TFT Array Substrate With Tilted Pixel Electrodes For ADS Displays
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Solution Overview
Problem
Existing TFT array substrates in ADS mode suffer from black stripes at pixel edges due to inconsistent electric field directions, leading to orientation disorder of liquid crystals, which affects transmittance and aperture ratio.
Innovation Solution
The TFT array substrate design includes a gate line and data line intersecting to form sub-pixel units with a thin film transistor, a common electrode, and pixel electrode layers, where the second pixel electrode layer overlaps the first and is tilted to match the initial orientation of liquid crystals, ensuring consistent electric field direction and reducing black stripe formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional pixel structure with strip-like pixel electrodes is used in ADS mode, then the display can achieve high resolution and wide viewing angle, but black stripes appear at pixel edges due to orientation disorder of liquid crystals
Solution Approach 1:
The patent introduces asymmetric tilt angles between the strip-like pixel electrodes and the initial alignment direction of liquid crystals. Instead of using symmetric orthogonal arrangements, the pixel electrodes are tilted at specific angles (e.g., 15-75 degrees) relative to the liquid crystal initial alignment direction. This asymmetric configuration modifies the electric field distribution at pixel edges, preventing the formation of black stripes while maintaining high resolution and wide viewing angle characteristics of ADS mode displays.
2Object-generated harmful factors
If a wider black matrix is used to shield orientation disorder regions, then black stripe visibility is reduced, but the aperture ratio and transmittance are degraded
Solution Approach 1:
The patent converts the previously harmful orientation disorder at pixel edges into a beneficial effect by using it to define the pixel structure itself. The tilt angle configuration causes the liquid crystal orientation disorder to naturally form dark regions that serve as the pixel boundaries, eliminating the need for additional black matrix shielding. This approach actually improves aperture ratio compared to traditional designs that required wide black matrices to mask similar defects.
3Ease of manufacture
If strip-like pixel electrodes are aligned perpendicular to initial liquid crystal orientation, then simple manufacturing is achieved, but electric field direction becomes inconsistent at pixel edges
Solution Approach 1:
The patent changes the angular parameter of pixel electrode alignment from the traditional 90-degree perpendicular arrangement to specific tilt angles ranging from 15 to 75 degrees relative to the initial liquid crystal alignment direction. This parameter modification optimizes the electric field distribution both within pixel centers and at pixel edges, ensuring consistent electric field direction throughout the pixel structure while maintaining manufacturing simplicity through standard photolithography processes.
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 reduces orientation disorder at pixel edges, enhancing aperture ratio and transmittance without additional processing steps, thereby improving optical utilization and reducing power consumption.
Implementation Method 1
the electric field direction in this place is inconsistent with direction of the fringe field for driving liquid crystals inside the pixel unit, so that an orientation disorder of liquid crystals occurs at the edge of the pixel unit
Implementation Method 2
allows liquid crystal molecules in all orientations in a liquid crystal cell, which are located directly above the electrode and between the slit electrodes, to be rotated
Data Source
AI summary
A thin film transistor (TFT) array substrate, including: a gate line and a data line, which are formed on a substrate, and a sub-pixel unit defined by intersecting of the gate line and the data line, wherein, the sub-pixel unit comprises a thin film transistor device, a first pixel electrode layer and a second pixel electrode layer; the first pixel electrode layer is insulated from the second pixel electrode layer; the second pixel electrode layer is located over the first pixel electrode layer, and the pattern of strip-like pixel electrodes of the second pixel electrode layer overlap up-and-down with the pattern of the first pixel electrode layer; and the strip-like pixel electrodes make a tilt angle with an initial orientation of liquid crystals, and a gate line is parallel to the strip-like pixel electrodes close to the gate line.