Continuous Luminescence Decay Sensor for Value Document Verification
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Solution Overview
Problem
Existing methods for checking the decay time of luminescence in documents of value are discontinuous due to pulsed illumination and relative movement, limiting the range of decay times that can be determined, especially at low movement speeds.
Innovation Solution
A sensor system with multiple detectors positioned along the direction of movement, allowing continuous illumination and detection of luminescence, enabling the determination of decay times across a wide range by using luminescence signals from overlapping and non-overlapping detection areas, and adjusting signal selection based on movement speed and document properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulsed illumination is used to check luminescence decay time, then the document can be illuminated and detected, but the check becomes discontinuous and limits the measurable decay time range
Solution Approach 1:
The patent applies continuous illumination instead of pulsed illumination, allowing the luminescence signal to be detected continuously as the document moves through the measurement plane. This eliminates the discontinuity caused by dark phases and enables reliable measurement of decay times across a wide range, resolving the contradiction between measurement precision and measurement continuity.
2Measurement precision
If a single detector is used at a fixed position, then the device structure is simple, but the measurable decay time range is limited especially at low movement speeds
Solution Approach 1:
The patent divides the detection function into multiple detectors positioned at different locations along the document movement path. Each detector captures luminescence signal at its specific position, and the system processes these segmented signals to accurately determine decay times across various movement speeds, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent transitions from a single-point detection to a spatial distribution of detectors along the movement direction. By adding the spatial dimension to the detection system, the patent enables accurate decay time measurement across different movement speeds without increasing temporal complexity, as the spatial arrangement provides additional measurement dimensions.
3Measurement precision
If the document moves slowly through the measurement plane, then more time is available for detection, but the decay time measurement range becomes limited
Solution Approach 1:
The patent uses multiple detectors positioned at different locations along the movement path to capture luminescence signals at different spatial positions. This segmentation allows the system to measure decay times accurately regardless of movement speed, as each detector provides independent measurement data that can be processed to determine decay characteristics across the full range.
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
Enables continuous and accurate measurement of luminescence decay times across a large range, even at low movement speeds, without interruptions, improving the precision and effectiveness of document authentication and verification processes.
Implementation Method 1
The excitation light of the illumination device is designed to excite a luminescence of the value document to be checked in such a way that the value document emits luminescence light that can be detected by the detectors
Implementation Method 2
the sensor has a plurality of detectors for detecting luminescence light, which the value document illuminated with the excitation light emits in different detection areas of the measurement plane
Data Source
Figure 1a~1c
Figure 2a~3d
Figure 4a~5b
AI summary
The invention relates to a sensor for verifying a value document, which is moved relative to the sensor. The sensor is designed to check the decay time of a luminescence of the value document based on luminescence signals of a plurality of detectors. The sensor comprises a lighting device for illuminating the value document with excitation light, and a plurality of detectors for continuous detection of luminescent light that the illuminated value document emits in different detection regions that are arranged offset with respect to each other along the movement direction of the value document. A first of the detectors of the sensor is designed to generate a first luminescence signal of a first detection region that in the measuring plane overlaps with the illuminated portion, and a second detector of the sensor is designed to generate a second luminescence signal of a preceding detection region which, viewed along the movement direction of the value document, is arranged in the measuring plane upstream of the first detection region.