Photo-Reactive Single Molecule Alignment for LCD Stability
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Solution Overview
Problem
Liquid crystal display (LCD) devices using polyimide (PI)-based alignment layers face limitations in display quality due to low thermal stability and hardness, leading to alignment instability and image sticking issues.
Innovation Solution
A liquid crystal display device is manufactured with a method involving a first and second substrate, a liquid crystal layer, and photo-reactive single molecules that form projections between the field-generating electrodes and the liquid crystal layer, stabilizing the initial alignment state through polymerization upon light exposure, eliminating the need for a PI-based alignment layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PI-based alignment layer including a photo-reactive group is used, then the initial alignment state can be formed, but thermal stability and hardness are low leading to alignment instability and image sticking
Solution Approach 1:
The patent removes the PI-based alignment layer entirely and replaces it with photo-reactive single molecules directly in the liquid crystal layer. This extraction eliminates the inherent weaknesses of the PI layer (low thermal stability and hardness) while preserving the alignment function through a different mechanism.
Solution Approach 2:
The patent changes the physical and chemical parameters of the alignment system by transitioning from a polyimide polymer layer to small molecule compounds with specific photo-reactive groups. This parameter change enables the formation of stable alignment structures through photo-polymerization, achieving both thermal stability and sufficient hardness.
2Manufacturing precision
If a PI-based alignment layer is used, then liquid crystal alignment can be achieved, but display quality is limited due to alignment instability and image sticking
Solution Approach 1:
The patent applies light irradiation in advance to the photo-reactive single molecules to form polymer projections that pre-establish the alignment structure. This preliminary action creates a stable template that guides liquid crystal alignment, ensuring both uniformity and long-term stability without the drawbacks of PI layers.
Solution Approach 2:
The patent creates a composite system where photo-reactive single molecules form polymer structures within the liquid crystal layer. This composite approach combines the advantages of photo-polymerization (thermal stability, hardness) with the liquid crystal medium, achieving superior alignment uniformity and stability simultaneously.
3Reliability
If photo-reactive single molecules are used to form projections, then alignment stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent merges the alignment layer function and the liquid crystal medium into a single integrated system. The photo-reactive single molecules are dissolved in the liquid crystal layer, combining what were previously separate components (alignment layer + liquid crystal) into one homogeneous composition, thereby simplifying the manufacturing process while maintaining alignment stability.
Solution Approach 2:
The photo-reactive single molecules self-organize and self-assemble into polymer projections when exposed to light, without requiring external alignment layers or complex processing steps. This self-service mechanism simplifies manufacturing by eliminating the need for separate alignment layer deposition and treatment processes.
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 enhances the uniformity and stability of liquid crystal alignment, improving display quality by reducing image sticking and alignment instability, while simplifying the manufacturing process and reducing costs associated with PI-based alignment layers.
Implementation Method 1
applying light in a state in which an electric field is applied to the liquid crystal layer and forming photo-polymer projections between the second field-generating electrode and the liquid crystal layer
Data Source
AI summary
A liquid crystal display device including: a first substrate including a first base substrate, a first field-generating electrode disposed on the first base substrate, and a second field-generating electrode disposed on the first field-generating electrode; a second substrate facing the first base substrate and disposed spaced apart from the first substrate; a liquid crystal layer including liquid crystals, in which an electric field is formed by the first field-generating electrode and the second field-generating electrode, being disposed between the first substrate and the second substrate and contacting the second field-generating electrode; and a plurality of first projections disposed between the second field-generating electrode and the liquid crystal layer.