Invisible LEP Ink for IR-Activated Security Images
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Solution Overview
Problem
Conventional electrophotographic printing processes struggle to create secure, invisible images under visible light that only become visible under infrared (IR) illumination, lacking effective solutions for producing colorless and transparent ink compositions that emit visible light when exposed to IR radiation.
Innovation Solution
A liquid electrophotographic (LEP) ink composition comprising a luminescent component, a resin, and a carrier liquid, which is colourless under visible light but emits visible light when exposed to IR radiation, allowing for the creation of secure, invisible images that become visible only under IR illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrophotographic printing processes use standard ink compositions, then the printing process is simple and cost-effective, but the images are visible under visible light and cannot provide security protection
Solution Approach 1:
The patent applies color changes by using luminescent components that are invisible under visible light but emit visible light when exposed to infrared radiation. This allows the ink to transition from being completely invisible to emitting specific colors (red, green, blue, yellow, or white) under IR illumination, providing security protection while maintaining simplicity in the printing process
Solution Approach 2:
The patent uses composite materials by combining luminescent components (such as quantum dots, nanocrystals, or fluorescent dyes) with conventional ink composition elements including resins, carriers, and additives. This composite approach enables the ink to maintain printability while gaining infrared-responsive luminescence properties for security applications
2Reliability
If the ink composition is made colorless and transparent under visible light, then security protection is improved, but the ability to detect and measure the ink under normal conditions becomes difficult
Solution Approach 1:
The patent applies periodic action by using infrared illumination as a periodic activation source. The ink remains invisible during normal conditions (first state), then becomes detectable when exposed to infrared radiation (second state). This periodic transition between invisible and visible states allows security protection while enabling detection through controlled IR illumination
Solution Approach 2:
The patent uses infrared radiation as an intermediary to enable detection of the invisible ink. The luminescent components in the ink act as mediators that convert infrared radiation into visible light, allowing the human eye or detectors to observe the hidden image only when IR illumination is applied, thus solving the detection difficulty
3Adaptability or versatility
If luminescent components are added to create IR-responsive invisible images, then security applications are enhanced, but the ink composition complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies parameter changes by adjusting the size, composition, and concentration of luminescent components to achieve different luminescence characteristics. By controlling parameters such as quantum dot size (affecting emission wavelength) and luminescent dye concentration, the ink can be tuned for specific security applications while maintaining compatibility with conventional printing processes
Solution Approach 2:
The patent uses inexpensive luminescent materials such as quantum dots, nanocrystals, or fluorescent dyes that can be readily synthesized or purchased. These materials are incorporated into conventional ink formulations using standard mixing and coating processes, enabling cost-effective production of security inks without requiring complex manufacturing 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 LEP ink composition effectively prints secure, invisible images on substrates that remain undetectable to the human eye under visible light but emit visible light when exposed to IR, enhancing security applications by providing a hidden visible image that can only be seen with IR illumination.
Implementation Method 1
a luminescent component which emits visible light on exposure to IR radiation
Implementation Method 2
The charged particles adhere to the image areas of the latent image while the background areas remain clean
Data Source
AI summary
Described herein is a LEP ink composition comprising a luminescent component, a resin; and a carrier liquid security liquid electrostatic ink composition for printing a security image.