Guest-Host Liquid Crystal Dimming Composition for Image Sticking Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing liquid crystal dimming devices face issues such as low dark state transmittance, poor contrast rate, image sticking, and display mura due to dye precipitation, alignment problems, and limited operation temperature range, particularly in high-temperature environments.
Innovation Solution
A liquid crystal dimming device with parallel alignment layers and a guest-host liquid crystal composition containing specific compounds to enhance transmittance, contrast, and stability, using a formulation of dichroic dyes and chiral agents to improve optical properties and reduce image sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the concentration of dichroic dye molecules is increased to improve dark state transmittance and contrast rate, then the optical properties are improved, but the dichroic dye molecules precipitate from the liquid crystals and affect the performance
Solution Approach 1:
The patent modifies the molecular structure parameters of the liquid crystal host compounds (introducing specific substituents like -OCH3, -OCF3, -CF3 groups) to change the interaction parameters between dye molecules and liquid crystal hosts, thereby preventing dye precipitation while maintaining high contrast ratios.
Solution Approach 2:
The patent creates a composite liquid crystal system by combining specifically designed host liquid crystal compounds with dichroic dye molecules and chiral agents, forming a stable composite material where the host-guest interaction prevents dye precipitation while achieving high optical performance.
2Illumination intensity
If the cell gap is increased to improve contrast rate, then the contrast rate is improved, but the optical anisotropy of the liquid crystal composition decreases
Solution Approach 1:
The patent changes the optical parameters of the liquid crystal composition by selecting host compounds with high optical anisotropy (Δn) values, thereby compensating for the reduction in optical anisotropy caused by increased cell gap and maintaining high contrast ratios.
3Illumination intensity
If chiral agents are introduced to increase the twist of liquid crystal molecules and reduce P value, then the contrast rate is increased, but display mura and image sticking occur
Solution Approach 1:
The patent optimizes the concentration parameters of chiral agents and adjusts the molecular structure parameters of host compounds to achieve the right balance between twist angle and display uniformity, preventing display mura while maintaining high contrast ratios.
Solution Approach 2:
The patent introduces self-aligning agents with specific local molecular structures that provide local alignment control, thereby compensating for the non-uniform twist caused by chiral agents and preventing display mura.
4Duration of action of stationary object
If the liquid crystal is driven for a long time to maintain display, then the display is maintained, but image sticking occurs due to polarization without control
Solution Approach 1:
The patent applies preliminary alignment treatment to the liquid crystal molecules through specially designed alignment layers and self-aligning agents, establishing a stable initial orientation that prevents uncontrolled polarization during long-term operation and reduces image sticking.
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 device achieves higher transmittance, better contrast, and improved stability with reduced image sticking and display mura, meeting the requirements for operation in construction and transportation fields.
Implementation Method 1
Using the selective absorption of light by dichroic dye molecules in liquid crystals
Implementation Method 2
The dye molecules are twisted with the twist of the liquid crystal molecules and absorb the light in multiple polarization directions
Implementation Method 3
chiral agents are introduced into the dye liquid crystals to increase the twist of the liquid crystal molecules within the liquid crystal cell and reduce the P (steepness factor) value
Data Source
AI summary
The present invention provides a liquid crystal dimming device. The liquid crystal dimming device of the present application sequentially comprises, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment; the guest-host liquid crystal composition layer comprises at least one dichroic dye, at least one chiral agent and at least one liquid crystal composition; wherein, the liquid crystal composition comprises at least one compound of general formula N. The liquid crystal dimming device of the present invention has an appropriate transmittance (Tr0, Tr255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. The dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.