Epoxy Overcoat Layer for Liquid Crystal Display Flatness
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Solution Overview
Problem
Current liquid crystal display manufacturing methods face challenges in achieving high-quality display performance due to issues with light efficiency and color reproducibility, particularly related to the planarization layer and overcoat layer materials used in liquid crystal displays.
Innovation Solution
The use of an epoxy-based polymer overcoat layer, comprising a cardo-based binder resin, epoxy-based monomer, and bisphenol A-based resin, which provides improved planarization and reflow characteristics, reducing shrinkage and outgassing, thereby enhancing display quality and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an acryl-based polymer is used for the overcoat layer, then the manufacturing process is simple, but the volumetric shrinkage is large causing poor flatness
Solution Approach 1:
The patent changes the chemical composition parameters of the overcoat layer material from acryl-based polymer to epoxy-based polymer. This parameter change fundamentally alters the curing mechanism and shrinkage characteristics, achieving low shrinkage (maintaining flatness) while remaining manufacturable through standard coating and curing processes.
2Ease of manufacture
If an acryl-based polymer is used for the overcoat layer, then the manufacturing process is simple, but the outgassing is large causing display defects
Solution Approach 1:
The patent changes the chemical composition parameters of the overcoat layer material from acryl-based polymer to epoxy-based polymer. This parameter change fundamentally alters the curing mechanism and shrinkage characteristics, achieving low shrinkage (maintaining flatness) while remaining manufacturable through standard coating and curing processes.
3Manufacturing precision
If a planarization layer is added on the quantum dot layer, then the flatness is improved, but the light efficiency decreases
Solution Approach 1:
The patent extracts the planarization function from a separate planarization layer and integrates it into the overcoat layer itself. By making the overcoat layer low-shrinkage through material selection (epoxy-based polymer), the layer inherently provides planarization without requiring an additional functional layer, thus maintaining light efficiency while achieving flatness.
Solution Approach 2:
The overcoat layer is designed to serve multiple functions simultaneously: protecting the color conversion layer, providing planarization for subsequent processing, and maintaining high light efficiency. The epoxy-based polymer material enables the overcoat layer to achieve low shrinkage for planarization while remaining optically transparent to preserve light efficiency.
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 epoxy-based polymer overcoat layer significantly reduces volumetric shrinkage and outgassing, leading to improved flatness and light efficiency, resulting in higher quality color reproduction and reduced manufacturing defects compared to acryl-based polymer overcoat layers.
Implementation Method 1
an epoxy-based polymer overcoat layer, comprising a cardo-based binder resin, epoxy-based monomer, and bisphenol A-based resin, which provides improved planarization and reflow characteristics, reducing shrinkage and outgassing
Data Source
Figure 1~2
Figure 3
Figure 4A
AI summary
A display device comprises a first base substrate (BS1); a liquid crystal layer (LC) disposed on the first base substrate; an overcoat layer (OC) disposed on the liquid crystal layer and comprising epoxy polymer; a color conversion layer (CFL) disposed on the overcoat layer; and a second base substrate (BS2) disposed on the color conversion layer. The epoxy polymer is a polymer obtained by polymerizing 1 part to 50 parts by weight of a cardo-based binder resin; 1 part to 50 parts by weight of an epoxy-based monomer; and 1 part to 50 parts by weight of a bisphenol-based resin, with respect to 100 parts by weight of the epoxy polymer.