Liquid Crystal Display Alignment Layer Using Electric Field Orientation
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Solution Overview
Problem
The existing rubbing alignment method for liquid crystal displays suffers from light leakage due to non-uniform cloth arrangement and incomplete contact between the rubbing roll and the substrate, leading to non-uniform liquid crystal alignment.
Innovation Solution
A method involving the application of an electric or magnetic field to an alignment layer containing a specific compound on the substrate to set the alignment direction, eliminating the need for physical contact and allowing for uniform alignment without light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rubbing alignment method is used to form the alignment layer, then the liquid crystal molecules can be aligned in a particular direction, but light leakage occurs due to non-uniform cloth arrangement and incomplete contact between the rubbing roll and the substrate
Solution Approach 1:
The patent replaces the mechanical rubbing system with a photoalignment system. Instead of using a rubbing roll and cloth to physically align the liquid crystal molecules, the invention uses a photoalignment layer that is cured by light exposure. The photoalignment layer contains photoreactive groups that undergo photoisomerization or photocrosslinking when exposed to polarized light, creating an alignment pattern without mechanical contact. This eliminates the fundamental cause of light leakage (non-uniform rubbing contact) while achieving the desired alignment uniformity.
2Ease of manufacture
If the rubbing alignment method is used, then the alignment layer can be formed, but the process requires physical contact between the rubbing roll and substrate which limits substrate flexibility and increases processing time
Solution Approach 1:
The patent replaces the mechanical rubbing process with a photochemical alignment process. The photoalignment layer is applied to the substrate and then cured by exposing it to polarized light. This photochemical process does not require physical contact between a rubbing roll and the substrate, allowing flexible substrates to be used without concern for mechanical damage or contact uniformity. The alignment is achieved through photoisomerization or photocrosslinking of the photoreactive groups in the photoalignment layer, which creates the necessary molecular orientation for liquid crystal alignment.
3Manufacturing precision
If the rubbing alignment method is used, then the liquid crystal molecules can be aligned, but non-uniform rubbing contact leads to non-uniform alignment and defects
Solution Approach 1:
The patent replaces the mechanical rubbing system with a photoalignment system that uses light exposure to create uniform alignment. The photoalignment layer contains photoreactive groups that undergo photoisomerization or photocrosslinking when exposed to polarized light. This photochemical process provides superior uniformity and consistency because light exposure can be uniformly distributed across the entire substrate surface, unlike mechanical rubbing which suffers from contact pressure variations, cloth non-uniformity, and roll alignment issues. The result is more reliable and consistent liquid crystal alignment without the defects caused by non-uniform rubbing.
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 ensures uniform liquid crystal alignment, prevents light leakage, and enables the use of flexible substrates, reducing processing time and improving productivity by eliminating the need for physical contact between the rubbing roll and the substrate.
Implementation Method 1
a photoalignment method in which a photoalignment layer including a compound of formula (I) is formed on a substrate, and the photoalignment layer is cured by light irradiation
Implementation Method 2
the photoalignment layer is cured by light irradiation to determine an alignment direction of the photoalignment layer
Data Source
AI summary
A method for forming an alignment layer for a liquid crystal display is disclosed. The method includes preparing a substrate and depositing an alignment layer on the substrate. The method also includes applying one of an electric field and a magnetic field to the alignment layer to set an alignment direction of the alignment layer.