Volumetrically Aligned Liquid Crystal Security Device
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Solution Overview
Problem
Existing security devices with optically variable devices (OVDs) that combine color-shifting and diffractive optical effects are vulnerable to separation and copying of their component parts, compromising security.
Innovation Solution
A security device featuring a liquid crystal layer with smectic, nematic, or cholesteric phases, where molecules are volumetrically aligned through the thickness of the layer to form a diffractive optical pattern, integrated with a substrate or primer layer for spontaneous alignment and cross-linking, ensuring the optical effects are embedded and difficult to separate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid crystal film is laminated to an embossed surface relief hologram film or embossed into the liquid crystal film to combine color-changing and diffractive effects, then security is enhanced, but the device can be compromised if the structures are separated, copied or altered separately and then re-joined together
Solution Approach 1:
The patent merges the liquid crystal layer and the diffractive optical element into a single integrated structure where the liquid crystal molecules are volumetrically aligned to form the diffractive pattern. This eliminates the need for separate laminated layers, making the device resistant to separation and counterfeiting while maintaining both color-changing and diffractive optical effects.
Solution Approach 2:
The patent uses a composite structure where liquid crystal material is combined with a diffractive optical element in a single layer. The liquid crystal molecules are aligned volumetrically through the thickness of the layer to create the diffractive pattern, creating a unified composite material that cannot be easily separated or counterfeited.
2Ease of manufacture
If traditional printing and photocopying processes are used to reproduce security images, then manufacturing is simple, but the optical effects cannot be reproduced
Solution Approach 1:
The patent changes the physical state and arrangement of liquid crystal molecules from a random orientation to a volumetrically aligned state that forms a diffractive optical pattern. This parameter change creates optical effects that cannot be reproduced by traditional printing or photocopying processes, as they cannot create the specific molecular alignment required for the optical effects.
Solution Approach 2:
The patent replaces traditional mechanical printing processes with a field-based approach using liquid crystal alignment. The diffractive optical pattern is created through the alignment of liquid crystal molecules rather than through mechanical printing, making the process resistant to traditional copying methods.
3Reliability
If liquid crystal molecules are aligned volumetrically through the thickness of the layer to form a diffractive optical pattern, then the optical effects are embedded and difficult to separate, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies a preliminary alignment treatment to the liquid crystal layer before the diffractive optical pattern is formed. This preliminary action prepares the liquid crystal molecules to align volumetrically through the thickness of the layer, ensuring that the diffractive optical pattern is embedded in the correct orientation and making the optical effects difficult to separate or replicate.
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 solution provides a robust security device that maintains both color-shifting and diffractive optical effects even if the substrate is removed, enhancing the device's resistance to counterfeiting by ensuring the optical effects are integral to the liquid crystal layer's structure.
Implementation Method 1
The Lippmann-Bragg structure has the optical property of reflecting a narrow band of wavelengths of light by the process of refraction from the body of the aligned liquid crystal. Importantly, as the plane of the liquid crystal is tilted relative to the illuminating and viewing angle, the wavelength of the selective band of reflected light shifts to a different color
Implementation Method 2
A liquid crystal layer having one of a smectic phase, a nematic phase, and a cholesteric phase and having molecules therein aligned volumetrically through at least a portion of the thickness of the liquid crystal layer in a predetermined manner to form a predetermined diffractive optical pattern or image
Data Source
AI summary
A security device includes a liquid crystal layer having one of a cholesteric phase, a nematic phase, and a cholesteric phase and having molecules therein aligned volumetrically in a predetermined manner to form a predetermined diffractive optical pattern or image. The molecules of the liquid crystal layer are volumetrically aligned in the predetermined manner through at least a portion of the thickness of the liquid crystal layer.