Foldable Display Window Laser Processing for Folding-Area Crack Control
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Solution Overview
Problem
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 method of manufacturing a foldable display device involves a window with varying surface roughness in the folding and non-folding areas, using a low-energy laser process in the folding area to reduce stress and damage, and a high-energy process in the non-folding area, with specific surface modifications to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-energy laser process is used in the folding area to separate the invalid area from the valid area, then the cutting efficiency is improved, but stress and damage are increased leading to cracks and defects
Solution Approach 1:
The patent applies different laser energies to different regions: a first (lower) laser energy is used specifically in the folding area to minimize stress and prevent cracks, while a second (higher) laser energy is used in the non-folding area to maintain cutting efficiency. This local differentiation of processing parameters resolves the contradiction between productivity and reliability by optimizing each region according to its specific requirements.
2Manufacturing precision
If the surface roughness in the folding area is high to match the non-folding area, then the manufacturing consistency is improved, but stress concentration is increased leading to crack formation during folding
Solution Approach 1:
The patent creates different surface roughness characteristics in different regions: the non-folding area has a first surface roughness profile, while the folding area has a second surface roughness profile optimized to reduce stress concentration during folding operations. This local quality differentiation allows the folding area to have smoother surfaces that minimize crack initiation while the non-folding area maintains its original surface characteristics.
3Reliability
If repeated folding operations are performed to test durability, then the reliability verification is improved, but stress accumulation is increased leading to crack propagation
Solution Approach 1:
The patent performs preliminary surface modification and stress reduction treatments on the folding area before the display device undergoes repeated folding operations. By pre-smoothing the surface and reducing residual stresses in the folding region through controlled laser processing, the device can withstand durability testing with fewer cracks and less stress accumulation, enabling effective reliability verification.
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 approach reduces stress and damage in the folding area, minimizing defects and enhancing the reliability of the foldable display device by ensuring smoother surface deformation 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
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.