Security Documents Using Colour Shifting Inks
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Solution Overview
Problem
Current security documents face challenges in providing overt, easily identifiable, and durable security features that are difficult to counterfeit, while being cost-effective and capable of withstanding everyday use.
Innovation Solution
A security document featuring a transparent plastics substrate with a window area coated with colour shifting ink compositions containing interference pigments and colour pigments, which exhibit the same colour at one viewing angle but change to different colours at another angle due to geometric metamerism, combined with an opacifying coating for durability and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If colour shifting inks with interference pigments are applied to provide overt security features, then the security feature is easily identifiable and visually appealing, but the security feature becomes difficult to control and replicate accurately
Solution Approach 1:
The patent applies parameter changes by utilizing the optical properties of interference pigments that change colour based on viewing angle. The security feature exploits this physical parameter (viewing angle) to create different colour appearances, making it easily identifiable while difficult to replicate with conventional printing methods that cannot produce genuine geometric metamerism.
Solution Approach 2:
The patent directly applies color changes through the use of colour shifting inks containing interference pigments. These pigments exhibit geometric metamerism, displaying different colours at different viewing angles. This creates an overt security feature that is visually striking and difficult to counterfeit, as reproducing the exact colour shifting effect requires the same specialized pigment technology.
2Reliability
If multiple colour shifting ink compositions with different interference pigments are used, then the security feature provides enhanced authenticity verification through geometric metamerism, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies local quality by using different interference pigment compositions in different areas or layers of the security feature. Each local region contains specifically formulated colour shifting inks that contribute to the overall geometric metamerism effect, allowing for enhanced authenticity verification while maintaining a systematic manufacturing approach.
Solution Approach 2:
The patent uses composite materials by combining multiple colour shifting ink compositions with different interference pigments. These composite ink formulations create a multi-layered colour shifting effect that provides robust authenticity verification. The complexity is managed through systematic layering and formulation rather than random complexity.
3Duration of action of stationary object
If the security document uses transparent plastics material with colour shifting inks, then the security feature is durable and can withstand everyday use, but the cost of production increases
Solution Approach 1:
The patent uses flexible shells and thin films by applying colour shifting ink compositions to transparent plastics material in the form of thin protective layers or coatings. This approach provides durability and resistance to everyday wear while using minimal amounts of expensive interference pigment materials, thereby managing production costs.
Solution Approach 2:
The patent applies partial action by using colour shifting inks selectively in specific areas or layers of the security document rather than throughout the entire document. This reduces the total quantity of expensive interference pigments required while still providing durable and effective security features in the critical areas.
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 provides a visually appealing and secure feature that is difficult to replicate, offering enhanced authenticity verification and durability, with the colour shifting effects being observable in both reflection and transmission, and the use of anti-Stokes materials for forensic identification.
Implementation Method 1
a first colour shifting ink composition including a first interference pigment and a first colour pigment and a second colour shifting ink composition including a second interference pigment and a second colour pigment
Implementation Method 2
the first colour shifting ink composition provides at a first viewing angle a first colour, when the first interference pigment is viewable and the second colour shifting ink composition provides at the first viewing angle substantially the same first colour when the second interference pigment is viewable, wherein at a second viewing angle, different from the first viewing angle, the first colour shifting ink composition provides a second colour from the first colour pigment and the second colour shifting ink composition provides a third colour from the second colour pigment, different from the first and second colour
Data Source
AI summary
A security document or device is provided which includes at least one area formed from a transparent plastics material which is exposed on at least one side to form a window or half-window, and a first color shifting ink composition and a second color shifting ink composition which both include different color pigments and interference pigments but which both, at a first viewing angle, exhibit substantially the same color when the interference pigments are viewable, and at other angles exhibit different colors when viewing the color pigments.