Photoreactive Mesogen Liquid Crystal Mixture for Photoalignment
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Solution Overview
Problem
Current liquid crystal display (LCD) manufacturing processes face challenges with the rubbing process for polyimide alignment, which leads to issues like mura, contamination, and high production costs, while also requiring complex steps and materials.
Innovation Solution
A liquid crystal mixture comprising a photoreactive mesogen that enables photoalignment of liquid crystals in situ using linearly polarized light after assembly, eliminating the need for a polyimide alignment layer and simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polyimide alignment layer with rubbing process is used, then liquid crystal alignment is achieved, but production complexity and costs increase due to multiple complex steps
Solution Approach 1:
The patent extracts and eliminates the polyimide alignment layer and rubbing process from the LCD manufacturing system. By using a photoreactive mesogen that performs alignment functions intrinsically within the liquid crystal mixture itself, the complex external alignment layer and mechanical rubbing process are removed, simplifying the overall device structure and production process while maintaining alignment functionality
Solution Approach 2:
The photoreactive mesogen enables the liquid crystal mixture to perform its own alignment function through photoinduced reactions when exposed to polarized light. This self-alignment capability eliminates the need for external polyimide layers and mechanical rubbing processes, allowing the system to achieve precise alignment independently through optical field control
2Manufacturing precision
If a polyimide alignment layer with rubbing process is used, then liquid crystal alignment is achieved, but production costs increase
Solution Approach 1:
The patent removes the expensive polyimide alignment layer material and the costly mechanical rubbing equipment from the manufacturing system. The photoreactive mesogen approach uses simpler photoalignment equipment and eliminates material costs associated with polyimide layers, thereby reducing overall production costs while achieving the same alignment precision
Solution Approach 2:
The patent replaces expensive, complex polyimide alignment layers with a cost-effective photoreactive mesogen additive that can be incorporated into the liquid crystal mixture. This approach uses cheaper materials and simpler processing steps, reducing manufacturing costs while maintaining alignment functionality
3Manufacturing precision
If rubbing process is used for polyimide alignment, then alignment is achieved, but image quality deteriorates due to mura and contamination
Solution Approach 1:
The patent replaces the mechanical rubbing process with an optical field-based photoalignment mechanism. Instead of using mechanical contact that causes contamination and mura defects, the photoreactive mesogen responds to polarized light fields to achieve alignment, eliminating mechanical sources of image quality degradation and producing cleaner, more uniform alignment results
4Device complexity
If photoreactive mesogen is used for photoalignment, then production complexity is reduced, but manufacturing precision must be maintained
Solution Approach 1:
The patent controls alignment precision by adjusting photoalignment parameters such as light intensity, wavelength, exposure time, and polarization angle. By optimizing these parameters, the photoreactive mesogen achieves precise liquid crystal alignment comparable to or better than conventional methods, maintaining high manufacturing precision while simplifying the overall production process
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
This approach allows for the fabrication of LCDs with planar alignment without the rubbing process, reducing production complexity and costs, and improving image quality by minimizing viewing-angle dependence and response times.
Implementation Method 1
a photoreactive mesogen, component A), which has a polymerisable group and enables a photoinduced reaction upon irradiation with light of a suitable wavelength
Implementation Method 2
enables photoalignment of liquid crystals in situ using linearly polarized light after assembly
Data Source
AI summary
The invention relates to a liquid crystal mixture characterised in that it comprises one or more photoreactive mesogens of formula Iwherein the parameters and groups occurring are defined as indicated in claim 1, to a process for the fabrication of liquid crystal displays using these liquid crystal mixtures and to a liquid crystal display obtainable by this process. The invention further relates to new compounds of formula I.