Dual-Sided Laser-Engraved Security Document With Color-Shift Images

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Solution Overview

Problem

Existing security documents lack effective personalized features that enhance security by providing color-shifting effects on both sides and are difficult to replicate or tamper with.

Innovation Solution

A security document with a substrate having a security feature extending through its thickness, featuring laser-engravable materials on both sides that exhibit color-change effects under different observation angles, and optionally a watermark for additional security, allowing personalized images to be engraved using a single laser with varying parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If laser engraving is performed on both sides of the substrate to provide personalized images, then security is enhanced through difficulty of replication, but the manufacturing process complexity increases

Engineering Contradiction:
ImprovesecurityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the security feature into multiple segments: laser-engravable material layers are positioned at different locations within the substrate thickness, allowing separate engraving operations on each side. This segmentation enables independent personalization on front and back sides while maintaining overall security through the integrated multi-layer structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent moves the laser-engravable material from the surface to embedded layers within the substrate thickness dimension. By positioning materials at different depths (first layer at first position, second layer at second position), the patent enables bilateral engraving access while protecting the security features within the bulk material, thus enhancing security without proportionally increasing manufacturing complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If color-change materials are embedded in the substrate to provide goniochromatic effects, then security is enhanced through anti-counterfeiting properties, but the manufacturing complexity increases

Engineering Contradiction:
ImprovesecurityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple security functions into a single integrated structure: laser-engravable materials with goniochromatic properties are embedded within the substrate layers, merging the color-change effect, laser engravability, and substrate integration into one unified security feature that enhances security without requiring separate manufacturing processes for each function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes materials whose optical parameters (color, reflectivity) change based on observation angle (goniochromatic effect). This parameter change provides inherent security verification that is difficult to replicate, while the materials are selected to be compatible with standard laser engraving processes, thereby enhancing security without proportionally increasing manufacturing complexity.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If multiple layers of laser-engravable material are positioned at different depths in the substrate, then personalized images can be engraved from both sides, but the device complexity increases

Engineering Contradiction:
Improvepersonalization capabilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the laser-engravable material into multiple distinct layers positioned at different depths within the substrate. The first layer is positioned to be accessible from the first side, while the second layer is positioned to be accessible from the second side. This segmentation enables independent personalization on each side of the document while maintaining a unified security structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes the thickness dimension of the substrate to position laser-engravable layers at different depths, enabling bilateral access for personalization. By distributing materials through the z-dimension (thickness) rather than only on surfaces, the patent achieves versatile personalization capability while keeping the overall device structure relatively simple and manageable.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

Enhances security by making it difficult to replicate or tamper with the document, while providing personalized images with color-shifting effects on both sides, and ensuring the images are not visible in transmission.

Implementation Method 1

The at least one layer of laser-engravable material includes at least a first material that exhibits a color-change effect when viewed in reflection at different observation angles

Methodology Applied
Scientific EffectGoniochromatic effect: Iridescence

Implementation Method 2

a first personalized image laser engraved in the at least one layer of laser-engravable material from the first side

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentEP4659964A1Personalized security document and method of personalizing a security document
Publication Date: 2025.12.10 TOPPAN SECURITY SAS
  • EP4659964A1 patent drawingFigure 1~2
  • EP4659964A1 patent drawingFigure 3~4
  • EP4659964A1 patent drawingFigure 5~6

AI summary

A personalized security document (10) includes a first personalized image (4, 4a) laser engraved in at least one layer of laser-engravable material (2, 12) from a first side (S1) of the security document (10), and a second personalized image (5, 5a) laser engraved in the at least one layer of laser-engravable material (2, 12) from a second side (S2) of the security document (10). Both the first personalized image and the second personalized image exhibit a color-change effect when viewed in reflection. In some cases, the two personalized images are engraved in two different layers of laser-engravable material (2, 12).