Adhesive Hardness Gradient in Flexible Display Bending Areas
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Solution Overview
Problem
Conventional display devices face defects and increased manufacturing costs during the bending process, which affects their visibility and durability at various angles.
Innovation Solution
A display device design featuring a substrate with a bending area between first and second regions, where the adhesive layer's hardness is selectively increased in the bending area to reduce stress and prevent exfoliation, using a protective film with an opening that reduces tensile stress on conductive layers and includes an organic layer to absorb bending stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the adhesive layer has uniform hardness throughout, then the manufacturing process is simple, but the bending area experiences excessive stress and exfoliation defects
Solution Approach 1:
The adhesive layer is designed with different hardness values in different regions: a first hardness in the bending area and a second hardness (higher than the first) in the non-bending areas. This local differentiation allows the bending area to flex without excessive stress while maintaining structural integrity in rigid areas, preventing exfoliation defects.
2Reliability
If the protective film base covers the entire substrate including bending area, then the protective coverage is complete, but the tensile stress on conductive layers increases during bending
Solution Approach 1:
The protective film base is segmented to have an opening that corresponds to the bending area, separating it from the first and second non-bending regions. This segmentation allows the bending area to move freely during bending operations, reducing tensile stress on the conductive layers while the protective film still covers and protects the non-bending regions.
3Ease of manufacture
If the adhesive layer uses a single material composition, then the manufacturing cost is low, but the stress distribution during bending is uneven
Solution Approach 1:
The adhesive layer uses a composite material composition with different hardness values in different regions. The first region (bending area) contains adhesive material with lower hardness to allow flexibility, while the second regions (non-bending areas) contain adhesive material with higher hardness for structural support, achieving uniform stress distribution during bending.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design minimizes defects and manufacturing costs by distributing stress evenly, enhancing the display device's durability and visibility at various angles while maintaining the integrity of the conductive layers.
Implementation Method 1
at least a portion of the adhesive layer that corresponds to the bending area has a hardness different from that of at least a portion of the adhesive layer corresponding to the first region, and the at least a portion of the adhesive layer that corresponds to the bending area has greater hardness than that of the at least a portion of the adhesive layer corresponding to the first region
Implementation Method 2
a protective film below the substrate and comprising a protective film base and an adhesive layer, wherein the protective film base corresponds to corresponds to (covers or overlaps with) at least a portion of the first region
Implementation Method 3
includes an organic layer to absorb bending stress
Data Source
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AI summary
A display device includes a substrate including a bending area between a first region and a second region and configured to be bent at the bending area, a display portion above the substrate in the first region, a protective film below the substrate and including a protective film base and an adhesive layer, wherein the protective film base has an opening corresponding to the bending area or the protective film base corresponds to at least a portion of the first region, and wherein the adhesive layer is between the substrate and the protective film base and forms an integral body above the first region, the bending area, and the second region, and at least a portion of the adhesive layer that corresponds to the bending area has a hardness different from that of at least a portion of the adhesive layer corresponding to the first region