Flexible Display Adhesive Layout for Repeated Folding Durability
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Solution Overview
Problem
Flexible display devices suffer from durability deterioration due to non-uniform stress distribution and delamination when continuously or repeatedly folded, as the adhesive layer exhibits elastic deformation and plastic deformation, leading to delamination between layers.
Innovation Solution
A flexible display device with an adhesive layer comprising multiple adhesive portions of varying adhesive strengths, including a viscoelastic first adhesive portion at the folding axis and a stronger second adhesive portion in non-folding areas, along with a third adhesive portion to connect them, which helps absorb and distribute stress uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform adhesive layer is used to adhere substrates in foldable display devices, then manufacturing is simplified, but non-uniform stress distribution during folding causes plastic deformation and delamination, deteriorating durability
Solution Approach 1:
The adhesive layer is designed with spatially varying adhesive strength, where the adhesive strength decreases from the peripheral areas toward the folding axis. This local quality variation allows different regions of the adhesive layer to perform different functions: peripheral areas provide strong adhesion to prevent delamination, while areas near the folding axis allow controlled stress release during folding, preventing plastic deformation and improving durability during repeated folding cycles
2Adaptability or versatility
If the adhesive layer is made thinner to satisfy foldable flexibility, then folding flexibility is improved, but adhesion strength between layers is reduced, leading to delamination
Solution Approach 1:
The adhesive layer's adhesive strength parameter is varied spatially rather than uniformly. By controlling the composition or thickness distribution of the adhesive material, the adhesive strength is reduced near the folding axis to accommodate folding flexibility while maintaining higher adhesive strength in peripheral areas to prevent delamination, thus resolving the contradiction between folding flexibility and adhesion strength
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
This configuration reduces plastic deformation and delamination, enhancing the durability of the flexible display device by effectively managing stress distribution during repeated folding.
Implementation Method 1
The first adhesive portion may have viscoelasticity, and a portion of the first adhesive portion at which the folding axis is positioned is thicker than the second adhesive portion.
Implementation Method 2
the adhesive layer positioned in the folding axis exhibits elastic deformation as compared to the peripheral areas
Data Source
AI summary
An embodiment provides a flexible display device adhesive that is foldable with respect a folding axis, that has a folding area corresponding to the folding axis, and that has non-folding areas. The flexible display device includes a first substrate configured to be flexible, a second substrate above the first substrate and configured to be flexible, and an adhesive layer between the first substrate and the second substrate to adhere the first substrate to the second substrate. The adhesive layer includes two or more adhesive portions having different adhesive strength.