Polymerizable Mesogens for Homeotropic Liquid Crystal Alignment
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Solution Overview
Problem
Conventional liquid crystal displays (LCDs) with vertically aligned nematic (VA) technology face challenges in achieving fast switching times and high contrast without the need for polyimide alignment layers, which are costly and can degrade electrical resistance, and struggle with gray level generation and viewing angle dependency.
Innovation Solution
Incorporating self-aligning, polymerizable mesogens into the liquid-crystalline medium to achieve homeotropic alignment without polyimide layers, using specific polymerizable compounds that align with substrate surfaces and induce vertical alignment, allowing for the elimination of polyimide layers and simplifying manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyimide alignment layers are used to achieve homeotropic alignment in VA displays, then alignment quality is improved, but manufacturing cost increases and electrical resistance degrades
Solution Approach 1:
The patent extracts and eliminates the polyimide alignment layer from the display structure by incorporating homeotropic alignment functionality directly into the liquid crystal composition through polymerizable mesogenic compounds. This removes the separate alignment layer component and its associated manufacturing steps, reducing both cost and complexity while maintaining alignment quality.
Solution Approach 2:
The patent merges the alignment function with the liquid crystal medium by incorporating polymerizable mesogenic compounds that provide homeotropic alignment capability within the LC composition itself. This combines what were previously separate functions (alignment layer + LC medium) into a single integrated system, eliminating the need for polyimide layers.
2Manufacturing precision
If polyimide alignment layers are used to achieve homeotropic alignment, then alignment quality is improved, but electrical resistance decreases
Solution Approach 1:
The patent removes the polyimide alignment layer that causes electrical resistance degradation and replaces its alignment function with polymerizable mesogenic compounds in the LC medium. This extraction eliminates the harmful electrical interaction while preserving the desired homeotropic alignment capability.
3Ease of manufacture
If conventional VA technology is used without polymerizable mesogens, then manufacturing is simpler, but switching times are slow and contrast is reduced
Solution Approach 1:
The patent changes the physical and chemical parameters of the liquid crystal medium by incorporating polymerizable mesogenic compounds with specific molecular structures and properties. These parameter changes enable faster switching times and higher contrast while maintaining a relatively simple manufacturing process that doesn't require additional alignment layers.
4Speed
If polymerizable self-alignment additives are incorporated into LC media, then switching times improve and contrast increases, but device complexity increases
Solution Approach 1:
The patent merges the alignment function with the liquid crystal medium itself, eliminating the need for separate alignment layers and their associated manufacturing complexity. The polymerizable mesogenic compounds provide homeotropic alignment capability within the LC composition, simplifying the overall device structure while improving switching performance.
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 enables the production of VA displays with improved switching times, high contrast, and reduced production costs, while maintaining favorable viewing angle dependencies and stability, without the need for polyimide layers, thus enhancing the overall performance and efficiency of LCDs.
Implementation Method 1
self-aligning, polymerizable mesogens (polymerizable self-alignment additives) that cause homeotropic (vertical) alignment of the LC media to a surface
Implementation Method 2
The principle of electrically controlled birefringence, the ECB effect (electrically controlled birefringence) or DAP effect (deformation of upright phases)
Implementation Method 3
polymerizable component includes self-aligning, polymerizable mesogens
Data Source
AI summary
The present invention relates to liquid crystal media (LCM media) containing a low-molecular-weight component and a polymerizable component. The polymerizable component comprises self-aligning, polymerizable mesogens (polymerizable self-orientation additives) that effect a homeotropic (vertical) alignment of the LCM media on a surface or the cell walls of a liquid crystal display (LCD display). The invention therefore also includes LCD displays with homeotropic alignment of the LCM medium without orientation layers. The invention discloses novel structures for polymerizable self-orientation additives.