Reactive Mesogen Alignment Layer for Wide Viewing Angle LCDs
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Solution Overview
Problem
Liquid crystal displays in vertically aligned mode face challenges with side visibility and response speed, particularly in achieving wide viewing angles and efficient alignment of liquid crystal molecules.
Innovation Solution
The use of alignment layers with reactive mesogens containing photoreactor groups, which include a vertical expression group and at least two photoreactor groups connected to this group, improves mechanical properties and allows for pretilt orientation of liquid crystal molecules, enhancing viewing angles and response speed by forming cross-linking portions when exposed to light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a plurality of domains are formed in one pixel to achieve wide viewing angle, then side visibility is improved, but device complexity increases due to additional cutouts or protrusions
Solution Approach 1:
The patent changes the chemical composition and molecular structure of the alignment layer by incorporating reactive mesogens with photoreactor groups. This allows the alignment layer to form cross-linked structures with different pretilt angles and orientations through photochemical reactions, achieving multiple domains without physical modifications like cutouts or protrusions.
Solution Approach 2:
The alignment layer is formed as a composite material containing main chains and multiple types of side chains, including reactive mesogens with photoreactor groups. This composite structure enables the formation of cross-linked networks that create multiple alignment domains, achieving wide viewing angles through material composition rather than structural complexity.
2Productivity
If alignment layers with reactive mesogens and photoreactor groups are used to improve mechanical properties and pretilt orientation, then response speed increases, but manufacturing complexity increases due to additional photopolymerization process
Solution Approach 1:
The patent replaces traditional mechanical or thermal alignment methods with photochemical alignment. The reactive mesogens with photoreactor groups undergo photopolymerization when exposed to light, creating cross-linked structures that define liquid crystal alignment. This optical-chemical method enables precise pretilt control and faster response speeds while the photopolymerization process can be integrated into existing manufacturing workflows.
3Illumination intensity
If liquid crystal molecules are aligned perpendicular to display panels in vertically aligned mode to achieve high contrast ratio, then front visibility is improved, but side visibility deteriorates
Solution Approach 1:
The patent segments the alignment direction into multiple domains within one pixel. By forming cutouts or protrusions in the field generation electrode, the alignment layer is divided into regions with different pretilt angles and orientations. This segmentation creates multiple domains that maintain high contrast ratio in the front view while improving side visibility through diversified light modulation characteristics.
Solution Approach 2:
The patent introduces asymmetry in the liquid crystal alignment by creating domains with different pretilt angles and orientation directions. The reactive mesogens with photoreactor groups enable the formation of asymmetric cross-linked structures that produce non-uniform alignment patterns, allowing the display to maintain high contrast in the front view while achieving wide viewing angles from the side through diversified domain orientations.
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 improves mechanical properties and side visibility by allowing liquid crystal molecules to be oriented with pretilts in multiple directions, increasing response speed and maintaining improved afterimage characteristics.
Implementation Method 1
at least any one of the plurality of side chains includes a reactive mesogen including a vertical expression group and at least two photoreactor groups connected to the vertical expression group
Data Source
AI summary
A liquid crystal display is provided, including a first insulating substrate; a second insulating substrate facing the first insulating substrate; a pixel electrode disposed on the first insulating substrate; a common electrode disposed on the first insulating substrate or the second insulating substrate; a first alignment layer disposed on the first insulating substrate; a second alignment layer disposed on the second insulating substrate; and a liquid crystal layer disposed between the first insulating substrate and the second insulating substrate, in which at least one of the first alignment layer and the second alignment layer include a main chain and a plurality of side chains which are connected to the main chain, and at least one of the plurality of side chains includes a reactive mesogen including a vertical expression group and at least two photoreactor groups connected to the vertical expression group.