Foldable Display Window Roughness Control for Laser-Cut Hinge Areas
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Solution Overview
Problem
Existing foldable display devices face issues with reliability due to stress and damage during the cutting process, leading to defects in the folding area.
Innovation Solution
A method involving a low-energy laser process for cutting the folding area of a display device, with varying surface roughness and height ranges for the window layers to reduce stress and damage, including a base layer, window functional layer, and window protective layer with different surface roughness in folding and non-folding areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard cutting process is used to separate the window from the display panel, then productivity is improved, but stress and damage occur in the folding area leading to defects
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions of the window. The folding area has a first surface roughness that is different from the non-folding area's second surface roughness. This local differentiation allows the folding area to better withstand stress during cutting and folding operations, preventing defects while maintaining overall productivity.
Solution Approach 2:
The patent modifies the surface roughness parameter of the window in the folding area to be less than in the non-folding area. This parameter change reduces stress concentration during the cutting process and folding operations, thereby improving reliability without significantly impacting the cutting efficiency.
2Ease of manufacture
If the window has uniform surface roughness across all areas, then manufacturing simplicity is maintained, but stress concentration occurs in the folding area during cutting
Solution Approach 1:
The patent implements different surface roughness values for different regions of the window. Specifically, the folding area has a first surface roughness that is less than the second surface roughness of the non-folding area. This local quality differentiation reduces stress concentration in the folding area during cutting and folding operations, while the manufacturing process remains relatively simple through selective region treatment.
3Strength
If high surface roughness is used throughout the window, then adhesion properties are improved, but damage and defects increase in the folding area
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions: the non-folding area has higher surface roughness (second surface roughness) that provides good adhesion properties, while the folding area has lower surface roughness (first surface roughness) that reduces stress concentration and prevents defects during folding operations. This local differentiation resolves the contradiction between adhesion strength and folding reliability.
Solution Approach 2:
The patent changes the surface roughness parameter based on location. The folding area maintains a lower surface roughness value that prevents damage during cutting and folding, while the non-folding area has a higher surface roughness value that ensures adequate adhesion. This spatially varying parameter approach optimizes both adhesion strength and folding area reliability.
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
Reduces stress and damage in the folding area, improving the reliability and reducing defects in the foldable display device.
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.