Flexible Display Protection Layers with Unequal Thickness for Bending
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Solution Overview
Problem
Flexible display devices are prone to cracks in metal lines and substrates at bending areas, leading to defects and reduced reliability.
Innovation Solution
A display device design with a substrate, a display element layer, an encapsulation layer, a polarizing layer, a first protection layer, and a second protection layer, where the first protection layer has a greater thickness than the second, and a support layer is included to prevent cracks during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the display device is made flexible to enable bending and folding, then adaptability and versatility are improved, but cracks are frequently generated in metal lines and substrates at bending areas, reducing reliability
Solution Approach 1:
The patent applies beforehand cushioning by introducing a protection layer between the substrate and the polarizing layer in advance, before bending occurs. This protection layer prevents cracks from propagating to the metal lines and substrate during bending operations, thus cushioning against future damage while maintaining flexibility
Solution Approach 2:
The protection layer serves as an intermediary element between the substrate and the polarizing layer. It mediates the stress during bending, preventing direct contact and crack propagation between the substrate/metal lines and the polarizing layer, thereby resolving the contradiction between flexibility and crack resistance
2Reliability
If a protection layer is added between the substrate and polarizing layer to prevent cracks, then reliability is improved, but device complexity increases
Solution Approach 1:
The protection layer is implemented as a thin film structure that is flexible and can accommodate bending without adding significant rigidity or complexity to the overall device structure. This thin film approach maintains reliability improvement while minimizing the increase in device complexity
3Reliability
If the first protection layer has greater thickness than the second protection layer to provide better crack protection, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by making the first protection layer (between substrate and polarizing layer) thicker than the second protection layer. This localized thickness variation provides enhanced crack protection where it is most needed (at the substrate-polarizing layer interface) while maintaining manageable manufacturing precision requirements through selective thickness control
Data Source
AI summary
A display device according to an embodiment of the present disclosure may include a substrate, a display element layer on the substrate, an encapsulation layer on the display element layer to seal the display element layer, a polarizing layer on the encapsulation layer, a first protection layer on the substrate and spaced apart from the polarizing layer, and a second protection layer on the substrate and covering a portion of the first protection layer, wherein the first protection layer has a thickness that is greater than a thickness of the second protection layer.