Liquid Crystal Composition for IPS Contrast and Low-Temperature Stability
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Solution Overview
Problem
Existing liquid crystal materials for IPS-type liquid crystal display devices face challenges in achieving higher contrast rate, transmittance, and low-temperature reliability, with limitations in dielectric anisotropy and elastic constants, leading to issues like light leakage and slow response speed.
Innovation Solution
A liquid crystal composition is designed with specific compounds of general formulas I, II, and III, which enhance the average elastic constant (Kave) and dielectric anisotropy ratio (ε⊥/Δε), improving material properties such as transmittance and contrast rate, while maintaining low-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the dielectric anisotropy (Δε) of liquid crystal medium is decreased to improve transmittance, then transmittance is improved, but the drive voltage adjustment range becomes limited and response speed decreases
Solution Approach 1:
The patent changes the dielectric parameters of the liquid crystal composition by selecting specific compounds with appropriate dielectric constants (ε∥ and ε⊥) to achieve an optimized Δε value that balances transmittance and response speed requirements
Solution Approach 2:
The patent uses a composite liquid crystal composition containing multiple compounds (cyclic compounds, linear compounds, and their combinations) to achieve synergistic effects that simultaneously optimize transmittance, response speed, and other performance parameters
2Object-affected harmful factors
If the average elastic constant (Kave) is increased to improve liquid crystal scattering and reduce light leakage, then light leakage is reduced, but the contrast rate and transmittance may be affected
Solution Approach 1:
The patent optimizes the elastic constant parameters by selecting liquid crystal compounds with specific K11, K22, and K33 values to achieve an appropriate Kave that minimizes light leakage while maintaining high transmittance
Solution Approach 2:
The patent combines multiple liquid crystal compounds with different elastic constant characteristics to create a composite composition that achieves optimized light leakage performance without sacrificing transmittance
3Measurement precision
If the dielectric constant perpendicular to molecular axis (ε⊥) is increased to improve contrast rate, then contrast rate is improved, but the drive voltage requirements change and may affect response speed
Solution Approach 1:
The patent adjusts the ε⊥ parameter by selecting compounds with specific dielectric constant characteristics to achieve optimal contrast rate while maintaining compatible drive voltage and response speed performance
Solution Approach 2:
The patent performs preliminary optimization of the dielectric constant parameters during composition design to ensure that the final composition meets contrast rate requirements while maintaining good response characteristics
4Illumination intensity
If the optical anisotropy (Δn) is increased to improve transmittance in positive liquid crystal, then transmittance is improved, but the retardation amount becomes fixed and may limit further optimization
Solution Approach 1:
The patent optimizes the optical anisotropy parameter Δn by selecting compounds with specific refractive index characteristics (ne and no) to achieve high transmittance while maintaining appropriate retardation characteristics for the application
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 composition achieves higher transmittance, contrast rate, and improved low-temperature storage performance by optimizing Kave and ε⊥/Δε, reducing light leakage and enhancing response speed.
Implementation Method 1
liquid crystal materials need to have higher contrast rate and transmittance, higher elasticity constants, higher dielectric constants and low-temperature reliability
Implementation Method 2
controlling the arrangement of the liquid crystal molecules by applying a transverse electric field between the pair of electrodes
Implementation Method 3
liquid crystal materials need to have higher contrast rate and transmittance... increasing Δn*d can be taken into consideration
Implementation Method 4
when an electric field is applied, liquid crystal molecules rotate, causing a delay, and light thereby leaks from the two orthogonal polarizers
Data Source
AI summary
The present invention provides a liquid crystal composition and a liquid crystal display device. The liquid crystal composition comprises at least one compound of general formula I and at least one compound selected from compounds of general formula II-1 and/or general formula II-2. The liquid crystal composition provided in the present invention has an appropriate optical anisotropy, an appropriate clearing point, a lower rotational viscosity, a higher Kave value and a higher ε⊥/Δε ratio, and has higher transmittance and contrast rate, and a remarkable low-temperature storage performance at the same time.