Optical Flat-Sample Testing With Window Retroreflection Stability
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Solution Overview
Problem
Existing methods for testing the authenticity and quality of value documents suffer from unstable measurement signals due to fluctuations in the distance between the samples and the optical sensor module, caused by lifting or fluttering of the documents during transport, leading to a wide acceptance range that may overlook unacceptable quality deviations or counterfeit documents.
Innovation Solution
A device and method that utilize an optical sensor module with a target measurement plane and a strategically positioned window to enhance the measurement signal through a retroreflection effect, reducing signal variation by maintaining a small module distance from the target measurement plane and employing a retroreflection effect to stabilize the measurement signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the value documents are transported past the sensor module at high speed, then productivity is improved, but the documents may lift or flutter out of the desired transport plane causing measurement signal distortion
Solution Approach 1:
A window is introduced as an intermediary element between the sensor module and the value documents. This window creates a retroreflection effect that stabilizes the measurement signal by reflecting light back through the sample, making the measurement less sensitive to distance fluctuations caused by document fluttering during high-speed transport
2Measurement precision
If mechanical boundaries are provided to reduce document fluttering, then measurement precision is improved, but the boundaries cannot be arranged arbitrarily close to the transport path due to risk of transport malfunction or document damage
Solution Approach 1:
The patent replaces the mechanical boundary system with an optical solution. Instead of using physical guides or constraints to stabilize document position, the invention uses the retroreflection effect created by the window to stabilize the measurement signal, eliminating the need for complex mechanical constraints in the transport path
3Ease of operation
If a wide acceptance range is allowed in the quality test, then ease of operation is improved, but actually unacceptable quality deviations or counterfeit documents may be overlooked
Solution Approach 1:
By replacing the mechanical stabilization approach with an optical retroreflection system, the invention achieves measurement signal stability that allows for tighter acceptance ranges in quality testing, thereby improving reliability without sacrificing ease of operation
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
The solution provides a more stable measurement signal that is less dependent on distance fluctuations, allowing for accurate detection of optical properties and ensuring reliable authenticity and quality testing of value documents.
Implementation Method 1
the window distance is selected sufficiently small that the measurement signal of the flat sample in the target measurement plane is increased by a retroreflection effect of the window
Data Source
AI summary
A device and a method for testing flat samples, include an optical sensor module which for optically testing the flat sample captures a measurement signal of the flat sample when the flat sample is located in the target measurement plane or at least approximately in the target measurement plane. A window is arranged between the sensor module and the flat sample at a window distance from the target measurement plane. The sensor module is arranged at a module distance from the target measurement plane. The module distance is selected to be sufficiently small for a signal variation of the measurement signal of the flat sample as a function of the measurement distance deviation in the region of the target measurement plane to be reduced by the retroreflection effect of the window compared to a signal variation occurring without the retroreflection effect.