Liquid Crystal Device Counter Electrode Potential Bias Compensation
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Solution Overview
Problem
Liquid crystal devices face display defects such as flicker and image persistence due to the occurrence of DC voltage components, which are not adequately addressed by existing inversion drive methods, and previous techniques fail to effectively reduce bias caused by parasitic capacitance and thickness differences in alignment films.
Innovation Solution
A liquid crystal device configuration with a pixel electrode, switching element, counter electrode, and dielectric layers made of silicon oxide, where the counter electrode potential is set relative to a reference potential to cancel the bias caused by parasitic capacitance and thickness differences, using dielectric layers with specific thickness and resistance ratios to manage electric charge distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inversion drive is performed to reduce DC voltage component, then flicker is suppressed, but display defects still occur due to remaining DC voltage component and electric charge bias
Solution Approach 1:
The patent changes the parameter of counter electrode potential from a conventional reference level to a specifically lowered potential value. This parameter change creates asymmetric electric potential differences during positive and negative polarity periods, which compensates for the DC voltage component and electric charge bias that remain after inversion drive, thereby suppressing display defects while maintaining the benefits of flicker reduction
Solution Approach 2:
The patent introduces asymmetry into the electric potential configuration by setting the counter electrode potential lower than the reference potential. This asymmetric potential arrangement creates different electric potential differences for positive and negative polarity periods, which counterbalances the residual DC voltage component and prevents electric charge bias accumulation, solving the display defects that persist under symmetric inversion drive
2Reliability
If dielectric layers with different thicknesses are used to compensate for alignment film thickness differences, then manufacturing complexity increases
Solution Approach 1:
The patent changes the parameter of dielectric layer thickness to create a specific thickness difference between the first and second dielectric layers. This thickness parameter adjustment compensates for the thickness difference between alignment films, enabling electric charge balance without requiring complex additional structures or processes
Solution Approach 2:
The patent applies different thicknesses to different dielectric layers based on their local requirements. The first dielectric layer has a greater thickness than the second dielectric layer, creating a localized structural difference that compensates for alignment film thickness variations and achieves overall electric charge balance in the liquid crystal device
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 reduces the bias of electric charges, thereby suppressing flicker and image persistence, improving display quality by optimizing the electric potential differences across the liquid crystal layer.
Implementation Method 1
a first dielectric layer which is provided between the first alignment film and the pixel electrode and is made of silicon oxide; a second dielectric layer which is provided between the second alignment film and the counter electrode, is made of silicon oxide
Implementation Method 2
the bias of electric charges, caused by change in transmittance of the liquid crystal device during positive and negative polarity durations
Implementation Method 3
a liquid crystal layer which is provided between the pixel electrode and the counter electrode; An electric field is applied between the pixel electrode and the counter electrode by the voltage, and the liquid crystal layer is driven by the electric field
Data Source
AI summary
In a liquid crystal device according to the embodiment of the invention, a high potential and a low potential relative to the counter electrode potential are alternately applied to the pixel electrode through the switching element. Here, the counter electrode potential is set to be lower than a reference potential, when the reference potential is an electric potential which is obtained by shifting an average electric potential between the high potential and the low potential by an average value between an amount of change in an electric potential of the pixel electrode, caused by a parasitic capacitance of the switching element when the high potential is being applied to the pixel electrode, and an amount of change in the electric potential of the pixel electrode caused by the parasitic capacitance when the low potential is being applied to the pixel electrode.