Liquid Crystal Light Control Sheet for Stable Contrast
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Solution Overview
Problem
Light control sheets containing a dichroic dye in the liquid crystal composition face challenges in maintaining consistent contrast by varying light transmittance between transparent and opaque states.
Innovation Solution
A light control device with a transparent polymer layer containing voids and a liquid crystal composition including a dichroic dye, designed to achieve specific absorbance and absorbance differences between transparent and opaque states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dichroic dye is added to the liquid crystal composition to achieve colorless transparency and colored opacity, then the light control device can provide visual privacy and aesthetic benefits, but the contrast of the device varies in the plane of the light control sheet
Solution Approach 1:
The patent applies local quality by creating non-uniform distribution of liquid crystal composition within the transparent polymer layer. Specifically, the liquid crystal composition is concentrated in voids or cavities rather than being uniformly distributed, which allows different regions to have different optical properties. This localized concentration helps maintain consistent contrast across the device while preserving the aesthetic colorless-transparent/colored-opaque transition.
Solution Approach 2:
The patent utilizes a porous structure by incorporating voids or cavities in the transparent polymer layer that are filled with liquid crystal composition. This porous configuration allows the liquid crystal to be localized in specific regions, improving contrast consistency while maintaining the desired aesthetic effects. The voids create distinct phases that enhance the optical contrast when the liquid crystal transitions between states.
2Adaptability or versatility
If the liquid crystal composition is dispersed in the transparent polymer layer to achieve opacity through light scattering, then the device can transition between transparent and opaque states, but the absorbance characteristics vary leading to contrast variation
Solution Approach 1:
The patent applies segmentation by dividing the liquid crystal composition into discrete droplets or regions within the transparent polymer layer. Rather than having a continuous dispersion, the liquid crystal is segmented into separate phases located in voids. This segmentation creates more uniform optical pathways and reduces variations in absorbance and scattering, thereby stabilizing contrast across the device while maintaining the transparent-opaque transition capability.
Solution Approach 2:
The patent creates a composite material structure by combining transparent polymer with liquid crystal composition in a phase-separated configuration. The composite consists of a continuous polymer matrix with dispersed liquid crystal phases in voids. This composite structure allows optimization of both phases' properties - the polymer provides mechanical stability and optical clarity, while the liquid crystal provides the transition mechanism - resulting in stable contrast and reliable state changes.
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 device effectively suppresses variation in contrast by controlling light scattering and absorbance, ensuring stable transitions between transparent and opaque states.
Implementation Method 1
an alignment layer that applies an alignment regulating force to the liquid crystal compound. In an example of the alignment regulating force, alignment of the molecules of the liquid crystal compound is regulated so that the major axes of the molecules become substantially perpendicular to the plane of the alignment layer when the light control sheet is not driven
Implementation Method 2
The drive signal inputted to the light control sheet forms an electric field acting against the alignment regulating force so that the major axes of the molecules of the liquid crystal compound become substantially parallel to the plane of the alignment layer
Implementation Method 3
A light control sheet comprising a transparent polymer layer, and particles of a liquid crystal composition dispersed in the transparent polymer layer achieves opacity by scattering light due to difference in refractive index between the transparent polymer layer and the particles
Implementation Method 4
Addition of a dichroic dye to the particles achieves colorless transparency when not driven, while imparting color to the opacity when driven
Data Source
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AI summary
A light control device includes a transparent polymer layer having voids, and a liquid crystal composition containing a liquid crystal compound and a dichroic dye, and contained in the voids, and reversibly changes state from transparent to opaque. The light control device in a transparent state has an absorbance of 0.33 or more and 1.1 or less. The absorbance in a transparent state may be 0.8 or less.