Polymer Liquid Crystal Vertical Alignment Layer Low UV Dose
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Solution Overview
Problem
Current liquid crystal display technologies face challenges in achieving precise vertical alignment with existing polymer materials, particularly in controlling alignment at low UV doses and maintaining optical stability, which affects viewing angle characteristics and display luminance.
Innovation Solution
A polymer composition for liquid crystal vertical alignment layers is developed, incorporating a moiety that is photochemically isomerizable but not crosslinked, a moiety that is photochemically crosslinkable, and a moiety that stabilizes vertical alignment, allowing for efficient control of liquid crystal alignment at low UV doses and improved optical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoalignment techniques are used for vertical alignment, then alignment control is achieved, but the required UV dose is high and optical stability is insufficient
Solution Approach 1:
The patent employs a composite alignment layer comprising multiple components: a cinnamic acid derivative (for photochemical crosslinking and vertical alignment), a cyano-polymer (for thermal stability and alignment memory), and a photopolymerization initiator. This composite structure enables effective vertical alignment at low UV doses while maintaining optical stability, resolving the contradiction between alignment precision and energy consumption.
2Shape
If slits and ribs are formed in electrodes to control liquid crystal inclination, then domain-dividing structure is created, but response speed distribution occurs and optical transmittance decreases
Solution Approach 1:
The patent replaces the mechanical approach of forming slits and ribs in electrodes with a chemical/photochemical approach using an alignment layer. The cinnamic acid derivative in the alignment layer photochemically crosslinks to create the domain-dividing structure, eliminating the need for mechanical electrode modifications. This substitution achieves uniform response speed across the display while maintaining optical transmittance.
3Manufacturing precision
If monomer is added to liquid crystals for polymer sustained alignment, then alignment control is improved, but characteristics change and remaining monomers cause adverse effects
Solution Approach 1:
The patent extracts the monomer from the liquid crystal mixture and places it in a separate alignment layer. The cinnamic acid derivative is applied as a distinct layer that is subsequently photochemically crosslinked. This separation eliminates the problems of characteristic changes and remaining monomer effects while preserving the alignment control benefits, as the alignment function is achieved through the crosslinked polymer network rather than monomer-liquid crystal interactions.
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 polymer composition enables the fabrication of vertical alignment layers that enhance viewing angle characteristics and display luminance by allowing precise control of liquid crystal alignment with reduced optical exposure, leading to improved performance in liquid crystal display elements.
Implementation Method 1
a moiety that is photochemically isomerizable but not photochemically crosslinked
Implementation Method 2
a moiety that is photochemically crosslinkable
Data Source
AI summary
The present invention relates to materials used for aligning liquid crystals of liquid crystal display elements and to a polymer for use in liquid crystal vertical alignment layer used in producing a liquid crystal vertical alignment layer.The polymer for use in a liquid crystal vertical alignment layer includes (a) a moiety that is photochemically isomerizable but not photochemically crosslinked, (b) a moiety that is photochemically crosslinkable, and (c) a moiety that stabilizes a vertical alignment. The polymer can be used to produce a vertical alignment layer that has a liquid crystal alignment property enabling control of alignment at a low UV dose and that offers a large pretilt angle and superior optical stability.