Security Document Window Ink Layering
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Solution Overview
Problem
Current security documents face challenges in maintaining authenticity due to the ease of counterfeiting and the limitations of existing visual security devices, which can be copied using reproduction techniques, necessitating the development of more complex visual effects.
Innovation Solution
The use of two distinct ink layers, one iridescent and one non-iridescent, where the iridescent ink conceals the non-iridescent color at certain viewing angles and vice versa, creating multiple regions with different optical effects, enhancing counterfeit resistance and memorability, and allowing for varied design possibilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single iridescent ink composition is used in a window region, then colour-shifting effect is achieved, but control over the colour palette is limited
Solution Approach 1:
The single ink composition is segmented into two distinct ink layers: a first ink layer containing non-iridescent transparent organic pigment and a second ink layer containing iridescent pigment. This segmentation allows independent control of each pigment type, expanding the colour palette while maintaining manufacturing simplicity.
Solution Approach 2:
The invention uses composite ink formulations where the first ink layer combines transparent organic pigment with binders and solvents, and the second ink layer combines iridescent pigment with similar components. These composite materials enable precise colour control through separate formulation optimization.
2Reliability
If multiple ink layers with different optical effects are used, then counterfeit resistance is enhanced, but device complexity increases
Solution Approach 1:
The first and second ink layers are applied in partially overlapping regions, creating three distinct zones: region A with only the first ink layer, region B with both ink layers overlapping, and region C with only the second ink layer. This local differentiation creates multiple visual effects in different areas, significantly enhancing counterfeit resistance.
Solution Approach 2:
The invention adds a dimensional aspect by creating visual effects that change with viewing angle. The iridescent second ink layer exhibits angle-dependent colour shifts, while the non-iridescent first ink layer provides consistent colour, creating a multi-dimensional visual experience that is difficult to counterfeit.
3Reliability
If the iridescent ink layer is made transparent to allow underlying colour visibility, then colour variety is improved, but security effect is reduced
Solution Approach 1:
The second ink layer's transparency is made dynamic through the iridescent effect. At certain viewing angles, the iridescent pigment appears more transparent, revealing the first ink layer's colour. At other angles, it appears more opaque, concealing the underlying layer. This dynamic transparency maintains both security effect and colour information.
Solution Approach 2:
The optical properties of the second ink layer are changed by varying the viewing angle parameter. This causes the apparent transparency and colour of the iridescent pigment to change, allowing the underlying first ink layer to be revealed or concealed depending on the observation angle, thus preserving both security and colour information.
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 significantly increases the security and aesthetic appeal of the documents by providing multiple visual effects that change with viewing angles, making it harder to replicate and more memorable for the public, while maintaining control over the color palette.
Implementation Method 1
the iridescent ink conceals the non-iridescent color at certain viewing angles and vice versa, creating multiple regions with different optical effects
Implementation Method 2
the at least one opacifying layer could be disposed on one or both sides of the substrate, comprising for example a polymeric coating (e.g. white ink) or a fibrous layer (e.g. paper)
Data Source
Figure 1(a)~1(d)
Figure 2(a)~2(d)
Figure 3(a)~3(d)
AI summary
A security document is disclosed having an at least semi-transparent or translucent window region of lower optical density than an adjacent non-window region of the security document. The window region is defined by at least one opacifying layer of the security document which is present in the non-window region and not in the window region of the document. The security document further includes an optically variable security device disposed at least partially in the window region, comprising a first ink layer and a second ink layer which at least partially overlap one another in the window region, wherein the first ink layer comprises a non-iridescent, semi-transparent ink composition with a visible colour which does not vary with viewing angle, and the first ink layer has a different composition from the at least one opacifying layer of the security document. The second ink layer comprises an iridescent, semi-transparent ink composition, the appearance of which varies according to the viewing angle.