Variable Thickness Dam for Flexible OLED Stress Relief
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Solution Overview
Problem
Flexible OLED devices face damage and display quality issues when operated under high temperature and high humidity conditions due to moisture penetration, leading to reduced lifespan and performance.
Innovation Solution
A flexible OLED device design featuring a flexible substrate with a dam structure that includes a thinner first dam in the folding region and a thicker second dam outside it, with an encapsulation film having a triple-layered structure of inorganic and organic layers to prevent moisture ingress and reduce stress during folding operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform thickness dam structure is used, then manufacturing simplicity is maintained, but stress concentration and encapsulation film damage occur in folding regions
Solution Approach 1:
The dam structure transitions from uniform thickness to variable thickness, with the first dam in the folding region having a first thickness and the second dam outside the folding region having a second thickness greater than the first thickness. This local differentiation allows the dam to provide enhanced stress relief where needed while maintaining manufacturing feasibility through a controlled thickness variation process.
2Strength
If the dam thickness is increased throughout, then stress relief during folding is improved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of uniformly increasing dam thickness throughout the structure, the invention applies increased thickness (second thickness) only to the second dam located outside the folding region, while maintaining a thinner first dam in the folding region. This localized approach provides stress relief where most needed without the manufacturing complexity and cost associated with uniformly thick dams throughout the entire structure.
3Reliability
If encapsulation film thickness is increased, then moisture barrier performance is improved, but flexibility and stress during folding worsen
Solution Approach 1:
The encapsulation system is segmented into multiple functional layers including the encapsulation film and the integrated dam structure. The dam structure itself is segmented into regions of different thicknesses (first dam and second dam) that perform different functions: the thinner first dam in the folding region maintains flexibility, while the thicker second dam outside the folding region provides enhanced moisture barrier performance and stress relief.
Data Source
AI summary
A flexible organic light emitting display (OLED) device includes a flexible substrate having a display area, a non-display area at a periphery of the display area and a folding region; at least one organic emitting diode on the flexible substrate in the display area; an encapsulation film covering the organic emitting diode; and a dam on the flexible substrate. The dam laterally surrounds the display area and includes: a first dam in the folding region; and a second dam outside the folding region, wherein the average thickness of the first dam is smaller than the average thickness of the second dam.