Rollable Display Adhesive Stress Dispersion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rollable display devices experience stress accumulation when rolled, leading to peeling of layers from the adhesive, as the distance from the end of the device to the central axis increases, causing adhesive failure.
Innovation Solution
A rollable display device design featuring adhesive layers with alternating regions of different moduli, where the first regions have a higher modulus for strong adhesion and the second regions have a lower modulus for stress dispersion, connected to a roll frame with the first end and opposite second end, and the second regions' area increases from the first end to the second end, facilitating stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive layers with uniform modulus are used, then manufacturing simplicity is maintained, but stress concentration occurs at greater distances from the central axis causing layer peeling
Solution Approach 1:
The adhesive layer is designed with spatially varying modulus, where the modulus at each position is determined by its distance from the central axis. This local variation in material property allows the adhesive to provide stronger bonding near the axis while offering greater stress dispersion capability at larger distances, thereby preventing layer peeling without requiring a complex multi-region segmented structure
Solution Approach 2:
The modulus of the adhesive layer is changed as a continuous function of the radial distance from the central axis. This parameter variation allows the adhesive to adapt its mechanical properties to the stress distribution pattern, providing optimal bonding strength and stress dispersion at each location along the flexible display unit
2Strength
If higher modulus adhesive is used throughout, then bonding strength is improved, but stress accumulation increases at distant regions causing peeling
Solution Approach 1:
The adhesive modulus is locally optimized based on position: regions closer to the central axis have higher modulus for strong bonding, while regions at larger distances have lower modulus to disperse stress effectively. This local differentiation resolves the contradiction between needing strong bonding and avoiding stress accumulation
3Stress or pressure
If lower modulus adhesive is used throughout, then stress dispersion is improved, but bonding strength decreases causing layer separation
Solution Approach 1:
Rather than using a uniformly low modulus adhesive, the invention implements spatially varying modulus where low modulus regions are strategically placed at larger distances from the axis for stress dispersion, while high modulus regions maintain bonding strength near the axis. This local differentiation prevents layer separation while enabling stress dispersion
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 design effectively disperses accumulated stress along the flexible display unit, reducing the likelihood of layer peeling and maintaining bonding force between layers, thereby enhancing the durability and reliability of the rollable display device.
Implementation Method 1
each of the adhesive layers includes first regions and second regions alternately disposed between a first end and a second end of the flexible display unit, and a modulus of the first regions is different from a modulus of the second regions
Data Source
AI summary
A rollable display device including a roll frame and a flexible display unit windable in the roll frame, the flexible display unit includes a flexible substrate, a display layer disposed on the flexible substrate, an encapsulation layer respectively disposed on and configured to seal the display layer, a polarization layer, a touch screen layer, and a protection layer sequentially disposed on the encapsulation layer, and adhesive layers disposed between the encapsulation layer and the polarization layer, the polarization layer and the touch screen layer, and the touch screen layer and the protection layer, in which each of the adhesive layers comprise first regions and second regions alternately disposed between a first end and a second end of the flexible display unit, and a modulus of the first regions is different from a modulus of the second regions.