Twist-Structure Liquid Crystal Display with Chiral Material
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Solution Overview
Problem
Vertical alignment type liquid crystal displays (LCDs) face issues with contrast and optical transmittance due to viewing angle dependencies, particularly at deep observation angles, caused by birefringence effects and polarizer orientation, which existing solutions like viewing angle compensation plates only partially address.
Innovation Solution
The implementation of a liquid crystal display with a twist structure and specific pretilt angles, combined with chiral material and optical anisotropic plates, ensures symmetrical viewing angles and improved optical transmittance across different azimuths, using a C plate or biaxial film as viewing angle compensation, and adjusting polarizer orientations to minimize optical through.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a vertical alignment type LCD is used with cross-nicol polarizers, then good black display quality is achieved, but viewing angle characteristics deteriorate at deep observation angles
Solution Approach 1:
The LCD is divided into multiple domains within each pixel, with each domain having liquid crystal molecules aligned in different directions. This segmentation allows the display to maintain good viewing angle characteristics across different observation directions while preserving the black display quality of vertical alignment type LCDs.
Solution Approach 2:
The patent introduces asymmetric electrode patterns (such as slits or projections) that create oblique electric fields, causing liquid crystal molecules to align at specific asymmetric angles. This asymmetric alignment compensates for the viewing angle dependence of the cross-nicol polarizer arrangement, improving viewing angle characteristics while maintaining black display quality.
2Adaptability or versatility
If multi-domain vertical alignment is implemented to improve viewing angle characteristics, then viewing angle symmetry is improved, but aperture ratio and optical transmittance are reduced
Solution Approach 1:
The patent applies local quality changes by forming slits or projections only in specific regions of the electrode structure, rather than across the entire pixel area. This allows multi-domain alignment to be achieved in localized areas, improving viewing angle symmetry while minimizing the impact on overall aperture ratio and optical transmittance.
3Area of stationary object
If mono-domain pretilt vertical alignment is used to maintain aperture ratio, then optical transmittance is preserved, but viewing angle characteristics remain asymmetric
Solution Approach 1:
The patent introduces asymmetric electrode patterns (slits or projections) that create oblique electric fields, causing liquid crystal molecules to align at specific asymmetric angles. This asymmetric alignment compensates for the viewing angle dependence of the cross-nicol polarizer arrangement, improving viewing angle symmetry while maintaining the aperture ratio and optical transmittance of mono-domain structures.
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 enhances display quality by achieving symmetrical viewing angles and reduced optical transmittance differences between 0° and 180° azimuths, improving contrast and display symmetry, while maintaining cost-effectiveness and manufacturability.
Implementation Method 1
Vertical alignment type liquid crystal displays (LCDs) face issues with contrast and optical transmittance due to viewing angle dependencies, particularly at deep observation angles, caused by birefringence effects and polarizer orientation
Implementation Method 2
adjusting polarizer orientations to minimize optical through
Data Source
AI summary
A liquid crystal display has (i) first and second substrates having electrodes and a pretilt angle of 88.5° to 89.5°, (ii) a liquid crystal layer, having a thickness d and made of liquid crystal molecule material which has a twist structure at a twist angle of 160° to 240° in a voltage application state, the liquid crystal layer containing chiral material having a pitch of p, where d/p is 0.2 to 0.74, (iii) a first polarizer disposed facing the first substrate, the first polarizer having as a transmission axis direction a first direction, (iv) a second polarizer disposed facing the second substrate, the second polarizer having as a transmission axis direction a second direction having an angle of 85° to 95° relative to the first direction, and (v) an optical anisotropic plate disposed at least one of between the first substrate and first polarizer and between the second substrate and second polarizer.