Pulsed Light Detection for Banknote Authentication
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Solution Overview
Problem
Existing devices for detecting reflected and emitted light from objects, such as banknotes and security documents, face challenges in distinguishing between genuine and counterfeit items due to varying light intensities, which can lead to detector saturation or inability to detect weak signals, making it difficult to accurately assess authenticity, especially during high-speed processing.
Innovation Solution
A device equipped with a power supply that provides a time-periodic current with alternating strong and weak light pulses, allowing for high-frequency detection of light reflected or emitted by objects, expanding the dynamic range and enabling quantified detection without prior knowledge of optical properties, using LED lighting and separate sensors for reflected and emitted light, and employing filters and optical shielding to isolate wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a detector is used to detect light reflected or emitted by objects with varying optical properties, then the detector can identify different objects, but the light intensity varies widely causing detector saturation or inability to detect weak signals
Solution Approach 1:
The patent applies periodic action by using pulsed illumination with alternating strong and weak light pulses. The detector synchronously samples reflected light during each pulse cycle, enabling it to handle varying intensities by switching between strong pulses (for low reflectivity objects) and weak pulses (for high reflectivity objects), thus preventing saturation while maintaining detection capability across different optical properties.
2Device complexity
If a single light intensity is used for illumination, then the detection system is simple, but it cannot accurately detect both highly reflective and low-reflective objects simultaneously
Solution Approach 1:
The patent implements dynamics by making the illumination intensity variable rather than fixed. The system dynamically switches between strong and weak light pulses based on the detection needs, allowing the same detector to reliably measure both highly reflective and low-reflective objects without requiring multiple detectors or complex calibration procedures.
3Productivity
If high-speed processing is implemented for detecting large numbers of objects during transport, then productivity increases, but the temporal resolution required for accurate detection becomes more demanding
Solution Approach 1:
The patent ensures continuity of useful action by implementing continuous pulsed illumination and continuous synchronous detection during object transport. The detector continuously samples reflected light during each pulse cycle, maintaining high temporal resolution even at high processing speeds, thereby enabling accurate detection of security features without compromising productivity.
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 solution allows for effective differentiation between genuine and counterfeit objects by expanding the dynamic range of optical measurements, ensuring accurate detection of light intensities across a range, and enabling efficient processing of large numbers of objects during transport.
Implementation Method 1
using LED lighting
Implementation Method 2
detecting light reflected by the object
Implementation Method 3
detecting light emitted by the object by fluorescence
Implementation Method 4
detecting light emitted by the object by fluorescence and phosphorescence
Implementation Method 5
employing filters and optical shielding to isolate wavelengths
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a device and to a method for detecting reflected and/or emitted light of an object (1), having at least one illumination device (2) illuminating the object (1) with pulsed light, having at least one sensor (4, 6) capturing the light reflected and/or emitted by the object (1), having a transport device transporting the object relative to the illumination device (2) and past the sensor (4, 6) in a transport direction, having a power supply (16, 17, 18, 19, 20, 21, 22) of the illumination device (2) supplying power to the illumination device, said power having a periodic function over time, wherein one period comprises at least two current pulses (23, 24) having different magnitudes.