Elastic Member Pattern Gradient for Foldable Display Flatness
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Solution Overview
Problem
Flexible or foldable display devices experience deterioration in flatness and reliability due to repeated folding and unfolding, leading to cracks and wrinkles in the folding region, where stress concentrations cause uneven surface curvature and reduced lifespan.
Innovation Solution
An elastic member with a first region for folding and a second region for unfolding, featuring a pattern design with varying length, width, opening area, and spacing of patterns to manage compressive and tensile stress, ensuring improved folding reliability and flatness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the elastic member has a uniform structure throughout, then manufacturing is simple, but stress distribution during folding is uneven causing cracks and wrinkles
Solution Approach 1:
The elastic member employs different pattern structures in different regions: the first region (folding region) contains patterns with first dimensions designed to relieve stress during folding, while the second region (unfolding region) has patterns with second dimensions. This local differentiation allows the folding region to better withstand repeated bending without cracks or wrinkles, while maintaining overall structural integrity.
Solution Approach 2:
The elastic member is divided into multiple columns (first column, second column, third column) with progressively varying pattern dimensions. The patterns are segmented into different size groups across columns, creating a gradient structure that distributes stress more evenly throughout the folding region during repeated folding and unfolding operations.
2Reliability
If the pattern size is increased to relieve stress, then folding reliability improves, but the elastic member occupies more space
Solution Approach 1:
Larger pattern dimensions are applied only in the first column where stress concentration is highest during folding, while subsequent columns have progressively smaller pattern dimensions. This localized approach to stress relief minimizes the overall area occupied by the elastic member while still providing adequate stress management where it is most needed.
Solution Approach 2:
The pattern dimensions are intentionally made asymmetric across different columns, with the first column having the largest patterns and subsequent columns having progressively smaller patterns. This asymmetric distribution optimizes stress relief in the critical folding region while minimizing the total area of the elastic member.
3Reliability
If different pattern sizes are used in different columns, then stress distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The patterns are segmented into discrete columns with clearly defined boundaries, where each column contains patterns of a specific size. This segmentation into modular units simplifies the manufacturing process compared to creating continuously varying patterns, as each column can be manufactured as a standardized unit with repeatable pattern dimensions.
Solution Approach 2:
The pattern dimensions are changed in discrete steps across columns rather than continuously, creating a parameter gradient that improves stress distribution. This stepwise parameter change is easier to manufacture than continuous variation, as it allows for standardized pattern blocks to be used in each column with progressively changing dimensions.
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 elastic member effectively secures sufficient elastic force to maintain flatness and reliability by adjusting pattern dimensions and spacing according to stress levels, reducing the magnitude of flatness unevenness and enhancing the display device's lifespan.
Implementation Method 1
an elastic member having a new structure capable of solving the above problems... improved folding reliability and low flatness even in repeated folding and restoration processes
Data Source
AI summary
An elastic member according to an embodiment includes: a first region and a second region, wherein a first direction defined as a width direction and a second direction defined as a longitudinal direction in the elastic member, the first region is defined as a folding region that is folded with the first direction as a folding axis, and the second region is defined as an unfolding region, a first pattern portion including a plurality of patterns is disposed in the first region, a length in the first direction is greater than a width in the second direction in the plurality of patterns, the first region includes a first column, a second column, and a third column that extend in the first direction and are sequentially disposed in the second direction around the folding axis, the first region includes a plurality of pattern regions respectively disposed in a plurality of columns of the first region, and a size of a pattern of the first column is greater than a size of a pattern of the second column.