Array Substrate Multi-Layer Signal Line Step Difference Reduction
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Solution Overview
Problem
The existing TFT-LCD array substrates experience signal line fractures at intersection regions due to large step differences, affecting touch control in non-display regions.
Innovation Solution
The array substrate design includes at least three layers of signal lines with specific overlapping regions and protruding portions to reduce step differences at intersection points, ensuring the third signal line is not fractured and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If signal lines are arranged densely in the non-display region to improve line density, then the aperture ratio is improved, but the step difference at intersection regions increases causing signal line fractures
Solution Approach 1:
The patent introduces a third layer for signal lines, transitioning from a two-layer arrangement to a three-dimensional multi-layer structure. This allows signal lines to be routed at different heights (Z-dimension), reducing planar congestion and step differences at intersections while maintaining high line density in the non-display region.
Solution Approach 2:
The patent applies different structural configurations to different regions: in intersection regions, the third signal line is positioned at a higher layer to reduce step differences, while in non-intersection regions, standard routing is maintained. This localized quality adjustment prevents fractures at critical intersection points without compromising overall line density.
2Ease of manufacture
If the third signal line is positioned closer to the base substrate to reduce manufacturing complexity, then the manufacturing process is simplified, but the step difference at intersection regions increases causing fractures
Solution Approach 1:
Instead of adjusting the third signal line's position in the XY-plane, the patent utilizes the Z-dimension (vertical layering) to resolve the contradiction. By positioning the third signal line at a higher layer specifically at intersection regions, the solution reduces step differences without complicating the manufacturing process, as the layering structure can be integrated into existing multi-layer fabrication processes.
3Reliability
If protruding portions are added to second signal lines to reduce overlapping regions, then step differences are reduced, but the device structure becomes more complex
Solution Approach 1:
The protruding portions are introduced only in specific locations where the second signal line intersects with the third signal line, rather than modifying the entire signal line structure. This localized modification reduces step differences at critical intersection points while maintaining simple structures in non-critical regions, thereby limiting the increase in overall device complexity.
Data Source
AI summary
An array substrate includes a base substrate and at least three layers of signal lines insulated from each other and arranged in a non-display region. The signal lines include first signal lines in a first layer and second signal lines in a second layer extending in an identical direction, and third signal lines in a third layer crossing the first and the second signal lines. A distance between each third signal line and the base substrate is larger than a distance between each first/second signal line and the base substrate. An orthogonal projection of each first signal line on the base substrate overlaps that of the corresponding third signal line to form a first overlapping region, an orthogonal projection of each second signal line overlaps that of the corresponding third signal line to form a second overlapping region which partially overlaps, or does not overlap, the first overlapping region.