Flexible Array Substrate Protection Layer Stress Distribution
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Solution Overview
Problem
Flexible display devices face breakage issues due to stress concentration on signal lines during bending, leading to poor performance.
Innovation Solution
A flexible array substrate with a protection layer having a higher Young's modulus than the signal lines, positioned on the signal lines away from the base substrate, to distribute stress and reduce breakage probability by overlapping with the signal lines' projections, and a method for forming this substrate involving multiple signal and protection layers with specific overlapping patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If signal lines are made flexible to enable bending, then bendability is improved, but stress concentration occurs during bending leading to breakage
Solution Approach 1:
The patent applies local quality by making only the bending area flexible while keeping the active area rigid. The bending area is specifically designed with flexible substrate and optimized signal line structures (including meander shapes and varying line widths) to accommodate bending without affecting the overall device performance or causing stress concentration on critical components.
Solution Approach 2:
The patent segments the substrate into distinct functional areas: a rigid active area for display components and a flexible bending area for bending operations. This segmentation allows each area to be optimized independently - the active area maintains structural integrity while the bending area provides flexibility through specific structural designs in the signal lines and protective layers.
2Strength
If protection layer with high Young's modulus is added to reduce stress on signal lines, then signal line strength is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the Young's modulus values for different layers. The protection layer has a higher Young's modulus than the signal line layer to provide stress resistance, while the signal line layer has intermediate stiffness, and the flexible substrate has the lowest Young's modulus to enable bending. This gradient of mechanical properties optimizes both protection and flexibility without requiring excessive layers.
Solution Approach 2:
The patent uses composite material structures with multiple layers having different mechanical properties. The signal line structure comprises a signal line layer embedded in a flexible substrate with a protection layer above, where each layer is made of materials with specific Young's modulus values. This composite structure provides both the necessary mechanical protection and the required flexibility for bending applications.
Data Source
AI summary
A flexible array substrate includes an active area and a bending area. The bending area is adjacent to the active area. The bending area includes a protection layer and at least one signal line disposed on the base substrate. The protection layer is located on the at least one signal line at a side away from the base substrate. An orthographic projection of the protection layer on the base substrate has an overlapping region with an orthographic projection of the at least one signal line on the base substrate, the Young modulus of the protection layer is larger than or equal to the Young modulus of the at least one signal line.