Flexible Display Multilayer Conductive Lines for Bend Reliability
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Solution Overview
Problem
Existing flexible display devices face failures and mechanical stress issues in bent portions due to inadequate conductive line designs, which affect product reliability and durability.
Innovation Solution
The flexible display device incorporates a conductive line layout on multiple layers, extending in a direction non-parallel to the bending direction, with strain-reducing designs such as diamond-shaped sub-traces and specific insulating layer patterning to minimize cracking and stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductive lines are arranged parallel to the bending direction in the bended section, then the layout is simple and manufacturing is easy, but the conductive lines are prone to cracking and mechanical failure due to bending stress
Solution Approach 1:
The patent applies dimensionality change by arranging conductive lines in multiple layers (first layer and second layer) rather than a single plane. The conductive lines in different layers are positioned at different depths within the bended section, allowing them to extend in directions non-parallel to the bending direction while maintaining electrical connectivity. This multi-layer configuration distributes bending stress across different spatial dimensions, preventing cracking that would occur in a single-layer parallel arrangement.
2Reliability
If conductive lines extend in a direction non-parallel to the bending direction in multiple layers, then reliability and durability in bent portions are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by configuring conductive lines differently in different spatial locations. Specifically, in the bended section, conductive lines in the first and second layers are arranged to extend in directions non-parallel to the bending direction, while in non-bended sections, the conductive lines can be arranged more simply. This localized optimization reduces cracking risk precisely where bending stress occurs, without unnecessarily complicating the entire conductive line structure.
Solution Approach 2:
The patent segments the conductive line structure into multiple independent layers, with each layer containing conductive lines that can be independently configured. This segmentation allows each layer's conductive lines to be optimized for stress distribution in the bended section, while maintaining overall electrical connectivity through the layered structure. The segmentation reduces the complexity of any single layer while achieving enhanced reliability through the collective multi-layer system.
3Device complexity
If a single layer of conductive lines is used, then the device structure is simple, but the conductive lines cannot adequately withstand bending stress without cracking
Solution Approach 1:
The patent transitions from a single-layer (2D) conductive line structure to a multi-layer (3D) structure. By positioning conductive lines in both a first layer and a second layer at different depths within the bended section, the structure utilizes the third dimension (depth/layer) to distribute bending stress. This dimensional transition allows conductive lines to extend in directions non-parallel to the bending direction, significantly improving resistance to cracking while maintaining reasonable structural complexity.
Data Source
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AI summary
Disclosed is a flexible display device. The flexible display device includes a base layer including a first portion in which an organic light emitting diode is disposed on a first surface and a second portion which has a bended section bent toward a second surface which is opposite to the first surface at the outside of the first portion; and conductive lines in the bended section, the conductive lines aredisposed on two or more layers, and the conductive lines extend in a direction which is not parallel to a bending direction of the bended section.