Polymer Security Print Media With Layered Transmitted-Light Watermark
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Solution Overview
Problem
Conventional watermarking techniques are not available for polymer document substrates, limiting the potential for forming integral security elements, and existing security features in polymer documents are typically applied post-manufacture, which can be detached without destroying the document integrity.
Innovation Solution
A security print medium for polymer substrates is developed with opacifying layers that form a multi-tone image visible in transmitted light, utilizing gaps in the layers to create a three-dimensional effect, and optionally enhanced with additional colored prints to achieve a multi-colored appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional watermarking techniques are used on polymer substrates, then integral security elements can be formed, but these techniques are not available for polymer substrates due to their non-fibrous construction
Solution Approach 1:
The invention changes the fundamental parameter of how watermarks are formed - instead of using fibre density variation in paper (conventional method), it uses controlled transparency variations in polymer layers. This allows conventional watermarking concepts to be applied to polymer substrates by changing the physical mechanism from fibrous to layered transparent material modulation.
Solution Approach 2:
The patent creates a composite security feature by combining multiple transparent or translucent polymer layers, each with specific transparency characteristics. These layers are superimposed to form the watermark image, effectively creating a new composite material structure that enables watermarking in polymer substrates.
2Adaptability or versatility
If security elements are applied after substrate manufacture, then security features can be added, but these elements can be detached without destroying document integrity
Solution Approach 1:
The watermarking process is merged with the substrate manufacturing process itself. The transparent/translucent layers are applied to the polymer substrate during manufacturing, making the security feature an integral part of the substrate structure rather than a separate appliqué that can be removed.
Solution Approach 2:
The security feature is created in advance during substrate manufacturing rather than being added later. The transparent layers are positioned and configured during the manufacturing process, ensuring the security element is built-in before the document enters service.
3Reliability
If multiple opacifying layers with gaps are used to create multi-tone image, then integral security feature is achieved, but manufacturing complexity increases
Solution Approach 1:
The watermark image is segmented into multiple transparency layers, each contributing a portion of the final multi-tone image. By dividing the image formation into discrete layers with specific gap patterns, the system achieves complex multi-tone effects while maintaining manufacturability through standardized layer application processes.
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 an integral security feature in polymer documents that enhances document security by creating a visually impactful, multi-tone image that is difficult to replicate, offering a robust and integral security element.
Implementation Method 1
the primary function of the opacifying layers (which are typically formed of a polymeric, non-fibrous, light-scattering material) is to render the majority of the document non-transparent
Implementation Method 2
a multi-tone image which is visible at least when the media is viewed in transmitted light
Data Source
Figure 1(a)~1(b)
Figure 2(a)~3(c)
Figure 4(a)~4(b)
AI summary
A security print medium is disclosed for forming security documents therefrom. The security print medium comprises a transparent or translucent polymer substrate having first and second opposing surfaces, and a plurality of overlapping opacifying layers disposed on the first and/or second surfaces of the polymer substrate, each of the opacifying layers being a layer of semi-opaque material disposed over substantially the whole area of the polymer substrate. In at least a region of the substrate, a multi-tonal image is exhibited by the plurality of overlapping opacifying layers in combination with one another, at least when the security print medium is viewed in transmitted light. Each of the plurality of overlapping opacifying layers has gap(s) in which the semi-opaque material of the layer is absent, the gap(s) of each layer being defined in accordance with a different respective sub-image, the sub-images in combination defining the multi- tonal image, wherein either all the sub-images are different negative image versions of the multi-tonal image or all the sub-images are different positive image versions of the multi-tonal image. As a result, the number of opacifying layers overlapping one another at any one location varies across the substrate, the resulting variation in optical density of the plurality of overlapping opacifying layers in combination with one another giving rise to the multiple tones of the multi-tonal image.