Active Matrix Substrate Branched Scanning Line Design
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Solution Overview
Problem
High-resolution liquid crystal display devices face challenges in achieving a sufficiently high numerical aperture due to increased line resistance and signal delay, which are exacerbated by the need to maintain a certain light-shielded area around contact holes to prevent light leak and alignment disturbances.
Innovation Solution
An active matrix substrate design featuring a transparent storage capacitor electrode that overlaps the pixel electrode, with a branched scanning line and strategically located contact holes to reduce line resistance and light-shielded areas, allowing for a higher numerical aperture while minimizing signal delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution is increased, then the display quality is improved, but the numerical aperture decreases due to enlarged non-display areas
Solution Approach 1:
The storage capacitor electrode is positioned in the vertical dimension (overlapping the pixel electrode) rather than extending horizontally, transforming a 2D planar structure into a 3D stacked structure. This dimensional change allows the storage capacitor to occupy vertical space instead of horizontal space, thereby increasing the numerical aperture while maintaining high resolution
2Reliability
If the light-shielded area around contact holes is increased to prevent light leak, then the alignment stability is improved, but the numerical aperture decreases
Solution Approach 1:
The light-shielding function is extracted from the contact hole structure and transferred to the pixel electrode edge and light-shielding layer. The contact hole itself is minimized in size, and the light-shielding responsibility is assigned to dedicated structures (pixel electrode edge and light-shielding layer) that can perform this function more efficiently with less area
3Loss of time
If the line width is increased to reduce line resistance, then the signal delay is reduced, but the numerical aperture decreases
Solution Approach 1:
The scanning line is configured to branch between pixels rather than extending continuously across the display area. This branching structure reduces the total length of light-shielding material required, as the lines terminate at pixel boundaries rather than spanning the entire panel width
Data Source
AI summary
A TFT substrate (10) includes a substrate (10a); a TFT (11) supported by the substrate; a scanning line (12); a signal line (13); a first interlayer insulating layer (15) provided so as to cover the TFT; a pixel electrode (16) electrically connected to a drain electrode (11d) of the TFT; and a transparent storage capacitor electrode (17) provided so as to overlap at least a part of the pixel electrode. At least the first interlayer insulating layer has a contact hole (CH) formed therein through which the pixel electrode is electrically connected to the drain electrode. The scanning line includes a first area (R1) in which the scanning line is branched into two branched lines (12a). The contact hole is located between the two branched lines.