Alignment Film Pre-Tilt Control for Liquid Crystal Displays
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Solution Overview
Problem
Liquid crystal display devices, particularly in the Super Vertical Alignment (SVA) mode, face challenges with response time and light leakage defects due to the pre-tilt angle of liquid crystal molecules, which is difficult to optimize with existing alignment films.
Innovation Solution
An alignment film is developed with a specific composition including first and second pre-tilt functional groups and a vertical alignment functional group linked to polysiloxane on a substrate, featuring a cyclic group and cross-linked structure to align liquid crystal molecules perpendicularly and tilted respectively, along with a sol-gel catalyst or aggregation inhibitor to enhance reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reactive mesogen is used in the liquid crystal layer to align molecules, then the pre-tilt angle can be controlled to improve viewing angle, but light leakage defects occur and response time becomes slow
Solution Approach 1:
The alignment film is divided into multiple functional segments: a first pre-tilt functional group with a specific pre-tilt angle to control liquid crystal molecule orientation, and a second pre-tilt functional group with a different pre-tilt angle to adjust response time. This segmentation allows independent optimization of viewing angle and response time while preventing light leakage defects
Solution Approach 2:
Different regions of the alignment film have different pre-tilt angles through the use of multiple pre-tilt functional groups. The first pre-tilt functional group provides a specific local orientation for viewing angle optimization, while the second pre-tilt functional group provides a different local orientation for response time control. This local quality variation resolves the contradiction between viewing angle and response time
2Speed
If the pre-tilt angle of liquid crystal molecules is increased to improve response time, then response time decreases, but light leakage defects increase
Solution Approach 1:
The alignment film segments the pre-tilt function into two distinct functional groups with different pre-tilt angles. The first pre-tilt functional group optimizes viewing angle while the second pre-tilt functional group optimizes response time. This segmentation prevents light leakage by balancing the pre-tilt angles, allowing response time improvement without sacrificing reliability
Solution Approach 2:
The patent changes the pre-tilt angle parameter by incorporating multiple pre-tilt functional groups with different pre-tilt angles into the alignment film. This parameter change allows independent optimization of response time and viewing angle while preventing light leakage defects through balanced angle configuration
3Ease of manufacture
If existing alignment films are used to control pre-tilt angle, then manufacturing is simple, but response time and light leakage cannot be simultaneously optimized
Solution Approach 1:
The alignment film uses a composite material structure incorporating polysiloxane as the base polymer and multiple pre-tilt functional groups (first pre-tilt functional group and second pre-tilt functional group) as additives. This composite structure maintains ease of manufacture through standard alignment film fabrication processes while achieving simultaneous optimization of response time and light leakage prevention through the synergistic effect of multiple functional groups
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 alignment film achieves a fast response time and reduces light leakage defects, improving the overall reliability and characteristics of the liquid crystal display device.
Implementation Method 1
The first pre-tilt functional group is cross-linked to the second pre-tilt functional group
Implementation Method 2
align liquid crystal molecules to be tilted with respect to the first or second display panels
Implementation Method 3
The first vertical alignment functional group includes a cyclic group and is aligned substantially perpendicularly to the substrate
Data Source
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AI summary
An alignment film includes a first pre-tilt functional group, a second pre-tilt functional group and a first vertical alignment functional group, which are linked to polysiloxane on a substrate. The first vertical alignment functional group includes a cyclic compound and is aligned substantially perpendicularly to the substrate. The first pre-tilt functional group is cross-linked to the second pre-tilt functional group and tilted with respect to the substrate.