3T Pixel Structure Source Hole Design for LCD Aperture Ratio
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Solution Overview
Problem
The conventional 3T pixel structure for VA-type LCDs faces manufacturing difficulties due to overlapped deep and shallow holes, which decrease the aperture ratio and yield, and increase inner resistances, affecting luminance and contrast.
Innovation Solution
A 3T pixel structure is designed with a source hole in the second dielectric layer allowing the upper common electrode to connect directly to the source of the charge-sharing TFT, eliminating the need for overlapped holes and reducing inner resistances by electrically connecting the source of the sub-pixel TFT and drain of the charge-sharing TFT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the conventional 3T pixel structure uses overlapped deep and shallow holes to connect electrodes, then the aperture ratio is reduced, but the electrical connection is achieved
Solution Approach 1:
The invention divides the connection structure into separate shallow holes and deep holes that do not overlap, with the shallow holes forming a first connection structure and deep holes forming a second connection structure. This segmentation eliminates the manufacturing complexity of overlapped holes while maintaining electrical connectivity through the pixel structure.
Solution Approach 2:
The invention transitions from a two-dimensional overlapped hole structure to a three-dimensional multi-layer structure with shallow holes in one dielectric layer and deep holes extending into lower layers. This dimensional change allows connections to be made through separate spatial paths rather than overlapping planes.
2Reliability
If the conventional 3T pixel structure uses overlapped deep and shallow holes, then the manufacturing process becomes complex, but electrical connection is established
Solution Approach 1:
The connection structure is segmented into independent shallow holes and deep holes that form separate connection paths. The shallow holes connect through the second dielectric layer while deep holes connect through the first dielectric layer to the lower common electrode, eliminating the need for complex overlapped hole structures and improving manufacturing yield.
Solution Approach 2:
The invention introduces an intermediate connection structure where the shallow holes serve as mediators between the upper common electrode and the deep holes. This intermediate layer simplifies the overall connection path and reduces structural complexity by breaking down the direct overlapped hole requirement into staged connections.
3Manufacturing precision
If the conventional structure uses deep and shallow holes, then the inner resistance increases, but the electrical connection is formed
Solution Approach 1:
The electrical connection path is segmented into multiple low-resistance paths through separate shallow holes and deep holes rather than relying on single overlapped holes. This segmentation provides redundant connection paths and reduces overall inner resistance while maintaining manufacturing feasibility.
Solution Approach 2:
The invention merges multiple connection structures (shallow holes, deep holes, and intermediate connections) into a unified electrical connection system. This combining of parallel connection paths reduces the total inner resistance by providing multiple conduits for current flow rather than relying on single high-resistance overlapped holes.
Data Source
AI summary
A 3T pixel structure is provided. The 3T pixel structure includes: a substrate, on which a lower common electrode and a scan line are positioned; a first dielectric layer, positioned on the lower common electrode, the scan line and the substrate; a charge-sharing thin film transistor (TFT), including a source, a drain, and a gate, the source and the drain of the charge-sharing TFT being positioned on the first dielectric layer; a data line, positioned on the first dielectric layer; a second dielectric layer, positioned on the source, the drain, the data line of the charge-sharing TFT and the first dielectric layer; and an upper common electrode, positioned on the second dielectric layer. The second dielectric layer has a source hole to allow the upper common electric layer to contact the first source and electrically connect to the first source through the source hole.