Hidden Image Security Printing on Transparent Substrates
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Solution Overview
Problem
Current security documents, particularly banknotes made of plastic substrates, face challenges in incorporating effective safety features like multitone watermarks and windowed security threads due to their material properties, making them vulnerable to counterfeiting.
Innovation Solution
A method for printing a security item on a transparent substrate where a first part of an image is printed on one side and a complementary part on the opposite side, both in register, using ink with different reflectivity than the substrate, allowing the image to be invisible at a perpendicular view but distinguishable when viewed at an angle, enhancing security against counterfeiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If plastic substrate is used for banknotes, then durability and lifespan are improved, but effectiveness of security features like watermarks and security threads deteriorates
Solution Approach 1:
The security feature is divided into two complementary parts: a first part printed on the front side of the transparent substrate and a second part printed on the back side. When viewed in transmission, both parts combine to form a complete security feature (such as a watermark or security thread), while in reflection only the first part is visible. This segmentation allows plastic banknotes to achieve security feature effectiveness comparable to paper banknotes.
2Illumination intensity
If image is printed on transparent substrate with same reflectivity, then visibility and aesthetic quality are improved, but detectability of security feature deteriorates
Solution Approach 1:
The ink used for printing the first part of the security feature has different reflectivity properties than the transparent substrate. Specifically, the ink has lower reflectivity in the visible spectrum, creating a visual contrast that makes the security feature detectable when viewed in reflection, while maintaining aesthetic quality and visibility when viewed in transmission.
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 method significantly improves the security level of documents by making them difficult to counterfeit and easy to verify, while being compatible with existing printing presses and capable of integration with other security features.
Implementation Method 1
using ink with different reflectivity than the substrate, allowing the image to be invisible at a perpendicular view but distinguishable when viewed at an angle
Data Source
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AI summary
The invention relates to a new method for printing a security item on a substrate of which at least a part is made of a transparent material, a first part (3) of an image (2) being printed on one side of the transparent material, and a second complementary part (4) of the image (2) being printed on the opposite side of the transparent material such that, at at least some angles (P°) of view, the image (2) is visible or can be visualised as a whole in which the first (3) and second (4) part of the image (2) are not distinguishable.