments can be excited, but plasma formation, voltage breakdown, and electromagnetic interference occur

Engineering Contradiction:
Improveexcitation reliabilityVSAvoidplasma formation and voltage breakdown
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

By concentrating electric flux density in specific localized regions through specialized electrode geometry, the patent achieves sufficient field strength for reliable pigment excitation at lower overall voltage levels. This prevents the air gap breakdown and plasma formation that occur with conventional high-voltage (30 kV) uniform field distribution, while maintaining excitation reliability in the concentrated field regions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention changes the spatial distribution parameter of electric flux density from uniform to non-uniform/concentrated. This parameter change allows the system to achieve the same excitation effect at lower voltage amplitudes, thereby reducing harmful effects like plasma formation and voltage breakdown that are voltage-threshold dependent.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If high voltage amplitude (30 kV) is used for excitation, then electroluminescent pigments can be reliably excited, but electromagnetic interference increases

Engineering Contradiction:
Improveexcitation reliabilityVSAvoidelectromagnetic interference
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The concentrated electrode design creates localized high-field regions that efficiently excite pigments without requiring system-wide high voltage. This reduces the overall electromagnetic field strength in the environment, minimizing electromagnetic interference while maintaining excitation reliability in the concentrated field zones through geometric field enhancement.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

By changing the electric flux density distribution from uniform to concentrated, the patent reduces the total voltage amplitude needed (from 30 kV to lower levels). This parameter change directly reduces the strength of emitted electromagnetic radiation, thereby reducing interference while maintaining excitation effectiveness through field concentration.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If decentralized authentication devices (small bill validators, ATMs) are implemented, then accessibility improves, but installation space becomes limited

Engineering Contradiction:
Improvedecentralized authentication capabilityVSAvoiddevice installation space
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The concentrated electrode design achieves efficient pigment excitation in localized regions, allowing the authentication device to be more compact. This enables decentralized applications (small validators, ATMs) to fit within limited installation spaces while maintaining reliable authentication capability through focused field concentration rather than requiring large uniform field areas.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent exploits spatial field concentration in three-dimensional space to achieve efficient excitation with compact electrode structures. This allows decentralized authentication devices to maintain functionality in reduced installation volumes by concentrating the electromagnetic interaction in specific spatial regions rather than requiring large planar electrode areas.

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

5Reliability

If conventional electrodes are used, then manufacturing is simpler, but excitation is less reliable and requires higher voltage

Engineering Contradiction:
Improveexcitation reliabilityVSAvoidelectrode manufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs electrode geometries (point electrodes, edge configurations, asymmetric shapes) that concentrate electric flux density in specific regions. While slightly more complex than uniform electrodes, these designs can be manufactured using standard techniques and achieve superior excitation reliability at lower voltages, offering a practical balance between manufacturing simplicity and performance.

Inventive Principle:
Principle #3Local quality

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 enables targeted and reliable excitation of electroluminescent pigments with lower voltage amplitudes, reducing plasma formation, voltage breakdown, and electromagnetic interference, while maintaining strong excitation, thus improving the reliability and compactness of the device.

Implementation Method 1

an electrode (6) which is used to generate an electric field (7) and is designed in such a way that an electric flux density of the electric field (7) that can be generated by the electrode (6) in a predetermined emission direction changes

Methodology Applied
Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

for the contactless excitation of at least one electroluminescent pigment (19), in particular in a value or security document (2)

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2976680B1Method and device for the contactless excitation of electroluminescent pigments
Publication Date: 2018.01.17 BUNDESDRUCKEREI GMBH
  • EP2976680B1 patent drawingFigure 1~2b
  • EP2976680B1 patent drawingFigure 3~5
  • EP2976680B1 patent drawingFigure 6~7

AI summary

The invention relates to a device for exciting at least one electroluminescent pigment, in particular in a value document or security document (2), without contact, wherein the device (1) comprises at least one electrode (6), wherein the at least one electrode (6) is designed in such a way that an electric flux density of the field (7) that can be generated by the electrode (6) in a predetermined emission direction (9) changes. The invention further relates to a method for contactless excitement.