Horizontal Electric Field LCD Charge Balancing
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Solution Overview
Problem
Horizontal electric field liquid crystal displays (LCDs) face image quality deterioration and reduced aperture ratio due to non-uniform charge amounts during frame periods caused by the inversion scheme, which results in flicker and image sticking issues.
Innovation Solution
The implementation of a horizontal electric field LCD design that uses two pixel electrodes for each liquid crystal cell, driven by a voltage difference, with a unique configuration of finger units and connection units to balance parasitic capacitance, eliminating the need for a common electrode and storage capacitor, thereby equalizing charge amounts across frame periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inversion scheme is used to prevent deterioration and image sticking of the liquid crystal cell, then reliability is improved, but non-uniformity of charge amounts occurs during frame periods causing image quality deterioration
Solution Approach 1:
The pixel electrode is divided into multiple finger units (first finger units and second finger units) that are alternately arranged. This segmentation allows different finger units to be charged through different data lines, balancing the parasitic capacitance effects and achieving uniform charge amounts across the liquid crystal cell during frame periods while maintaining the inversion scheme.
Solution Approach 2:
Different regions of the pixel electrode (different finger units) are connected to different data lines with different voltage levels. This creates local quality differences in the electric field distribution, where odd-numbered finger units receive different voltages than even-numbered finger units, compensating for the non-uniform charge amounts caused by parasitic capacitance in the inversion scheme.
2Stability of the object's composition
If a common electrode and storage capacitor are used in the liquid crystal display panel, then stability of voltage supply is improved, but aperture ratio is reduced
Solution Approach 1:
The invention extracts and eliminates the common electrode and storage capacitor from the liquid crystal display panel structure. By using the segmented pixel electrode configuration with multiple data lines, the patent achieves voltage supply stability and uniform charge distribution without requiring these additional components, thereby increasing the aperture ratio.
Solution Approach 2:
The pixel electrode serves multiple functions: it acts as both the driving electrode for liquid crystal molecules and the storage element for maintaining voltage during frame periods. The segmented finger units with different connections to data lines provide both the electric field for liquid crystal switching and the charge balancing function that would otherwise require separate storage capacitors.
3Device complexity
If parasitic capacitance is not balanced in the liquid crystal display panel, then device complexity is reduced, but non-uniformity of charge amounts occurs causing flicker and image sticking
Solution Approach 1:
The pixel electrode uses asymmetric segmentation with different numbers of first and second finger units, or different widths of alternating finger units. This asymmetric design creates different parasitic capacitance values in different regions, which are deliberately used to balance the overall charge distribution and eliminate non-uniformity caused by the inversion scheme.
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 prevents image quality deterioration, increases aperture ratio, and reduces power consumption by balancing charging voltages and eliminating the need for a storage capacitor, while maintaining stable drive operations.
Implementation Method 1
liquid crystals of an in-plane switching (IPS) mode are driven due to a horizontal electric field between a pixel electrode and a common electrode that are positioned parallel to each other on a lower substrate
Implementation Method 2
An arrangement state of liquid crystal molecules changes due to an electric field produced by the voltage difference, and thus an amount of transmitted light is adjusted or the transmitted light is intercepted
Implementation Method 3
the liquid crystal cell Clc is charged to a positive data voltage Vdata(+) output by the data drive circuit and then is kept at a positive pixel voltage Vp(+) due to a parasitic capacitor Cgs (refer to FIG. 1), etc. of the TFT
Data Source
AI summary
A horizontal electric field liquid crystal display (LCD) is disclosed. The horizontal electric field LCD includes a first liquid crystal cell driven by a voltage difference between a first pixel electrode and a second pixel electrode, a second liquid crystal cell driven by a voltage difference between a third pixel electrode and a fourth pixel electrode, a first data line to which a first analog data voltage is supplied, a second data line to which a second analog data voltage and a fourth analog data voltage are supplied, a third data line to which a third analog data voltage is supplied, a first gate line that receives a first scan pulse to select the first liquid crystal cell, a second gate line that receives a second scan pulse to select the second liquid crystal cell, first, second, third, and fourth thin film transistors. The second pixel electrode is spaced apart from the second gate line, and the fourth pixel electrode is spaced apart from the first gate line.