Display Panel Scan Line Layout for Overlay Misalignment Tolerance
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Solution Overview
Problem
Display panels often experience process deviations leading to misaligned metal overlays, causing electrical connection issues and luminance deviations between subpixels with flip structures, resulting in defects such as brightened or darkened points.
Innovation Solution
A display device design featuring symmetrical scan lines and auxiliary patterns connected through contact holes, with wider contact portions to maintain electrical connectivity and stability even with misaligned overlays, ensuring consistent luminance and storage capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard width scan lines and auxiliary patterns are used, then manufacturing precision is maintained, but electrical connection reliability deteriorates due to overlay misalignment
Solution Approach 1:
The scan line is designed with different widths at different locations: a wider contact portion (second width) at the contact area and a narrower line portion (first width) at the transmission area. This local variation in width provides tolerance for overlay misalignment at the contact portion while maintaining signal integrity in the line portion, thereby ensuring electrical connection reliability despite manufacturing deviations.
Solution Approach 2:
The contact portion of the scan line is designed with an increased width in advance to create a buffer zone that can accommodate potential overlay misalignment. This pre-designed wider contact area acts as a cushion that prevents complete loss of electrical connection even when the auxiliary pattern and scan line do not perfectly align during manufacturing.
2Stability of the object's composition
If symmetrical scan line structure is used, then luminance consistency between flip subpixels is improved, but device complexity increases due to additional symmetry constraints
Solution Approach 1:
While the overall scan line structure maintains symmetry between flip subpixels for luminance consistency, the scan line itself incorporates an asymmetric feature: the contact portion is centered relative to the auxiliary pattern's seating pattern portion. This controlled asymmetry in the contact alignment, combined with the symmetrical layout between subpixels, achieves both luminance consistency and manufacturing robustness.
3Reliability
If wider contact portions are added to scan lines, then electrical connection reliability is improved, but aperture ratio decreases due to increased space occupation
Solution Approach 1:
The scan line width is locally increased only at the contact portion where electrical connection is needed, while the line portion maintains its original narrower width. This localized widening minimizes the overall area occupied by the scan line structure, thereby reducing the impact on aperture ratio while still providing the necessary tolerance for overlay misalignment at the critical contact area.
Data Source
AI summary
A display device includes data lines are disposed on or over a substrate in a first direction, a first scan line extends through a first subpixel in a second direction, a first auxiliary pattern is disposed in the first subpixel in the second direction and electrically connected to the first scan line through one or more first contact holes in an interlayer insulating film, the first scan line includes a first line portion and a wider first contact portion, the first auxiliary pattern includes a first line pattern portion and a wider first seating pattern portion, the first contact portion is connected to the first seating pattern portion through the one or more first contact holes, the first contact portion is symmetrical with respect to a central axis of the first line portion, and the first seating pattern portion is symmetrical with respect to a central axis of the first line pattern portion.