Flexible Window with High and Low Refractive Layers for Foldable Displays
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Solution Overview
Problem
The use of polymer films in flexible electronic device windows compromises both optical properties and impact resistance, limiting the durability and display quality of foldable or rollable display devices.
Innovation Solution
A window structure comprising a base layer, a high refractive layer made from a first resin composition containing a highly stretchable material, and a low refractive layer made from a second resin composition with hollow particles and a fluorine-containing initiator, optimized to improve both optical properties and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polymer film is used as a substrate for flexible display windows, then flexibility is achieved, but optical properties and impact resistance deteriorate
Solution Approach 1:
The window is divided into multiple functional layers: a flexible polymer substrate layer and a separate hard coating layer comprising multiple sub-layers (first hard coating layer with high refractive index, second hard coating layer with low refractive index, and third hard coating layer with fluorine-containing compounds). This segmentation allows the flexible substrate to provide bendability while the hard coating layers provide optical performance and impact resistance, resolving the contradiction between flexibility and reliability.
Solution Approach 2:
The invention uses composite material structures where a polymer film substrate is combined with hard coating layers made from different resin compositions. The hard coating layers contain specific materials (first hard coating layer with high refractive index materials, second hard coating layer with low refractive index materials, third hard coating layer with fluorine-containing compounds) that collectively provide both flexibility and improved optical properties and impact resistance, addressing the limitations of using a single polymer film material.
2Reliability
If a hard coating layer is added to improve impact resistance, then durability increases, but device complexity increases
Solution Approach 1:
Different regions of the window surface are treated with different hard coating layers having specific local properties: the first hard coating layer provides high refractive index for impact resistance, the second hard coating layer provides low refractive index for anti-reflective properties, and the third hard coating layer provides fluorine-containing compounds for chemical resistance and non-stick properties. This local quality approach optimizes each layer's function while maintaining overall system efficiency.
Solution Approach 2:
The multi-layer hard coating structure serves multiple functions simultaneously: impact resistance, optical performance enhancement, chemical resistance, and non-stick properties. By integrating these functions into a unified hard coating system applied directly on the flexible substrate, the invention achieves multi-functionality without requiring separate components, thereby managing complexity.
3Reliability
If anti-reflective coating is applied to improve optical properties, then display quality increases, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes specific parameters of the hard coating layers to achieve desired optical properties: the first hard coating layer has a refractive index of 1.60-1.80 and thickness of 50-150 nm, the second hard coating layer has a refractive index of 1.30-1.50 and thickness of 30-100 nm, and the third hard coating layer has a thickness of 10-50 nm. These parameter specifications provide clear manufacturing targets that balance optical performance with manufacturability, reducing precision requirements while maintaining display 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 window structure enhances the optical properties and durability of the display device, providing improved abrasion resistance, chemical resistance, and reduced reflectance, while maintaining flexibility and impact resistance.
Implementation Method 1
a low refractive layer which is disposed on the high refractive layer and includes a second polymer derived from a second resin composition containing hollow particles
Implementation Method 2
a low refractive layer which is disposed on the high refractive layer and includes a second polymer derived from a second resin composition containing hollow particles and a first initiator including fluorine
Implementation Method 3
a high refractive layer which is disposed on the base layer and includes a first polymer derived from a first resin composition containing a highly stretchable material
Data Source
AI summary
A window includes a base layer, a high refractive layer which is disposed on the base layer and includes a first polymer derived from a first resin composition containing a highly stretchable material, and a low refractive layer which is disposed on the high refractive layer and includes a second polymer derived from a second resin composition containing hollow particles and a first initiator including and fluorine. The highly stretchable material is represented by Formula A-1 or Formula A-2 below, and the second resin composition contains about 5 wt % or less of the first initiator with respect to the total amount of the second resin composition.