Security Composite Body with Refractive Index Relief Structure
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Solution Overview
Problem
Existing security documents with viewing-angle-dependent features, such as those using lenticular lenses, face limitations in resolution and alignment during production, allowing potential falsification and lacking full-color information storage capabilities.
Innovation Solution
A method involving a composite body with transparent layers of different refractive indices, where a relief structure at the interface between these layers creates a viewing-angle-dependent effect by refracting light differently based on the angle of incidence, allowing for optically perceptible features on opposite sides of the structure, enabling register-accurate insertion of information that can be viewed from both sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lenticular lenses are used to create viewing-angle-dependent security features, then the security effect is improved, but the resolution and alignment precision deteriorate
Solution Approach 1:
The patent changes the refractive index parameter by using a transparent filling material with a different refractive index than the surrounding plastic material. This creates a relief structure at the interface that produces viewing-angle-dependent optical effects with higher resolution and better alignment precision, resolving the contradiction between security effect and manufacturing precision
Solution Approach 2:
The patent uses composite materials consisting of transparent plastic material and transparent filling material with different refractive indices. This composite structure enables the creation of high-precision relief structures at the interface that provide both strong security effects and excellent alignment precision, simultaneously addressing both requirements
2Reliability
If lenticular lenses are used for security features, then viewing-angle-dependent effects are achieved, but full-color information storage capability is lost
Solution Approach 1:
The patent adds a new dimension to information storage by creating relief structures at the material interface. This interface structure provides an additional optical dimension that maintains viewing-angle-dependent effects while enabling full-color information storage through the transparent filling material, resolving the information loss contradiction
3Reliability
If complex relief structures are created at material interfaces, then security features are enhanced, but production complexity increases
Solution Approach 1:
The patent employs self-service principles where the relief structure is formed automatically during the lamination process itself. The transparent filling material is applied to the first plastic material before lamination, and the relief structure emerges naturally at the interface during bonding, eliminating the need for separate complex relief structure creation equipment and reducing production complexity while maintaining high security feature quality
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
This approach enhances the security features by providing a novel, difficult-to-produce composite body with improved viewing-angle-dependent effects, preventing easy falsification and enabling full-color information storage, while maintaining structural integrity and minimal energy input during production.
Implementation Method 1
A security composite body (100) is produced from different plastic materials which are transparent in volume and have different refractive indices. Light passing through the interface is refracted differently depending on an angle of incidence relative to a local surface normal at the interface due to the different refractive indices.
Data Source
Figure 1a~1d
Figure 1e~1f
Figure 2
AI summary
The invention relates to a security composite body (100) and a method for producing such a security composite body (100), said method comprising the following steps: providing a transparent layer (1) made of a first plastic material having a first index of refraction n1, wherein the transparent layer has a top side (4) and an opposite bottom side (6); forming a relief structure (5) in the top side (4) of the transparent layer (1); covering at least the relief structure (5) with a second plastic material (11), which has a second index of refraction n2 that deviates from the first index of refraction n1; joining the at least one second plastic material (11) and optionally additional at least partially transparent layers (21, 31, 91, 92) with the one transparent layer (1) to form the security composite body (100), so that a bottom side (6) of the transparent layer (1) faces a bottom side (106) of the security composite body (100) and a top side (4) of the transparent layer (1) faces the top side (104) of the security composite body (100) and the second plastic material (11) forms a complementary structure that is adapted to the relief structure (5) and that lies directly against the relief structure; and introducing two features (61, 71) into the security composite body (100), wherein the two features (61, 71) are introduced into the security composite body (100) in exact alignment with the relief structure (5) on opposite sides of the relief structure (5), so that an effect of the one feature that depends on the angle of observation can be perceived when the composite body is observed from the top side (104) and an effect of the other feature (71) that depends on the angle of observation can be perceived when the composite body is observed from the bottom side (106) of the composite body.