Foldable Display Window Surface Roughness for Crack-Resistant Hinges
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Solution Overview
Problem
Existing foldable display devices face challenges in maintaining reliability due to stress and damage during the manufacturing process, particularly in the folding area, leading to defects such as cracks from repeated folding operations.
Innovation Solution
A foldable display device with a window featuring different surface roughness in folding and non-folding areas, where the folding area has a lower surface roughness to reduce stress and damage during the laser cutting process, and a method involving distinct laser processes for cutting the display module, using a lower energy laser beam in the folding area to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform laser cutting process is applied to both folding and non-folding areas, then manufacturing efficiency is maintained, but stress and damage accumulate in the folding area leading to cracks and reduced reliability
Solution Approach 1:
The patent segments the laser cutting process into two distinct operations: a first laser process for the non-folding area and a second laser process for the folding area. This segmentation allows each area to receive customized treatment - the non-folding area gets standard high-energy cutting for efficiency, while the folding area gets low-energy cutting to minimize stress and prevent cracks, thereby resolving the contradiction between manufacturing efficiency and reliability.
Solution Approach 2:
The patent applies local quality by differentiating the laser process parameters based on the specific requirements of different areas. The folding area, which experiences repeated stress during device usage, receives a specialized low-energy laser process that creates less internal stress and damage. This localized adjustment ensures that the critical folding area has enhanced reliability without compromising the overall manufacturing efficiency of the non-folding areas.
2Productivity
If high energy laser beam is used for cutting in the folding area, then cutting speed and productivity are improved, but stress and damage increase leading to crack formation during repeated folding
Solution Approach 1:
The patent changes the laser beam energy parameter specifically for the folding area by implementing a second laser process with lower energy compared to the first laser process used in the non-folding area. This parameter change reduces the stress and damage induced during cutting in the folding area, preventing crack formation during repeated folding operations while maintaining acceptable cutting speed through optimized process parameters.
3Ease of manufacture
If the window has uniform surface roughness throughout, then manufacturing simplicity is maintained, but the folding area experiences higher stress concentration leading to defects
Solution Approach 1:
The patent applies local quality by creating different surface roughness characteristics in different areas of the window. The folding area is processed to have reduced surface roughness compared to the non-folding area. This localized surface treatment reduces stress concentration in the folding area, preventing defect formation during repeated folding, while the overall manufacturing process remains relatively simple through area-specific processing.
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 approach reduces stress and damage in the folding area, minimizing defects and enhancing the reliability of the foldable display device by ensuring smoother surface modifications and reduced crack formation during repeated folding.
Implementation Method 1
performing a first laser process along a first cutting line in the non-folding area of the cutting line to separate a first portion of the invalid area from the valid area, and performing a second laser process along a second cutting line in the folding area of the cutting line to separate a second portion of the invalid area from the valid area
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A display device includes a display panel for displaying an image, and including a folding area configured to be folded about a folding axis, and a non-folding area adjacent to the folding area, and also includes a window on the display panel, including a flexible material, and configured to be folded along the display panel, wherein a side surface of the window has a first surface roughness in the non-folding area, and has a second surface roughness in the folding area that is less than the first surface roughness.