LCD Pixel Structure Shielding Electrode Parasitic Capacitance
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Solution Overview
Problem
The aperture ratio of liquid crystal display (LCD) pixel structures is limited by parasitic capacitance (Cpd) between the pixel electrode and data line, leading to crosstalk and decreased brightness, as widening the gap between them reduces the aperture ratio and utilizing a metal layer for storage capacitance decreases the aperture ratio further.
Innovation Solution
A pixel structure with a shielding electrode made from the same metal layer as the TFT, positioned between the pixel electrode and data line, and a data line formed by two connected metal pattern layers, which reduces parasitic capacitance through electric field shielding, allowing the pixel electrode to be closer to the data line without decreasing the aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the pixel electrode is positioned closer to the data line to increase aperture ratio, then the aperture ratio improves, but parasitic capacitance increases causing crosstalk
Solution Approach 1:
A shielding electrode is introduced as an intermediary element positioned between the pixel electrode and the data line. This shielding electrode acts as a mediator that blocks the electric field coupling between the pixel electrode and data line, thereby reducing parasitic capacitance while allowing the pixel electrode to be positioned closer to the data line for higher aperture ratio
2Object-affected harmful factors
If the width between pixel electrode and data line is increased to reduce parasitic capacitance, then parasitic capacitance decreases, but aperture ratio becomes lower
Solution Approach 1:
The shielding electrode serves as a mediator that enables the pixel electrode to be positioned closer to the data line without increasing parasitic capacitance. By introducing this intermediate shielding structure, the electric field interference is blocked, allowing tighter spacing while maintaining low parasitic capacitance and high aperture ratio
3Object-affected harmful factors
If the overlapped area of storage capacitance is increased to decrease Cpd ratio, then the Cpd to total capacitance ratio decreases, but aperture ratio decreases
Solution Approach 1:
The shielding electrode acts as a mediator that reduces parasitic capacitance through electric field shielding, thereby decreasing the Cpd to total capacitance ratio without requiring increased storage capacitance overlapped area. This allows the aperture ratio to be maintained at high levels while still achieving low crosstalk
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration increases the storage capacitance value, reduces parasitic capacitance, and maintains a higher aperture ratio, thereby enhancing display quality and utilization of the backlight module.
Implementation Method 1
A pixel structure with a shielding electrode made from the same metal layer as the TFT, positioned between the pixel electrode and data line, and a data line formed by two connected metal pattern layers, which reduces parasitic capacitance through electric field shielding
Data Source
AI summary
A pixel structure of a liquid crystal display (LCD) includes a scan line, a data line and a thin film transistor (TFT) disposed on the substrate. The TFT has a source electrically connected to the date line and a gate electrically connected to the scan line. A shielding electrode disposes on the substrate, wherein the same metal layer makes the shielding electrode, the source and the drain. Furthermore, the data line makes at least two different patterned metal, layers which are not formed simultaneously and the patterned metal layers are electrically connected to each other. A pixel electrode covers the part of the shielding electrode and electrically connects to the drain.