Diffractive Film with Patterned Color Lacquer for OVD Security

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Solution Overview

Problem

Existing methods for creating multicolour diffractive security elements on value documents face limitations in achieving high flexibility and preserving the diffractive effect when applying a colour lacquer layer over a diffractive relief structure, as the lacquer layer tends to fill or level the relief structure, thereby destroying the diffractive effect.

Innovation Solution

A film with a light-permeable replication lacquer layer featuring a diffractive relief structure, a light-permeable colour lacquer layer applied only in specific areas to form a pattern or grid, and a reflective layer, where the colour lacquer layer is positioned between the replication lacquer layer and the reflective layer, with specific spacing and thickness to maintain the diffractive effect and chrominance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a colour lacquer layer is applied over a diffractive relief structure, then chrominance and design flexibility are improved, but the diffractive effect is destroyed due to filling and leveling of the relief structure

Engineering Contradiction:

Improvedesign flexibility and chrominanceVSAvoiddiffractive effect

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The film is divided into multiple functional layers: a replication lacquer layer containing the diffractive relief structure, and a separate color lacquer layer applied in specific patterns. This segmentation allows the diffractive structure and color elements to coexist without mutual interference, as each layer performs its specific function independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The color lacquer layer is applied selectively in specific areas rather than uniformly across the entire surface. By controlling the spatial distribution of color elements with specific spacing (50-250 μm), the invention preserves the diffractive effect in uncoated regions while adding chrominance only where needed, thus maintaining local optical properties.

Inventive Principle:

Principle #3Local quality

2Area of stationary object

If the colour lacquer layer is applied in a continuous layer, then complete color coverage is achieved, but the diffractive relief structure is completely filled and the OVD effect is lost

Engineering Contradiction:

Improvecolor coverage areaVSAvoiddiffractive effect

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

Instead of applying color lacquer uniformly across the entire surface, the invention applies color elements partially and selectively in specific patterns with controlled spacing. This partial action approach provides sufficient color coverage for design purposes while leaving gaps that preserve the underlying diffractive relief structure and its optical effects.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If the spacing between color elements is small, then color coverage and design detail are improved, but the individual elements become visible and disrupt the uninterrupted OVD appearance

Engineering Contradiction:

Improvecolor pattern detailVSAvoidvisual uniformity of OVD

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention optimizes the spacing parameter between color elements to fall within a specific range (50-250 μm). This parameter change ensures that the color elements are close enough to provide adequate color coverage and design detail, yet far enough apart to prevent individual elements from being visually distinguishable, thus maintaining the appearance of an uninterrupted OVD.

Inventive Principle:

Principle #35Parameter 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

This approach allows for high flexibility in design, preserving the diffractive effect and chrominance by reducing the diffractive effect only in overprinted areas, enabling an uninterrupted optically variable device (OVD) appearance while achieving multicolour effects through suitable overlaying and refractive index differences.

Implementation Method 1

display a diffractive, optically variable effect. This can be achieved by a surface relief structure

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

the visibility of which is improved by provision of a reflective layer

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS9459385B2Film and method for producing same

Publication Date: 2016.10.04 LEONHARD KURZ STIFTUNG & CO KG

AI summary

A film and a process for its production includes a light-permeable replication lacquer layer with a diffractive relief structure formed in a first side of the replication lacquer layer, a light-permeable color lacquer layer, formed only in areas, arranged on the relief structure, and a reflective layer, formed at least in areas, arranged on the first side of the replication lacquer layer. In areas of the film where the color lacquer layer and the reflective layer overlap, the color lacquer layer is arranged between the replication lacquer layer and the reflective layer.