IPS LCD Helical Twist Alignment for Contrast and Viewing Angle
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Solution Overview
Problem
In-plane switching (IPS) mode liquid crystal display (LCD) devices face challenges in achieving high contrast ratios due to disordered alignment of liquid crystal molecules, leading to light leakage during the black state, which decreases contrast and requires high driving voltages to improve transmittance.
Innovation Solution
The IPS mode LCD device incorporates a homeotropically aligned first alignment layer and a homogeneously aligned second alignment layer, with a liquid crystal layer having a helical twist structure, utilizing the flexoelectric or dielectric effect to control the alignment and refractive indices, ensuring optimal black color properties and reduced driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional IPS mode LCD device uses horizontally aligned liquid crystal molecules, then the viewing angle is improved, but the contrast ratio deteriorates due to light leakage during the black state
Solution Approach 1:
The invention divides the alignment layers into two distinct types: a first alignment layer providing homeotropic alignment (vertical orientation) and a second alignment layer providing homogeneous alignment (horizontal orientation). This segmentation allows different regions of the liquid crystal layer to have different alignment characteristics, enabling both wide viewing angle and high contrast ratio performance
Solution Approach 2:
The patent applies different alignment properties to different locations within the device. The first alignment layer creates a vertical alignment region that suppresses light leakage for high contrast, while the second alignment layer creates a horizontal alignment region that enables wide viewing angle. This local differentiation of qualities resolves the contradiction between contrast ratio and viewing angle
2Illumination intensity
If the transmittance is improved by increasing the driving voltage, then the brightness is enhanced, but the power consumption increases
Solution Approach 1:
The invention changes the alignment parameters of the liquid crystal molecules by using dual alignment layers with different alignment modes. This parameter change allows the liquid crystal to achieve high transmittance states more efficiently, reducing the voltage required for switching and thereby lowering power consumption while maintaining high brightness
3Adaptability or versatility
If the liquid crystal molecules are aligned horizontally to achieve wide viewing angle, then the adaptability is improved, but the black color properties deteriorate due to disordered alignment
Solution Approach 1:
The invention segments the alignment function into two separate alignment layers with different orientations. The first alignment layer ensures proper molecular orientation for black color properties, while the second alignment layer provides the horizontal alignment needed for wide viewing angle, thus resolving the contradiction between these two requirements
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 the contrast ratio and viewing angle while maintaining low driving voltages, enabling high-quality images with short response times and improved transmittance without increasing the driving voltage.
Implementation Method 1
utilizing the flexoelectric or dielectric effect to control the alignment and refractive indices
Implementation Method 2
utilizing the flexoelectric or dielectric effect to control the alignment and refractive indices
Implementation Method 3
the LCD device uses the optical anisotropy and polarization properties of liquid crystal molecules to produce an image
Implementation Method 4
the LCD device uses the optical anisotropy and polarization properties of liquid crystal molecules to produce an image
Implementation Method 5
a liquid crystal layer having a twisted helical structure when an electric field is not generated
Data Source
AI summary
A liquid crystal display device includes first and second substrate facing each other, a pixel electrode and a common electrode on an inner surface of the first substrate and generating an electric field substantially parallel to the first substrate, a first alignment layer on the inner surface of the first substrate and homeotropically aligned, a first polarizer on an outer surface of the first substrate and having a first polarization axis, a second alignment layer on an inner surface of the second substrate and homogeneously aligned, a second polarizer on an outer surface of the second substrate and having a second polarization axis perpendicular to the first polarization axis, and a liquid crystal layer between the first and second alignment layers.