Reflective Micro-Imaging Security Element with Dual Adhesive Embedding
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Solution Overview
Problem
Security threads in banknotes with microlenses face issues with surface adhesion, leading to instability due to undesired lifting of paper webs, which reduces the banknote's stability in circulation.
Innovation Solution
A security element with reflective micro-imaging elements and microstructures arranged in specific patterns, featuring adhesive layers on both sides to ensure secure embedding within the banknote, preventing lifting and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microlenses are used for enlarged imaging of security features, then the imaging capability is improved, but the adhesive cannot be applied to the lens surface causing instability
Solution Approach 1:
The patent introduces an adhesive layer applied to the back surface of the microlens array substrate as an intermediary solution. This allows the security thread to be firmly embedded in the banknote without requiring adhesive on the optical surface, thus maintaining both imaging capability and stability. The adhesive layer on the back surface acts as a mediator between the microlens array and the banknote substrate.
2Reliability
If the security element is embedded in the banknote, then the security feature is protected, but the paper webs may lift between windows reducing stability
Solution Approach 1:
The patent applies adhesive layers to both the front and back surfaces of the security thread before embedding it in the banknote. This preliminary application of adhesive ensures that both the top and bottom of the security thread are firmly bonded to the banknote substrate, preventing any lifting of paper webs between the windows during circulation.
3Length of stationary object
If reflective micro-imaging elements are used instead of microlenses, then the thickness can be reduced, but adhesive application becomes possible on both sides
Solution Approach 1:
The patent inverts the conventional approach by applying adhesive to the back surface of the microlens array substrate rather than the front optical surface. This inversion allows adhesive application without compromising the optical functionality, enabling both thickness reduction and proper embedding in the banknote.
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 effectively prevents the lifting of paper webs between windows, ensuring high durability and stability of the banknote by securely gluing the security element on both sides, thus maintaining the enlarged image visibility and authenticity.
Implementation Method 1
one or more optics arrangements, each of which only enlarges the image of an associated object in front of the upper side
Implementation Method 2
Micro-imaging elements are preferably designed as micro-concave mirrors, which have a reduced focal length compared to refractive micro-lenses
Data Source
Figure 1~2
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AI summary
The invention relates to a security element for an article (2, 37) to be protected, having an upper face (13) and a lower face (15), one or more imaging optical arrangements, which all image a respective associated object to a magnified scale only in front of the upper face (13), wherein the one optical arrangement or at least one of the optical arrangements comprises a plurality of reflective micro-imaging elements (8) arranged two-dimensionally in a first pattern, and the associated object is in the form of a microstructure object having a plurality of microstructures (6), which are arranged in a microstructure pattern so matched to the first pattern that the microstructure object is imaged to a magnified scale in front of the upper face (13) by means of the reflective micro-imaging elements. On both its upper face (13) and its lower face (15) the security element (1) has an adhesive layer (14, 16), with which the security element (1) can be embedded in the article (2, 37) to be protected such that both the upper face (13) and the lower face (15) are adhesively secured to the article (2, 37) to be protected.