In-Plane Switching LCD With Overlapping Common Electrode
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Solution Overview
Problem
Horizontal electric field type LCDs face reduced aperture ratio due to non-transmittance areas where pixel and common electrodes are located on the same plane, while fringe field type LCDs suffer from increased parasitic capacitance and reduced transmittance in larger sizes.
Innovation Solution
A horizontal electric field type liquid crystal display device with a common electrode overlapping the pixel electrodes, featuring a wider common electrode and a gap between pixel electrodes to form a fringe field, reducing parasitic capacitance and maximizing light transmittance across the pixel area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pixel electrode and common electrode are disposed on the same level plane, then horizontal electric field is formed between them, but aperture ratio is reduced due to non-transmittance areas
Solution Approach 1:
The patent transitions from a two-dimensional same-plane electrode configuration to a three-dimensional overlapping configuration where the common electrode is positioned at a lower level than the pixel electrode. This vertical dimensionality change allows the electric field to extend over the pixel electrode area, converting non-transmittance areas into transmittance areas and improving aperture ratio while maintaining horizontal electric field formation.
2Area of stationary object
If common electrode is formed at under layer overlapping pixel electrode, then aperture ratio is improved, but parasitic capacitance increases in larger LCD sizes
Solution Approach 1:
The patent applies local quality by creating a gap between the pixel electrode and the common electrode at specific locations, particularly at the edges and corners. This localized gap reduces the overlapping area and minimizes parasitic capacitance formation in critical regions, while still maintaining sufficient overlap in the central area to ensure high aperture ratio and proper electric field distribution.
3Object-generated harmful factors
If gap between pixel electrodes is narrowed to reduce parasitic capacitance, then transmittance is lowered
Solution Approach 1:
The patent implements local quality by creating gaps between pixel electrodes and between pixel electrodes and common electrodes at specific locations (edges and corners) rather than uniformly across the entire structure. This localized gap placement reduces parasitic capacitance without significantly impacting the overall light transmittance area, as the gaps are positioned where they least interfere with the central pixel electrode functionality.
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 ensures high light transmittance and lower driving power consumption by forming a horizontal electric field over the pixel electrodes and minimizing parasitic capacitance, combining the benefits of both horizontal electric field and fringe field types.
Implementation Method 1
the horizontal electric field is formed between the pixel electrode and the common electrode and the space over the pixel electrode and the common electrode
Implementation Method 2
The liquid crystal display device (or LCD) represents video data by controlling the light transmittance of the liquid crystal layer using the electric fields driven by thin film transistor (or TFT)
Data Source
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AI summary
The present disclosure relates to a high light transmittance in-plane switching liquid crystal display device. The present disclosure suggests a horizontal electric field type liquid crystal display device comprising: a substrate (SUB); a plurality of gate lines (G) disposed in horizontal direction on the substrate; a plurality of data lines (DL) disposed in vertical direction on the substrate; a plurality of pixel area defined by the crossing the plurality of the gate lines and the plurality of the data lines; a first pixel electrode (PXL1) having a plurality of segments arraying with a predetermined distance within the pixel area; a second pixel electrode (PXL2) having a plurality of segments arraying in parallel with the first pixel electrode (PXL1) within the pixel area; and a common electrode (COM) overlapping with the first pixel electrode (PXL1) and the second pixel electrode (PXL2) within the pixel area.