Thin Film Transistor Substrate with Capacitive Coupling
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Solution Overview
Problem
Multi-domain vertical alignment liquid crystal display panels suffer from 'white-blurring' when viewed from a diagonal direction due to complex pixel structures and reduced transmittance caused by capacitive coupling, opaque metal films, and increased manufacturing steps.
Innovation Solution
A thin film transistor substrate with intersecting bus lines and sub-pixel electrodes, where one sub-pixel electrode has a direct electrical connection and the other is capacitively coupled, eliminating the need for additional capacitive electrodes and reducing slit widths, thus simplifying the pixel structure and maintaining effective transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive electrode is formed of the same opaque metal film as the pixel TFT to achieve capacitive coupling, then the capacitive coupling is achieved, but the effective area of the pixel and transmittance decrease
Solution Approach 1:
The pixel electrode is divided into multiple sub-pixel electrodes (first sub-pixel electrode and second sub-pixel electrode) that are spatially separated by the gate bus line. This segmentation allows capacitive coupling to occur through the gate bus line without requiring additional capacitive electrodes that would reduce the effective pixel area.
Solution Approach 2:
The gate bus line serves dual functions: it provides electrical connection to the gate electrode of the TFT and simultaneously acts as a capacitive electrode for coupling voltage to the second sub-pixel electrode. This multi-functionality eliminates the need for separate capacitive electrodes, maintaining effective pixel area while achieving capacitive coupling.
2Adaptability or versatility
If the pixel electrode is divided into multiple sub-pixel electrodes with capacitive coupling to achieve multi-domain alignment, then viewing angle characteristics improve, but the pixel structure becomes complex
Solution Approach 1:
The gate bus line performs multiple functions simultaneously: it serves as the gate electrode connection, acts as a capacitive electrode for voltage coupling to the second sub-pixel electrode, and provides structural separation between sub-pixels. This reduces overall structure complexity while enabling multi-domain alignment.
Solution Approach 2:
The invention merges the gate bus line with the capacitive electrode function, combining what would traditionally be separate elements into a unified structure. This simplification reduces manufacturing complexity while maintaining the sub-pixel electrode configuration needed for improved viewing angles.
3Reliability
If additional capacitive electrodes are added to achieve capacitive coupling, then the capacitive coupling is achieved, but the number of manufacturing steps increases
Solution Approach 1:
The gate bus line is designed to serve dual purposes: electrical connection to the TFT gate and capacitive coupling to the second sub-pixel electrode. By making the gate bus line perform both functions, no additional capacitive electrodes or manufacturing steps are required beyond the standard TFT fabrication process.
4Adaptability or versatility
If the pixel electrode is divided into sub-pixel electrodes with capacitive coupling, then multi-domain alignment is achieved, but transmittance decreases due to reduced effective area
Solution Approach 1:
The pixel electrode is segmented into sub-pixel electrodes that are arranged to maximize light transmission while maintaining the capacitive coupling function. The gate bus line serves as the dividing element, and its dual function ensures that no additional opaque materials are introduced, preserving transmittance.
Solution Approach 2:
By making the gate bus line serve as both the electrical connection and capacitive electrode, the invention avoids adding extra opaque layers or structures that would block light. This maintains high transmittance while achieving multi-domain alignment through sub-pixel electrode configuration.
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 display quality by maintaining effective pixel area and transmittance while preventing short circuits and reducing manufacturing complexity, allowing for greater design freedom and improved viewing angles.
Implementation Method 1
a second thin film transistor capacitively coupled to the second sub-pixel electrode
Data Source
AI summary
The present invention relates to a thin film transistor substrate and a liquid crystal display panel for use in a liquid crystal display apparatus, and aims to provide a thin film transistor substrate and a liquid crystal display panel with good display quality. The thin film transistor substrate has a first sub-pixel electrode 16 and second sub-pixel electrode 17 arranged on the opposite sides of the gate bus line 12, a first thin film transistor 20a that establishes direct electrical connection with the first sub-pixel electrode 16, and a second thin film transistor 20b capacitively coupled to the second sub-pixel electrode 17. Since capacitance is formed where conventionally a source electrode and pixel electrode are connected via a contact hole, excessively opaque wiring is not required, which ensures sufficient effective area and transmittance of a pixel.