Display Fan-Out Line Stacking for Narrow Non-Display Borders
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Solution Overview
Problem
The challenge in display devices is to minimize the non-display area without reducing the number of lines in the non-display area, particularly at the corner portions, while maintaining effective line resistance.
Innovation Solution
The implementation of a display device design that includes a substrate with a display area, a first area, a second area, and a bending area, featuring fan-out lines with sub-routing lines and sub-pad lines, where the number of sub-routing lines exceeds sub-pad lines, and these lines overlap in the thickness direction to manage line resistance effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the non-display area is minimized to increase display area, then the display area increases, but the line resistance increases due to fewer lines available in the reduced non-display area
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement of lines to a three-dimensional stacked configuration. Multiple lines are arranged in different layers (first layer, second layer, third layer) vertically above each other, allowing more lines to fit within the same horizontal footprint of the non-display area. This vertical stacking enables adequate line resistance to be maintained even when the non-display area width is minimized.
Solution Approach 2:
The patent implements a nested structure where multiple fan-out lines are contained within each other across different layers. The first fan-out line, second fan-out line, and third fan-out line are positioned at different vertical levels, with each line nested within the vertical space occupied by the others. This nesting approach maximizes the utilization of the limited non-display area while maintaining sufficient line dimensions for acceptable resistance.
2Reliability
If the number of lines in the non-display area is increased to maintain line resistance, then the line resistance improves, but the non-display area width increases
Solution Approach 1:
Instead of increasing the horizontal width of the non-display area to accommodate more lines, the patent utilizes the vertical dimension by stacking multiple lines in different layers. This allows a greater number of lines (first, second, and third fan-out lines) to be positioned within the same horizontal footprint, thereby maintaining adequate line resistance without increasing the non-display area width.
Solution Approach 2:
The patent employs thin film structures for the fan-out lines arranged in multiple layers. These thin film conductive layers allow for compact vertical stacking of multiple lines within a limited space, enabling high line density in the non-display area without requiring additional horizontal area. The thin film approach facilitates the nesting of multiple conductive layers at different vertical positions.
Data Source
AI summary
A display device includes: a substrate; a display area including pixels arranged on the substrate; a first area disposed at one side of the display area; a second area including pads arranged on the substrate; a bending area disposed between the first area and the second area; and a fan-out line disposed in the first area, the bending area, and the second area. The fan-out line includes: a plurality of sub-routing lines arranged in the first area and electrically connected to each other; and a plurality of sub-pad lines arranged in the second area and electrically connected to each other. The number of the plurality of sub-routing lines is greater than the number of the plurality of sub-pad lines.