Liquid Crystal Optical Assembly to Prevent Encapsulation Bubbles
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Solution Overview
Problem
Existing optical devices with active liquid crystal films encapsulated between substrates face issues with bubble formation and appearance changes due to temperature changes, leading to defects such as bubbles and deformation, especially when using high-temperature and high-pressure encapsulation methods.
Innovation Solution
The optical device incorporates an active liquid crystal film capable of switching between transparent and black modes, using a guest-host liquid crystal layer with a nematic liquid crystal compound and anisotropic dye, encapsulated between substrates with controlled thermal expansion and alignment films, along with a shrinkable film to mitigate pressure differences and prevent bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature and high pressure encapsulation is used, then the transmittance-variable film can be sealed between substrates, but bubbles form and defects occur due to pressure and temperature changes
Solution Approach 1:
The patent changes the physical state parameters of the adhesive material from solid to liquid by heating above its melting point during encapsulation, then allows it to solidify upon cooling. This phase transition enables the adhesive to flow and fill gaps uniformly under pressure, preventing bubble formation while maintaining strong bonding between substrates and the transmittance-variable film.
Solution Approach 2:
The adhesive material undergoes a phase transition from solid to liquid during the encapsulation process by applying heat above its melting temperature. This liquid state allows the adhesive to flow and conform to the substrate surfaces, eliminating air pockets and ensuring complete wetting. Upon cooling, the adhesive solidifies to provide mechanical strength and permanent sealing without the defects associated with traditional high-temperature encapsulation methods.
2Stability of the object's composition
If rigid substrates are used for encapsulation, then structural stability is achieved, but deformation and residual stress occur under temperature changes
Solution Approach 1:
The patent employs a thin adhesive film that can flex and accommodate thermal expansion differences between the rigid substrates and the transmittance-variable film. This flexible adhesive layer absorbs dimensional changes during temperature cycling, preventing stress concentration and deformation of the rigid substrates while maintaining the structural integrity of the entire encapsulated assembly.
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 an optical device with excellent durability and reduced defects, maintaining optimal transmittance switching performance across various temperature conditions without bubble formation, suitable for applications like eyewear and vehicle sunroofs.
Implementation Method 1
an active liquid crystal film capable of switching between transparent and black modes, using a guest-host liquid crystal layer with a nematic liquid crystal compound and anisotropic dye
Implementation Method 2
along with a shrinkable film to mitigate pressure differences and prevent bubble formation
Data Source
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AI summary
The present application relates to an optical device. The present application provides an optical device capable of varying transmittance, and such an optical device can be used for various applications such as eyewear, for example, sunglasses or AR (augmented reality) or VR (virtual reality) eyewear, an outer wall of a building or a sunroof for a vehicle.