Same Potential Line Shields Pixel Electrode from Crosstalk
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Solution Overview
Problem
Active matrix liquid crystal display devices experience crosstalk and voltage loss due to parasitic capacitance between signal lines and pixel electrodes, leading to display color differences and reduced gray scale performance, especially in vertical alignment types.
Innovation Solution
The implementation of a signal line and a same potential line positioned on both sides of the pixel electrode, creating a uniform electric field distribution that shields the pixel electrode from neighboring electrodes, thereby reducing parasitic capacitance and coupling, and simplifying the peripheral circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active matrix scheme is used to drive the liquid crystal display device, then high contrast and high-speed response are achieved, but parasitic capacitance or coupling between signal line and pixel electrode causes crosstalk and display color differences
Solution Approach 1:
A same potential line is introduced as an intermediary element between the signal line and the pixel electrode. This same potential line is connected to the signal line at one end and extends toward the pixel electrode, acting as a mediator to equalize the electric potential distribution and reduce parasitic capacitance coupling effects that cause crosstalk.
Solution Approach 2:
The solution adds a new spatial dimension to the circuit layout by introducing the same potential line that extends in the same direction as the signal line but is positioned adjacent to the pixel electrode. This dimensional arrangement creates a more uniform electric field distribution and reduces coupling effects.
2Ease of operation
If signal line is connected to pixel electrode for voltage application, then liquid crystal molecules can be tilted to display gray scale, but parasitic capacitance causes voltage loss and reduces driving voltage efficiency
Solution Approach 1:
The same potential line serves as an intermediary conductive path that distributes voltage more uniformly from the signal line to the pixel electrode region. This reduces voltage loss by minimizing parasitic capacitance effects and ensuring more efficient voltage application across the liquid crystal layer.
3Adaptability or versatility
If vertically aligned liquid crystal is used for wide viewing angle, then viewing angle is improved, but parasitic capacitance causes liquid crystal molecules to tilt slightly, resulting in light transmission and black display failure
Solution Approach 1:
The same potential line is designed to maintain equipotential conditions in the region adjacent to the pixel electrode. By extending the same potential line in the same direction as the signal line and connecting it to the signal line, the invention creates a more uniform electric potential distribution that prevents unwanted tilting of vertically aligned liquid crystal molecules, thereby maintaining precise alignment and proper black display performance.
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 solution effectively prevents crosstalk, maintains display color consistency, and enhances the viewing angle and gray scale performance of liquid crystal display devices by suppressing parasitic capacitance and coupling, while also simplifying the circuit construction.
Implementation Method 1
creating a uniform electric field distribution that shields the pixel electrode from neighboring electrodes
Implementation Method 2
parasitic capacitance or coupling occurring between a signal line, which is connected to a switching element of a single pixel electrode, and a pixel electrode, which is neighboring across the signal line
Data Source
AI summary
A liquid crystal display device includes a liquid crystal layer, a pixel electrode, a switching element, a signal line, and a same potential line. The liquid crystal layer is composed of liquid crystal that has a negative dielectric anisotropy and so is vertically aligned in an initial alignment state. The pixel electrode has a first side and a second side. The first side being opposite from the second side. The switching element is used for applying driving voltage selectively to the pixel electrode. The signal line is connected to the switching element and is located adjacent to the first side of the pixel electrode. The same potential line extends in the same direction as the signal line and is applied with the same voltage as that applied to the signal line. The same potential line is located adjacent to the second side of the pixel electrode.