Thin Film Transistor Substrate Aperture Ratio Optimization
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Solution Overview
Problem
The existing thin film transistor substrates for liquid crystal display devices face a reduction in aperture ratio due to the increased number of gate lines and common lines, which affects the display's luminance and efficiency, especially in double rate driving (DRD) mode, where the common line parallel to the gate line reduces the aperture ratio by 8-12%.
Innovation Solution
A thin film transistor substrate design where a common line is formed parallel to the data line, and a common line parallel to the gate line is removed, with the common electrodes connected through a connection portion overlapping the data line, allowing for improved aperture ratio and reduced electric field interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common line parallel to the gate line is added to connect common electrodes in DRD mode, then the number of data lines is reduced to half, but the aperture ratio is reduced by 8-12%
Solution Approach 1:
The patent extracts and removes the common line parallel to the gate line from the pixel region, eliminating the source of aperture ratio reduction while maintaining the DRD mode functionality through alternative connection methods
Solution Approach 2:
The patent repositions the common line to run in the same direction as the data line (second direction) rather than parallel to the gate line (first direction), changing the spatial arrangement to avoid aperture ratio loss while achieving the same electrical connection function
2Device complexity
If the number of gate lines is increased to support DRD mode, then the number of data drive ICs is reduced to 1/2 times, but the aperture ratio is reduced
Solution Approach 1:
The patent removes the problematic common line structure that causes aperture ratio reduction, allowing DRD mode operation without the penalty of reduced aperture ratio
Solution Approach 2:
The patent merges the function of the common line with the data line routing, using the same conductive structure to achieve both data transmission and common electrode connection functions
3Reliability
If a common line is formed in the pixel region to connect common electrodes, then the common electrodes are connected, but electric field interference occurs causing luminance difference spots
Solution Approach 1:
The patent extracts the common line from the pixel region entirely, removing it from areas where it would create electric field interference with pixel electrodes, while maintaining necessary electrical connections through alternative routing
Solution Approach 2:
The patent uses the data line as an intermediary structure that serves dual purposes: transmitting data signals and connecting common electrodes, thereby eliminating the need for a separate common line that would cause interference
Data Source
AI summary
A thin film transistor substrate and a method for fabricating the same are discussed. According to an embodiment, the thin film transistor substrate includes a gate line arranged on a substrate in a first direction; a data line arranged in a second direction crossing the gate line to define adjacent first and second pixel regions, the data line being used in common by the first and second pixel regions; an entire common line arranged in the second direction substantially parallel with the data line; a thin film transistor including a gate electrode connected with the gate line, a source electrode connected with the data line, a drain electrode formed to face the source electrode, and an active layer formed to be overlapped with the gate electrode by interposing a gate insulating film between the active layer and the gate electrode; and a pixel electrode connected with the drain electrode.