Security Device Surface Relief Structure Ridge Reduction

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Solution Overview

Problem

Existing methods for producing security device components using a cast-cure process often result in a ridge of cured material at the periphery of the security device, which is undesirable and can impede further processing, as they rely on high pressure that deforms the support layer and causes excess material to escape, leading to incomplete or imprecisely defined surface relief structures.

Innovation Solution

A method involving a support layer and a casting relief structure, where a curable material is applied with varying volume per unit area across the surface region, with a primary portion carrying the main surface relief structure and an ancillary portion with decreasing thickness towards the lateral edge, reducing the prominence of the ridge by distributing excess material effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high pressure is applied during the cast-cure process to ensure complete conforming of curable material to the cast, then the surface relief structure is fully formed, but a ridge of cured material forms at the periphery and the support layer deforms

Engineering Contradiction:
Improvesurface relief structure formationVSAvoidridge formation and support layer deformation
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The curable material is segmented into two distinct regions: a first region providing the main casting material and a second region providing an ancillary material with different properties. This segmentation allows each region to serve its specific function - the first region forms the precise surface relief structure while the second region absorbs excess material flow and prevents ridge formation at the periphery.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the curable material are given different properties. The first region has properties optimized for precise relief structure formation, while the second region has properties (different viscosity, elasticity, or volume) optimized for absorbing pressure spikes and preventing ridge formation. This local differentiation resolves the contradiction between complete conforming and ridge prevention.

Inventive Principle:
Principle #3Local quality

2Object-generated harmful factors

If the curable material layer is made thinner or the casting region is reduced to minimize excess material, then ridge formation is reduced, but surface relief structure elements become incomplete and edges are imprecisely defined

Engineering Contradiction:
Improveridge formationVSAvoidsurface relief structure completeness and edge definition
Core Design Contradiction:
Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The casting region is segmented into a first casting region for the main relief structure and a second casting region for the ancillary material. This allows the first region to maintain precise edges and complete structure formation while the second region absorbs excess material flow, preventing ridges without compromising the quality of the primary relief structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The curable material is applied with different volumes in different regions. The first region receives sufficient material thickness to ensure complete and precise relief structure formation, while the second region receives controlled amounts of material that will be absorbed during pressing, preventing ridge formation at the periphery without affecting the completeness of the main structure.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If uniform volume per unit area of curable material is applied across the entire surface region, then material application is simple, but excess material escapes at the periphery causing ridge formation

Engineering Contradiction:
Improvematerial application processVSAvoidridge formation from excess material
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The material application process is made non-uniform by applying different volumes per unit area to different regions. The first region receives a first volume per unit area optimized for complete relief structure formation, while the second region receives a second volume per unit area that accounts for expected material flow and pressure spike absorption. This local differentiation prevents ridge formation while maintaining manufacturing feasibility through a modified but still practical application process.

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

This approach effectively reduces or eliminates the ridge of cured material at the periphery, ensuring precise formation of the surface relief structure while maintaining the integrity of the security device component, preventing deformation and incomplete elements.

Implementation Method 1

curing the curable material, thereby fixing a surface relief structure in the surface of the cured curable material

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Data Source

PatentEP3544822B1Security device components and methods of manufacture thereof
Publication Date: 2021.03.31 DE LA RUE INTERNATIONAL LTD
  • EP3544822B1 patent drawingFigure 1A~1B
  • EP3544822B1 patent drawingFigure 2A~2B
  • EP3544822B1 patent drawingFigure 3A~3C

AI summary

A security device component is provided, together with methods of manufacturing thereof. The security device component comprises a layer of cured curable material carrying a surface relief structure in the surface thereof. A first sub-region of the surface relief structure has a first relief structure. A second sub-region of the surface relief structure, abutting the first sub-region, has a second relief structure different from the first relief structure. The first relief structure defines a primary portion of the surface relief structure and the second relief structure defines an ancillary portion of the surface relief structure. The ancillary portion of the surface relief structure has a thickness that decreases from the primary portion of the surface relief structure towards at least one lateral edge of the layer of curable material.