TFT Pixel Structure with Extending Electrode for Parasitic Capacitance Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional TFT-LCD pixel structures experience display picture quality degradation due to varying gate-drain parasitic capacitance caused by misalignment during manufacturing, leading to different feed-through voltages across pixels.
Innovation Solution
A pixel structure design that includes an extending electrode connected to the scan line, with its end overlapping the drain electrode, maintaining a constant gate-drain parasitic capacitance by ensuring the overlapping areas remain unchanged despite misalignment, achieved through specific electrode configurations and patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional TFT manufacturing process is used with standard electrode layout, then manufacturing process is simple, but gate-drain parasitic capacitance varies due to misalignment causing display quality degradation
Solution Approach 1:
The drain electrode is divided into multiple segments (first drain electrode, second drain electrode, third drain electrode) arranged in different orientations. This segmentation allows the parasitic capacitance from misalignment in one direction to be compensated by the geometric arrangement of multiple segments, maintaining stable total parasitic capacitance despite manufacturing variations.
Solution Approach 2:
Different portions of the drain electrode are designed with different orientations and positions relative to the gate electrode. The first drain electrode overlaps in a first direction, the second in a second direction, and the third in a third direction. This local variation in electrode orientation creates direction-independent parasitic capacitance characteristics.
2Device complexity
If gate electrode and drain electrode are designed with standard overlapping configuration, then device structure is simple, but parasitic capacitance is sensitive to misalignment
Solution Approach 1:
The drain electrode segments are intentionally designed with asymmetric orientations relative to the gate electrode. Rather than symmetric placement, the electrodes are arranged at different angles (first, second, and third directions) to create a configuration where misalignment in any single direction does not dominate the parasitic capacitance behavior.
Solution Approach 2:
The solution transitions from a single-direction overlapping configuration to a multi-directional arrangement. By adding the dimensional aspect of angular orientation with multiple drain electrode segments pointing in different directions, the design achieves parasitic capacitance stability that is insensitive to linear misalignment variations.
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
The design provides high tolerance for misalignment, maintaining stable display picture quality and preventing image flicker by keeping gate-drain parasitic capacitance consistent across pixels.
Implementation Method 1
the so-called gate-drain parasitic capacitance (Cgd) exists due to the overlapping of the gate electrode and the drain electrode
Data Source
AI summary
A pixel structure includes a scan line, a data line, a gate electrode electrically connected to the scan line, a semiconductor layer disposed on the gate electrode, a drain electrode, an extending electrode, and a pixel electrode. The scan line and the data line cross each other, and are insulated. The drain electrode includes a contact part disposed outside the gate electrode, an electrode part disposed on the semiconductor pattern and a connecting part extending from the contact part along a direction to connect the electrode part, and partially overlapping the gate electrode. The pixel electrode is connected to the contact part. The extending electrode is connected to the scan line. A first end of the extending electrode points to the semiconductor layer along the direction, and overlaps the drain electrode. A first width of the connecting part is equal to the second width of the extending electrode.