TFT Array Substrate Transparent Common Electrode Aperture Ratio
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Solution Overview
Problem
Conventional TFT-LCD array substrates face issues with reduced aperture ratio due to opaque common electrodes, leading to adverse effects like crosstalk and viewing issues such as flickers and horizontal white-lines, while also experiencing capacitive coupling between data lines and pixel electrodes.
Innovation Solution
The use of a conductive transparent material, such as Indium Tin Oxide (ITO), is integrated to form a portion of the common electrode, reducing capacitive coupling and increasing the aperture ratio without compromising the storage capacitor's capacitance, by employing a specific layering and patterning process during the manufacturing of the TFT array substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opaque metal layer is used to form the common electrode, then the storage capacitor can maintain pixel electrode potential effectively, but the aperture ratio of the pixel is reduced
Solution Approach 1:
The common electrode is formed using a composite structure combining opaque metal layer and transparent conductive material layer. This composite approach maintains the capacitive coupling function while improving light transmission, directly resolving the contradiction between storage capacitor performance and aperture ratio.
Solution Approach 2:
The invention changes the optical parameters of the common electrode by introducing transparent conductive material, transforming it from fully opaque to partially transparent. This parameter change allows the electrode to maintain electrical function while improving optical performance and aperture ratio.
2Device complexity
If an opaque common electrode is used, then the storage capacitor structure is simple, but capacitive coupling between data line and pixel electrode occurs causing display issues
Solution Approach 1:
The transparent conductive material layer acts as an intermediary between the opaque metal layer and the pixel electrode. This intermediary layer reduces direct capacitive coupling while maintaining the storage capacitor's electrical function, eliminating display issues like flickers and white lines.
Solution Approach 2:
The invention applies different material properties to different parts of the common electrode structure. The opaque metal layer provides structural support and primary capacitance, while the transparent conductive material layer reduces capacitive coupling interference, creating localized functional zones that together solve the contradiction.
Data Source
AI summary
A TFT array substrate comprises an insulator base; a first metal layer on the insulator base, a first portion thereof forming a gate electrode of a TFT; a gate insulating layer overlying the first metal layer and the insulator base; an amorphous silicon layer and a first layer of conductive transparent material both on the gate insulating layer; a doped amorphous silicon layer positioned on the amorphous silicon layer; a second metal layer on the doped amorphous silicon layer and the first layer of conductive transparent material, a first portion thereof forming source and drain electrodes of the TFT; a passivation layer on the second metal layer; and a second layer of conductive transparent material on the passivation layer, a first portion thereof forming a pixel electrode, wherein the first layer of conductive transparent material forms a portion of a common electrode of the array substrate.