Polysiloxane Alignment Film for Liquid Crystal Display Side Visibility
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Solution Overview
Problem
The Super Vertical Alignment (SVA) mode in liquid crystal display devices experiences persistence defects due to unhardened reactive mesogen remaining in the liquid crystal layer, which reduces display quality, and there is a need for a uniform alignment of liquid crystal molecules.
Innovation Solution
A liquid crystal display device with a reduced residual polymer in the liquid crystal layer, utilizing an alignment film composed of first and second polysiloxanes with specific bonding structures and pre-tilting functional groups to uniformly align and tilt liquid crystal molecules, and a phase separation enhancer to improve alignment and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If reactive mesogen is used in the liquid crystal layer to pre-tilt liquid crystal molecules, then the side visibility is improved, but non-hardened reactive mesogen remains in the liquid crystal layer causing persistence defects and reducing display quality
Solution Approach 1:
The patent extracts and removes the harmful unhardened reactive mesogen from the liquid crystal layer through a dual-layer alignment film structure. The first polysiloxane layer interacts with liquid crystal molecules to provide alignment, while the second polysiloxane layer with cross-linking chains prevents reactive mesogen from remaining in the liquid crystal layer, thereby eliminating persistence defects while maintaining the pre-tilting effect for improved side visibility.
Solution Approach 2:
The patent employs a composite alignment film structure consisting of two different polysiloxane layers with distinct functions. The first polysiloxane layer provides liquid crystal molecule alignment through vertical functional groups, while the second polysiloxane layer with cross-linked pre-tilting functional groups prevents residual reactive mesogen formation. This composite structure resolves the contradiction by combining the benefits of pre-tilting for side visibility with mechanisms to eliminate persistence defects.
2Ease of operation
If a conventional alignment layer is used to align liquid crystal molecules, then the alignment function is provided, but uniform alignment is difficult to achieve and persistence defects occur
Solution Approach 1:
The patent segments the alignment function into two distinct polysiloxane layers, each with specialized functions. The first polysiloxane layer focuses on uniform alignment of liquid crystal molecules through its vertical functional groups, while the second polysiloxane layer with cross-linked pre-tilting functional groups prevents persistence defects. This segmentation allows each layer to optimize its specific function, achieving both uniform alignment and elimination of persistence defects.
Solution Approach 2:
The patent applies local quality by giving each polysiloxane layer distinct properties tailored to its specific function. The first polysiloxane layer has properties optimized for liquid crystal interaction and uniform alignment, while the second polysiloxane layer has cross-linked pre-tilting functional groups specifically designed to prevent residual reactive mesogen. This localized functional differentiation enables precise control over alignment quality and defect prevention.
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 reduces the persistence defects and enhances the uniform alignment of liquid crystal molecules, leading to improved display quality and side visibility in liquid crystal display devices.
Implementation Method 1
First portion of silicon atoms of the second polysiloxanes is bonded to vertical functional groups interacting with the liquid crystal molecules in the liquid crystal layer
Implementation Method 2
first pre-tilting functional groups causing the liquid crystal molecules in the liquid crystal layer to be tilted with respect to at least one of the first and second display panels
Implementation Method 3
second pre-tilting functional groups cross-linked to the first pre-tilting functional groups through second cross-linking chains
Data Source
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AI summary
A liquid crystal display device, including a liquid crystal layer interposed between a first display panel and a second display panel; and an alignment film formed on at least one of the first and second display panels, the alignment film including first polysiloxanes and second polysiloxanes disposed on the first polysiloxanes, wherein a first portion of silicon atoms of the second polysiloxanes are bonded to vertical functional groups interacting with liquid crystal molecules in the liquid crystal layer, and to first pre-tilting functional groups aligning the liquid crystal molecules in the liquid crystal layer to be tilted with respect to at least one of the first and second display panels by being crosslinked. The bonding structure of the first and the second polysiloxanes being different.