Liquid Crystal Display Polymer Layer UV Exposure
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Solution Overview
Problem
The existing PSA technology for liquid crystal display devices can cause display unevenness and image sticking due to the deterioration of alignment films and interlayer insulation films under ultraviolet rays irradiation, and incomplete polymerization leading to residual monomers and initiators in the liquid crystal layer.
Innovation Solution
A liquid crystal display device with a polymer layer formed by radical polymerizable monomers that generate radicals through self-cleavage reactions by light irradiation, eliminating the need for additional polymerization initiators and reducing the duration of ultraviolet rays exposure, thereby minimizing residual impurities and film deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If long-time ultraviolet rays irradiation is used to polymerize monomers, then complete polymerization is achieved, but alignment films and interlayer insulation films deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the monomer system by introducing specific photopolymerizable monomers with high reactivity and appropriate polymerization rates. This allows the polymerization process to reach completion faster, reducing UV exposure time from what would traditionally require long irradiation to a optimized shorter duration that prevents film deterioration while ensuring complete polymerization.
Solution Approach 2:
The patent incorporates polymerization initiators and optimizes monomer composition before the polymerization step, preparing the liquid crystal composition in advance so that upon UV irradiation, the polymerization proceeds rapidly and completely. This preliminary preparation eliminates the need for prolonged irradiation, thereby protecting the alignment and insulation films from degradation.
2Object-affected harmful factors
If short-time ultraviolet rays irradiation is used to avoid film deterioration, then polymerization is incomplete, but this causes image sticking
Solution Approach 1:
The patent modifies the chemical composition parameters by selecting monomers with specific photopolymerization characteristics and optimizing their concentrations. This formulation ensures that the polymerization reaction reaches completion within a short UV irradiation time, eliminating residual monomers that would cause image sticking, while the shortened exposure time prevents film deterioration.
Solution Approach 2:
The patent uses photopolymerizable monomers that replicate the alignment-inducing properties of traditional PSA polymers but achieve their effect through a faster polymerization mechanism. This copying of the alignment function through a different chemical pathway enables complete polymerization in short time, avoiding both image sticking and film damage.
3Reliability
If polymerization initiators are added to achieve complete polymerization, then residual initiators remain in the liquid crystal layer, but these cause display unevenness
Solution Approach 1:
The patent changes the chemical parameters by selecting polymerization initiators with appropriate half-life characteristics and decomposition temperatures, and by optimizing their concentration in the liquid crystal composition. This ensures complete polymerization while minimizing residual initiator content to levels that do not cause display unevenness or image sticking.
Solution Approach 2:
The patent employs a composite liquid crystal composition containing multiple components including photopolymerizable monomers, polymerization initiators, and liquid crystal materials in optimized ratios. This composite formulation ensures complete polymerization through synergistic effects while the specific composition minimizes harmful residues, preventing display defects.
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 solution enhances alignment stability, prevents display unevenness, and reduces image sticking by ensuring complete polymerization and minimizing the impact on organic insulating materials, resulting in improved long-term reliability and display quality.
Implementation Method 1
at least one kind of the radical polymerizable monomers is a compound including a structure which generates radicals through self-cleavage reaction by light irradiation
Implementation Method 2
the polymer layer is formed by polymerization of one or more kinds of radical polymerizable monomers contained in the liquid crystal layer
Data Source
AI summary
Provided is a liquid crystal display device reducing display unevenness and image sticking even though employing a PSA polymerization step in which monomers are added to a liquid crystal layer. The liquid crystal display device includes a pair of substrates, at least one of the substrates including an alignment film and a structure consisting of an organic insulating material; a polymer layer that is formed on the alignment film to control the alignment of liquid crystal molecules; and a liquid crystal layer containing a liquid crystal material, the layer being placed between the pair of substrates, wherein the polymer layer is formed by polymerization of one or more kinds of radical polymerizable monomers contained in the liquid crystal layer, and at least one kind of the radical polymerizable monomers includes a structure which generates radicals through self-cleavage reaction by light irradiation and two or more radical polymerizable groups.