PS-TN Liquid Crystal Display Stabilization for Fast Response
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Solution Overview
Problem
Current LCDs face challenges in achieving fast response times while maintaining a 90° TN LC director configuration, high transmittance, and low driving voltage, which are necessary for applications like gaming and virtual reality.
Innovation Solution
A method involving a polymer-stabilized twisted nematic (PS-TN) LCD with a chiral additive inducing a helical twist in the LC medium, followed by polymerization to stabilize the 90° TN configuration, using a small amount of polymerizable mesogenic compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a short pitch TN LCD is used to achieve fast response time, then the decay response time is reduced, but the 90° TN LC director configuration becomes unstable and transforms into the 270° STN configuration
Solution Approach 1:
The patent applies a preliminary action by using photopolymerization to stabilize the 90° TN configuration before the instability can occur. The polymer network is formed in advance to lock the LC molecules in the desired orientation, preventing the spontaneous transformation to 270° STN configuration that would otherwise occur with short pitch designs.
Solution Approach 2:
The patent introduces an intermediary element - a polymer network formed from polymerizable compounds - that acts as a mediator to maintain the 90° TN configuration. This polymer network serves as a structural framework that holds the LC molecules in place, allowing the short pitch design to function without transforming into the unstable STN configuration.
2Stability of the object's composition
If polymer stabilization is applied to maintain 90° TN configuration, then the configuration stability is improved, but the transmittance and contrast ratio decrease and driving voltage increases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration of polymerizable compounds (1-30 wt%, preferably 5-20 wt%) and the polymerization conditions. By optimizing these parameters, the patent achieves sufficient stabilization while minimizing the negative effects on transmittance, contrast ratio, and driving voltage that would occur with higher polymer concentrations.
Solution Approach 2:
The patent uses partial action by incorporating a limited amount of polymerizable compounds rather than using full polymerization or higher concentrations. This partial stabilization approach provides just enough structural support to maintain the 90° TN configuration while leaving the majority of the LC medium unpolymerized, thus preserving good optical properties and low driving voltage requirements.
3Illumination intensity
If a small amount of polymerizable mesogenic compounds is used for stabilization, then the transmittance is maintained, but the stabilization effect may be insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration of polymerizable compounds within a specific range (1-30 wt%, preferably 5-20 wt%). This precise parameter control ensures that there is enough polymer to provide reliable stabilization of the 90° TN configuration while keeping the concentration low enough to maintain high transmittance properties.
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 method achieves fast response times, high transmittance, and low driving voltage, overcoming the limitations of prior art TN LCDs and PS-TN LCDs.
Implementation Method 1
the chiral additives induce in the LC molecules of the LC medium a helical twist along an axis perpendicular to the substrates with a given pitch p
Implementation Method 2
after applying the voltage or while applying the voltage, polymerizing the polymerizable mesogenic compounds of the polymerizable component B of the LC medium between the first and second substrate, preferably by exposure to UV radiation, thereby stabilizing the twisted nematic configuration of the LC medium
Implementation Method 3
applying an electric voltage, and the 90° TN configuration can then be stabilized by photopolymerization
Data Source
AI summary
The present invention relates to a method of manufacturing a liquid crystal display (LCD) of the polymer stabilized ultra fast (PS-UF) twisted nematic (TN) mode, to an LCD obtained by this method and to an LC medium used therein.