Flexible Display Barrier Layer Protrusion Stress Distribution
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Solution Overview
Problem
Flexible OLED displays are prone to degradation and cracking due to external moisture and oxygen, and existing barrier layers are not effectively protected against repeated bending or stretching.
Innovation Solution
A flexible display device design featuring a substrate, a display unit, an encapsulation substrate with protrusions, and a barrier layer that includes organic and inorganic layers, where the encapsulation substrate is two-dimensionally stretchable and the protrusions have varying sectional areas to distribute stress evenly, preventing cracks and delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flat barrier layer is used on the encapsulation substrate, then the manufacturing process is simple, but the barrier layer cracks or delaminates when the flexible display is repeatedly bent or stretched
Solution Approach 1:
The encapsulation substrate is divided into multiple protrusions that are spaced apart from each other, creating a segmented structure. This segmentation allows the substrate to flex and stretch without causing cracks in the barrier layer, as the protrusions can independently deform to accommodate mechanical stress while maintaining barrier layer integrity.
Solution Approach 2:
The encapsulation substrate transitions from a flat two-dimensional structure to a three-dimensional structure with protrusions extending upward. This dimensional change creates additional space and flexibility, allowing the substrate to absorb mechanical stress through vertical deformation of the protrusions rather than horizontal cracking of the barrier layer.
2Adaptability or versatility
If the encapsulation substrate is made two-dimensionally stretchable for flexibility, then the display can be bent and stretched, but stress concentration causes cracks in the barrier layer
Solution Approach 1:
The protrusions are designed with varying horizontal sectional areas along their height, creating local quality variations. The larger base area provides stress distribution, while the narrower upper portions allow for controlled deformation. This local quality variation enables the substrate to stretch and bend while preventing stress concentration that would otherwise cause barrier layer cracking.
Solution Approach 2:
The protrusions act as pre-formed stress-absorbing elements that cushion mechanical stress before it reaches the barrier layer. By designing the substrate with these protrusions beforehand, the structure is prepared to absorb and distribute stress during bending or stretching, preventing crack formation in the barrier layer.
3Ease of manufacture
If the protrusions have uniform cross-sectional area, then the manufacturing is easier, but stress is not evenly distributed during bending
Solution Approach 1:
The horizontal sectional area of the protrusions is changed along their height, transitioning from a uniform cross-section to a tapered or varied cross-section. This parameter change optimizes stress distribution during bending and stretching, with larger base areas providing structural support and smaller upper areas allowing controlled deformation, thereby improving both stress distribution and manufacturing feasibility.
Data Source
AI summary
A flexible display device is disclosed. In one aspect, the display device includes a substrate, a display unit formed over the substrate and a filler formed over the substrate and the display unit. An encapsulation substrate is formed over the encapsulation substrate, and a barrier layer is formed over the encapsulation substrate. The encapsulation substrate includes a base layer and a plurality of protrusions formed over a first surface of the base layer and spaced apart from each other. The barrier layer is formed over the first surface so as to cover the plurality of protrusions and a portion of the base layer exposed between the plurality of protrusions, and the first surface faces the display unit.