Homeotropic Liquid Crystal Optical Element for LC Display Phase Control
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Solution Overview
Problem
Existing liquid crystal display devices face challenges with high production costs, limited heat resistance, non-uniform orientation of liquid crystal polymers, and narrow temperature range for maintaining birefringence properties, leading to issues with viewing angle compensation and phase difference control.
Innovation Solution
A birefringence layer is formed using crosslinkable polymerizable liquid crystal monomers with an additive for homeotropic orientation, followed by baking to create a three-dimensional crosslinked structure, which includes an isotropic layer for protection and reduces haze, allowing for uniform orientation and high heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a viewing angle compensation film is produced by sealing liquid crystal molecules into a cell and subjecting them to photopolymerization, then the film achieves homeotropic orientation, but the production cost significantly increases due to the large number of production steps
Solution Approach 1:
The patent extracts the liquid crystal molecules from the complex cell structure and applies them directly to the alignment layer in a solution state, eliminating the need for cell assembly, sealing, and alignment procedures. This simplifies the production process while maintaining homeotropic orientation through the alignment layer's directional guidance
Solution Approach 2:
The patent prepares the alignment layer in advance with specific surface treatment (such as ITO coating and photolithography patterning) to create the homeotropic orientation environment before applying the liquid crystal solution. This preliminary preparation ensures that when the liquid crystal molecules are applied, they automatically orient correctly without requiring subsequent alignment steps
2Ease of manufacture
If liquid crystal polymers are used for homeotropic orientation, then the film can be produced with fewer steps, but the orientation uniformity decreases and heat resistance is limited
Solution Approach 1:
The patent changes the physical state parameter of the liquid crystal material from polymerized (solid) to monomeric (solution) form. This allows the liquid crystal molecules to remain mobile and responsive to the alignment layer's orienting field during application, ensuring uniform homeotropic orientation. After application, UV irradiation polymerizes the monomers in their oriented state, locking in the uniform orientation while maintaining manufacturing simplicity
3Ease of manufacture
If liquid crystal polymers are used for homeotropic orientation, then production is simplified, but the temperature range for maintaining birefringence properties becomes narrow
Solution Approach 1:
The patent utilizes the phase transition parameter of liquid crystal monomers, applying them in a liquid solution state for easy processing and orientation, then transforming them into a crosslinked polymer network through UV irradiation. This final crosslinked structure maintains stable birefringence properties across a wide temperature range while preserving the manufacturing simplicity of using liquid crystal solutions
4Manufacturing precision
If the additive for homeotropic orientation remains on the surface after baking, then orientation is maintained, but haze increases and reliability decreases
Solution Approach 1:
The patent removes the additive from the surface of the baked film through washing or extraction processes. The additive, which served its function during the orientation and baking phases, is no longer needed on the surface and its removal eliminates the source of haze and reliability issues while the crosslinked liquid crystal polymer maintains the homeotropic orientation
Solution Approach 2:
The patent incorporates a protective coating or surface treatment step after baking that prevents additive migration to the surface during subsequent handling and use. This beforehand protection ensures that the additive remains confined to the bulk where it can maintain orientation without causing surface haze, thereby preserving both orientation and optical quality
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 low-cost, high-heat-resistant optical element with improved uniformity and reliability in maintaining birefringence properties, reducing haze to 0.1 or less, and enhancing phase difference control and contrast for liquid crystal display devices.
Implementation Method 1
a birefringence layer having a structure obtained by fixing liquid crystal monomers each having a polymerizable group at a terminal thereof in a state where the monomers are homeotropically oriented; the birefringence layer contains an additive for promoting homeotropic orientation of the liquid crystal monomers
Implementation Method 2
the birefringence layer has a structure obtained by fixing liquid crystal monomers each having a polymerizable group at a terminal thereof in a state where the monomers are homeotropically oriented
Implementation Method 3
an optical element which includes a base material having light permeability; and a birefringence functional layer which includes at least a birefringence layer
Data Source
AI summary
An object of the present invention is to provide an optical element which can suppress a production cost, has good heat resistance; uniformly maintains the fixed orientation of a liquid crystal polymer in a wide temperature range, shows a low haze with reliability without reducing birefringence property owing to a physical factor from its external surface, and can maintain desired birefringence property with reliability. The present invention relates to an optical element formed by forming, on the upper surface of a base material having light permeability, at least a birefringence layer having a structure obtained by fixing liquid crystal monomers each having a polymerizable group at a terminal thereof in a state where the monomers are homeotropically oriented, forming an isotropic layer constituted by the liquid crystal monomers on the upper surface of the birefringence layer, and removing an additive layer formed on the upper surface of the isotropic layer.