Foldable Display Devices with Multilayer Dams for Power-Line Protection
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Solution Overview
Problem
Display devices, particularly flexible and foldable ones, are prone to defects due to the lack of effective protection for power supply lines, leading to potential damage and malfunction.
Innovation Solution
A display device structure featuring a multilayer dam structure is implemented over power supply lines, with layers made of the same materials as adjacent insulating layers and spacers, providing enhanced protection and reducing the likelihood of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power supply lines are exposed without protection in flexible and foldable display devices, then device complexity is reduced, but reliability deteriorates due to potential damage and malfunction
Solution Approach 1:
The protective structure is divided into multiple segments: first dam, second dam, third dam, and fourth dam arranged in sequence along the power supply line. Each dam provides localized protection at different positions, segmenting the protection function to enhance reliability without requiring a single complex protective structure
Solution Approach 2:
The protection is extended from a two-dimensional planar layout to a three-dimensional multilayer structure by stacking dams at different vertical levels. The first and second dams are positioned at different heights, creating a stepped protective configuration that adds vertical dimension to the protection scheme
2Reliability
If a multilayer dam structure is implemented over power supply lines, then reliability is improved by preventing damage, but device complexity increases due to additional layers and materials
Solution Approach 1:
The same material is used for both the second insulating layer and the first dam, and the same material is used for the third insulating layer and the second dam. This multi-functional approach allows these layers to serve both as insulators and as protective dams, reducing the total number of distinct materials and processes required
Solution Approach 2:
The protective dam function is merged with the insulating layers. The second insulating layer is combined with the first dam material, and the third insulating layer is combined with the second dam material, creating integrated structures that perform both insulation and protection functions simultaneously
3Reliability
If multiple dams with different heights are used to protect power supply lines, then protection effectiveness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The protection is divided into multiple dams of different heights (first dam, second dam, third dam, fourth dam) positioned at different locations along the power supply line. Each dam is segmented to provide targeted protection at specific critical points, allowing differentiated height design based on local protection needs rather than uniform height throughout
4Ease of manufacture
If the lowermost layer of the first dam is made of the same material as the second insulating layer, then ease of manufacture is improved by reducing material types, but manufacturing precision may be affected by material uniformity requirements
Solution Approach 1:
The second insulating layer and the first dam are made of the same material, allowing this material to serve dual functions: electrical insulation and physical protection. This reduces the number of distinct material deposition processes and simplifies the manufacturing workflow
Solution Approach 2:
Using the same material for both the second insulating layer and the first dam creates material homogeneity, which simplifies the manufacturing process by reducing the variety of materials that need to be handled, stored, and processed separately
Data Source
AI summary
A display device includes a display area and a peripheral area surrounding the display area, a thin film transistor in the display area, a first insulating layer, the first insulating layer covering the thin film transistor, a signal line on the first insulating layer, the signal line being coupled to the thin film transistor, a second insulating layer on the first insulating layer, the second insulating layer covering the signal line, a power supply line in the peripheral area, the power supply line configured to supply power to a pixel circuit including the thin film transistor, and a first dam including a multilayer structure on the power supply line and overlapping at least a part of the power supply line, in which multilayer structure including a lowermost layer including the same material as the second insulating layer, and the lowermost layer is above the power supply line.