Liquid Crystal Display Polymer Layer Vertical Alignment
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Solution Overview
Problem
Liquid crystal display devices without alignment films often suffer from display defects such as hysteresis and luminous dots/lines in black displays due to insufficient vertical alignment of liquid crystal molecules, particularly when using certain monomers like lauryl acrylate or biphenyl monomers without a stable linear structure.
Innovation Solution
A liquid crystal display device is developed where a polymer layer is formed by polymerizing monomers with a specific structure, such as a compound with a biphenyl group directly bonded to a functional group at the 4 or 4' position, which provides a high vertical alignment regulating force for liquid crystal molecules, eliminating the need for an alignment film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an alignment film is not formed and polymerization is performed under conventional conditions, then the production process is simplified and cost is reduced, but display defects such as hysteresis and luminous dots/lines occur due to insufficient vertical alignment
Solution Approach 1:
The patent changes the chemical structure parameters of the monomer by introducing a biphenyl group directly bonded to the functional group at the 4 or 4' position. This structural parameter change enhances the vertical alignment regulating force, allowing satisfactory display quality without an alignment film. The specific structural parameters (biphenyl group at 4/4' position) resolve the contradiction by providing sufficient alignment control through molecular design rather than process complexity.
Solution Approach 2:
The patent creates a composite molecular structure by combining a biphenyl group with specific functional groups (acrylate, methacrylate, ethacrylate, vinyl, or allyl groups) to form a new monomer type. This composite material approach generates a monomer with enhanced alignment properties that simultaneously achieves process simplification and display quality, resolving the technical contradiction between ease of manufacture and reliability.
2Ease of manufacture
If conventional monomers like lauryl acrylate or biphenyl monomers without stable linear structure are used, then the manufacturing process is simpler, but vertical alignment of liquid crystal molecules is insufficient causing display defects
Solution Approach 1:
The patent modifies the molecular structure parameters by positioning the biphenyl group directly at the 4 or 4' position of the functional group, creating a stable linear structure. This parameter change (specific positional arrangement) enhances the vertical alignment precision while maintaining manufacturing simplicity, as the monomer structure itself provides the alignment function without complex manufacturing steps.
3Manufacturing precision
If a polymer layer is formed to control alignment, then vertical alignment is improved, but display defects still occur when monomers lack stable linear structure
Solution Approach 1:
The patent designs a composite monomer structure combining a biphenyl group with polymerizable functional groups. The biphenyl group provides stable linear structure and alignment control, while the functional groups enable polymerization. This composite material approach ensures that the polymer layer formed from this monomer simultaneously achieves high alignment precision and reliable display quality without defects.
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 solution ensures a stable and high vertical alignment of liquid crystal molecules, reducing display defects like luminous dots and lines, thereby achieving satisfactory display quality without the need for an alignment film.
Implementation Method 1
the monomers and the like are polymerized to form a polymer layer in a state where liquid crystal molecules are tilted by applying a voltage between the substrates... Such monomers and the like are polymerized by heat or irradiation of light (for example, ultraviolet rays)
Data Source
AI summary
The present invention provides a liquid crystal display device in which display defects are not easily generated even when an alignment film is not formed. The liquid crystal display device of the present invention includes a pair of substrates; and a liquid crystal layer that is held between the pair of substrates, wherein both substrates of the pair of substrates do not substantially include an alignment film, at least one substrate of the pair of substrates includes a polymer layer that controls the alignment of liquid crystal molecules adjacent thereto, the polymer layer is formed by polymerization of monomers of at least one kind included in a liquid crystal layer composition, and the monomers of at least one kind contain a compound represented by the following formula (1):(wherein A represents an acrylate group, a methacrylate group, an ethacrylate group, a vinyl group, or an allyl group; a represents 0 or 1; and m represents a natural number of 4 to 12).