Thermochromic Cover Layer for Hidden Marking Verification
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Solution Overview
Problem
Existing multi-layer card-shaped data carriers personalized by laser engraving irreversibly alter the substrate's optical properties, and methods for incorporating hidden markings require additional reading devices, which is inconvenient.
Innovation Solution
A card-shaped data carrier with a thermochromic cover layer that is opaque below its change temperature and transparent above it, allowing a hidden marking to be visible without additional reading devices, using laser radiation outside the visible spectrum to incorporate the marking into the marking layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a camouflage layer is used to hide the marking in the visible spectral range, then the marking is invisible to the human eye, but the marking cannot be viewed without an additional infrared reading device
Solution Approach 1:
The patent applies a thermochromic cover layer that changes its optical properties with temperature. Below its change temperature, the layer is opaque and hides the marking; above its change temperature, the layer becomes translucent or transparent, allowing the marking to be viewed with the naked eye. This eliminates the need for additional infrared reading devices while maintaining the hidden marking capability.
Solution Approach 2:
The patent changes the temperature parameter of the thermochromic cover layer to control its transparency. By heating the layer above its change temperature, the marking becomes visible; by cooling it below the change temperature, the marking is hidden again. This dynamic parameter change enables simple verification without complex equipment.
2Adaptability or versatility
If laser radiation is used to incorporate the hidden marking, then subsequent individualization is possible, but the thermochromic cover layer must be pervious to the laser wavelength
Solution Approach 1:
The patent segments the functional requirements into different layers: the thermochromic cover layer provides temperature-dependent transparency and is pervious to infrared radiation, while the marking layer contains the hidden information and absorbs infrared radiation. This segmentation allows each layer to be optimized for its specific function, enabling both subsequent individualization and simple verification.
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
Enables simple, interactive verification and subsequent individualization of the data carrier through temperature loading, providing authenticity protection and optical enhancement without the need for additional reading devices.
Implementation Method 1
The thermochromic cover layer is opaque below its change temperature and hides the marking, whereas it is translucent or transparent above its change temperature, allowing the viewing of the marking
Implementation Method 2
the marking layer absorbs radiation energy outside the visible spectral range, so that the hidden marking can be incorporated into the marking layer through the thermochromic cover layer by means of laser radiation of a wavelength outside the visible spectral range
Implementation Method 3
the thermochromic cover layer is pervious to radiation outside the visible spectral range
Data Source
AI summary
A multi-layer card-shaped data carrier has a marking layer containing a hidden marking, and a thermochromic cover layer arranged over the marking layer at least in the area of the hidden marking. The thermochromic cover layer is opaque below its change temperature, hides the marking, and is translucent or transparent above its change temperature, enabling viewing of the marking. The thermochromic cover layer is pervious to radiation outside the visible spectral range and the marking layer absorbs radiation energy outside the visible spectral range, so that the hidden marking can be incorporated into the marking layer through the thermochromic cover layer by laser radiation of a wavelength outside the visible spectral range.