Optically Variable Security Element with Microlens Masking
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Solution Overview
Problem
Current security elements for data carriers, such as identity cards and banknotes, lack an effective means to prevent unauthorized reproduction and ensure high protection against forgery while maintaining an attractive visual appearance.
Innovation Solution
A security element comprising a central body with an arrangement of similar microlenses and a laser-sensitive recording layer, where a mask layer with a macroscopic void area is used to create micro-characteristics visible through the microlenses, providing a unique visual effect that is difficult to replicate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional numbering methods or laser engraving are used for personalization, then individualization is achieved, but security against unauthorized reproduction is insufficient
Solution Approach 1:
The patent divides the personalization approach into two distinct layers: a macroscopic visible layer (mask layer with visible numbers/characters) and a microscopic security layer (micro-characteristics visible only through microlenses). This segmentation allows the visible personalization to be separate from the security features, preventing unauthorized reproduction while maintaining ease of manufacturing through laser marking.
Solution Approach 2:
The patent introduces a new dimension of observation by incorporating microlenses that require specific viewing angles to see the micro-characteristics. This dimensional change from conventional flat viewing to angled viewing through lenses creates a new security dimension that cannot be reproduced by standard copying methods, while the mask layer maintains conventional visibility for normal personalization.
2Reliability
If microlenses are used to create angle-dependent visual effects, then security against forgery is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated security element structure: the mask layer serves both as the visible personalization layer and as a protective overlay, while the microlenses simultaneously focus light for viewing micro-characteristics and create the angle-dependent optical effect. This consolidation reduces overall device complexity compared to separate security features.
Solution Approach 2:
The microlenses act as an intermediary optical element between the mask layer and the recording layer with micro-characteristics. They mediate the light path to enable angle-dependent viewing of security features without requiring complex mechanical structures or multiple separate components, thereby managing device complexity while maintaining high forgery protection.
3Manufacturing precision
If laser radiation is used to produce micro-characteristics, then high precision marking is achieved, but the mask layer may be damaged
Solution Approach 1:
The patent applies preliminary action by positioning the mask layer at a specific distance from the focal plane of the microlenses before laser marking occurs. This pre-positioning ensures that the laser energy is focused on the recording layer to create precise micro-characteristics while the mask layer, being out of focus, receives diffused energy that prevents damage. The spatial arrangement is established beforehand to protect the mask layer.
Solution Approach 2:
The patent applies local quality by creating different laser energy distribution zones: a concentrated focal zone on the recording layer for precise micro-characteristic formation, and a diffused non-focal zone at the mask layer position that prevents damage. This localized energy distribution allows high precision marking without compromising mask layer integrity, as each layer receives the appropriate energy intensity for its function.
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 offers high protection against forgery and an attractive visual appearance by creating micro-characteristics that are recognizable only through specific viewing angles, making it challenging to reproduce the security element.
Implementation Method 1
an arrangement of similar microlenses (26) arranged on the first main surface (22) of the central body (20), the refractive effect of which defines a focal plane
Implementation Method 2
a mask layer (30) which lies between the arrangement of microlenses (26) and the laser-sensitive recording layer (40) and is arranged outside the focal plane of the microlenses (26), and a macroscopic void area (34) which has been produced in the mask layer (30) by the action of laser radiation
Data Source
Figure 1~2
Figure 3a~5b
Figure 6~8
AI summary
The invention relates to an optically variable security element (12) for security papers, value documents and other data storage media, comprising a single or multi-layered central body (20) having opposing first and second main surfaces (22, 24), an arrangement of similar micro-lenses (26) on the first main surface (22) of the central body (20), the refracting effect of the micro-lenses defining a focal plane (28), a laser-sensitive recording layer (40) disposed on the second main surface (24) of the central body (20), a mask layer (30) which is disposed between the arrangement of micro-lenses (26) and the laser-sensitive recording layer (40) and outside the focal plane (28) of the micro-lenses, and a plurality of micro-markings (44) produced in the laser-sensitive recording layer (40) by the action of laser radiation, wherein each micro-marking (44) is assigned to a micro-lens (26) and is visible when the security element (12) is viewed through the associated micro-lens (26). The mask layer (30) has a macroscopic recess area (34) in register with the plurality of micro-markings (44).