Liquid Crystal Display Device with Chiral Dopants for Wide Viewing Angle
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Solution Overview
Problem
Conventional twisted nematic (TN) type LCDs have restrictive viewing angles due to strong viewing angle dependence of effective LC birefringence, leading to optical dark fringes and deficient image quality near multi-domain boundaries in wide-viewing-angle LCDs like MVA and PVA modes.
Innovation Solution
The use of TN type liquid crystals with chiral dopants to achieve continuous-domain or multi-domain alignments, optimizing optical path difference Δnd and LC rotation d/p ratio for at least 90% transmittance across all azimuthal angles, eliminating dark fringes and enhancing viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional TN type LCD is used, then high optical transmittance is achieved, but viewing angle is very restrictive
Solution Approach 1:
The LCD is divided into multiple domains within each pixel, with each domain having LC molecules aligned in different in-plane directions. This segmentation allows the device to achieve both high transmittance and wide viewing angle by combining the optical effects of different domains
Solution Approach 2:
Different regions (domains) of the LCD have different LC alignment characteristics. By optimizing the alignment direction in each local domain, the overall device achieves wide viewing angle while maintaining high transmittance in each local region
2Adaptability or versatility
If MVA or PVA modes are used to achieve wide viewing angle, then viewing angle is improved, but optical dark fringes appear near protrusions or electrode patterns
Solution Approach 1:
The harmful protrusions or electrode patterns that cause dark fringes are removed from the structure. Instead, alignment films with specific molecular orientations are used to define domain boundaries, eliminating the source of optical defects while maintaining wide viewing angle
Solution Approach 2:
Alignment films serve as an intermediary between the electrodes and the liquid crystal molecules. These films control LC alignment through surface interactions rather than physical protrusions, eliminating dark fringes while achieving the desired multi-domain configuration
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 approach achieves higher transmittance without dark fringes near domain boundaries, wider viewing angles, and higher contrast ratios by ensuring maximal polarization rotation effects, thereby improving image quality.
Implementation Method 1
uses TN type LC with chiral dopants, such that the LC molecules within the display area can form a continuous-domain or multi-domain alignments
Implementation Method 2
optimizing optical path difference Δnd and LC rotations of d/p ratio, such that at least 90% transmittance can be achieved for LC aligning along all azimuthal angles
Implementation Method 3
The intensity of light passing through a LCD device is controlled by the alignments of liquid crystal (LC) molecules between two transparent electrodes of the device. Depending on the polarization and refraction properties of light passing through the LC molecules with different alignments
Implementation Method 4
The wide viewing angle of the PVA mode is achieved by using the fringe-field effect and optical compensation by retardation films
Data Source
AI summary
The present invention provides an improved type of liquid crystal (LC) display device with wide-viewing angle and high optical transmittance. The LC display of the present invention consists of: at least one LC alignment apparatus, which makes the LC molecules within the display area forming a continuous-domain or multi-domain alignments, and hence improve its wide-viewing-angle characteristics; a LC layer formed by Nematic type LC with chiral dopants, and with optimal parameters of the optical path difference Δnd and LC rotations of d/p ratio, such that LC molecules can be aligned along all radial directions to achieve optimal transmittance, and thus producing an wide-viewing-angle LC display improved transmittance without the formation of dark fringes in the display area.