Display Encapsulation Structure for Narrow-Bezel Moisture and Crack Control
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Solution Overview
Problem
Existing display devices face challenges in reducing the bezel size due to the presence of various structures, circuits, and lines, which also increases the risk of moisture and oxygen penetration, leading to potential image abnormalities and reliability issues.
Innovation Solution
A display device structure with a narrow bezel design incorporating a substrate, display and non-display areas, a circuit unit, protective and overcoat layers, a common electrode, and inorganic encapsulation layers with protrusions and separation layers to prevent moisture and oxygen penetration and diffusion, using undercut structures to manage the encapsulation layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the bezel size is reduced, then the display area is increased, but the risk of moisture or oxygen penetration increases
Solution Approach 1:
The encapsulation layer is divided into multiple segments including a first encapsulation layer, a second encapsulation layer, and a bridge portion. This segmentation allows the encapsulation structure to extend into the non-display area while maintaining effective moisture and oxygen barriers, thus protecting the display area even when the bezel is reduced.
Solution Approach 2:
The encapsulation layer extends from the display area into the non-display area in the horizontal dimension, and also has vertical thickness variations. This multi-dimensional extension creates a larger protective envelope without increasing the visible bezel size, effectively blocking moisture and oxygen pathways.
2Adaptability or versatility
If various structures and circuits are placed on the bezel, then the functionality is improved, but the bezel size cannot be reduced
Solution Approach 1:
Circuits and functional structures are moved from the horizontal bezel area into the vertical dimension by extending them into the non-display area beneath the encapsulation layer. This allows full utilization of the non-display area for circuit placement while maintaining a narrow visible bezel.
Solution Approach 2:
The circuit structures are nested within the non-display area, with the encapsulation layer enveloping them. This nesting arrangement allows circuits to be integrated without increasing the external bezel dimensions, as the encapsulation layer provides the protective boundary.
3Reliability
If the encapsulation layer is made continuous, then the protection against moisture is improved, but cracks may spread more easily
Solution Approach 1:
The encapsulation layer is segmented into a first encapsulation layer, a second encapsulation layer, and a bridge portion connecting them. This segmentation creates discontinuities that can act as crack stoppers, preventing crack propagation while the bridge portion maintains moisture barrier continuity.
Solution Approach 2:
Different portions of the encapsulation structure have different properties: the first and second encapsulation layers provide strong moisture barriers, while the bridge portion is designed with specific thickness and material properties to resist crack propagation. This local differentiation optimizes both protection and strength.
4Reliability
If the inorganic encapsulation layer thickness is increased, then the moisture barrier is improved, but the manufacturing complexity increases
Solution Approach 1:
The inorganic encapsulation layer has varying thickness at different locations: it is thicker in the display area and non-display area where moisture protection is critical, and thinner in the bridge portion where the structure already has enhanced crack resistance through segmentation. This local quality variation optimizes protection while managing manufacturing complexity.
Data Source
AI summary
A display device may include a display area, a non-display area, a circuit unit disposed on a substrate and disposed in the non-display area, a protective layer disposed on the circuit unit, an overcoat layer on the protective layer, a common electrode extending from the display area to the non-display area and disposed on the overcoat layer, an inorganic encapsulation layer extending from the display area to the non-display area and disposed on an upper portion and a side of the common electrode, a first protrusion protruding from the substrate, located further outside the common electrode, and having a first eaves, a second protrusion protruding from the substrate, located between the first protrusion and the display area, and having a second eaves, and a first separation inorganic layer disposed on the first protrusion, including the same material as the inorganic encapsulation layer, and separated from the inorganic encapsulation layer.