Alignment Composition Cross-Linking for LCD Afterimage Reduction
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Solution Overview
Problem
The existing alignment compositions for liquid crystal display panels, which include reactive mesogens as side chains of alignment polymers, often result in reduced mechanical strength and increased afterimage formation due to decreased cross-linking, affecting the display's transmissivity and response speed.
Innovation Solution
An alignment composition is developed that includes a polyimide backbone with a vertical alignment side chain and a reactive mesogen, where the reactive mesogen is separated from the alignment polymer, and a photo-reactive side chain is introduced to increase the degree of cross-linking, enhancing the mechanical strength and reducing afterimage formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If reactive mesogen is included as a side chain of alignment polymer, then transmissivity and response speed are improved, but degree of cross-linking is reduced and mechanical strength is reduced
Solution Approach 1:
The patent divides the alignment layer into two separate components: an alignment polymer without reactive mesogen side chains and a reactive mesogen compound. This segmentation allows the alignment polymer to provide structural strength while the separate reactive mesogen provides the desired optical properties and cross-linking capability, resolving the contradiction between mechanical strength and response speed.
Solution Approach 2:
The reactive mesogen is extracted from the alignment polymer structure and formulated as a separate compound. This extraction eliminates the negative effect of reactive mesogen side chains reducing cross-linking density, while still allowing the reactive mesogen to improve transmissivity and response speed when used in combination with the alignment polymer.
2Illumination intensity
If reactive mesogen is included as a side chain of alignment polymer, then transmissivity is improved, but degree of cross-linking is reduced
Solution Approach 1:
By segmenting the alignment layer into separate alignment polymer and reactive mesogen components, the patent enables the reactive mesogen to achieve high cross-linking density without being constrained by the polymer backbone structure. This segmentation allows both high transmissivity (from reactive mesogen orientation) and high cross-linking (from separate formulation) to coexist.
Solution Approach 2:
The patent creates a composite alignment system combining alignment polymer and reactive mesogen compound in specific ratios. This composite approach leverages the complementary properties of each component: the alignment polymer provides structural stability while the reactive mesogen provides optical performance and cross-linking, achieving both high transmissivity and high cross-linking degree.
3Speed
If reactive mesogen is included as a side chain of alignment polymer, then response speed is improved, but afterimage appears on screen
Solution Approach 1:
The patent segments the alignment layer into separate alignment polymer and reactive mesogen components, which resolves the contradiction between response speed and afterimage characteristics. The separate reactive mesogen formulation enables proper cross-linking that prevents afterimage while maintaining the fast response properties.
Solution Approach 2:
By formulating a composite alignment system with specific combinations of alignment polymer and reactive mesogen compound, the patent achieves both fast response speed and improved afterimage characteristics. The composite structure allows optimal cross-linking density that stabilizes the alignment and prevents afterimage formation while maintaining liquid crystal response 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
The proposed alignment composition improves the afterimage characteristics of display panels by increasing the degree of cross-linking, thereby enhancing the mechanical strength and display quality while reducing afterimage formation.
Implementation Method 1
the reactive mesogen may be represented by the following Chemical Formula 1... M4 represents an alkenyl group having a carbon number of 2 to 20 and including an unsaturated carbon bond as an end group... a an oxotetrahydrofuryl group having —(C═CH2)— substituted for at least one —CH2—, or an epoxy group
Data Source
AI summary
An alignment composition is presented that includes an alignment polymer and a reactive mesogen. The alignment polymer includes a polyimide backbone and a vertical alignment side chain combined with the polyimide backbone. The reactive mesogen may be represented by the formulaM5-M1-M2-M3-M4in which M1 represents a divalent organic group including an aromatic ring group, M2 representsM3 represents a single bond, —O—, —O—(CH2)a—O—, or —(CH2)a—O—, wherein “a” represents an integer of 1 to 20, M4 represents an alkenyl group or an alkynyl group having a carbon number of 2 to 20 an alkenylcarbonyl group having a carbon number of 3 to 20, an alkenylcarbonyloxy group having a carbon number of 3 to 20, a an oxotetrahydrofuryl group having —(C═CH2)— substituted for at least one —CH2—, or an epoxy group. M5 represents -M2-M3-M4 or -M3-M4.