Flexible Window Hard Coating Reverse Curvature Crack Prevention
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Solution Overview
Problem
Existing flexible displays face damage and cracking issues due to the brittleness of hard coating layers when the display is unfolded or deformed, leading to reduced lifespan and reliability.
Innovation Solution
A flexible window with a hard coating layer having a reverse curvature is developed, attached to a flexible transparent base film, and protected by thicker and thinner protective films, which compensates for deformation and prevents cracking by applying a tensile force when not attached to a display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating layer is applied to protect the flexible display, then scratch resistance and surface hardness are improved, but the coating layer becomes brittle and cracks during folding or deformation
Solution Approach 1:
The hard coating layer is formed with a reverse curvature (convex on the outside surface) that is opposite to the curvature of the flexible display when folded. This pre-applied curvature allows the coating to accommodate the deformation stress during folding, preventing crack formation while maintaining scratch resistance.
Solution Approach 2:
The invention changes the curvature parameter of the hard coating layer by forming it on a jig with a specific radius of curvature. The coating layer is applied with a convex curvature that compensates for the concave curvature experienced during display folding, thereby resolving the brittleness issue.
2Reliability
If the hard coating layer is formed with reverse curvature to prevent cracking, then reliability during deformation is improved, but the surface becomes non-flat when not in use
Solution Approach 1:
The reverse curvature is preliminarily applied to the hard coating layer during manufacturing to counteract the deformation that will occur during use. This preliminary anti-action ensures that when the display is folded, the coating layer experiences minimal stress and remains crack-free.
3Reliability
If protective films are added to protect the hard coating layer, then durability is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
Protective films are applied selectively - a first protective film on the convex outer surface where damage is most likely to occur, and a second protective film on the flexible substrate. This localized protection approach provides maximum durability where needed while minimizing overall complexity.
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 flexible window effectively prevents damage to the hard coating layer during deformation, enhancing the durability and lifespan of flexible displays by maintaining the hard coating layer's integrity and flatness when attached or detached.
Implementation Method 1
forming a hard coating layer by curing the hard coating solution with ultraviolet rays
Data Source
AI summary
A flexible window for a display panel, the flexible window including a flexible transparent base film attachable to the display panel; and a hard coating layer attached to the transparent base film, the hard coating layer having a concave first side opposite the flexible transparent base film when the hard coating layer is separated from the display panel.