Coin Surface Inspection via Multi-Wavelength Reflection Profiles
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Solution Overview
Problem
Existing coin processing machines are unable to reliably detect optically altered or soiled coins, which are accepted despite EU regulations, due to limitations in detecting deviations in geometric and physical properties.
Innovation Solution
A method that records the reflection profiles of coins in multiple optical wavelength ranges, compares them to reference profiles, and determines contamination by assessing conformity, allowing for the detection of altered or soiled coins with reduced computational effort and hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If geometric and physical properties are used for coin detection, then coin processing machines can detect forgeries, but they cannot reliably detect optically altered or soiled coins
Solution Approach 1:
The patent changes the detection parameter from geometric/physical properties to optical reflection properties at different wavelengths. By measuring reflection profiles in multiple wavelength ranges (e.g., UV, visible, infrared) and comparing them to reference profiles, the system can detect optical alterations and soiling that geometric measurements cannot identify, thereby improving detection reliability without significantly increasing system complexity
Solution Approach 2:
The patent replaces mechanical/geometric measurement methods with optical measurement methods. Instead of using physical sensors to measure coin dimensions and properties, the system uses optical recording devices to capture reflection profiles, substituting mechanical detection with optical detection to enable identification of optically altered coins
2Reliability
If image processing algorithms are used to check coins, then coin images can be analyzed, but computing effort and hardware costs increase significantly
Solution Approach 1:
The patent extracts only the essential reflection profile data from coin images at different wavelengths, rather than processing entire coin images. By measuring and comparing one-dimensional reflection profiles instead of analyzing complete two-dimensional images, the system achieves contamination detection with significantly reduced computational effort and hardware requirements while maintaining reliability
Solution Approach 2:
The patent creates simplified reference profiles that represent the expected reflection characteristics of clean coins at different wavelengths. These reference profiles serve as templates for comparison, allowing the system to detect contamination by comparing measured profiles against stored references without requiring complex image processing algorithms
3Reliability
If single wavelength range recording is used, then measurement process is simple, but detection of colored soiling is insufficient
Solution Approach 1:
The patent segments the optical spectrum into multiple wavelength ranges (e.g., ultraviolet, visible, infrared) and records reflection profiles separately for each range. This segmentation allows the detection system to identify different types of soiling based on their characteristic absorption and reflection patterns at specific wavelengths, improving reliability while maintaining measurement efficiency through systematic multi-range analysis
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 effectively detects contamination in coins by comparing recorded profiles with reference profiles, ensuring reliable identification of soiled coins with lower processing effort and hardware requirements, and is adaptable to various types of soiling.
Implementation Method 1
surface points of the coin image in at least two optical wavelength ranges are recorded, in which case a profile is created for each of the wavelength ranges, which represents the reflection in the relevant wavelength range
Data Source
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AI summary
The invention relates to a method for surface testing of coins (1) for contamination, in particular due to chemical processes, wherein: - a coin (1; 1a, 1b) to be examined is moved relative to an optical recording device (20) such that areas of the surface of the coin image are located in the recording area of the recording device (20), - during the movement of the coin (1; 1a, 1b) to be examined with the optical recording device (20) along at least one surface area (O; O1, O2, O3) and during this time surface points of the coin image (10; 10a, 10b) are recorded in at least two optical wavelength ranges, wherein a profile (P; P1, P2, P3) is created for each of the wavelength ranges, which represents the reflection in the respective wavelength range for a number of temporally successive recordings taken of the coin image (10; 10a, 10b) of the coin (1;1a, 1b) were created during their movement, - at least one reference profile (R; R1, R2, R3) of a reference coin is recorded and made available beforehand, which is centered such that the center of the coin image captured in the recording area of the recording device (20) corresponds to the center of the created reference profile (R; R1, R2, R3), and which is stretched or compressed such that the width of the captured coin image in the created reference profile (R; R1, R2, R3, R4) corresponds to a predetermined standard width, - the created profile (P; P1, P2, P3) of the coin to be examined (1; 1a, 1b) is shifted and stretched or compressed such that the center of the captured coin image (10; 10a, 10b) of the coin to be examined (1; 1a, 1b) is in the center of the created profile (P; P1, P2, P3) lies and that the width of the captured coin image (10; 10a, 10b) in the created profile (P; P1, P2, P3) corresponds to the specified standard width, - the created profile (P;P1, P2, P3) of the coin under investigation (1; 1a, 1b) is compared with at least one reference profile (R; R1, R2, R3, R4) of the reference coin and a corresponding conformity value is determined, and - contamination is detected if the determined conformity value indicates a conformity below a predetermined threshold.;