Laser Writing Security Features on Banknotes
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Solution Overview
Problem
The existing method for generating security features on banknotes and tax stamps is time-consuming and costly due to the use of mechanical numbering devices, which require frequent cleaning and are accident-sensitive and maintenance-intensive, necessitating multiple devices per printing machine and separate printing steps.
Innovation Solution
A method involving the use of substrate sheets with printing inks that change luminescence or infrared absorption intensity upon laser exposure, allowing for simultaneous or sequential printing and curing of security features like serial numbers, QR codes, and barcodes in a continuous or semi-continuous process, eliminating the need for mechanical numbering devices and reducing maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical numbering devices are used for generating security features, then individual security features like serial numbers can be printed, but the process becomes time-consuming and maintenance-intensive requiring frequent cleaning and multiple devices per printing machine
Solution Approach 1:
The patent replaces mechanical numbering devices with a laser-based writing system that uses optical fields to generate security features. The laser writing device writes serial numbers and other security features directly onto cured printing ink layers without mechanical contact, eliminating the need for mechanical cylinders, drums, and cleaning mechanisms while maintaining high reliability and enabling continuous high-speed production
Solution Approach 2:
The patent extracts the security feature generation process from the mechanical printing sequence by performing laser writing after the printing ink has cured. This separates the security feature application from the main printing process, allowing the printing machine to operate continuously at high speed while security features are added in a maintenance-free laser writing step
2Reliability
If mechanical numbering devices are used for generating security features, then security features can be applied, but device complexity increases and maintenance requirements increase
Solution Approach 1:
The patent replaces complex mechanical numbering devices with a simplified laser writing system. Instead of mechanical cylinders with numerals that require positioning, cleaning, and maintenance, the invention uses a laser beam controlled by digital data to write security features directly onto the banknote substrate, dramatically reducing device complexity while improving reliability
Solution Approach 2:
The laser writing system is self-adjusting and requires no manual intervention for positioning or cleaning. The laser beam is precisely controlled by computer software to write security features at the correct locations, and the cured printing ink layer itself serves as the writing surface that retains the laser-written features without requiring additional mechanical components
3Reliability
If separate printing steps are used for security features, then security features can be applied, but production time increases
Solution Approach 1:
The patent applies preliminary action by having the printing machine print and cure the base printing ink layers first, which then serve as the substrate for laser writing. This preliminary curing step enables the subsequent laser writing to be performed quickly without interfering with the main printing process, reducing total production time while ensuring reliable security feature application
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 enables high-speed, low-maintenance generation of secure features with high resolution and high protection against forgery, reducing production time and costs while enhancing the reliability of security features.
Implementation Method 1
the printing ink of at least one of the printing ink layers comprises a) at least one pigment and/or at least one dye, which changes its luminescence intensity upon exposition to laser radiation
Implementation Method 2
b) at least one pigment and/or at least one dye, which changes its infrared absorption intensity upon exposition to laser radiation
Implementation Method 3
exposing the printed substrate sheet obtained in step ii) before and/or after the curing step iii) to laser radiation so as to create at least one security feature
Data Source
AI summary
A method for generating at least one security feature on a banknote and/or a tax stamp comprises the following steps: i) providing a substrate sheet in form of a sheet of paper or of a polymer foil or a composite comprising at least one paper layer and at least one polymer foil, ii) printing onto each of the two surfaces of the substrate sheet each one or more printing ink layers so as to generate at least one banknote and/or at least one tax stamp on the substrate sheet, wherein each printing ink layer extends over a part or the whole of the surface area of the substrate sheet, and wherein the printing ink of at least one of the printing ink layers comprises a) at least one pigment and/or at least one dye, which changes its luminescence intensity upon exposition to laser radiation and/or b) at least one pigment and/or at least one dye, which changes its infrared absorption intensity upon exposition to laser radiation, iii) curing the printing ink layers, iv) exposing the printed substrate sheet obtained in step ii) before and/or after the curing step iii) to laser radiation so as to create at least one security feature on the at least one banknote and/or on the at least one tax stamp of the printed substrate sheet.