Multi-image optical device with filter layers for secure authentication
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Solution Overview
Problem
Existing non-printed optical watermarks on high-security documents lack design complexity, color integration, and flexibility, are limited to paper substrates, and have low security due to ease of simulation and widespread manufacturing availability, along with challenges in material chain of custody.
Innovation Solution
Incorporating advanced optical features such as continuous-tone, color-shifting, and diffractive patterns on substrates using filter layers and imaging techniques, allowing for complex designs, color inclusion, and secure authentication through varying light conditions, and applying these features to diverse substrates like paper and polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-printed optical watermarks are produced using traditional dandy roll or cylinder mould processes, then grayscale watermark images can be created, but design complexity and color integration are limited
Solution Approach 1:
The patent segments the watermark creation process into separate printed image layers (front side and back side) that are applied independently to the substrate. Each layer can contain complex color designs without constraining the other, allowing high design complexity while using standard printing processes rather than specialized watermark manufacturing equipment.
Solution Approach 2:
The patent transitions from traditional single-layer grayscale watermarks to multi-layer color watermarks by adding a dimensional aspect of color and multiple image layers. This allows complex designs with full color integration while maintaining manufacturing simplicity through conventional printing techniques applied to separate substrate surfaces.
2Reliability
If non-printed optical watermarks are created as separate components from printed images, then watermark transparency can be achieved, but alignment between printed image and watermark is difficult
Solution Approach 1:
The patent merges the watermark creation with the printed image design by applying both the visible printed image and the watermark image to the same substrate surface using the same printing process. This integration ensures automatic alignment between the printed design and watermark elements, eliminating registration issues while maintaining the transparency and optical effects of the watermark.
3Reliability
If pre-printed images are used to simulate non-printed optical watermarks, then security level increases, but simulation risk and detection difficulty increase
Solution Approach 1:
The patent uses color changes and optical variable devices that alter appearance under different lighting conditions. The watermark incorporates color-shifting pigments and optical features that change color or transparency when viewed from different angles or under different light sources, making simulation detection easier while maintaining high security. This dynamic optical behavior is difficult to replicate with static pre-printed images.
4Adaptability or versatility
If traditional watermark processes are used, then paper substrates can be processed, but application to polymer and paperless substrates is limited
Solution Approach 1:
The patent employs universal printing processes and optical variable devices that can be applied to multiple substrate types including paper, polymer, and paperless materials. The methodology uses standard printing technologies and optically variable inks that are compatible with various substrate compositions, enabling wide substrate versatility while maintaining manufacturing simplicity through process compatibility.
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
Enhances design complexity and security by enabling multiple color images and secure authentication, reducing the risk of simulation and extending application to various substrates, while ensuring secure material tracking.
Implementation Method 1
the first color image elements and the second color image elements are different colors when the optical device is viewed from different angles
Implementation Method 2
Variations in the substrate thickness modify translucent characteristics of the substrate, which may be viewed by holding the substrate against a light source
Implementation Method 3
Incorporating advanced optical features such as continuous-tone, color-shifting, and diffractive patterns on substrates
Data Source
AI summary
A system and method are provided for constructing an optical device having a substrate and a filter layer provided on the substrate. The filter layer includes features that render a first image and gaps between the features. An image layer is provided on the filter layer and includes image elements provided within the gaps between the features. The first image is rendered in reflected light and the second image is rendered in transmitted light. According to one example, a second filter layer may be provided on a second side of the substrate such that features of the filter layer and second features of the second filter layer may be at least partially out of vertical alignment in order to define a plurality of light ray entry angles.