Retardation Layer Design for LCD Transmittance and Viewing Angle
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Solution Overview
Problem
Conventional liquid crystal display devices with alignment division techniques suffer from low transmittance due to dark lines at the boundaries of domains with different tilt azimuths of liquid crystal molecules, which hinders the achievement of both improved viewing angle characteristics and high transmittance simultaneously.
Innovation Solution
Incorporating a retardation layer with specific in-plane phase differences between the polarizing plates and the liquid crystal layer, where the retardation layers have areas with different in-plane phase differences that overlap domain boundaries, allowing for orthogonal slow axes and optimized alignment of liquid crystal molecules to enhance transmittance and viewing angle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If alignment division technique is used to improve viewing angle characteristics, then viewing angle characteristics are improved, but dark lines appear at domain boundaries resulting in low transmittance
Solution Approach 1:
A retardation layer is introduced as an intermediary component between the liquid crystal layer and the polarizing plate. This retardation layer has a specific in-plane phase difference (0.05 μm ≤ in-plane phase difference < 0.20 μm) that acts as an optical mediator to compensate for the phase differences caused by domain boundaries, thereby reducing dark lines and improving transmittance while maintaining the alignment division structure for viewing angle characteristics.
Solution Approach 2:
The invention changes the optical parameter (in-plane phase difference) of the retardation layer to a specific range (0.05 μm ≤ in-plane phase difference < 0.20 μm) that is optimized for compensating domain boundary effects. This parameter optimization allows the system to simultaneously achieve good viewing angle characteristics from alignment division and high transmittance by controlling the phase compensation effect.
2Adaptability or versatility
If the number of domains is increased to improve viewing angle characteristics, then viewing angle characteristics are improved, but the area ratio of dark lines increases resulting in even lower transmittance
Solution Approach 1:
The retardation layer serves as a universal intermediary that compensates for phase differences regardless of the number of domains. By maintaining a specific in-plane phase difference, it effectively reduces dark lines even when multiple domains (four or more) are used, allowing the system to increase domain count for better viewing angle characteristics without proportionally increasing dark line area penalty.
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
The solution effectively reduces dark lines at domain boundaries, resulting in higher transmittance and improved viewing angle characteristics, enabling a liquid crystal display device that balances these performance metrics.
Implementation Method 1
a first retardation layer having a first in-plane phase difference is disposed between the first polarizing plate and the liquid crystal layer, a second retardation layer having a second in-plane phase difference is disposed between the second polarizing plate and the liquid crystal layer
Implementation Method 2
a voltage is applied to the liquid crystal layer to change the alignment of the liquid crystal molecules so as to control the amount of light that is transmitted through the liquid crystal display panel
Implementation Method 3
one pixel region is divided into multiple domains (alignment regions)... the azimuth of the absorption axis of one of the polarizing plates corresponds to an X-axis direction and the azimuth of the absorption axis of the other polarizing plate corresponds to a Y-axis direction
Data Source
AI summary
A liquid crystal display device includes: a first polarizing plate; a first substrate; a first vertical alignment film; a liquid crystal layer; a second vertical alignment film; a second substrate; and a second polarizing plate, wherein a first retardation layer is disposed between the first polarizing plate and the liquid crystal layer and includes first and second areas having mutually different in-plane phase differences, a second retardation layer is disposed between the second polarizing plate and the liquid crystal layer and includes third and fourth areas having mutually different in-plane phase differences, the first and third areas overlap boundaries between at least four domains of liquid crystal molecules in a pixel region and have an in-plane phase difference in a predetermined range, and in-plane slow axes of the first and third areas and absorption axes of the first and second polarizing plates each have a predetermined azimuth.