Light Control Sheet With Dichroic Dye for High Opaque Contrast
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Solution Overview
Problem
Existing light control sheets struggle to achieve a high contrast between transparent and opaque states, with insufficient differentiation in apparent hue and inadequate light blocking in the opaque state.
Innovation Solution
A light control sheet comprising a light control layer with an organic polymer layer containing voids filled with a liquid crystal composition and dichroic dye, sandwiched between transparent electrode layers, which switches states based on voltage application to align the liquid crystal compound and dichroic dye, ensuring a parallel light transmittance ratio greater than 80 between opaque and transparent states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a dichroic dye is added to a liquid crystal composition, then the light control sheet can switch between transparent and opaque states, but the contrast between transparent and opaque states is insufficient and the apparent hue differentiation is inadequate
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration of dichroic dye (0.1-10 wt%) and liquid crystal compound (90-99.9 wt%) in the composition, adjusting the ratio between these components to optimize the contrast ratio. It also controls the void size (1-100 μm) and polymer content (10-90 wt%) to achieve the desired optical properties while maintaining manufacturability
Solution Approach 2:
The patent creates a composite material system combining organic polymer, liquid crystal compounds, and dichroic dye in specific proportions. This composite approach allows the material to exhibit both the transparency of the polymer-liquid crystal matrix and the coloration properties of the dichroic dye, achieving high contrast while maintaining ease of manufacture through a unified material system
2Manufacturing precision
If the liquid crystal composition is optimized for high contrast, then the parallel light transmittance ratio improves, but the light blocking performance in opaque state becomes inadequate
Solution Approach 1:
The patent applies local quality by creating voids with specific size ranges (1-100 μm) distributed throughout the polymer matrix, where the liquid crystal composition fills these voids. This localized structuring ensures that light scattering occurs at optimal interfaces, simultaneously improving parallel light transmittance ratio and light blocking performance in the opaque state
Solution Approach 2:
The patent utilizes a porous polymer matrix with controlled void structures that fill with liquid crystal composition. The porous structure provides numerous polymer-liquid crystal interfaces that scatter light effectively, achieving both high parallel light transmittance ratio when aligned and adequate light blocking when disordered, while maintaining manufacturing precision through controlled void formation
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 solution enhances the contrast between transparent and opaque states, allowing for clear differentiation and effective light blocking in the opaque state, with a total light transmittance of 30% or less and a black or near-black coloration.
Implementation Method 1
the transparent electrode layers changes potential difference between the transparent electrode layers such that the light control layer switches from a transparent state to an opaque state exhibiting a first color due to change in alignment of the liquid crystal compound and the dichroic dye
Implementation Method 2
The light control layer includes the liquid crystal compound and the dichroic dye such that a parallel light transmittance PTa in the opaque state and a parallel light transmittance PTb in the transparent state satisfy a relationship PTb/PTa>80
Data Source
AI summary
A light control sheet includes a light control layer including an organic polymer layer including voids and a liquid crystal composition filling the voids, transparent electrode layers, and transparent support layers. The liquid crystal composition includes a liquid crystal compound and a dichroic dye, the light control layer is sandwiched between the transparent electrode layers, the light control layer and the transparent electrode layers are sandwiched between the transparent support layers, the light control sheet switches from a transparent state to an opaque state exhibiting a first color due to change in alignment of the liquid crystal compound and the dichroic dye in response to change in potential difference between the transparent electrode layers, and a parallel light transmittance PTa in the opaque state and a parallel light transmittance PTb in the transparent state satisfy a relationship PTb/PTa>80.