Foldable Cover Window Primer Resin Layer Hardness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flexible cover windows for foldable display devices have low surface hardness and strength, leading to potential damage and deterioration of optical properties due to uneven adhesive surfaces, resulting in issues like tangerine peel stains, decreased light transmittance, and increased haze.
Innovation Solution
A cover window assembly comprising a cover glass with a primer resin layer having a greater storage modulus than the optically transparent adhesive, and a protective layer on top, which enhances surface hardness, puncture strength, and optical properties by absorbing external shocks and preventing warpage during folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If thin tempered glass and protective film are bonded using optically transparent adhesive, then the cover window assembly can be made flexible and transparent, but the surface hardness becomes low (about B̃6B of pencil hardness) and strength becomes low (1 kgf or less)
Solution Approach 1:
The patent applies composite materials by combining thin tempered glass, primer resin layer, protective film, and optically transparent adhesive into a multi-layer composite structure. Each material contributes specific properties: the tempered glass provides base strength and transparency, the primer resin layer enhances adhesion and surface hardness, the protective film provides additional protection, and the adhesive bonds layers while maintaining optical clarity. This composite approach resolves the contradiction by integrating materials with complementary properties to achieve both flexibility and enhanced strength.
Solution Approach 2:
The patent changes the storage modulus parameter of the primer resin layer to be greater than that of the optically transparent adhesive. This parameter change ensures that the primer resin layer maintains higher rigidity and surface hardness while still allowing the overall assembly to remain flexible. The specific parameter relationship (storage modulus of primer resin layer > storage modulus of adhesive) directly addresses the contradiction by optimizing the mechanical properties of the bonding interface.
2Ease of manufacture
If optically transparent adhesive with low storage modulus is used for bonding, then the bonding process is easier, but tangerine peel stain is caused easily due to surface unevenness, resulting in deterioration of optical properties
Solution Approach 1:
The patent introduces a primer resin layer as an intermediary between the thin tempered glass and the optically transparent adhesive. This intermediary layer has a storage modulus greater than the adhesive, providing a more stable and uniform surface that prevents tangerine peel staining. The primer resin layer acts as a mediator that transfers the bonding function while ensuring surface uniformity and maintaining optical properties, thus resolving the contradiction between ease of bonding and manufacturing precision.
Solution Approach 2:
The patent changes the storage modulus parameter of the primer resin layer to be greater than that of the optically transparent adhesive. This parameter optimization ensures that the primer resin layer maintains higher rigidity and surface uniformity, preventing the formation of tangerine peel stains while still allowing the overall assembly to remain flexible. The specific parameter relationship directly addresses the contradiction by optimizing the mechanical properties of the bonding interface.
3Adaptability or versatility
If the cover window assembly is made thinner for flexibility, then the foldable display device can achieve better flexibility, but the surface hardness and strength are reduced
Solution Approach 1:
The patent uses composite materials with different thicknesses and properties: thin tempered glass for flexibility and transparency, primer resin layer for enhanced adhesion and surface hardness, protective film for additional protection, and optically transparent adhesive for bonding. This composite structure allows the assembly to achieve both flexibility and enhanced strength by distributing mechanical loads across multiple materials with complementary properties.
Solution Approach 2:
The patent optimizes the storage modulus parameter of the primer resin layer to be greater than that of the adhesive, creating a hierarchical structure where each layer has appropriate mechanical properties for its function. This parameter optimization ensures that the thin tempered glass maintains flexibility while the primer resin layer provides the necessary surface hardness and puncture strength, resolving the contradiction between thickness and mechanical properties.
Data Source
AI summary
A cover window assembly of embodiments is attached onto a flexible display panel by an optically transparent adhesive, and comprises a cover glass, a primer resin layer directly coated on the cover glass, and a protective layer disposed on the primer resin layer. The primer resin layer may have a greater storage modulus than the optically transparent adhesive.