IPS LCD Floating Electrode Shields Crosstalk
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Solution Overview
Problem
In-Plane Switching (IPS) mode LCD devices face challenges with transmittance and viewing angle crosstalk, leading to light leakage and aperture ratio loss, while attempts to address these issues, such as increasing the black matrix layer or overlapping data lines with common electrodes, result in parasitic capacitance and reduced luminance.
Innovation Solution
The IPS mode LCD device features first and second substrates with gate and data lines forming unit pixel regions, island-shaped electrode patterns overlapping with data lines, and common electrodes partially overlapping with these patterns, along with a pixel electrode connected to the drain electrode, utilizing a gate insulating layer and passivation layer to minimize capacitance and maintain high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the black matrix layer width is increased to prevent light leakage, then viewing angle crosstalk is improved, but the aperture ratio is reduced
Solution Approach 1:
The patent introduces a floating electrode pattern as an intermediary element between the data line and the common electrode. This floating electrode serves as a mediator that shields the liquid crystal from the data line's electric field, preventing crosstalk without requiring an increased black matrix layer width, thus maintaining the aperture ratio while solving the viewing angle crosstalk problem
2Area of stationary object
If data lines are overlapped with common electrodes to improve transmittance, then aperture ratio is improved, but parasitic capacitance increases
Solution Approach 1:
The floating electrode pattern acts as an intermediary that electrically isolates the data line from the common electrode. By introducing this intermediate conductive layer connected to ground or reference potential, the patent reduces the direct capacitive coupling between data and common electrodes, thereby minimizing parasitic capacitance while still allowing the electrodes to be positioned in overlapping configurations for improved aperture ratio
3Object-affected harmful factors
If the black matrix layer is increased to reduce crosstalk, then viewing angle performance is improved, but transmittance is reduced
Solution Approach 1:
The floating electrode pattern serves as an active shielding intermediary that electronically suppresses crosstalk through electrostatic shielding rather than physically blocking light with a larger black matrix layer. This approach maintains high transmittance by minimizing the amount of light-blocking material while effectively preventing viewing angle crosstalk through the electrostatic field shielding provided by the floating electrode
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 configuration reduces parasitic capacitance by approximately 50%, maintains high transmittance, and improves the aperture ratio without increasing the black matrix layer width, effectively addressing viewing angle crosstalk and luminance issues.
Implementation Method 1
liquid crystal molecules of the liquid crystal layer 3 formed between the first and second substrates 1 and 2 are aligned by an electric field induced between the pixel electrode 6 and the common electrode 9
Implementation Method 2
the pixel electrode and the common electrode are formed in parallel on the pixel region of the first substrate whereby a transverse electric field parallel to the two substrates is generated so as to align the liquid crystal layer
Data Source
AI summary
An IPS mode LCD device includes first and second substrates facing each other, gate and data lines on the first substrate and crossing each other to define a plurality of unit pixel regions, first and second electrode patterns formed in an island shape at a pre-determined interval therebetween and overlapped with sides of the data line, a plurality of common electrodes formed in the unit pixel regions, each of the common electrodes having outermost common electrodes partially overlapped with the first and second electrode patterns, a pixel electrode alternately provided with the common electrodes within the pixel unit region, and a liquid crystal layer formed between the first and second substrates.