Display Device With Varying Cavity Density In Bendable Region
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Solution Overview
Problem
Flexible display devices with bent regions experience non-uniform curvature and increased stress variations, leading to potential defects like cracks, due to the application of resin after bending, which fails to control curvature and distribute stress effectively.
Innovation Solution
A display device design featuring a substrate with flat regions and a bendable region, where the second passivation layer has cavities with varying densities and depths to manage bending stress, and support members on the substrate to maintain flatness, ensuring uniform curvature and enhanced strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If resin is applied to the bent region after bending to compensate strength, then the strength of the bent region is improved, but the curvature becomes non-uniform and stress variations increase
Solution Approach 1:
The cavity pattern is formed in the second passivation layer before the bending process. This preliminary formation of stress-compensating cavities allows the structure to be pre-configured with varying density regions that will counteract bending stresses uniformly, rather than attempting to apply compensation after bending has already created non-uniform curvature and stress distribution
2Length of stationary object
If the display device is made thinner to reduce curvature, then the device thickness is reduced, but stress variations in the bent region increase
Solution Approach 1:
The second passivation layer is designed with locally varying cavity densities - higher density in regions experiencing higher bending stress and lower density in regions experiencing lower stress. This local differentiation of structural properties allows the thinner display device to maintain uniform stress distribution across the bent region, compensating for the increased stress variations that would normally result from reduced thickness
3Ease of manufacture
If uniform cavity density is used in the second passivation layer, then manufacturing is simplified, but stress compensation becomes ineffective at achieving uniform curvature
Solution Approach 1:
The cavity pattern in the second passivation layer is designed with spatially varying density - regions with higher cavity density are positioned where bending stress is higher, while regions with lower cavity density are positioned where bending stress is lower. This local differentiation optimizes stress compensation to achieve uniform curvature across the bent region, while the cavities can still be formed using standard manufacturing techniques like photolithography and etching
Data Source
AI summary
A display device including a substrate including first and second flat regions spaced apart from each other, and a bendable region between the first and second flat regions, a display layer on a first surface of the substrate in the first flat region, a first passivation layer on the first surface of the substrate in the bendable region, a second passivation layer on a second surface of the substrate, the second passivation layer defining cavities spaced apart from each other in the bendable region, and support members on the second surface of the substrate in the first flat region and the second flat region, wherein a first density of the cavities corresponding to a first area in the bendable region is less than an average density of the cavities, and wherein a first bending stress of the substrate at the first area is greater than an average bending stress of the substrate in the bendable region.