Liquid Crystal Display Device with Polyamic Acid Alignment Film
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Solution Overview
Problem
Liquid crystal display devices face challenges in achieving a balance of characteristics such as short response time, high voltage holding ratio, low threshold voltage, large contrast ratio, long service life, and low flicker rate, while also maintaining stability to ultraviolet light and heat, which existing technologies have not adequately addressed.
Innovation Solution
A liquid crystal display device is developed using a composition that includes specific compounds and a polyamic acid-based alignment film with photoreactive groups, which are derived from tetracarboxylic acid dianhydrides and diamines, to optimize the alignment of liquid crystal molecules, thereby enhancing the device's performance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional liquid crystal composition is used, then the device can be manufactured with standard materials, but the response time is too long and the voltage holding ratio is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating specific liquid crystal compounds with optimized molecular structures and adjusting their concentration ratios. This changes the physical parameters of the composition including viscosity, dielectric anisotropy, and elastic constants, which collectively improve both response time and voltage holding ratio simultaneously
Solution Approach 2:
The patent creates a composite liquid crystal composition by combining multiple different liquid crystal compounds with complementary properties. The composite formulation integrates compounds with fast response characteristics and compounds with high voltage holding characteristics, achieving synergistic effects that satisfy both requirements
2Use of energy by moving object
If the threshold voltage is reduced for low power consumption, then power efficiency improves, but the contrast ratio decreases
Solution Approach 1:
The patent optimizes the dielectric anisotropy parameter of the liquid crystal composition to enhance the electro-optic response. By carefully selecting compounds with appropriate dielectric properties and adjusting their ratios, the system achieves lower threshold voltage while maintaining sufficient contrast ratio through the optimized optical anisotropy parameter
3Duration of action of stationary object
If the service life is extended for long-term use, then stability to ultraviolet light and heat is required, but this limits the choice of materials
Solution Approach 1:
The patent extracts and isolates specific stabilizing compounds and additives from the overall composition to protect the liquid crystal molecules from ultraviolet light and heat degradation. These extracted protective components are added in controlled amounts to enhance stability without significantly restricting the selection of main liquid crystal compounds for achieving desired electro-optic properties
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 achieves a liquid crystal display device with improved response time, voltage holding ratio, contrast ratio, and reduced flicker rate, while maintaining stability across a wide temperature range and resistance to ultraviolet light and heat, effectively addressing the balance of desired characteristics.
Implementation Method 1
a polyamic acid-based alignment film with photoreactive groups, which are derived from tetracarboxylic acid dianhydrides and diamines, to optimize the alignment of liquid crystal molecules
Implementation Method 2
The optical anisotropy of the composition relates to the contrast ratio of the device
Data Source
AI summary
Subject The subject is to provide liquid crystal display device that has characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate. Means for solution The invention relates to a liquid crystal display device including an electrode group formed on one or both of a pair of substrates that are opposed to each other, and a plurality of active devices connected to the electrode group, and a liquid crystal alignment film formed on the opposing surfaces of the pair of substrates, and a liquid crystal composition sandwiched in between the pair of substrates.