Ultrasonic Bonding Security Device to Substrate
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Solution Overview
Problem
Current security documents are vulnerable to harvesting, where malicious actors remove and reuse hard-to-reproduce components to create counterfeit documents, as the bond between security devices and substrates can be broken, allowing intact security features to be used in producing counterfeit notes.
Innovation Solution
Ultrasonic bonding of security devices to substrates using a thermoplastic polymer, creating a strong bond that is difficult to separate and altering the security device in a way that makes it unsuitable for reuse in counterfeit documents, thereby preventing harvesting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bonding methods are used to attach security devices to substrates, then the manufacturing process is simple and cost-effective, but the bond can be broken allowing security devices to be harvested for counterfeiting
Solution Approach 1:
The patent applies ultrasonic bonding which changes the bonding parameters from traditional adhesive-based methods to mechanical vibration-based welding. This creates a bond between the thermoplastic polymer layer and substrate that is significantly stronger and resistant to harvesting attempts, while maintaining manufacturing efficiency through a streamlined process that eliminates drying and curing steps.
Solution Approach 2:
The patent replaces traditional chemical bonding (adhesives) with ultrasonic mechanical vibration bonding. The ultrasonic probe generates high-frequency vibrations that melt and weld the thermoplastic polymer to the substrate, creating a bond that is both strong and difficult to separate without damaging the security device.
2Reliability
If security devices are strongly bonded to substrates to prevent harvesting, then resistance to counterfeiting increases, but the security devices become harder to replace or reposition during manufacturing
Solution Approach 1:
The patent performs ultrasonic bonding at the exact moment when the security device is positioned on the substrate, during the same manufacturing pass. The ultrasonic probe bonds the thermoplastic polymer to the substrate immediately while the device is in its final position, eliminating the need for separate positioning and bonding steps. This preliminary action ensures both ease of manufacture and strong bonding.
3Reliability
If the bond between security device and substrate is made permanent to prevent harvesting, then security against counterfeiting improves, but the ability to repair or replace damaged security devices is reduced
Solution Approach 1:
The patent converts the potential harm of permanent bonding (inability to repair) into a benefit by designing the bonding system to damage the security device during the bonding process itself. The ultrasonic welding intentionally alters or degrades the optical properties of the security device, making any harvested device immediately recognizable as counterfeit. This eliminates the need for repairability while maintaining security.
4Reliability
If ultrasonic bonding is applied to enhance security, then resistance to harvesting increases, but the manufacturing equipment and process complexity increase
Solution Approach 1:
The patent designs the ultrasonic bonding system to perform multiple functions simultaneously: it bonds the security device to the substrate, trims excess material, and intentionally degrades the security device's optical properties to prevent harvesting. This multi-functionality reduces the need for separate equipment and processes, making the added security cost-effective despite the introduction of ultrasonic technology.
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 ultrasonic bonding enhances the security of documents by making it harder to separate the security device from the substrate and visibly altering it, reducing its suitability for use in counterfeit production, thus increasing the document's resistance to harvesting and counterfeiting.
Implementation Method 1
applying for a predetermined welding time, vibrational energy through the ultrasonic probe to produce an ultrasonic weld
Implementation Method 2
applying vibrational energy through the ultrasonic probe to produce an ultrasonic weld bonding a section of the first surface to a section of the third surface
Implementation Method 3
the third surface including a thermoplastic polymer... applying vibrational energy through the ultrasonic probe to produce an ultrasonic weld bonding a section of the first surface to a section of the third surface
Data Source
AI summary
A security document (200) includes a substrate (205) having a first surface and a second surface opposite to the first surface, the first surface having a cellulosic material. The security document further includes an optical security device (220) having optical indicia of authenticity of the security document and a third surface, the third surface having a thermoplastic polymer. The security document also includes an ultrasonic weld (225) forming a bond between a section of the first surface and a section of the third surface.