FFS Liquid Crystal Display Using Negative Dielectric Anisotropy
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Solution Overview
Problem
Current FFS mode liquid crystal displays face challenges in achieving high transmittance and display performance due to the limitations of using n-type liquid crystal compositions optimized for VA mode, which are not suitable for the distinct alignment and electric field requirements of FFS mode, leading to issues like burn-in and drip traces.
Innovation Solution
A liquid crystal display configuration using a specific n-type liquid crystal composition with compounds represented by General Formula (i), (ii), or (iii), and (IV), optimized for FFS mode, featuring negative dielectric anisotropy, aligned with parallel alignment layers, and a fringe electric field structure to maintain high transmittance and reduce display defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If p-type liquid crystal composition is used in FFS mode, then voltage is easily lowered, but transmittance is deteriorated due to liquid crystal molecules tilting along the fringe electric field
Solution Approach 1:
The patent changes the dielectric anisotropy parameter from positive to negative, fundamentally altering how liquid crystal molecules respond to the electric field. This parameter change allows molecules to align with their major axis parallel to the substrate while their polarization direction (minor axis) responds to the fringe electric field, resolving the contradiction between low driving voltage and high transmittance
2Illumination intensity
If n-type liquid crystal composition optimized for VA mode is used in FFS mode, then transmittance can be improved, but display defects such as burn-in and drip traces occur due to mismatched alignment and electric field requirements
Solution Approach 1:
The patent applies different alignment conditions to different parts of the system: the alignment layers are configured to induce homogeneous alignment with parallel alignment directions, while the fringe electric field structure is specifically designed to work with n-type material. This local optimization of alignment and electric field configuration allows n-type material to function correctly in FFS mode without displaying VA-mode defects
Solution Approach 2:
The patent introduces alignment layers as an intermediary element that mediates between the n-type liquid crystal composition and the FFS mode requirements. The alignment layers induce homogeneous alignment with parallel alignment directions, enabling the n-type material to achieve proper orientation for FFS operation and eliminating display defects associated with mismatched configurations
3Device complexity
If FFS mode structure with electrodes only on array substrate is used, then device complexity is reduced, but it becomes difficult to predict and prevent burn-in and drip trace issues
Solution Approach 1:
The patent takes preliminary action by specifically configuring the alignment layers to induce homogeneous alignment with parallel alignment directions before the liquid crystal material is introduced. This pre-established alignment configuration, combined with the fringe electric field structure, creates a predictable environment that prevents burn-in and drip trace issues even with the simplified electrode structure where electrodes are provided only in the array substrate
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 optimized liquid crystal composition achieves high-speed responsiveness, minimizes display defects, and provides excellent display characteristics for applications like liquid crystal TVs or monitors, while also reducing the occurrence of burn-in and drip marks.
Implementation Method 1
the liquid crystal composition has negative dielectric anisotropy and contains one or more of compounds selected from the group of compounds represented by the following General Formula (i), General Formula (ii), or General Formula (iii)
Implementation Method 2
alignment layers which induce homogeneous alignment between the liquid crystal layer and each of the first and second substrates, in which an alignment direction of each alignment layer is parallel
Implementation Method 3
in the case of using the n-type liquid crystal composition, since the polarization direction of the n-type composition is the minor axis direction of the molecules, the influence of the fringe electric field simply rotates the liquid crystal molecules along the major axis and the major axis of the molecule is maintained in a parallel arrangement, thus the transmittance does not decrease
Data Source
AI summary
This invention provides an FFS type liquid crystal display containing one type or two or more types of compounds selected from the group of compounds represented by General Formula (i), General Formula (ii), and General Formula (iii) and one type or two or more types of compounds selected from compounds represented by General Formula (II). This display makes it possible to realize excellent display characteristics without deteriorating various liquid crystal display characteristics such as dielectric anisotropy, viscosity, nematic-phase maximum temperature, nematic-phase stability at low temperatures, or γ1 and the display burn-in characteristics.