Coin Imaging Lighting Angles for Discrimination Accuracy
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Solution Overview
Problem
Existing coin processing systems face challenges in accurately discriminating between valid and invalid coins due to variations in coin surface reflectance caused by aging and wear, leading to high discrimination errors and prolonged processing times, especially when handling large batches of coins.
Innovation Solution
The implementation of a currency processing system utilizing a linear array of optical coin-imaging sensors with multiple light emitting sources that provide near-normal and high-angle of incidence lighting, enabling high-speed imaging and processing by capturing multiple spectral characteristics of coins, and allowing for real-time reconfiguration to capture uniform and edge-enhanced images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional single-angle lighting is used for coin imaging, then the device structure is simple, but discrimination errors increase due to variations in coin surface reflectance
Solution Approach 1:
The lighting system is segmented into multiple independent light sources positioned at different angles (e.g., 0°, 45°, 90°). Each light source illuminates the coin from a specific angle to capture different surface characteristics. This segmentation allows the system to overcome surface reflectance variations by combining information from multiple angles, thereby improving authentication accuracy without requiring an overly complex unified lighting structure.
Solution Approach 2:
Different regions of the coin surface are illuminated with light at optimal angles specific to each region's characteristics. For example, raised features may be illuminated from one angle to maximize shadow contrast, while flat areas use a different angle. This local optimization of lighting quality enhances the capture of surface topography details, improving measurement precision while keeping each individual light source relatively simple.
2Productivity
If multiple light sources are used to capture spectral characteristics, then processing speed increases, but device complexity increases
Solution Approach 1:
The sensor system is divided into multiple linear arrays, each associated with a specific light source angle. Each sensor array independently captures images illuminated by its corresponding light source. This segmentation allows parallel processing of multiple coin surfaces simultaneously, significantly increasing processing speed. The modular nature of segmented sensors also keeps individual components manageable in complexity.
Solution Approach 2:
The system transitions from single 2D camera imaging to multiple linear array sensors capturing data from different angular dimensions. By adding the angular dimension to the imaging process, the system captures comprehensive surface information that enables faster authentication. This dimensional expansion improves productivity while the linear array structure maintains relative simplicity compared to complex multi-camera 3D systems.
3Loss of time
If 2D camera systems are used for coin imaging, then the system is compact, but processing time increases and cost increases
Solution Approach 1:
The patent replaces traditional mechanical 2D camera imaging systems with an optical-based linear array sensor system. This substitution enables high-speed parallel capture of coin surface characteristics from multiple angles simultaneously, dramatically reducing processing time. The optical linear arrays are specifically designed for coin denomination detection and can process multiple coins in rapid succession, overcoming the time limitation of sequential 2D camera systems while maintaining manageable complexity through specialized optical design.
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 approach significantly reduces discrimination errors, enhances processing speed, and improves the accuracy of coin authentication and validation, while also being more cost-effective and compact compared to traditional 2D camera systems.
Implementation Method 1
The first light emitting device emits light onto a surface of a passing coin at normal or near-normal incidence, while the second light emitting device emits light onto the surface of the passing coin at high-angle incidence
Data Source
AI summary
Currency processing systems, coin processing machines, and methods of imaging coins are presented herein. A currency processing system is disclosed which includes a housing with an input area for receiving coins and receptacles for stowing processed coins. A disk-type coin processing unit is coupled to the coin input area and coin receptacles. The coin processing unit includes a rotatable disk for imparting motion to coins, and a sorting head adjacent the rotatable disk with shaped regions for guiding moving coins to exit channels through which the coins are discharged to the coin receptacles. A sensor arrangement mounted adjacent the rotatable disk includes one light emitting device for emitting light onto a coin surface at near-normal incidence. A photodetector senses light reflected off the coin surface and outputs a coin-image signal for processing the coin.