Photoalignment Layer for Liquid Crystal Displays
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Solution Overview
Problem
The alignment of liquid crystals in liquid crystal displays is often affected by dust and static electricity issues in traditional rubbing methods, and photoalignment methods face challenges in achieving stable anisotropy and reliability.
Innovation Solution
A liquid crystal display is manufactured using a photoalignment layer formed by polymerizing cyclobutane dianhydride (CBDA) and its derivatives with a diamine, where the decomposition efficiency of the alignment layer is controlled between 10% and 30% through exposure to polarized light, enhancing anisotropy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rubbing method is used to align liquid crystals, then the liquid crystals can be aligned in a predetermined direction, but fine dust or static electricity may occur causing serious manufacturing problems
Solution Approach 1:
The patent replaces the mechanical rubbing method with a photoalignment method using polarized light irradiation. The polymer alignment layer is formed by polymerizing photofunctional groups through light exposure, which induces anisotropy and aligns liquid crystals without mechanical contact, thereby eliminating dust generation and static electricity issues inherent in rubbing methods
Solution Approach 2:
The patent changes the alignment mechanism from mechanical force (rubbing) to optical field induction (polarized light). By controlling the irradiation conditions and polymerization parameters, the alignment layer develops controlled anisotropy that directs liquid crystal orientation without physical contact, resolving the contradiction between alignment quality and contamination
2Reliability
If the decomposition efficiency of the photoalignment layer is too high, then the alignment force is improved, but the reliability and stability of liquid crystal alignment deteriorates
Solution Approach 1:
The patent optimizes the decomposition efficiency parameter of the photoalignment layer to a specific range (10-30%) through controlled polymerization of CBDA and diamine. This parameter optimization ensures sufficient alignment force while maintaining long-term stability and reliability of the liquid crystal alignment, preventing both insufficient alignment and excessive decomposition
3Reliability
If photodecomposition is used to align liquid crystals, then initial alignment is achieved, but the alignment force needs to be improved for more stable alignment
Solution Approach 1:
The patent uses a composite polymer alignment layer formed by polymerizing cyclobutane dianhydride (CBDA) and diamine with specific molecular structures. This composite material provides both initial alignment capability through photodecomposition and enhanced alignment force through controlled decomposition efficiency, achieving stable and reliable liquid crystal alignment
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 improves the alignment and reliability of liquid crystals by controlling the decomposition efficiency of the photoalignment layer, ensuring stable anisotropy and reducing afterimage issues, while maintaining a high contrast ratio and optimal voltage in the black state.
Implementation Method 1
the liquid crystals are arranged by using anisotropy, has been developed. Examples of a material usable in the photoalignment method include polymers containing a photofunctional group such as azobenzene, cumarine, imide, chalcone, and cinnamate, and in the polymers, a reaction such as photoisomerization, photocrosslinking, and photodecomposition, anisotropically occurs by radiation of polarized light
Implementation Method 2
a reaction such as photoisomerization, photocrosslinking, and photodecomposition, anisotropically occurs by radiation of polarized light
Implementation Method 3
a reaction such as photoisomerization, photocrosslinking, and photodecomposition, anisotropically occurs by radiation of polarized light
Implementation Method 4
the first alignment layer is formed by polymerizing at least one of cyclobutane dianhydride (CBDA) and a cyclobutane dianhydride (CBDA) derivative, and diamine
Data Source
AI summary
Provided is a liquid crystal display that includes: a first substrate; a thin film transistor disposed on the first substrate; a first electrode connected to the thin film transistor; and a first alignment layer disposed on the first electrode. The first alignment layer is formed by polymerizing a diamine and at least one of cyclobutane dianhydride (CBDA) and a cyclobutane dianhydride (CBDA) derivative. A decomposition efficiency representing a change in imidization ratio included before and after light exposure of the first alignment layer is in a range of 10% to 30%.