Polymerizable Liquid Crystal Composition for PSA-VA Displays
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Solution Overview
Problem
Current liquid crystal compositions for PSA-VA and PSA-IPS displays face issues with unsuitable polymerizable components, leading to high rotary viscosity, poor photoelectric performance, and residual images due to inadequate polymerization rates and tilt angles, which affect the voltage holding ratio and display quality.
Innovation Solution
A polymerizable liquid crystal compound with a faster polymerization rate and improved photoelectric properties is developed, specifically designed for PSVA and PSA-IPS modes, combining specific chemical structures to enhance intermiscibility and ultraviolet resistance, thereby reducing residual images and increasing the voltage holding ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymerizable components are used in PSA-VA and PSA-IPS displays, then the liquid crystal composition can be formulated, but the rotary viscosity becomes high and photoelectric performance deteriorates
Solution Approach 1:
The patent modifies the molecular structure parameters of polymerizable components by introducing specific ester groups (isobutyrate, pivalate, trimethylacetyl) and adjusting alkyl chain lengths. These parameter changes optimize the balance between rotary viscosity and photoelectric performance, enabling faster response times while maintaining adequate voltage holding ratios.
Solution Approach 2:
The patent creates composite liquid crystal compositions by combining multiple polymerizable compounds with different molecular structures and properties. The composition includes compounds with formula (1) having specific ester groups, compounds with formula (2) with different terminal groups, and conventional liquid crystal compounds, achieving synergistic effects that reduce rotary viscosity while improving photoelectric performance.
2Reliability
If conventional polymerizable components are used, then the liquid crystal composition can be formulated, but the polymerization rate is insufficient leading to residual images
Solution Approach 1:
The patent introduces polymerizable components with specific ester groups (isobutyrate, pivalate, trimethylacetyl) that have higher polymerization rates. The molecular weight and structural parameters of these components are optimized to enable complete polymerization within the UV irradiation time, eliminating residual monomers that cause residual images while maintaining adequate voltage holding ratios.
Solution Approach 2:
The patent uses photoinitiators as intermediaries to catalyze the polymerization reaction of the polymerizable components. The photoinitiators absorb UV light and generate radicals that initiate and accelerate the polymerization process, ensuring complete polymerization of the high polymerization rate components within the available irradiation time, thereby preventing residual image formation.
3Reliability
If conventional polymerizable components are used, then the liquid crystal composition can be formulated, but the tilt angle is insufficient affecting voltage holding ratio
Solution Approach 1:
The patent modifies the molecular structure parameters of polymerizable components by introducing specific ester groups and adjusting alkyl chain lengths to achieve optimal tilt angles. The balance between the rigid core structure and flexible terminal groups is optimized to generate sufficient tilt angle upon polymerization, ensuring adequate voltage holding ratios for display operation.
Solution Approach 2:
The patent introduces polymerizable components with different local molecular structures into specific regions of the liquid crystal composition. The components with formula (1) and (2) have specific local ester groups that promote tilt angle formation in critical areas, while other components maintain bulk properties, achieving local optimization of tilt angle to improve voltage holding ratio.
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 new compound achieves a higher voltage holding ratio and faster response times while minimizing residual images, improving the overall display performance by optimizing pretilt angles and polymerization rates.
Implementation Method 1
The PSA principle is being applied to different typical LC displays such as PSA-VA, PSA-OCB, PS-IPS/FFS and PS-TN liquid crystal displays. Taking the most widely used PSA-VA display as an example, the pretilt angle of the liquid crystal cell can be obtained by a PSA method
Implementation Method 2
Liquid crystal composition and liquid crystal display element... a liquid crystal composition formed by combining a specific polymerizable compound and a specific liquid crystal component
Data Source
AI summary
Provided are a polymerizable compound represented by formula I and a liquid crystal composition comprising the polymerizable compound, particularly a PSVA liquid crystal composition for displays or TV applications and a PSA-IPS liquid crystal composition for an IPS mode; in particular, the polymerizable compound has a faster polymerization rate, and a “material system” formed from the selected polymerizable component and liquid crystal component has a lower rotary viscosity and better photoelectric properties, and has a high VHR after (UV) photoradiation, this avoiding the problem of the occurrence of residual images to final displays.