MVA Liquid Crystal Display Stabilizing Alignment With Second TFT
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MVA liquid crystal display devices suffer from alignment disturbances and image sticking issues due to long propagation distances of liquid crystal molecule tilt, leading to display quality degradation and afterimages, especially at oblique viewing angles.
Innovation Solution
A liquid crystal display device with a second TFT connected between sub-pixels and a control electrode, along with a triangular alignment control electrode and modified slit structures, is used to stabilize liquid crystal alignment and prevent image sticking, improving display quality and viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional MVA liquid crystal display device is used, then the viewing angle characteristic is improved, but alignment disturbances occur due to long propagation distances of liquid crystal molecule tilt, causing image sticking and afterimages
Solution Approach 1:
The pixel electrode is divided into multiple sub-pixel electrodes (first sub-pixel electrode and second sub-pixel electrode) within one pixel region. This segmentation allows independent control of each sub-pixel electrode through separate TFTs, enabling shorter propagation distances for liquid crystal molecule tilt and preventing alignment disturbances that cause image sticking and afterimages, while maintaining the MVA mode's viewing angle characteristics
Solution Approach 2:
Different sub-pixel electrodes are controlled with different voltages applied to adjacent pixels (dot inversion drive). Specifically, when one pixel's sub-pixel electrodes are at high voltage, adjacent pixels' sub-pixel electrodes are at low voltage, creating local variations in electric field distribution that suppress alignment disturbances and improve both viewing angle characteristics and alignment stability
2Adaptability or versatility
If one pixel is divided into plural capacitance-coupled sub-pixels, then the discolor phenomenon is suppressed, but device complexity increases due to additional TFTs and capacitance coupling structures
Solution Approach 1:
Multiple sub-pixel electrodes within one pixel region are capacitance-coupled together, merging their electrical characteristics to create a combined capacitance effect. This allows voltage division across sub-pixels without requiring separate driving circuits for each, suppressing the discolor phenomenon while avoiding proportional increases in driving circuit complexity
Solution Approach 2:
The capacitance coupling structure serves multiple functions simultaneously: it divides voltage across sub-pixel electrodes to suppress discolor, maintains alignment stability through controlled electric fields, and enables dot inversion drive for preventing image sticking. This multi-functionality achieves improved display characteristics without proportional increases in device complexity
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
The solution effectively stabilizes liquid crystal alignment, prevents image sticking, and enhances display quality by shortening the propagation distance of liquid crystal molecule tilt and generating a lateral electric field to maintain vertical alignment, thereby reducing afterimages and improving viewing angle characteristics.
Implementation Method 1
an auxiliary capacitance bus line 18a kept at a constant potential and constituting an auxiliary capacitance between itself and the control electrode
Implementation Method 2
one pixel is divided into plural capacitance-coupled sub-pixels... since a potential is divided according to the capacitance ratio of the respective sub-pixels, voltages different from each other can be applied to the respective sub-pixels
Implementation Method 3
a liquid crystal sealed between these substrates... liquid crystal molecules are twist-aligned... liquid crystal molecules are tilted by a slit or a bank
Implementation Method 4
an active matrix liquid crystal display device in which a TFT (Thin Film Transistor) as a switching element is provided for each pixel (sub-pixel) exhibits an excellent display characteristic
Data Source
AI summary
In a liquid crystal display device in which in order to prevent image sticking in a half tone type MVA using a floating sub-pixel, a second TFT is provided between a sub-pixel directly connected to a TFT and the floating sub-pixel, its alignment is improved and a display quality is improved. A control capacitance electrode of an adjacent pixel is extended to provide an alignment control electrode in a corner portion of a pixel in which a propagation distance of liquid crystal alignment is long, and the propagation distance of the liquid crystal alignment is shortened, and at the same time, a slit part is formed of electrodes different from each other in voltage polarity to stabilize the alignment.