Artificially Soiled Banknote Test Decks for Reproducible Calibration

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Solution Overview

Problem

Existing banknote sorting apparatus calibration methods rely on manually selected soiled banknotes, which are limited by availability, costly, and result in non-reproducible test decks, leading to performance deviations and reduced lifetime due to mechanical weaknesses.

Innovation Solution

Artificially soiled banknotes with distinct soil patterns classified as 'fit' or 'unfit for further circulation' are produced, using defined optical properties to create a test deck that emulates real-world soiling, allowing consistent calibration and evaluation of sorting apparatus performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manually selected soiled banknotes are used to create test decks, then the test deck reflects real-world soiling patterns, but the process is time-consuming, costly, and produces non-reproducible results

Engineering Contradiction:

Improvereproducibility of test deckVSAvoidtime for manual selection and compilation

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies the copying principle by creating artificial soil patterns that replicate the appearance and optical properties of real soil stains on banknotes. Instead of manually collecting and reproducing actual soiled banknotes, the invention uses printed copies (artificial soil patterns) that mimic real soiling characteristics. This allows test decks to be reproduced consistently across different locations and times while maintaining the essential features needed for calibration, thereby resolving the contradiction between reliability and time consumption.

Inventive Principle:

Principle #26Copying

2Measurement precision

If manually selected soiled banknotes are used for test decks, then expert classification is possible, but the process becomes costly and complex

Engineering Contradiction:

Improveaccuracy of soiling level classificationVSAvoidcomplexity of manual selection process

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by defining specific optical parameters (optical density, colour spatial modulation, spectral properties) that objectively characterize soil patterns. Instead of relying on expert subjective judgment, the invention transforms the classification task into measuring and comparing these defined parameters. This reduces complexity by providing clear, objective criteria for classification while maintaining or improving measurement precision through consistent parameter-based evaluation.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If test decks are created from circulated banknotes, then real soiling variation is captured, but the test deck has limited lifetime due to mechanical fragility

Engineering Contradiction:

Improverepresentation of real soiling patternsVSAvoidlifetime of test deck

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies copying by creating durable artificial representations of soil patterns through printing processes. Instead of using fragile actual soil stains on circulated banknotes, the invention produces robust printed copies that replicate the optical characteristics of real soiling. These artificial soil patterns can be repeatedly applied to fresh banknotes, extending the test deck's lifetime while maintaining accurate representation of real soiling patterns for calibration purposes.

Inventive Principle:

Principle #26Copying

4Adaptability or versatility

If manually compiled test decks are used, then specific soil patterns can be selected, but performance deviations between different test decks occur

Engineering Contradiction:

Improveselection of specific soil patternsVSAvoidconsistency across test decks

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies parameter changes by establishing standardized optical parameters that define soil patterns. This allows different test decks to be created using the same parameter-based definitions, ensuring consistency across multiple test decks. The defined parameters (optical density, colour spatial modulation, spectral properties) serve as reproducible specifications that can be applied uniformly, eliminating variations between manually compiled test decks while still allowing selection of specific soil patterns needed for different calibration scenarios.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4231257B1Test deck of artificially soiled banknotes, manufacturing process and uses thereof

Publication Date: 2026.01.28 EUROPEAN CENTRAL BANK

Figure 1A~1C
Figure 1D~1E
Figure 2A~3B

AI summary

The present invention relates to a method of producing a test deck of artificially soiled banknotes, a test deck of artificially soiled banknotes, a use of the inventive test deck of artificially soiled banknotes for calibrating and/or evaluating performance of fitness sorting of a sorting apparatus for banknotes , and a method for calibrating and/or evaluating performance of fitness sorting of a sorting apparatus for banknotes using the inventive test deck, respectively according to the independent claims.