Foldable Display Ultra-Elastic Sheet Stress Distribution
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Solution Overview
Problem
Foldable display devices face issues with layer separation and defects like buckling or peeling due to uneven stress distribution during folding, as the natural folding shape of materials is not adequately supported, leading to interlayer adhesion failure.
Innovation Solution
Incorporating an ultra-elastic sheet with a modulus of elasticity between 50 GPa to 80 GPa, such as a metal sheet or INVAR®, under the display panel, coupled with supporting members that rotate, to distribute stress evenly and prevent peeling, while enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If layers are adhered by pressure sensitive adhesive to form a foldable display module, then the display device can be folded, but the natural folding shape of materials causes uneven stress distribution leading to layer separation and peeling defects
Solution Approach 1:
The patent introduces an ultra-elastic sheet with specifically controlled elastic modulus (50-80 GPa) to change the mechanical parameters of the folding structure. This parameter change allows the supporting members to flexibly adapt to the natural folding shapes of different layers while distributing stress evenly, preventing layer separation and peeling defects during folding operations
Solution Approach 2:
The ultra-elastic sheet acts as an intermediary element between the rigid supporting members and the display layers. It mediates the stress transmission during folding, allowing the supporting members to provide structural support while the ultra-elastic sheet accommodates the natural folding shapes of the display layers, preventing direct stress concentration at adhesive interfaces
2Shape
If the natural folding shape is forced to fit a set shape, then the display device can be assembled, but compression stress increases causing buckling and peeling defects
Solution Approach 1:
By selecting ultra-elastic sheets with specific elastic modulus values (50-80 GPa), the patent optimizes the balance between shape conformity and mechanical strength. This parameter optimization allows the supporting members to maintain their set shape while the ultra-elastic sheet provides sufficient flexibility to accommodate natural folding shapes without generating excessive compression stress
Solution Approach 2:
The ultra-elastic sheet serves as a pre-configured cushioning element that anticipates and absorbs compression stresses during folding. By being adhered to the supporting members before assembly, it provides built-in stress relief that prevents buckling and peeling defects before they occur during the folding process
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 ultra-elastic sheet effectively reduces the likelihood of layer peeling and improves the mechanical strength of the foldable display device, ensuring stable folding and reduced defects.
Implementation Method 1
an ultra-elastic sheet adhered under a display panel of a foldable display module to prevent (or reduce the likelihood of) layers of the display module from peeling when folding the display device
Data Source
AI summary
A foldable display device according to one or more exemplary embodiments of the present invention includes: a first supporting member; a second supporting member coupled to the first supporting member and configured to be rotated with respect to the first supporting member; an ultra-elastic sheet adhered to the first supporting member and the second supporting member; and a display module adhered to the ultra-elastic sheet.