Embedded Thermochromic Security Document Layer for Laser Color Portraits
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Solution Overview
Problem
Existing security documents face challenges in preventing counterfeiting due to complex and expensive technologies involving multiple layers of inks or laser and inkjet processes, or insecure surface applications, necessitating a need for a more robust and cost-effective solution to enhance security and integrity.
Innovation Solution
A single layer incorporating thermochromic pigments are embedded in a substrate of the security document using a single layer incorporating thermochromic pigments, activated by a single laser wavelength to produce different colors based on laser parameters, with controlled thickness and curing techniques to ensure reproducibility and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple layers of inks or laser and inkjet processes are used to enhance security, then security and integrity are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple security functions into a single laser-engravable material layer. This layer integrates thermochromic pigments that respond to laser irradiation, eliminating the need for separate ink layers and laser/inkjet processes while maintaining security and integrity requirements
Solution Approach 2:
The laser-engravable material layer serves multiple functions simultaneously: it acts as a security feature through laser-induced color changes, provides personalization capability through color portrait engraving, and serves as a tamper-evident element. This multi-functionality reduces overall system complexity compared to separate specialized layers
2Ease of manufacture
If surface printing is used for color portraits, then manufacturing simplicity is maintained, but security and tamper resistance deteriorate
Solution Approach 1:
The patent replaces traditional surface printing mechanisms with laser-induced chemical changes in the laser-engravable material. The laser light directly activates thermochromic pigments to produce permanent color changes, eliminating the need for physical ink application while enhancing tamper resistance through subsurface embedding
Solution Approach 2:
The laser-engravable material layer is embedded within the polycarbonate substrate structure, nesting the functional material inside the protective substrate. This embedding provides tamper resistance while maintaining manufacturing simplicity through integration into the substrate fabrication process
3Reliability
If laser engraving is used for security features, then tamper resistance is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent utilizes changes in laser parameters (wavelength, pulse duration, power) to achieve different color outcomes from the same laser-engravable material. This parameter control enables diverse security features and personalization without requiring multiple material layers or complex manufacturing processes
Solution Approach 2:
The laser-engravable material is printed using conventional printing methods (screen printing, flexography, offset printing, pad printing, or inkjet printing) before lamination, allowing for cost-effective manufacturing. The thermochromic pigment layer is applied as a printable coating that can be mass-produced using standard printing infrastructure
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 cost-effective and secure method to personalize security documents by embedding thermochromic pigments in a substrate, enhancing image quality and security through reproducible color changes using a single laser, making counterfeiting difficult.
Implementation Method 1
The layer of laser-engravable material includes at least one type of thermochromic pigments configured to irreversibly change color from an initial color to a plurality of different colors upon irradiation with laser light of a single wavelength, wherein the color after the change varies with one or more laser parameters of the laser light
Implementation Method 2
upon irradiation with laser light of a single wavelength, preferably a pulsed laser light with a wavelength of around 500 nm
Data Source
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AI summary
A personalizable security document (10) includes a layer of laser-engravable material (4) embedded in a substrate (1) of the security document (10). The layer of laser-engravable material (4) can be irradiated with laser light of a single wavelength to form a color portrait (5) of a holder of the security document (10), due to the layer of laser-engravable material (4) including thermochromic pigments that change their color in an irreversible manner upon irradiation with laser light. A reproducible result can be obtained by carefully controlling the height of the laser-engravable material layer inside the substrate (1), in particular, during manufacturing of the personalizable security document (10).