Liquid Crystal Alignment Layer Using Polarized UV and Rubbing
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Solution Overview
Problem
Conventional methods for aligning liquid crystals in liquid crystal display devices, such as the rubbing alignment method and photo-alignment method, face issues like light leakage due to disordered rubbing fabrics and lack of physical contact, and the photo-alignment method suffers from low anchoring energy leading to image sticking, making them unsuitable for large-scale production.
Innovation Solution
A method combining the rubbing alignment method with photo-alignment by using polarized ultraviolet rays to align the alignment material on the substrate, ensuring uniform alignment of liquid crystals even where rubbing fabrics do not contact the substrate, thereby addressing the limitations of both methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rubbing alignment method is used, then liquid crystal alignment is achieved, but light leakage occurs due to disordered rubbing fabrics and lack of physical contact
Solution Approach 1:
The patent replaces the mechanical rubbing process with a photo-alignment process using polarized ultraviolet rays. Instead of relying on mechanical contact between rubbing fabrics and substrate, the invention uses optical energy to induce molecular alignment in the alignment layer, eliminating the source of light leakage while maintaining alignment functionality
Solution Approach 2:
The patent changes the alignment mechanism from mechanical (rubbing) to optical (photo-alignment). By using polarized ultraviolet radiation, the alignment layer undergoes photo-isomerization or photo-dimerization that creates surface grooves and molecular orientation without mechanical contact, thereby preventing light leakage while achieving uniform liquid crystal alignment
2Object-affected harmful factors
If the photo-alignment method is used, then light leakage is prevented, but anchoring energy is low causing image sticking
Solution Approach 1:
The patent employs a composite alignment layer that combines materials responsive to both mechanical rubbing and photo-alignment. This composite structure enables the layer to gain high anchoring energy through rubbing while also benefiting from uniform alignment through photo-exposure, thereby preventing image sticking while maintaining light leakage prevention
Solution Approach 2:
The patent performs preliminary rubbing to create surface grooves and molecular orientation, then follows with photo-alignment to reinforce and uniformize the alignment. This sequential approach ensures that the alignment layer develops both the structural features for high anchoring energy and the uniformity needed to prevent light leakage and image sticking
3Ease of operation
If rubbing fabrics are used for alignment, then alignment direction is controlled, but disordered arrangement causes alignment inconsistencies
Solution Approach 1:
The patent replaces the mechanical rubbing system with a photo-alignment system that uses polarized ultraviolet rays. This substitution eliminates the variability inherent in mechanical rubbing fabric arrangement, as the optical process provides uniform, directional alignment control without depending on the physical state or arrangement of rubbing materials
Solution Approach 2:
The alignment layer itself performs the alignment function through photo-isomerization or photo-dimerization when exposed to polarized ultraviolet light. This self-aligned process eliminates the need for external rubbing fabrics, ensuring consistent and uniform alignment direction control without the variability introduced by mechanical contact
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 enhances anchoring energy, prevents image sticking, and minimizes light leakage, enabling the production of high-quality liquid crystal display devices by ensuring uniform liquid crystal alignment across the entire substrate.
Implementation Method 1
irradiating polarized ultraviolet rays onto the substrate having the alignment material coated thereon
Implementation Method 2
irradiating polarized ultraviolet rays onto the substrate having the alignment material coated thereon
Implementation Method 3
rubbing the substrate having the alignment material coated thereon
Data Source
AI summary
A method for forming an alignment layer for a liquid crystal display device, and a method for manufacturing a liquid crystal display device using the same are disclosed. The method includes preparing a substrate, coating an alignment material on the substrate, rubbing the substrate having the alignment material coated thereon, and irradiating ultraviolet (UV) rays onto the substrate having the alignment material coated thereon. The UV rays are irradiated over at least one area of the substrate having the alignment material coated thereon.