Liquid Crystal Optical Device Low Haze Alignment
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Solution Overview
Problem
Existing liquid crystal optical devices with high cured material content exhibit high haze values when viewed from angles other than perpendicular, making them unsuitable for large windows, and their production is hindered by the need for voltage application during curing and rubbing treatment, which complicates uniformity and productivity.
Innovation Solution
A liquid crystal composition containing a nematic liquid crystal and optically active materials with different rotatory directions, where one is non-curable and the other is curable, allowing for a nematic phase formation with low haze and improved productivity, and the curable compound is cured without voltage application, eliminating the need for rubbing treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cured material content is increased to at least 20 mass % in liquid crystal/cured material composite devices, then the device structure is stabilized and polymerization is facilitated, but the haze value increases when viewed from slant directions, reducing transparency quality
Solution Approach 1:
The invention changes the parameter of cured material content from the conventional at least 20 mass % to specifically 5 mass % or less. This parameter change resolves the contradiction by achieving sufficient structure stability and polymerization at lower cured material content, thereby maintaining transparency with low haze values when viewed from slant directions.
2Manufacturing precision
If voltage is applied during curing of curable compound in PSCT devices, then the liquid crystal alignment is controlled to achieve desired optical state, but the production process becomes complex and uniformity across large panels is difficult to achieve
Solution Approach 1:
The invention applies preliminary action by pre-aligning the liquid crystal molecules using alignment films before curing the polymer. This preliminary alignment ensures uniform liquid crystal orientation throughout the panel, and the subsequent curing process simply fixes this pre-established alignment without requiring voltage application during curing, thereby simplifying the production process while maintaining manufacturing precision.
3Manufacturing precision
If rubbing treatment is performed on substrate surfaces to achieve liquid crystal alignment, then the alignment is established for optimal optical performance, but the production process complexity increases and productivity decreases
Solution Approach 1:
The invention replaces the mechanical rubbing treatment with an alignment film-based method. The alignment films, formed on the inner surfaces of the first and second transparent substrates, provide alignment cues to the liquid crystal molecules through their molecular structure and surface properties, eliminating the need for mechanical rubbing while achieving the same alignment quality, thereby improving productivity.
4Stability of the object's composition
If heating is applied during polymerization to prevent liquid crystal phase separation, then uniform liquid crystal distribution is maintained, but the production process complexity and energy consumption increase
Solution Approach 1:
The invention changes the polymerization conditions by conducting the process at low temperatures, specifically at room temperature or slightly elevated temperatures without intensive heating. This parameter change is made possible by the low cured material content formulation, which allows sufficient polymerization and phase stabilization without requiring high thermal energy input, thereby preventing liquid crystal phase separation while reducing energy consumption.
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 solution results in a liquid crystal optical device with low haze in the transparent state, improved productivity, and enhanced transparency across various viewing angles, while simplifying the production process by eliminating the need for voltage application and rubbing treatment.
Implementation Method 1
containing a nematic liquid crystal and at least two types of optically active materials having different optical rotatory directions
Implementation Method 2
the other one of the optically active materials is a curable compound
Data Source
AI summary
The present invention provides a liquid crystal optical device showing small haze value in transparent state and being excellent in productivity, a process for producing such a device, and a liquid crystal composition for producing such a device.The liquid crystal composition of the present invention is a liquid crystal composition containing a nematic liquid crystal and at least two types of optically active materials having different optical rotatory directions, wherein one of the optically active materials having different optical rotatory directions is a non-curable compound, the other one of the optically active materials is a curable compound, and the liquid crystal composition as a whole shows a nematic phase. By sandwiching the liquid crystal composition between inner faces of a pair of insulation substrates at least one of which is transparent, and curing the curable compound in a state that the liquid crystal is aligned, it is possible to obtain a liquid crystal optical device showing small haze value in transparent state and being excellent in productivity.