Flexible Display Stress Control Member Thickness Optimization
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Solution Overview
Problem
Flexible display devices face delamination issues when bent due to uneven stress distribution, leading to potential failure and reduced reliability.
Innovation Solution
A flexible display device design with a stress control member having varying thicknesses in different areas, where the thickness of the central portion overlapping with the bending axis is minimized, and gradually increases towards the ends, using a pressure-sensitive adhesive to manage stress and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the adhesive member has uniform thickness across all areas, then the manufacturing process is simple, but delamination occurs during bending due to uneven stress distribution
Solution Approach 1:
The adhesive member is designed with different thicknesses in different areas: a first thickness in the bending area and a second thickness in the non-bending area. This local differentiation allows the adhesive to accommodate stress variations during bending, preventing delamination while maintaining manufacturing feasibility through a single-layer structure with controlled thickness variation.
2Strength
If the adhesive member has greater thickness in the bending area, then bonding strength is improved, but stress concentration increases leading to delamination
Solution Approach 1:
The thickness parameter of the adhesive member is changed based on location: the first thickness in the bending area is specifically controlled to be less than or equal to twice the second thickness in the non-bending area. This parameter optimization ensures sufficient bonding strength while preventing stress concentration that would cause delamination during bending operations.
3Reliability
If the adhesive member has smaller thickness in the bending area, then stress concentration is reduced, but bonding strength may be insufficient
Solution Approach 1:
The thickness parameter is optimized within a specific range: the first thickness in the bending area is less than or equal to twice the second thickness in the non-bending area, while maintaining a minimum threshold to ensure adequate bonding strength. This balanced parameter selection prevents both delamination and bonding failure.
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
This design effectively reduces the likelihood of delamination during bending, enhancing the reliability and durability of flexible display devices by optimizing stress distribution and adhesive properties.
Implementation Method 1
A flexible display device includes a display panel including a bending area bendable about a bending axis extending in a first direction, and a first non-bending area and a second non-bending area spaced apart from each other in a second direction crossing the first direction with the bending area between the first non-bending area and the second non-bending area, an outer member over a first surface of the display panel, and a stress control member between the display panel and the outer member
Implementation Method 2
using a pressure-sensitive adhesive to manage stress and prevent delamination
Data Source
AI summary
A flexible display device includes a display panel including a bending area, a first non-bending area, and a second non-bending area, an outer member over a first surface of the display panel, and a stress control member between the display panel and the outer member, and including a first control area overlapping with the bending area, and a second control area and a third control area overlapping with the first non-bending area and the second non-bending area, respectively, such that the first control area is between the second control area and the third control area, and a maximum thickness of the first control area is less than a thickness of an end of the second control area and a thickness of an end of the third control area spaced apart from a bending axis in the second direction.