TFT Array Substrate Metal Shielding Layer Coupling Capacitance
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Solution Overview
Problem
In TFT array substrates, reducing coupling capacitance between the pixel electrode and the source electrode to improve display contrast often results in a decreased aperture ratio, which affects the performance of electronic display apparatus.
Innovation Solution
A TFT array substrate design that includes a metal layer connected to a stable voltage signal line through a via hole, with insulation layers between the source/drain electrodes and the pixel electrode, preventing charging and discharging and thus minimizing the impact of coupling capacitance on the pixel electrode voltage, while maintaining a higher aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the overlapping area between the pixel electrode and the source electrode is reduced to reduce coupling capacitance, then the coupling capacitance is reduced, but the aperture ratio of the pixel unit is also reduced
Solution Approach 1:
A metal layer is introduced as an intermediary component between the source electrode and the pixel electrode. This metal layer is connected to a stable voltage signal line (such as a common electrode or ground line) through a via hole, acting as a shield to reduce the coupling capacitance between the source electrode and pixel electrode without requiring reduction of their overlapping area, thus maintaining the aperture ratio while reducing harmful capacitive coupling.
Solution Approach 2:
The metal layer is connected to a stable voltage signal line to create an equipotential region between the source electrode and pixel electrode. By maintaining a constant potential in the metal layer, the voltage difference between the source electrode and pixel electrode is reduced, thereby reducing the coupling capacitance effect without needing to reduce the overlapping area between these electrodes.
2Object-generated harmful factors
If the pixel electrode area is reduced to reduce coupling capacitance, then the coupling capacitance is reduced, but the contrast of the display apparatus is influenced
Solution Approach 1:
The metal layer serves as a shielding intermediary that reduces coupling capacitance between the source electrode and pixel electrode. This allows the pixel electrode to maintain its full area for optimal display contrast and light emission, while the metal layer absorbs or shields the capacitive coupling effects, preventing them from degrading display performance.
Solution Approach 2:
The metal layer connected to a stable voltage signal line provides preliminary shielding against coupling capacitance effects before they can significantly impact the pixel electrode voltage. By establishing this protective structure in advance, the pixel electrode can maintain stable voltage and optimal contrast without being adversely affected by capacitive coupling from the source electrode.
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 design effectively reduces the influence of coupling capacitance on the pixel electrode voltage, allowing for improved contrast and aperture ratio in electronic displays without the need to reduce the pixel electrode area.
Implementation Method 1
a metal layer and a second insulation layer are sequentially formed between the source/drain electrodes and the pixel electrode, and the metal layer is connected with a stable voltage signal line through a metal layer lead via hole
Data Source
AI summary
A TFT array substrate, a manufacturing method thereof and a display apparatus. The TFT array substrate comprises: a substrate (10) having a gate electrode (12), a gate insulation layer (17), a semiconductor active layer (18), a data line, a source electrode (14)/a drain electrode (15), a pixel electrode (16) formed thereon. The data line being connected with the source electrode (14). The drain electrode (15) is connected with the pixel electrode (16), wherein a first insulation layer (19), a metal layer (20) and a second insulation layer (21) are sequentially formed between the source electrode (14)/a drain electrode (15) and the pixel electrode (16). The metal layer (20) is connected with the stable voltage signal line through a through-hole (23) of the metal layer lead, thus the influence of the coupling capacitance of the TFT array substrate to the voltage of the pixel electrode is reduced, and meanwhile, the aperture ratio of the pixel unit is increased.