Reflective LCD Optical Axis Alignment for Contrast
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Solution Overview
Problem
Reflective and transflective liquid crystal display devices face challenges in maintaining a high contrast ratio and color reproducibility due to the optical anisotropy of liquid crystal molecules, which is affected by the alignment direction of liquid crystal molecules and the optical axis of light source members.
Innovation Solution
The display device optimizes the alignment direction of liquid crystal molecules and the optical axis of a light control member and polarizer by incorporating a half-wave retardation layer and a quarter-wave retardation layer, with specific angular relationships between their optical axes, and uses a light control member with different refractive indices to improve image display quality using external light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the alignment direction of liquid crystal molecules and the optical axis of the light control member are not optimized, then the device structure is simpler, but the contrast ratio and color reproducibility deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the alignment direction of liquid crystal molecules and the optical axis orientation of the light control member. Specifically, the light control member's optical axis is set at a specific angle (e.g., 45 degrees) relative to the liquid crystal molecule alignment direction, and the polarizer's transmission axis is oriented at a complementary angle. This angular parameter optimization resolves the contradiction by achieving high contrast ratio and color reproducibility through precise geometric parameter control rather than adding complex optical layers.
Solution Approach 2:
The patent implements local quality by optimizing the optical properties of specific components at specific orientations. The light control member is designed with its optical axis at a predetermined angle to control light polarization locally, while the liquid crystal molecules are aligned in a specific direction to achieve uniform optical response. This localized optimization of orientation parameters enables high display quality without requiring complex overall system design.
2Manufacturing precision
If the optical axis of the light control member is misaligned with the liquid crystal molecule alignment direction, then the manufacturing process is simpler, but color reproducibility and contrast ratio worsen
Solution Approach 1:
The patent resolves this contradiction by establishing specific angular parameter relationships between optical components. The light control member's optical axis is set at a defined angle (e.g., 45 degrees) relative to the liquid crystal molecule alignment direction, and the polarizer's transmission axis is oriented at a complementary angle. This precise parameter control ensures consistent color reproducibility and contrast ratio, eliminating display quality variations that would result from misalignment.
3Manufacturing precision
If multiple optical layers with specific angular relationships are added, then the contrast ratio and color reproducibility improve, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent simplifies manufacturing by focusing on optimizing angular parameters of existing optical layers rather than adding multiple complex layers. By setting the light control member's optical axis at a specific angle (e.g., 45 degrees) relative to the liquid crystal alignment and configuring the polarizer accordingly, the patent achieves high display quality through parameter optimization of a streamlined optical stack, avoiding the need for multiple additional optical layers with complex angular relationships.
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 color reproducibility of the displayed images, minimizing light leakage and color deviation, thereby improving the overall display quality.
Implementation Method 1
The polarizing member may further comprise a half-wave retardation layer disposed under the polarizer (between the polarizer and the light control member), and a quarter-wave retardation layer disposed under the half-wave retardation layer (between the half-wave retardation layer and the light control member). An angle between a first optical axis of the half-wave retardation layer and a second optical axis of the quarter-wave retardation layer may be 60°±5°.
Implementation Method 2
The light control member may further comprise a plurality of first optical parts having a first refractive index, and a second optical part having a second refractive index that is lower than the first refractive index and filling a space between the plurality of first optical parts.
Implementation Method 3
the reflective or transflective liquid crystal display device may suffer from changes of a contrast ratio and a degree of color reproducibility according to an alignment direction of liquid crystal molecules and a direction of an optical axis of a light source member due to optical anisotropy of the liquid crystal molecules.
Data Source
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AI summary
A display device comprises a liquid crystal display panel comprising a first substrate, a second substrate facing the first substrate and comprising a reflective layer, and a liquid crystal layer disposed between the first and second substrates, a light control member disposed on the liquid crystal display panel and comprising a first optical part, and a polarizing member disposed on the light control member and comprising a polarizer. The liquid crystal layer comprises a first liquid crystal molecule adjacent to the first substrate, and a long axis of the first liquid crystal molecule projected on the first substrate is aligned in a first direction. An extending direction of a long axis of the first optical part projected on the first substrate is parallel to the first direction, and the polarizer has a transmission axis extending in a second direction.