Security Device Using Subtractive Color Mixing

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Solution Overview

Problem

Existing see-through security features on documents, while effective, lack novel and surprising effects to prevent counterfeiting, and are challenging to fabricate due to complex registration requirements.

Innovation Solution

A security device utilizing subtractive color mixing, where overlapping patterns on both sides of a substrate result in a single perceived color when viewed in transmission, making it difficult to counterfeit while easy to verify, by using patterns that are distinguishable in reflection but indistinguishable in transmission due to color mixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional see-through security features are used with complementary images on both sides, then the security feature is readily verifiable by users, but the feature lacks novel and surprising effects to prevent counterfeiting

Engineering Contradiction:
Improveverification simplicityVSAvoidcounterfeiting resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies color change principles by using patterns in different colors on opposite sides of the substrate that overlap to produce a single perceived color in transmission. Specifically, a first pattern of a first color and a second pattern of a second color are placed on one side, while a third pattern of the first color and a fourth pattern of the second color are placed on the other side, with the first and second patterns overlapping the fourth and third patterns respectively. This creates a striking optical effect where the document appears to have different color characteristics when viewed in reflection versus transmission, providing both ease of verification and enhanced counterfeiting resistance.

Inventive Principle:
Principle #32Color changes

2Reliability

If patterns are overlapped on both sides of the substrate to produce subtractive color mixing, then a striking optical effect is achieved, but precise registration is required which increases manufacturing complexity

Engineering Contradiction:
Improvecounterfeiting resistanceVSAvoidregistration precision
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes subtractive color mixing through overlapping colored patterns to create a striking optical effect. When viewed in transmitted light, the overlapping patterns of different colors mix subtractively to produce a single perceived resultant color, while in reflected light the patterns remain distinguishable by their individual colors. This color-based approach creates a visually striking and memorable security feature that is difficult to counterfeit.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent combines multiple patterns of different colors on both sides of the substrate into a unified optical effect. The first pattern of the first color and the second pattern of the second color on one side are merged with the third pattern of the first color and the fourth pattern of the second color on the other side through precise overlapping. This merging creates a cohesive security feature where the subtractive color mixing produces a single perceived color in transmission, integrating multiple elements into a unified visual experience that enhances both verification and counterfeiting resistance.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If patterns are made distinguishable in reflected light by color, then verification from both sides is possible, but the patterns must be precisely registered to produce the single color effect in transmission

Engineering Contradiction:
Improveverification easeVSAvoidpattern registration
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent employs color differentiation to enable verification from both sides of the substrate while maintaining the ability to produce a single perceived color in transmission. The first and second patterns on one side and the third and fourth patterns on the other side are designed with specific colors that are distinguishable in reflected light, allowing users to verify the security feature from either side. When precisely registered and viewed in transmitted light, these colored patterns mix subtractively to produce a unified color effect, thus accommodating both ease of verification and the striking optical effect.

Inventive Principle:
Principle #32Color changes

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 security device provides a striking and memorable optical effect that is challenging to replicate, with improved verification simplicity and increased counterfeiting resistance due to precise registration requirements and the disappearance of the image in transmission, enhancing document authenticity.

Implementation Method 1

when the viewing region is viewed in transmitted light, the viewing region is sufficiently transparent that subtractive colour mixing between the overlapped different colours results in a perceived single resultant colour being visible

Methodology Applied
Scientific EffectSubtractive color mixing: Absorption Spectroscopy

Implementation Method 2

The substrate carries an obscuring material aligned with the second indicia so as to prevent the second indicia from being viewed from the one side of the substrate under reflected radiation

Methodology Applied
Scientific EffectLight absorption and transmission: Absorption (EM radiation)

Data Source

PatentEP2170622B9Security device and method
Publication Date: 2014.09.10 DE LA RUE INTERNATIONAL LTD
  • EP2170622B9 patent drawingFigure 1a~1c
  • EP2170622B9 patent drawingFigure 2~4b
  • EP2170622B9 patent drawingFigure 5a~5c

AI summary

A security device comprises a substrate (1) having a viewing region (2). A first pattern (3) of a first colour (A) and a second pattern (4) of a second colour (B) are printed on one side of the viewing region (2). A third pattern (5) of the first colour (A) and a fourth pattern (6) of the second colour (B) are printed on the other side of the viewing region (2). The first and second patterns (3,4) on the one side of the viewing region overlap the fourth and third patterns (6,5) respectively on the other side of the viewing region whereby a) when each side of the viewing region is viewed in reflected light, the patterns on that side can be distinguished by at least their colours, and b) when the viewing region is viewed in transmitted light, from either side of the substrate, the viewing region is sufficiently transparent that subtractive colour mixing between the overlapped different colours results in a perceived single resultant colour being visible.