Lateral Electric Field LCD Pixel Segmentation for Viewing Angle Stability
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Solution Overview
Problem
Lateral electric field liquid crystal display devices, particularly in the FFS mode, suffer from significant shifts in voltage-transmittance characteristics when viewed from oblique angles, leading to undesirable coloration and gradation inversion, due to the uneven rotation of liquid crystals and pretilt angles affecting the electro-optical properties.
Innovation Solution
The implementation of a lateral electric field liquid crystal display device design where each pixel is divided into two regions with orthogonal strip electrode directions and orthogonal liquid crystal alignment azimuths, ensuring the electric fields and liquid crystal orientations are orthogonal, and setting the pretilt angles to either 0 degrees or opposite directions within these regions to maintain consistent viewing angles across different azimuths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lateral electric field mode is used to improve viewing angle characteristics, then the viewing angle dependency is reduced, but shifts in voltage-transmittance characteristics and coloration occur when viewed from oblique angles
Solution Approach 1:
The pixel is divided into two distinct regions with different liquid crystal alignment azimuths (first region with azimuth θ1 and second region with azimuth θ2). This segmentation allows each region to compensate for the optical anisotropy effects that cause viewing angle dependency, thereby resolving the contradiction between improved viewing angle characteristics and consistent voltage-transmittance properties.
Solution Approach 2:
Different regions within the pixel are assigned different local properties (different alignment azimuths θ1 and θ2) to optimize performance. The first region and second region have deliberately different alignment characteristics that compensate for each other's deficiencies when viewed from oblique angles, maintaining consistent voltage-transmittance characteristics across the entire pixel while preserving wide viewing angle characteristics.
2Adaptability or versatility
If the liquid crystal is rotated within a plane parallel to the substrate to suppress picture quality changes, then viewing angle characteristics are improved, but chromaticity shifts occur due to changes in effective retardation
Solution Approach 1:
The pixel is divided into two regions with different liquid crystal alignment azimuths to compensate for the chromaticity shifts that occur in lateral electric field modes. By having the first region with alignment azimuth θ1 and the second region with alignment azimuth θ2, the effective retardation changes are balanced, preventing net chromaticity shifts when viewed from oblique angles.
Solution Approach 2:
The two regions are designed with asymmetric alignment azimuths (θ1 and θ2 are different) to counterbalance the symmetric chromaticity shifts that occur in conventional single-alignment lateral electric field modes. This asymmetric configuration ensures that when viewed from oblique angles, the chromaticity shifts in one region are compensated by the opposite shifts in the other region.
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 significantly reduces the shift in voltage-transmittance characteristics and coloration issues, providing stable and uniform display quality across various viewing angles by compensating for the effects of pretilt angles and electric field orientations, resulting in improved viewing angle characteristics and reduced color distortion.
Implementation Method 1
controlling a display by rotating the liquid crystal within a plane substantially in parallel to the substrate by an electric field between the plan electrode and the strip electrode
Implementation Method 2
the axes of molecules of the nematic liquid crystal aligned horizontally are rotated within a plane that is in parallel to the substrate by the lateral electric field
Implementation Method 3
alignment processing of the liquid crystal is performed by photo-alignment
Implementation Method 4
a strip electrode or strip electrodes formed in a strip form on the plan electrode via an insulating film
Data Source
AI summary
The liquid crystal display device includes a transparent electrode formed in a plan form and a strip or strips transparent electrode disposed thereon via an insulating film, and controls display by rotating the liquid crystal aligned substantially in parallel to a substrate within a plane that is substantially in parallel to the substrate by an electric field between the both electrodes. Each pixel constituting the display is divided into two regions, the extending directions of the strip electrode in each of the regions are orthogonal, the alignment azimuths of the liquid crystal of each of the regions are orthogonal, and the angles formed between the extending directions of the strip electrode and the alignment azimuth of the liquid crystal are the same.