Special-shaped TFT Parasitic Capacitance Stabilization

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Solution Overview

Problem

The existing liquid crystal display technology faces issues with parasitic capacitance changes due to process variations, leading to screen flickers and afterimages.

Innovation Solution

A special-shaped thin-film transistor is designed with a first compensation electrode connected to the first gate portion and a first source electrode with extension parts that overlap the gate and compensation electrodes, ensuring a consistent overlapping area and thus constant parasitic capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the source electrode is shifted left and right due to process variation, then the overlapping area between source electrode and gate electrode changes, but this causes parasitic capacitance to change and leads to screen flickers and afterimages

Engineering Contradiction:
Improvepositioning precision of source electrodeVSAvoiddisplay quality (screen flickers and afterimages)
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The source electrode is divided into multiple segments (first source electrode segment, second source electrode segment, third source electrode segment) with different overlapping areas with the gate electrode. This segmentation allows the total parasitic capacitance to remain stable even when individual segments shift due to process variation, as the capacitance changes in different segments compensate for each other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different segments of the source electrode are designed with different local properties - specifically, different overlapping areas with the gate electrode. The first segment has a larger overlapping area while the second and third segments have smaller overlapping areas. This local differentiation ensures that when process variation occurs, the overall parasitic capacitance remains stable.

Inventive Principle:
Principle #3Local quality

2Power

If the overlapping area of source electrode and gate electrode is increased to improve transistor performance, then parasitic capacitance increases, but this causes feeding voltage to increase and may cause screen flickers

Engineering Contradiction:
Improvetransistor performanceVSAvoidparasitic capacitance
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The source electrode is segmented into multiple parts with different overlapping areas. This allows the transistor to achieve good performance through the total overlapping area while distributing the parasitic capacitance across multiple segments, making the total parasitic capacitance more stable against process variations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the parameter distribution of overlapping areas across different source electrode segments. By having the first segment with a larger overlapping area and the second and third segments with smaller overlapping areas, the design optimizes the balance between transistor performance and parasitic capacitance stability.

Inventive Principle:
Principle #35Parameter changes

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 solution effectively stabilizes the parasitic capacitance, preventing changes caused by process variations and thereby reducing the occurrence of screen flickers and afterimages.

Implementation Method 1

an overlapping area of the source electrode 4 and the gate electrode 1 will generate parasitic capacitance

Methodology Applied
Scientific EffectParasitic capacitance: Parasitic Capacitance

Data Source

PatentUS12328942B2Special-shaped thin-film transistor and array substrate
Publication Date: 2025.06.10 SHENZHEN CHINA STAR OPTOELECTRONICS SEMICON DISPLAY TECH CO LTD
  • US12328942B2 patent drawing
  • US12328942B2 patent drawing
  • US12328942B2 patent drawing

AI summary

A special-shaped thin-film transistor and an array substrate are provided. The special-shaped thin-film transistor includes a first gate portion, a first compensation electrode, and a first source electrode. The first compensation electrode is connected to the first gate portion. The first source electrode includes a first extension part, a first source portion, and a second extension part which are connected in sequence. Part of the first extension part overlaps the first gate portion, and part of the second extension part overlaps the first compensation electrode.