Liquid Crystal Control Layer Without Alignment Film
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Solution Overview
Problem
Liquid crystal devices without alignment films suffer from high residual DC, leading to afterimages and alignment defects, which degrade the quality and reliability of the display.
Innovation Solution
A liquid crystal device with conductive substrates and a liquid crystal control layer formed by polymerizing polymerizable monomers, containing compounds with fluorene, aromatic amino, or nitrogen-containing aromatic heterocyclic groups, to control alignment without an alignment film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no liquid crystal alignment film is provided on substrate surfaces, then device complexity is reduced and manufacturing is simplified, but liquid crystal molecule alignment controllability deteriorates and residual DC increases causing afterimages
Solution Approach 1:
A polymer layer is introduced as an intermediary between the substrate and liquid crystal molecules. This polymer layer, formed by polymerizing polymerizable monomers, serves as a mediator that provides the necessary alignment control functionality without requiring a traditional liquid crystal alignment film, thus resolving the contradiction between simplified structure and effective alignment control
Solution Approach 2:
The chemical structure of the polymer layer is optimized by incorporating specific functional groups (fluorene structure-containing groups, aromatic amino groups, or nitrogen-containing aromatic heterocyclic groups) to change the physical and chemical parameters of the alignment control interface, enabling effective liquid crystal alignment without a conventional alignment film
2Ease of manufacture
If no liquid crystal alignment film is provided, then manufacturing process is simplified, but residual DC increases causing DC afterimages
Solution Approach 1:
The polymer layer acts as an intermediary that reduces residual DC between the conductive substrate and liquid crystal molecules, preventing DC afterimages while maintaining the manufacturing simplicity advantage of not using a traditional alignment film
Solution Approach 2:
The polymer layer is constructed from composite molecular structures containing specific functional groups (fluorene, aromatic amino, or nitrogen-containing aromatic heterocyclic groups) combined with polymerizable monomers, creating a material with optimized electrical and alignment properties that reduces residual DC while simplifying manufacturing
3Ease of manufacture
If no liquid crystal alignment film is provided, then production cost is reduced, but burn-in occurs and AC afterimages increase
Solution Approach 1:
The chemical composition and molecular structure parameters of the polymer layer are specifically optimized by incorporating stable aromatic structures (fluorene, aromatic amino, or nitrogen-containing aromatic heterocyclic groups) that provide long-term stability and prevent burn-in and AC afterimages, achieving this without the cost of traditional alignment films
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 significantly reduces DC and AC afterimages and initial alignment defects, enhancing the quality and reliability of the liquid crystal device.
Implementation Method 1
ultraviolet light is then emitted to the liquid crystal cell to polymerize the polymerizable monomers when a voltage is applied between the substrates
Data Source
AI summary
This liquid crystal display device is provided with: a pair of substrates which have conductive films, respectively; a liquid crystal layer which is arranged between the pair of substrates and contains a liquid crystal; and a liquid crystal control layer which is formed on the substrate-side interface of the liquid crystal layer by means of polymerization of a polymerizable monomer, and which controls the alignment of the liquid crystal. With respect to this liquid crystal display device, at least one of the pair of substrates is not provided with a liquid crystal alignment film, and the liquid crystal control layer contains a compound that has at least one partial structure which is selected from the group consisting of a fluorene structure-containing group, an aromatic amino group and a nitrogen-containing aromatic heterocyclic group.