PVDF Cover Window Coating for Flexible, Scratch-Resistant Touch Displays
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Solution Overview
Problem
Display apparatuses with touch panels are susceptible to reduced sensing sensitivity due to user interaction, which affects the performance of the touch panel, and there is a need for a cover window that maintains flexibility, hardness, and scratch resistance.
Innovation Solution
A cover window comprising a window substrate made of polyvinylidene fluoride (PVDF) with a hard coating layer on at least one surface, where the substrate is a copolymer of PMMA and PVDF, and the coating layer is made of polysilsesquioxane or acrylic polymer, providing enhanced hardness and scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover window is made with high hardness and scratch resistance, then durability is improved, but sensing sensitivity of the touch panel deteriorates
Solution Approach 1:
The cover window uses a composite structure consisting of a polymer resin layer (providing flexibility and touch sensitivity) combined with a hard coating layer (providing scratch resistance). This composite material approach allows both contradictory requirements to be satisfied simultaneously - the polymer layer maintains sensing sensitivity while the hard coating layer provides durability.
Solution Approach 2:
Different regions of the cover window have different properties: the polymer resin layer has soft, flexible properties for touch sensitivity, while the hard coating layer has rigid, durable properties for scratch resistance. Each layer performs its specific function locally, resolving the contradiction between hardness and sensing sensitivity.
2Adaptability or versatility
If a cover window is made with high flexibility, then adaptability is improved, but hardness and scratch resistance deteriorate
Solution Approach 1:
The cover window combines a flexible polymer resin layer with a hard coating layer. The polymer resin provides the necessary flexibility and adaptability, while the hard coating layer compensates for the lack of scratch resistance in the polymer material, achieving both requirements through material composition.
Solution Approach 2:
The cover window has different local properties: the polymer resin layer provides flexibility and adaptability, while the hard coating layer provides scratch resistance. This spatial differentiation of material properties resolves the contradiction between flexibility and hardness.
3Strength
If the thickness of the cover window is increased, then strength is improved, but the overall device thickness and weight increase
Solution Approach 1:
The cover window uses a composite structure with a polymer resin layer and a hard coating layer. This composition provides high strength and durability without requiring increased thickness, as the hard coating layer enhances mechanical properties while maintaining a thin profile.
Solution Approach 2:
The polymer resin layer functions as a flexible thin film that provides both structural integrity and touch sensitivity. This thin film approach maintains cover window strength while minimizing thickness, avoiding the need for thicker materials.
Data Source
AI summary
A cover window includes a window substrate having a first hardness and including polyvinylidene fluoride (PVDF), and a hard coating layer on at least one surface of the window substrate and having a second hardness which is greater than that of the window substrate.