Fluorinated Benzene Liquid Crystal for IPS VA Displays
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Solution Overview
Problem
Liquid crystal display devices, particularly those operating in IPS and VA modes, face challenges with response time, contrast, driving voltage, and temperature range due to limitations in existing liquid crystal compounds, including poor compatibility, high viscosity, and narrow mesomorphic ranges.
Innovation Solution
A liquid crystal compound with a specific structure, where hydrogen on a benzene ring is replaced by chlorine and fluorine, exhibiting stability, wide nematic phase range, low viscosity, suitable optical and dielectric anisotropy, and excellent compatibility, is developed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydrogen on a benzene ring is replaced by fluorine to create liquid crystal compounds, then the compounds can be used in IPS and VA modes, but compatibility with other compounds in low temperature regions deteriorates
Solution Approach 1:
The patent introduces different substituent groups (fluorine, chlorine, cyanobiphenyl groups) at specific positions of the benzene ring to create local variations in molecular properties. This allows the compound to maintain negative dielectric anisotropy while improving low-temperature compatibility and expanding the liquid crystal phase range, thereby resolving the contradiction between adaptability and low-temperature performance.
Solution Approach 2:
The patent uses composite molecular structures combining fluorinated benzene rings with cyanobiphenyl groups and various substituent patterns. This composite approach creates liquid crystal compounds that exhibit both the required negative dielectric anisotropy for IPS/VA modes and improved low-temperature compatibility, simultaneously achieving adaptability and temperature range expansion.
2Stability of the object's composition
If hydrogen on a benzene ring is substituted by chlorine and fluorine, then the compound shows liquid crystallinity, but the clear point decreases and viscosity increases
Solution Approach 1:
The patent systematically varies the substituent groups (fluorine, chlorine, cyanobiphenyl) and their positions on the benzene ring to optimize molecular parameters. By adjusting these chemical parameters, the compound maintains liquid crystallinity and negative dielectric anisotropy while improving the clear point and reducing viscosity, thereby resolving the contradiction between composition stability and clear point.
3Stability of the object's composition
If hydrogen on a benzene ring is substituted by chlorine, then the compound shows liquid crystallinity, but the mesomorphic range becomes significantly narrow
Solution Approach 1:
The patent employs composite molecular structures with fluorinated benzene rings combined with cyanobiphenyl groups and various substituent patterns. This composite design expands the mesomorphic range while maintaining liquid crystallinity and negative dielectric anisotropy, resolving the contradiction between composition stability and mesomorphic range duration.
4Adaptability or versatility
If a liquid crystal compound with negative dielectric anisotropy is used for IPS and VA modes, then viewing angle is improved, but response time, contrast, and driving voltage characteristics deteriorate
Solution Approach 1:
The patent optimizes molecular parameters by introducing fluorine and chlorine substituents at specific positions, which adjusts the balance between dielectric anisotropy, viscosity, and elastic constants. This parameter optimization improves response time and contrast while maintaining the negative dielectric anisotropy required for IPS/VA modes, thereby resolving the contradiction between viewing angle and response characteristics.
Solution Approach 2:
The patent introduces specific substituent groups (fluorine, chlorine, cyanobiphenyl) at localized positions on the benzene ring to create local property variations. This local quality adjustment optimizes the balance between dielectric anisotropy and viscosity, improving response time and contrast while preserving the viewing angle advantages of IPS/VA modes.
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 compound improves response time, reduces electric power consumption, lowers driving voltage, and enhances contrast while allowing the liquid crystal display device to operate effectively across a wide temperature range.
Implementation Method 1
A liquid crystal display device utilizes optical anisotropy and dielectric anisotropy inherent to a liquid crystal compound
Implementation Method 2
A liquid crystal display device utilizes optical anisotropy and dielectric anisotropy inherent to a liquid crystal compound
Implementation Method 3
has high clear point (transition temperature between a liquid crystal phase and an isotropic phase)
Data Source
AI summary
Such a liquid crystal compound is provided that has stability to heat, light and so forth, has a nematic phase in a wide temperature range, has a small viscosity, a suitable optical anisotropy, and suitable elastic constants K33 and K11 (K33: bend elastic constant, K11: splay elastic constant), and has suitable negative dielectric anisotropy and excellent compatibility with other liquid crystal compounds. A liquid crystal composition containing the liquid crystal compound, and a liquid crystal display device containing the liquid crystal composition are also provided.The liquid crystal compound is represented by one of formulas (a) to (d), the liquid crystal composition contains the liquid crystal compound, and the liquid crystal display device contains the liquid crystal composition:wherein Ra and Rb are independently linear alkyl or linear alkoxy, rings A1, A2, B and C are independently trans-1,4-cyclohexylene or 1,4-phenylene, Z11, Z12, Z2 and Z3 are independently a single bond or alkylene, and one of X1 and X2 is fluorine, and the other thereof is chlorine.