Flexible Substrate Uneven Pattern for Foldable Display Crack Resistance
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Solution Overview
Problem
Flexible display devices, particularly those with foldable designs, face issues with substrate cracking due to stress concentration at folded sites, which compromises their durability and reliability.
Innovation Solution
A display device configuration featuring a flexible substrate with a bending region having an uneven pattern and varying thickness, where wirings are arranged on convex portions to distribute stress and prevent cracking, along with a manufacturing method that forms these patterns to enhance flexibility and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate is used to enable foldable display devices, then adaptability and flexibility are improved, but the substrate is easily cracked due to stress concentration at folded sites, worsening reliability
Solution Approach 1:
The substrate is designed with different thicknesses in different regions: a first thickness in the display region and a second thickness (greater than the first) in the bending region. This local variation in thickness provides different mechanical properties to different parts of the substrate, allowing the thinner display region to maintain flexibility while the thicker bending region resists cracking during folding operations.
Solution Approach 2:
The substrate is divided into distinct regions with different characteristics: a display region and a bending region, each optimized for its specific function. The bending region is further segmented into multiple portions that can independently deform during folding, distributing stress and preventing crack propagation across the entire substrate.
2Adaptability or versatility
If the substrate is thinned to improve flexibility, then adaptability is improved, but dimensional stability deteriorates
Solution Approach 1:
Different regions of the substrate have different thicknesses optimized for their specific requirements. The display region uses a thinner first thickness to achieve flexibility and adaptability, while the bending region uses a thicker second thickness to maintain dimensional stability and resist deformation during folding, thus resolving the contradiction between flexibility and dimensional stability.
3Ease of operation
If wirings are arranged in the bending region, then signal transmission is enabled, but stress concentration increases leading to cracking
Solution Approach 1:
The wirings are arranged in the top or bottom parts of convex portions in the uneven pattern, utilizing the vertical dimension created by the thickness variation. This three-dimensional arrangement allows signal transmission while positioning wirings in locations that experience lower stress during folding, thus reducing crack risk while maintaining functionality.
Solution Approach 2:
The wiring arrangement is specifically optimized for the bending region's unique mechanical environment. Wirings are placed in convex portions where the local geometry provides stress relief during folding, allowing signal transmission without compromising the substrate's crack resistance in this critical region.
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 solution effectively enhances the flexibility and reliability of foldable display devices by reducing the likelihood of cracking at folded sites, ensuring high durability and maintaining the integrity of the display region.
Implementation Method 1
an uneven pattern alternately arranged with regions, the thickness of the substrate being different in each region
Data Source
AI summary
There is provided a display device including a flexible substrate having a first surface and a second surface opposite to the first surface, the substrate including a display region on the first surface and a bending region on a part of the first surface or on a part of the second surface, the display region being arranged with a plurality of pixels, the bending region including an uneven pattern alternately arranged with regions, the thickness of the substrate being different in each region; and a plurality of wirings transmitting a signal for driving the plurality of pixels, each of the plurality of wirings being arranged in a top part or a bottom part of a convex portion in the uneven pattern in the bending region.