Foldable Display Substrate Hole Layout for Crack-Resistant Bending
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Solution Overview
Problem
Flexible display devices face issues with cracks and deformations during repeated folding due to varying compressive stresses, limiting design freedom and reliability.
Innovation Solution
A display substrate design with defined folding and unfolding regions, featuring holes of varying sizes and distributions to manage compressive stress and enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the base material is folded with large curvature, then the display can be compactly carried, but compressive stress concentrates on the inner surface causing cracks
Solution Approach 1:
The patent applies local quality by creating different hole sizes at different locations within the folding region. Specifically, holes closer to the folding line have larger diameters to counteract higher compressive stress, while holes farther away have smaller diameters. This non-uniform hole distribution allows each local region to have optimized stress compensation properties tailored to the local stress conditions.
Solution Approach 2:
The patent changes the parameter of hole diameter based on position within the folding region. The hole diameter is varied continuously or discretely across the folding region, with the diameter parameter being larger near the folding line and smaller toward the edges. This parameter change strategy enables dynamic adaptation to the varying stress field during folding.
2Reliability
If multiple holes are added to disperse stress, then cracking is prevented, but the structure becomes more complex
Solution Approach 1:
The patent segments the folding region into multiple zones based on distance from the folding line, with each zone containing holes of a specific size. This segmentation approach divides the complex stress field into manageable regions, where each region can be independently optimized. The segmentation is reflected in the patterned arrangement of holes with different diameters in different spatial zones.
3Ease of manufacture
If uniform holes are used throughout the folding region, then manufacturing is simpler, but stress dispersion is insufficient
Solution Approach 1:
The patent introduces asymmetry in the hole distribution pattern by varying hole sizes based on their position relative to the folding line. Instead of using identical holes throughout, the design creates an asymmetric pattern where hole diameter correlates with distance from the folding line. This asymmetric design optimizes stress dispersion while maintaining a systematic manufacturing approach.
Data Source
AI summary
A display substrate according to the embodiment includes: a base material having a long direction and a short direction, and including one surface and the other surface, and a first region and a second region; and a hole passing through the one surface and the other surface of the base material, wherein the first region is defined as a folding region in which the one surface is folded to face, the second region is defined as an unfolding region, the hole includes a first hole formed in the first region, and the first hole includes at least three first holes having different sizes in the long direction of the base material.