Coplanar Reflective Security Features Using Metallic Nanoparticles

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Solution Overview

Problem

Current security features in documents are vulnerable to reproduction by advanced color copiers and printers, lacking unique characteristics that distinguish originals from copies, and there is a need for features that display variable information securely and with high resolution.

Innovation Solution

The development of reflective features comprising coplanar elements with varying reflectivity as the angle of incidence changes, utilizing metallic nanoparticles, which can form images or patterns that are obscured or visible depending on the viewing angle, providing a unique and difficult-to-reproduce appearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional printing inks are used to create security features, then the features can be reproduced by color copiers and printers, but the security against forgery is compromised

Engineering Contradiction:

Improvesecurity against forgeryVSAvoidreproducibility by copiers

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses metallic nanoparticles that exhibit angle-dependent reflectivity, causing the printed feature to appear different depending on the viewing angle. This optical property change makes the feature difficult to reproduce accurately by copiers, as they capture only one angle's appearance

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent changes the optical parameters of the printed feature by using nanoparticles with specific size distributions (50-500 nm range) and controlled aggregation states. These parameter changes create the desired angle-dependent reflectivity that resists copying

Inventive Principle:

Principle #35Parameter changes

2Reliability

If metallic nanoparticles are used to create variable reflectivity, then the security feature becomes difficult to reproduce, but the manufacturing complexity increases

Engineering Contradiction:

Improvedifficulty of reproductionVSAvoidnanoparticle composition control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent specifies particular parameter ranges for the nanoparticles (50-500 nm size, controlled aggregation) to achieve the desired optical properties. By defining these parameters, the complexity of nanoparticle synthesis is managed while still achieving secure features

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite structures involving metallic nanoparticles dispersed in an ink formulation. This composite approach allows the nanoparticles to provide the security function while the ink matrix handles the delivery and positioning, simplifying the overall manufacturing process

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If coplanar elements with different reflectivity are used, then variable information can be displayed securely, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvevariable information displayVSAvoidcoplanarity control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent divides the security feature into multiple coplanar elements (first element, second element, etc.) with different nanoparticle compositions or arrangements. Each element can display different variable information, and their coplanar arrangement ensures consistent optical behavior across the feature

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different nanoparticle characteristics to different regions (elements) of the security feature. Each element has locally optimized properties (different nanoparticle sizes, concentrations, or types) to create the desired variable reflectivity pattern while maintaining overall coplanarity

Inventive Principle:

Principle #3Local quality

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

These features offer enhanced security by creating a variable appearance that is challenging to replicate, allowing for secure display of variable information with high resolution, effectively combating counterfeiting.

Implementation Method 1

the first element causes incident light to be reflected with a first intensity that varies as the angle of incidence changes relative to a surface of the reflective feature

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS9533523B2Reflective features with co-planar elements and processes for making them

Publication Date: 2017.01.03 SICPA HOLDING SA

AI summary

The invention relates to a reflective feature, e.g., reflective security feature or reflective decorative feature, comprising a first element at least partially coplanar with a second element. The first element causes incident light to be reflected with a first intensity that varies as the angle of incidence changes relative to a surface of the reflective feature. The invention also relates to a direct write printing process for forming such a reflective feature from an ink comprising metallic nanoparticles.