Display Device Encapsulation Layer Stress Relief
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Solution Overview
Problem
Display devices face stress issues when bent or folded, leading to potential damage to the encapsulation layer, particularly in areas with varying surface energies and organic insulating material distribution.
Innovation Solution
A display device design featuring a substrate with flat and bending portions, where the encapsulation layer includes a first inorganic layer, an organic insulating layer with increased volume and height in bending areas, and a second inorganic layer with greater surface length, distributed to manage stress and prevent damage during bending or folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the encapsulation layer is made uniform in thickness across flat and bending portions, then the manufacturing process is simplified, but the bending portion experiences stress concentration and potential damage
Solution Approach 1:
The organic encapsulation layer is designed with varying thickness: thicker in the bending portion and thinner in the flat portion. This local quality variation allows the bending portion to accommodate stress during folding while the flat portion maintains proper encapsulation, thereby resolving the contradiction between manufacturing simplicity and structural reliability.
2Reliability
If the organic encapsulation layer thickness is increased in the bending portion, then stress relief during bending is improved, but the manufacturing precision and uniformity become more difficult to control
Solution Approach 1:
A pattern portion is formed on the first inorganic encapsulation layer in the bending portion before depositing the organic encapsulation layer. This preliminary action creates a template that guides the organic material deposition, ensuring the organic layer achieves the desired varying thickness profile with proper precision despite the complexity of the structure.
3Reliability
If a pattern portion with different surface energy is added to control organic material distribution, then the organic encapsulation layer forms correctly in bending areas, but the device structure and fabrication process become more complex
Solution Approach 1:
The pattern portion acts as an intermediary element between the first inorganic encapsulation layer and the organic encapsulation layer. By having different surface energy, it mediates the deposition process to ensure proper organic material distribution in the bending portion, accepting the added structural complexity as necessary to achieve reliable material control.
Data Source
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AI summary
A display device includes: a substrate including a flat portion and a bending portion disposed on a side of the flat portion; a light emitting element layer disposed on the substrate and including light emitting elements disposed in the flat portion and the bending portion; and an encapsulation layer disposed over the flat portion and the bending portion and including a first inorganic encapsulation layer disposed on the light emitting element layer, an organic encapsulation layer disposed on the first inorganic encapsulation layer, and a second inorganic encapsulation layer disposed on the organic encapsulation layer. At least a portion of the organic encapsulation layer disposed in the bending portion includes a portion protruding in a direction upward from the substrate, and a maximum height of the organic encapsulation layer disposed in the bending portion is greater than a maximum height of the organic encapsulation layer disposed in the flat portion.