Gas Barrier Layer Positioning for Flexible Display Durability
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Solution Overview
Problem
Existing display devices with gas barrier layers are prone to damage when bent, as they experience tensile and compression stresses, leading to deterioration and gas/water penetration, which affects the organic EL element's stability.
Innovation Solution
Positioning the gas barrier layer near the neutral plane where no stress is generated during bending, ensuring minimal or no stress on the gas barrier layer, and positioning the display portion similarly to minimize damage from external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas barrier layer is provided on the substrate surface to block oxygen and water, then the protection against gas penetration is improved, but the layer is damaged when the device is bent due to tensile and compression stresses
Solution Approach 1:
The gas barrier layer is repositioned from the outer surface to the neutral plane within the substrate thickness dimension. This dimensional relocation places the layer in a stress-free zone during bending, eliminating the contradiction between providing gas barrier protection and withstanding bending stresses.
Solution Approach 2:
The position parameter of the gas barrier layer is changed from surface-level to neutral-plane-level. This parameter change transforms the layer's mechanical environment from high-stress to zero-stress conditions, resolving the damage issue while maintaining the gas barrier function.
2Reliability
If the gas barrier layer is positioned on the substrate surface, then the gas barrier function is maximized, but the layer experiences maximum stress during bending
Solution Approach 1:
The gas barrier layer is relocated along the thickness dimension from the outer surface to the neutral plane. This repositioning reduces the layer's exposure to bending stresses while maintaining its gas barrier effectiveness, as the neutral plane experiences minimal stress during flexing.
Solution Approach 2:
The neutral plane acts as an intermediary position that provides both mechanical protection (zero stress) and functional protection (gas barrier). By positioning the layer at this intermediary location, both the stress resistance and gas barrier requirements are satisfied simultaneously.
3Ease of operation
If the display portion is positioned on the substrate surface, then the display function is optimized, but the display portion is damaged when external force bends the substrate
Solution Approach 1:
The display portion is repositioned from the outer surface to the neutral plane within the substrate. This dimensional relocation protects the display portion from bending stresses while maintaining its display functionality, as the neutral plane remains stable during flexing.
Data Source
AI summary
A display device includes a substrate, a display portion formed on the substrate, an upper layer which covers the display portion, and a gas barrier layer provided between at least a part of the substrate and the display portion. The gas barrier layer is positioned near to the position which forms a neutral plane when bending moment in a direction in which the substrate is warped acts on the overall display device.