Light-Guiding Structure for Security Documents
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Solution Overview
Problem
Existing security documents with light-guiding structures face disruptions in edge lighting when opaque layers are introduced, leading to a loss of waveguide properties and inability to encode and verify information effectively.
Innovation Solution
A security element with a light-guiding structure comprising a transparent core and cladding, where the core's refractive index is greater than the cladding's, allowing for total reflection and light transmission to an exit surface, with local modifications in volume transmission properties using preparations to create patterns or filter light, enabling targeted information encoding and verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If opaque layers are introduced into security documents with light-guiding structures, then additional security features or information can be added, but the waveguide property is disrupted and edge lighting is lost
Solution Approach 1:
The patent applies local quality by creating specific transparent zones within the document body that maintain optical transparency and waveguide properties, while other areas can contain opaque security features. This allows different regions to have different optical properties - transparent regions for light conduction and opaque regions for additional security elements.
Solution Approach 2:
The document body is segmented into distinct functional zones: transparent light-guiding regions that maintain waveguide properties and separate opaque regions that can contain additional security features without interfering with the optical path. This segmentation allows both transparent and opaque elements to coexist.
2Loss of information
If printed layers are applied to security documents, then information can be encoded, but the light conduction through the document body is disrupted
Solution Approach 1:
Printed information is placed in localized areas that do not interfere with the main light conduction path. The printed layers are positioned in regions where they either do not block the optical path or where the light guidance occurs through different mechanisms that are not affected by the printed information.
3Illumination intensity
If the entire document body acts as a waveguide, then edge lighting occurs, but introducing opaque layers disrupts this waveguide property
Solution Approach 1:
The waveguide function is segmented from the entire document body to specific transparent zones. These dedicated light-guiding regions maintain the waveguide property and produce edge lighting, while other segmented regions can contain opaque layers and additional security features without affecting the optical guidance in the transparent zones.
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 allows for the creation of a secure, verifiable security element that maintains light conduction integrity regardless of additional layers, providing enhanced intensity differences and pattern visibility at the exit surface, facilitating effective information encoding and verification.
Implementation Method 1
the refractive index of the core being greater than the refractive index of the cladding, so that in the Core wave guidance can take place using a total reflection at a core - cladding interface
Implementation Method 2
the transparent material of the core is modified locally in a targeted manner with regard to its volume transmission property using a preparation. This makes it possible to locally impair or completely prevent the propagation of light in the core
Data Source
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AI summary
The invention relates to a method for producing a security element (1) and to a security element (1), in particular for a value or security document, comprising a light-guiding structure, wherein the light-guiding structure comprises a transparent core (2) and a likewise transparent cladding (7), and wherein the refractive index of the core (2) is greater than the refractive index of the cladding such that a total reflection for light wave guidance can take place at the interface between core (2) and cladding (7) and thus a light wave guidance to an exit surface (75) of the core (2) is possible. A volume transmission property of the core (2) is locally modified such that during light guidance in the light-guiding structure an intensity pattern of the emerging light, which is dependent on the exit location and is caused by the locally modified volume transmission property can be observed at the exit surface (75).