Foldable Display Adhesive Gradient for Narrow-Bezel Bonding
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Solution Overview
Problem
Existing flexible display devices face challenges in maintaining durability and reliability due to the limitations of adhesive members used in combining components, particularly in minimizing the non-display area and ensuring effective bonding.
Innovation Solution
The use of an adhesive layer with an ionic surfactant concentration gradient, where the concentration increases from one surface to another, enhances the bonding between the display panel and window, improving durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional adhesive layer with uniform composition is used to bond the display panel and window, then the bonding is simple to achieve, but the bonding strength and reliability are insufficient for foldable devices
Solution Approach 1:
The adhesive layer is designed with a concentration gradient of ionic surfactants, where the surfactant concentration varies from one surface to the other. This creates different local properties within the same adhesive layer: one surface has high surfactant concentration for optimal contact angle and bonding, while the other has lower concentration. This local quality variation resolves the contradiction by improving bonding reliability through tailored surface properties without requiring multiple separate adhesive layers.
Solution Approach 2:
The patent applies an external electric field to change the physical state and distribution of ionic surfactants within the adhesive layer. By controlling the electric field parameters (strength, direction, duration), the surfactant concentration gradient can be dynamically adjusted to achieve optimal contact angles for bonding. This parameter change approach allows a single adhesive layer to adapt its properties for reliable bonding under varying conditions.
2Area of stationary object
If the non-display area is minimized to increase visibility, then the display visibility is improved, but the durability and reliability of adhesive members are compromised
Solution Approach 1:
The adhesive layer with ionic surfactant concentration gradient provides locally optimized bonding properties at the reduced non-display area boundaries. The varying surfactant concentration ensures that even in minimized bonding regions, the contact angle and adhesion strength are sufficient for reliable assembly. This allows the non-display area to be minimized for better visibility while maintaining adhesive reliability through enhanced local bonding quality.
3Strength
If the contact angle between adhesive layer and substrate is not optimized, then the adhesive application is simple, but the bonding strength is insufficient
Solution Approach 1:
The contact angle of the adhesive layer is controlled by changing the distribution state of ionic surfactants through external electric field application. By adjusting electric field parameters, the surfactant molecules reorient and redistribute, directly controlling the contact angle to achieve optimal bonding strength. This parameter change mechanism allows precise control of bonding strength without complicating the adhesive composition with multiple additives.
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 approach improves the structural integrity and longevity of foldable display devices by optimizing the adhesive layer's contact angle through electro-dewetting phenomena, ensuring robust bonding and minimizing non-display areas.
Implementation Method 1
adjusting an angle of contact between a target substrate and an adhesive layer using an electro-dewetting phenomenon
Implementation Method 2
a first portion in which a concentration of the ionic surfactant increases in a direction from the first surface toward the second surface
Data Source
AI summary
A display device includes: a display panel including a display area and a non-display area surrounding the display area, a window on the display panel, and an adhesive layer disposed on the display panel and including an ionic surfactant. The adhesive layer includes a first surface adjacent to the window, a second surface facing the first surface, and a first portion in which a concentration of the ionic surfactant increases in a direction from the first surface toward the second surface.