Flexible Display Bending Area Neutral Plane Shift
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Solution Overview
Problem
Conventional display apparatuses face challenges in reducing the size of the bezel and preventing damage to signal lines during bending, which can lead to cracks and increased thickness.
Innovation Solution
A display apparatus design featuring a flexible substrate with a bending area, a resin layer, and a protecting pattern that shifts the neutral plane to compressive stress, reducing the risk of signal line damage and allowing for a thinner resin layer, thereby minimizing bezel size and improving manufacturing workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the resin layer thickness is reduced to minimize bezel size, then the bezel area is reduced, but the signal line becomes more susceptible to damage from tensile stress during bending
Solution Approach 1:
The patent changes the stress state parameter of the signal line from tensile to compressive by repositioning the neutral plane. This is achieved by adjusting the layer structure and material properties in the bending area, allowing the signal line to withstand bending stresses without damage even with a reduced resin layer thickness.
Solution Approach 2:
The patent converts the potentially harmful tensile stress that could damage the signal line into beneficial compressive stress. By positioning the neutral plane within the protecting pattern, the signal line experiences compressive stress during bending, which prevents crack formation and maintains reliability while allowing for a thinner resin layer.
2Ease of manufacture
If the resin layer is made thinner to improve manufacturing workability and reduce bezel size, then manufacturing efficiency improves, but the bending area becomes more vulnerable to stress damage
Solution Approach 1:
The patent changes the mechanical parameter of stress type from tensile to compressive in the bending area by repositioning the neutral plane. This allows the use of a thinner resin layer while maintaining or even improving the strength of the bending area, as compressive stress is less likely to cause cracking in the signal line and surrounding structures.
3Area of stationary object
If the neutral plane is positioned to reduce bezel size, then the resin layer can be thinner, but compressive stress acts on the signal line which may cause damage
Solution Approach 1:
The patent accepts the compressive stress condition resulting from neutral plane repositioning but demonstrates through structural design that this stress state is actually beneficial. The compressive stress prevents tensile cracking of the signal line, and the protecting pattern structure is designed to accommodate and distribute this compressive stress uniformly, converting a potential harmful factor into a protective mechanism.
Data Source
AI summary
A display apparatus includes a flexible substrate including a first area in which an image is displayed, a second area spaced apart from the first area, and a bending area between the first area and the second area, a first insulation layer on an upper surface of the flexible substrate in the bending area, a first source-drain pattern on the upper surface of the flexible substrate in the first area, and a signal line on the first insulation layer in the bending area, and a protecting pattern corresponding to the entire bending area, a first pattern film on a lower surface of the flexible substrate in the first area, a second pattern film spaced apart from the first pattern film, the second pattern film being on the lower surface of the flexible substrate in the second area, and a resin layer on a second source-drain pattern in the bending area.