IPS LCD Comb Electrode Asymmetry Prevents Pixel End Domains
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Solution Overview
Problem
In IPS-Pro type liquid crystal display devices, the formation of domains at pixel end portions leads to reduced transmittance due to fringe electric fields rotating 180 degrees, causing opposite rotation in the liquid crystal layer, resulting in dark lines and decreased image quality.
Innovation Solution
The implementation of a liquid crystal display device with a comb-like electrode structure where one side of the comb has a linking portion, and the width of the slits is greater than the electrodes, along with a pretilt angle that causes the liquid crystal to rise from the end portions towards the electrodes, preventing domain formation and enhancing transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pixel electrodes and common electrodes are layered on top of each other with an electrode insulating layer in between to form fringe electric fields, then the transmittance is improved, but domains are generated at pixel end portions causing dark lines and reduced image quality
Solution Approach 1:
The patent applies asymmetry by making the slit width greater than the electrode width, creating an asymmetric comb-like structure. This asymmetric configuration modifies the fringe electric field distribution at pixel end portions, preventing the 180-degree rotation that causes domain formation while maintaining the high transmittance benefit of the layered electrode structure.
Solution Approach 2:
The patent applies local quality by giving different dimensions to different parts of the electrode structure - specifically, making the slit width greater than the electrode width only at critical regions. This localized dimensional variation targets the pixel end portions where domains form, allowing the majority of the pixel area to maintain optimal electric field distribution for high transmittance.
2Object-affected harmful factors
If the slit width is made greater than the electrode width in a comb-like structure, then domain formation is prevented, but the electrode area ratio decreases potentially affecting electric field strength
Solution Approach 1:
The patent applies parameter changes by optimizing the ratio between slit width and electrode width in the comb-like structure. By setting the slit width greater than the electrode width, the patent changes the geometric parameters to prevent domain formation while maintaining sufficient electric field strength through the layered electrode configuration and appropriate material selection.
3Stability of the object's composition
If a pretilt angle is applied to make liquid crystal rise from end portions towards electrodes, then consistent alignment is achieved preventing domains, but the alignment control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-aligning the liquid crystal molecules with a pretilt angle before applying the full driving voltage. This preliminary alignment ensures that liquid crystal molecules at pixel end portions rise from the ends towards the electrodes, establishing a stable alignment pattern that prevents domain formation during normal operation.
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 effectively prevents domain generation at pixel end portions, thereby increasing transmittance and improving image quality by ensuring consistent liquid crystal alignment, even at the pixel edges.
Implementation Method 1
IPS (in-plane switching) type liquid crystal display devices have an in-plane electric field of which the main component is parallel to the plane of the liquid crystal formed between pixel electrodes and common electrodes formed on the same substrate, and thus, the liquid crystal layer is driven. Therefore, in the IPS type liquid crystal display devices, rotation within the liquid crystal layer is a main change in the alignment of the liquid crystal layer as an electric field is applied.
Implementation Method 2
the liquid crystal layer is driven by applying an electrical field of which a main component is parallel to the liquid crystal plane
Implementation Method 3
electric lines of force in arc form are formed so as to connect the electrodes in different layers, and the electric field is distributed in the vicinity of the center of the electrodes. Such electric fields in arc form that connect electrodes in different layers are referred to as fringe electric fields.
Implementation Method 4
the alignment in the liquid crystal layer has such a pretilt angle that the liquid crystal rises from the end portions in the comb-like structure towards the root in the interface close to the electrodes
Data Source
AI summary
An object of the present invention is to prevent the domain from being generated in the pixel end portions so that the transmittance can increase in an IPS type liquid crystal display device where the size of the pixels is extremely small. In the liquid crystal display device according to the present invention, the electrodes close to the liquid crystal layer have a comb-like structure having a linking portion only at one pixel end, the end portion of the comb-like structure has a structure for preventing the domain from growing, the width of the slits in the comb-like structure is greater than the width of the electrodes, and the alignment of the liquid crystal layer has such a pretilt angle that the liquid crystal rises from the end portion in the comb-like structure towards the root in the interface close to the electrode.