Angle-Dependent Luminescent Security Device
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Solution Overview
Problem
Current UV fluorescent security features on banknotes and documents are increasingly vulnerable to counterfeiting, necessitating a more robust authentication method that can operate with existing UV lamps without requiring new equipment or materials.
Innovation Solution
A security device with multiple luminescent layers and an optically variable structure that filters luminescent radiation, allowing a complete image to be visible only when viewed at specific angles, enhancing the robustness against copying and counterfeiting by varying the spectral content of luminescence with the angle of emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single luminescent layer is used for security authentication, then the device complexity is low and manufacturing is simple, but the security robustness against counterfeiting is insufficient
Solution Approach 1:
The luminescent security feature is divided into multiple separate luminescent layers (first luminescent layer and second luminescent layer), each positioned on opposite sides of the optically variable structure. This segmentation allows each layer to contribute differently to the overall luminescent image based on viewing angle, thereby enhancing security robustness while maintaining manageable device complexity through modular layering.
Solution Approach 2:
The patent introduces angular dependence as a new dimension for security authentication. By positioning luminescent layers on opposite sides of an optically variable structure and controlling their emission based on viewing angle, the system transforms a traditionally two-dimensional flat security feature into a three-dimensional angularly-dependent authentication mechanism, significantly improving counterfeiting resistance.
2Reliability
If an optically variable structure is added to control luminescent radiation angles, then the robustness against counterfeiting is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The optically variable structure serves multiple functions simultaneously: it acts as a structural support for positioning luminescent layers, functions as an angular-dependent optical filter to control which luminescent radiation passes through, and provides the mechanism for creating the angle-dependent authentication effect. This multi-functionality reduces the need for additional separate components, thereby managing manufacturing precision requirements while achieving enhanced security.
Solution Approach 2:
The optically variable structure acts as an intermediary element positioned between the first and second luminescent layers. It mediates the luminescent radiation from both layers, selectively transmitting radiation from the first layer at specific angles while allowing radiation from the second layer to pass through. This intermediary role simplifies the overall system architecture compared to using multiple complex independent control mechanisms.
3Reliability
If multiple luminescent layers are used with angle-dependent emission control, then the security feature becomes more robust, but the device complexity increases
Solution Approach 1:
The patent combines multiple luminescent layers and an optically variable structure into a single integrated security feature assembly. The first luminescent layer, second luminescent layer, and optically variable structure are merged into one functional unit where the layers are positioned on opposite sides of the structure, creating a unified angle-dependent authentication system that enhances security while managing complexity through integration.
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 significantly improves the robustness of luminescent security features by ensuring that only a complete image is visible at predetermined angles, making it more difficult to counterfeit while maintaining compatibility with existing UV lamp technology.
Implementation Method 1
a first luminescent layer which, when stimulated, emits luminescent radiation of at least a first wavelength
Implementation Method 2
a second luminescent layer which, when stimulated, emits luminescent radiation of at least a second wavelength
Implementation Method 3
an optically variable structure for controlling said luminescent radiation of said first luminescent layer, said structure being constructed and arranged to permit emission of luminescent radiation of said first wavelength through said structure at a first range of angles, said structure being constructed and arranged to minimize emission of luminescent radiation from said first luminescent layer for a second range of angles
Data Source
AI summary
A security device with multiple layers. A substrate provides the backing to a first luminescent layer. An optically variable structure is positioned between the first luminescent layer and a second luminescent layer. Both the first and second luminescent layers emit luminescent radiation when stimulated. When the first layer is stimulated, the optically variable structure filters the emitted luminescent radiation such that the emitted luminescent radiation only escapes the optically variable structure at a predetermined range of emission angles. A user, when viewing the security device from the predetermined range of angles as both layers are stimulated, can see a completed image of a predetermined indicia. When the security device is viewed at angles other than the predetermined range of angles as both layers are stimulated, a user will only see an incomplete image of the predetermined indicia.