Active Matrix Substrate Floating Electrode Shielding
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Solution Overview
Problem
Active matrix LCD devices of the horizontal electric field type face issues with electric field leakage from signal lines, leading to alignment defects and reduced display quality, and existing solutions either compromise aperture size or fail to adequately suppress field leakage.
Innovation Solution
The implementation of an active matrix substrate with common potential lines and floating electrodes, where the floating electrodes are formed on a second insulating film above the signal lines and extend beyond the signal lines to overlap the common potential lines, effectively reducing electric field leakage and capacitive coupling, thereby increasing the aperture ratio and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of the black matrix is expanded to suppress electric field leakage from signal lines, then display quality is improved, but the aperture ratio decreases
Solution Approach 1:
A shield electrode is introduced as an intermediary component between the signal line and the liquid crystal layer. This shield electrode is connected to the common electrode and positioned to overlap the signal line, effectively mediating the electric field interaction and suppressing leakage without requiring expansion of the black matrix, thus resolving the contradiction between display quality and aperture ratio
Solution Approach 2:
The solution transitions from a two-dimensional planar shielding approach (black matrix on the counter substrate) to a three-dimensional layered shielding structure. The shield electrode is positioned in the vertical dimension above the signal line on the TFT substrate, creating electrostatic shielding in the space between substrates without occupying pixel aperture area
2Reliability
If common potential lines are formed below the signal line to suppress electric field leakage, then alignment defect is reduced, but device complexity increases
Solution Approach 1:
The common potential lines serve multiple functions: they provide electrostatic shielding to suppress electric field leakage from the signal line, maintain proper potential distribution in the liquid crystal layer, and are integrated with the existing common electrode structure. This multi-functionality reduces alignment defects without significantly increasing device complexity
Solution Approach 2:
The common potential lines are merged with the common electrode structure, combining the shielding function with the existing potential distribution system. This integration approach reduces alignment defects while avoiding separate complex shielding structures
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 enhances the aperture ratio by minimizing electric field leakage and reduces display defects, such as line defects, while maintaining high display quality even under wide viewing angles.
Implementation Method 1
electric field leaking from the signal line upon the liquid crystal molecules
Implementation Method 2
a floating electrode is formed on level above the signal line with a second insulating film in between, as overlapping the signal line and at least a portion of each of the common potential lines
Implementation Method 3
effectively reducing electric field leakage and capacitive coupling
Data Source
AI summary
A pixel electrode connected to a signal line through a switching element and a common electrode connected to a common wiring are disposed, as alternating with each other, within each pixel region. Common potential lines are disposed on level below the signal line with an insulating film in between and also on both sides of the signal line when seen in plan view. A floating electrode is disposed on level above the signal line with a protective film in between, as overlapping the signal line and the common potential lines on both sides of the signal line.