Liquid Crystal Display Device With Second Thin Film Transistor
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Solution Overview
Problem
Liquid crystal display devices experience luminance degradation and flickers when driven at low frequencies due to increased holding time and pixel voltage drop, leading to defects like image sticking and reduced transmittance.
Innovation Solution
The implementation of a liquid crystal display device with a second thin film transistor using a common voltage as a source, synchronized with the pixel voltage, to minimize luminance degradation and improve flickers by adjusting the capacitance ratio between storage capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the display device is driven at a low frequency to reduce power consumption, then power consumption is reduced, but luminance deteriorates and flickers occur due to increased holding time and pixel voltage drop
Solution Approach 1:
The pixel electrode is divided into multiple regions with different voltages applied to different areas. The pixel electrode is segmented into a first region and a second region, allowing differential voltage control to compensate for voltage drop during low-frequency holding periods, thereby maintaining display quality while enabling power-saving low-frequency operation
Solution Approach 2:
The invention changes the voltage parameter distribution across the pixel electrode by applying different voltages to different regions. By adjusting the voltage difference between the first and second regions of the pixel electrode, the system compensates for holding period effects and maintains effective voltage levels during low-frequency driving
2Reliability
If the area of the storage capacitor is increased to solve pixel voltage drop, then voltage holding capability is improved, but device area increases and manufacturing complexity rises
Solution Approach 1:
Instead of increasing the area of a single storage capacitor, the invention segments the pixel electrode into multiple regions that function as distributed voltage holding elements. This approach achieves voltage holding capability without requiring a large single capacitor area, thereby avoiding increased device area and manufacturing complexity
3Device complexity
If a single gate line and single data line are used per pixel, then device complexity is reduced, but kickback voltage from parasitic capacitors causes liquid crystal deterioration
Solution Approach 1:
The pixel electrode is segmented into multiple regions with different voltage levels, which allows the system to manage and reduce the impact of kickback voltage from parasitic capacitors. By creating voltage differences across segmented regions, the invention mitigates the harmful effects of kickback voltage on liquid crystal while maintaining a simple single gate line and single data line configuration per pixel
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 reduces luminance degradation and flickers, enhancing display quality by synchronizing the common voltage with the pixel voltage, thereby improving the alignment of liquid crystal molecules and maintaining effective voltage consistency across frames.
Implementation Method 1
a first drain electrode connected to a pixel electrode... a second drain electrode connected to a common electrode... adjusting the capacitance ratio between storage capacitors
Data Source
AI summary
A liquid crystal display device includes a plurality of gate lines and data lines that intersect each other on a substrate and define a plurality of sub-pixels, a plurality of common electrodes and pixel electrodes that are alternately disposed within the sub-pixels, a first thin film transistor comprising a first gate electrode connected to the gate line, a first source electrode connected to the data line, and a first drain electrode connected to the pixel electrode, a first common line applied with a first common voltage, and a second thin film transistor comprising a second gate electrode connected to the gate line, a second source electrode connected to the first common line, and a second drain electrode connected to the common electrode.