Stacked Conductive Lines in Display Non-Display Regions
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Solution Overview
Problem
The increasing number of conductive lines in display devices for touch sensors leads to a higher likelihood of line defects such as cracks and disconnections due to the reduced size of the non-display region, which poses challenges in maintaining reliability and power efficiency.
Innovation Solution
The arrangement of conductive lines in alternating layers with overlapping regions exposed by insulating layers, allowing for a wider contact area and reducing the likelihood of defects, while also optimizing the structure to minimize line resistance and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of conductive lines is increased to support higher resolution touch sensors, then the functionality and resolution are improved, but the likelihood of line defects such as cracks and disconnections increases
Solution Approach 1:
The patent transitions from planar 2D line arrangement to 3D stacked layers, allowing conductive lines to be distributed across multiple vertical layers (first through fourth lines in alternating layers). This dimensional change increases the available routing space without expanding the planar footprint, thereby supporting higher resolution while reducing line density in any single layer and minimizing defect rates.
Solution Approach 2:
The patent implements nested conductive lines where the fourth line is disposed within the third line, and earlier lines are nested within subsequent lines. This nesting arrangement allows multiple conductive paths to coexist in a compact vertical stack, increasing the effective number of lines for high-resolution support while maintaining a small non-display region footprint and reducing the likelihood of defects through optimized spatial distribution.
2Area of stationary object
If the non-display region is reduced to increase display area, then the display area is improved, but the space for routing conductive lines is reduced leading to increased line defects
Solution Approach 1:
By stacking conductive lines across multiple vertical layers (first through fourth lines in alternating layers with insulating layers between them), the patent utilizes the third dimension to route more lines within the same planar footprint. This enables a smaller non-display region to accommodate the required number of conductive lines without increasing line density to defective levels, thus maintaining reliability while maximizing display area.
Solution Approach 2:
The nested arrangement of conductive lines (fourth line within third line, etc.) allows multiple signal paths to be packed into a compact vertical structure within the non-display region. This nesting efficiently utilizes the limited space in the reduced non-display region, providing adequate routing for high-resolution displays without forcing lines into overly dense configurations that would increase defect rates.
3Device complexity
If conductive lines are arranged in alternating layers with step differences, then the three-dimensional routing capability is improved, but the step differences create potential locations for cracks and defects
Solution Approach 1:
The patent introduces insulating layers (first insulating layer between first and second lines, second insulating layer between second and third lines, third insulating layer exposing portions of third line) as intermediary elements between conductive lines in alternating layers. These insulating layers act as stress-absorbing mediators that fill and smooth the step differences created by the layered arrangement, preventing stress concentration that would otherwise lead to cracks and defects at the interfaces between layers with different heights.
Data Source
AI summary
A display device includes: a substrate including a display region having pixels and a non-display region disposed along at least part of the periphery of the display region; first lines in the non-display region of the substrate; a first insulating layer disposed on the first lines; second lines disposed on the first insulating layer in the non-display region; a second insulating layer disposed on the second lines; a third line disposed on the second insulating layer, the third line overlapping portions of the first and second lines in the non-display region; a third insulating layer disposed on the third line, the third insulating layer exposing a portion of the third line in a first region that overlaps with the first and second lines; and a fourth line on the third insulating layer, the fourth line overlapping the third line and in direct contact with the third line in the first region.