Segmented Adhesive Layers for Flexible Display Impact Protection
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Solution Overview
Problem
Flexible display devices face challenges in providing robust protection against external impacts, such as bending and folding, which can lead to damage and stress on the display panel.
Innovation Solution
A display device design featuring multiple adhesive layers with specific shear moduli and thicknesses is implemented, including a first lower adhesive layer with a higher shear modulus and thickness under the display panel, and an upper adhesive layer with a lower shear modulus and greater thickness, to absorb and distribute external impacts effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single adhesive layer is used under the display panel, then the structure is simple, but the protection against external impact is insufficient
Solution Approach 1:
The adhesive layer is divided into multiple sub-layers (first lower adhesive layer, second lower adhesive layer, and third lower adhesive layer) with different thicknesses arranged in sequence from the display panel outward. This segmentation allows each layer to contribute differently to impact absorption, with thinner layers closer to the panel providing structural support and thicker outer layers providing cushioning, thereby resolving the contradiction between protection effectiveness and structural simplicity.
2Reliability
If the adhesive layer thickness is increased to absorb impact, then protection is improved, but the folding smoothness is reduced
Solution Approach 1:
Different regions of the adhesive structure have different thicknesses tailored to their specific functions. The first lower adhesive layer has a smaller thickness (1-5 μm) to maintain folding smoothness and flexibility, while the second and third lower adhesive layers have progressively larger thicknesses (5-10 μm and 10-20 μm) to provide impact absorption. This local differentiation resolves the contradiction by optimizing thickness for each specific functional requirement rather than using a uniform thickness throughout.
3Reliability
If the shear modulus of the adhesive layer is increased to protect the panel, then impact resistance is improved, but the flexibility for folding is reduced
Solution Approach 1:
The adhesive system is segmented into multiple layers with different shear modulus characteristics. The first lower adhesive layer has a higher shear modulus (200-300 kPa) to provide structural support and impact resistance, while the second and third lower adhesive layers have progressively lower shear moduli to provide flexibility and cushioning. This segmentation allows the system to simultaneously achieve both high impact resistance and good folding flexibility, resolving the contradiction between these two opposing requirements.
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 protects the display panel from external impacts, reduces stress, and assists in the recovery of the panel during folding and unfolding, enhancing its durability and usability.
Implementation Method 1
each of a shear modulus of the first lower adhesive layer and a shear modulus of the second lower adhesive layer is about 200 kPa to about 300 kPa at about −25° C. to about −15° C.
Implementation Method 2
The first and second lower adhesive layers may support the display panel so that the display panel is not damaged by an external impact, may reduce a stress applied to the display panel, and may assist in recovery of the display panel.
Data Source
AI summary
A display device includes a display panel having a folding area and a non-folding area, a first lower adhesive layer disposed under the display panel in the folding area and the non-folding area and having a first thickness, and a second lower adhesive layer disposed under the first lower adhesive layer in the folding area and the non-folding area and having a second thickness greater than the first thickness.