Reactive Mesogen Protrusions for Curved LCD Pre-Tilt Control
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Solution Overview
Problem
Liquid crystal displays face challenges in maintaining pre-tilt angles and preventing afterimages due to uniformity issues in the alignment of liquid crystal molecules, particularly when the display is curved, leading to texture defects and reduced transmittance.
Innovation Solution
Incorporating a reactive mesogen with specific chemical structures, such as those represented by Chemical Formula 1, into alignment layers to form protrusions that differentiate pre-tilt angles and improve heat resistance, combined with photoreactive groups for controlled polymerization and reduced afterimages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform alignment layers are used in curved displays, then manufacturing is simplified, but pre-tilt angle uniformity deteriorates leading to texture defects
Solution Approach 1:
The patent applies local quality by creating protrusions with different heights, densities, or distributions in different regions of the alignment layer. This allows the pre-tilt angle to be locally adjusted to compensate for curvature-induced non-uniformity, while the overall manufacturing process remains relatively simple. The protrusions can be positioned specifically in regions where pre-tilt angle compensation is needed.
Solution Approach 2:
The patent changes physical parameters of the alignment layer by forming protrusions with varying heights, densities, or material compositions. These parameter changes create localized variations in surface properties that compensate for the non-uniform pre-tilt angles caused by display curvature, thereby improving manufacturing precision without significantly complicating the manufacturing process.
2Device complexity
If conventional alignment layers are used, then device complexity is reduced, but afterimage defects increase due to insufficient pre-tilt angle control
Solution Approach 1:
The patent applies preliminary action by forming protrusions in the alignment layer before the liquid crystal layer is assembled. These pre-formed protrusions establish the correct pre-tilt angles in advance, preventing afterimage defects from occurring during display operation. The protrusions are created through photopolymerization or other processes that occur during the alignment layer formation stage.
Solution Approach 2:
The patent replaces conventional mechanical or chemical alignment methods with a photopolymerization-based approach. By incorporating photoreactive groups into the alignment layer material and using light irradiation to form protrusions, the patent substitutes traditional alignment mechanisms with an optical-chemical process that provides better pre-tilt angle control and reduces afterimage defects.
3Manufacturing precision
If photoreactive groups are added to alignment layers, then pre-tilt angle control improves, but manufacturing complexity increases
Solution Approach 1:
The patent merges the alignment layer material with photoreactive groups, combining the functions of alignment and photopolymerization into a single integrated layer. This eliminates the need for separate alignment layers and photopolymerization processes, thereby improving pre-tilt angle control while minimizing the increase in manufacturing complexity. The protrusions are formed directly within the alignment layer itself.
4Illumination intensity
If protrusions are formed in alignment layers, then transmittance is maintained in curved displays, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses photoreactive groups as intermediaries that mediate between the light irradiation process and the formation of protrusions. These photoreactive groups absorb light energy and convert it into chemical changes that create the protrusions, providing a controlled and precise mechanism for forming the desired structures while maintaining light transmittance in curved displays.
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 effectively differentiates pre-tilt angles between liquid crystal molecules adjacent to different alignment layers, reducing texture defects and maintaining high transmittance even when the display is curved, thereby enhancing the display's viewing angle and image quality.
Implementation Method 1
the reactive mesogen is polymerized to form a plurality of protrusions
Implementation Method 2
The liquid crystal display forms the electric field to the liquid crystal layer, thereby displaying an image by determining an arrangement of liquid crystal molecules included the liquid crystal layer and controlling transmittance of a light passing through the liquid crystal layer
Implementation Method 3
The photoreactive group derivative included in the plurality of first side chains may be combined with the polymer of the reactive mesogen included in the plurality of protrusions
Data Source
AI summary
A liquid crystal display includes: a first substrate, a second substrate overlapping the first substrate, a liquid crystal layer positioned between the first substrate and the second substrate and including a plurality of liquid crystal molecules, a first alignment layer positioned between the first substrate and the liquid crystal layer, a second alignment layer positioned between the second substrate and the liquid crystal layer, and a plurality of protrusions positioned at at least one of between the first alignment layer and the liquid crystal layer and between the second alignment layer and the liquid crystal layer, wherein at least one among the plurality of protrusions includes a polymer of a reactive mesogen, and the reactive mesogen is represented by Chemical Formula 1:Pa—A1—OCH2nO—A2—Pb Chemical Formula 1.