TFT Array Pixel Electrode Storage Capacitor Repair
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Solution Overview
Problem
Thin Film Transistor Liquid Crystal Display (TFT-LCD) storage capacitors, particularly the MIM type, are prone to defects such as particles or holes during manufacturing, leading to charge leakage and resulting in bright/dark spots, which compromise the display's functionality.
Innovation Solution
A method to repair storage capacitors in TFT-LCD arrays by transforming the MIM structure into a MII structure by cutting and welding specific connection lines, allowing the top electrode and common line to form a conductive channel, effectively converting the storage capacitor type and enhancing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MIM storage capacitor structure is used, then capacitance is larger, but defects such as particles or holes are easily generated during manufacturing
Solution Approach 1:
The patent extracts the problematic connection line between the drain and top electrode, separating the storage capacitor formation process from the transistor connection process. By removing this intermediate connection that is prone to defects, the storage capacitor is formed directly between the common line and pixel electrode, eliminating the defect-prone MIM structure while maintaining capacitance functionality.
Solution Approach 2:
Instead of forming a storage capacitor using the traditional MIM structure (metal-insulator-metal) with intermediate layers, the patent inverts the approach by using a direct metal-insulator-semiconductor structure where the pixel electrode itself serves as one of the capacitor electrodes. This inversion eliminates the need for intermediate metal layers and connection lines that are prone to manufacturing defects.
2Reliability
If connection line is added from drain to top electrode, then electrical connection is established, but device complexity increases
Solution Approach 1:
The patent merges the storage capacitor formation with the existing transistor structure by utilizing the common line and pixel electrode directly as capacitor electrodes. The connection between drain and top electrode is achieved through the pixel electrode itself rather than adding a separate connection line, thereby establishing electrical connection while reducing structural complexity.
Solution Approach 2:
The pixel electrode serves dual functions: as the transparent electrode for liquid crystal control and as one electrode of the storage capacitor. The common line also serves as both a signal transmission line and the other electrode of the storage capacitor. This multi-functionality eliminates the need for additional dedicated connection lines for capacitor formation.
Data Source
AI summary
A thin film transistor array comprising a substrate, a plurality of scan lines, a plurality of data lines, a plurality of thin film transistors, a plurality of common lines, a plurality of top electrodes, a plurality of connection lines and a plurality of pixel electrodes is provided. Wherein, each thin film transistor is disposed in one of the pixel areas and driven through the corresponding scan line and data line. Each thin film transistor includes a gate, a source and a drain. The drain of the thin film transistor is electrically connected to the corresponding top electrode by the corresponding connection line. Besides, the drain of the thin film transistor is electrically connected to the pixel electrode, and a portion of the connection line is not covered by the pixel electrode.