Foldable Display Bending Structure to Prevent TMAH Corrosion
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Solution Overview
Problem
Existing display devices face issues with corrosion and cracking in bending areas due to the presence of tetramethylammonium hydroxide (TMAH) and the disposition of metal and inorganic material layers, which affect product reliability and durability.
Innovation Solution
The display device design includes a base substrate with a concave curved pattern in the bending area, omitting metal and inorganic layers, and features a planarization layer, bank, touch buffer layer, and protective layer to prevent TMAH accumulation and enhance bending flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal layers and inorganic material layers are disposed in the bending area, then structural strength is improved, but corrosion and cracking occur due to TMAH accumulation
Solution Approach 1:
The patent removes the metal layer and inorganic material layer from the bending area to eliminate the source of TMAH accumulation and subsequent corrosion. This extraction of problematic layers from the critical bending region prevents reliability issues while maintaining structural integrity through alternative design configurations.
Solution Approach 2:
The patent applies different structural configurations to different regions: the bending area has no metal or inorganic layers to prevent corrosion, while other areas maintain the necessary layered structure for strength. This local differentiation allows the structure to be optimized for both reliability in the bending zone and overall structural requirements elsewhere.
2Reliability
If a concave curved pattern is formed on the base substrate in the bending area, then the position of the neutral plane is adjusted, but manufacturing complexity increases
Solution Approach 1:
The patent introduces a concave curved pattern on the base substrate surface in the bending area to modify the neutral plane position and stress distribution. This curvature adjustment helps prevent cracking during bending operations by optimizing the mechanical stress profile, despite adding some manufacturing steps.
3Weight of moving object
If the display device is made lightweight by removing layers, then portability is improved, but structural strength may be compromised
Solution Approach 1:
The patent removes the metal layer and inorganic material layer from the bending area, reducing weight while strategically maintaining structural integrity through the preserved base substrate and carefully designed layer configuration in non-bending regions.
Solution Approach 2:
The patent creates a lightweight structure by selectively removing layers only from the bending area where they would cause corrosion, while maintaining necessary structural layers in other regions. This local optimization achieves weight reduction without compromising overall structural strength.
Data Source
AI summary
A display device includes a base substrate including a display area and a non-display area, a planarization layer disposed on the base substrate, a bank disposed on the planarization layer, a touch buffer layer disposed on a portion of the bank and the planarization layer, a touch sensor portion disposed on the touch buffer layer, and a protective layer covering the touch sensor portion on the touch buffer layer.