Wide Band Variable Transmittance Optical Device Using Guest-Host Liquid Crystal
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Solution Overview
Problem
Current liquid crystal guest-host devices for eyewear applications lack wideband absorption (>175 nm) and suffer from polarization dependence, which limits their optical performance and transmission swing, making them unsuitable for eyewear due to visual distortion issues.
Innovation Solution
A variable transmission optical device using a guest-host mixture of a liquid crystal host and dichroic guest dye between plastic substrates, with an electronically active cell that exhibits a wide absorption band (>175 nm) and controlled transmission states, and optionally includes an electronically passive layer or a second active cell for enhanced light reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional liquid crystal guest-host systems are used for eyewear, then the device can change transmission state, but the absorption band is limited to less than 175 nm and polarization dependence causes visual distortion
Solution Approach 1:
The patent uses a composite guest-host mixture containing multiple dichroic dyes (azure, blue, purple, red) dissolved in liquid crystal host material. This composite approach broadens the absorption band to greater than 175 nm while the specific molecular structures and concentrations are optimized to reduce polarization dependence and eliminate visual distortion for eyewear applications
Solution Approach 2:
The patent optimizes specific parameters including the concentration of each dichroic dye (0.1-5% w/w), the liquid crystal host material properties, cell thickness (3-10 micrometers), and operating temperature range to achieve wideband absorption (>175 nm) while minimizing polarization dependence and visual distortion effects
2Illumination intensity
If polarizer-based liquid crystal systems are used, then minimal transmission (nearly zero) can be achieved, but light transmission is limited to below 50% and polarization dependence increases
Solution Approach 1:
The patent extracts and eliminates the polarizer component from the traditional liquid crystal display structure. By using a guest-host system without polarizers, the invention achieves minimal transmission through the dichroic absorption properties alone, thereby reducing polarization dependence while maintaining effective light blocking in the dark state
Solution Approach 2:
The patent changes the fundamental operating parameters by using dichroic dyes with high absorption coefficients and optimizing their concentration and molecular orientation in the liquid crystal host, enabling dark state transmission control without relying on polarizer-based mechanisms
3Manufacturing precision
If glass substrates are used in liquid crystal devices, then manufacturing precision can be maintained, but the device is unsuitable for eyewear applications due to weight and comfort issues
Solution Approach 1:
The patent uses thin plastic substrate films instead of traditional glass substrates. These flexible thin films are coated with transparent conductive oxides and alignment layers, providing the necessary optical and electrical properties while dramatically reducing weight and improving comfort for eyewear applications
Solution Approach 2:
The patent changes the substrate material parameter from glass to plastic with controlled thickness (typically 0.5-2 mm), maintaining manufacturing precision through modern coating and alignment techniques while achieving the weight reduction necessary for comfortable eyewear
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 achieves a wide transmission swing with minimal polarization dependence, providing improved optical performance and reduced visual distortion, enabling effective light control across a broad spectrum while maintaining clarity and protection.
Implementation Method 1
The liquid crystal host material includes non-polarizing liquid crystal material having an axis of orientation that is alterable by adjustment of voltage applied across the substrates that can change between a clear-state orientation and a dark-state orientation perpendicular thereto
Implementation Method 2
The dye guest mixture comprises dichroic dyes which are dissolved within the liquid crystal host and which align with the orientation of the liquid crystal material
Data Source
AI summary
We describe a wide band variable transmission optical device having an electronically active cell comprising a guest-host mixture of a liquid crystal host and a dichroic guest dye material contained between a pair of plastic substrates. The liquid crystal host has an axis orientation that is alterable between a clear state orientation and a dark state orientation and the dichroic guest dye material includes one or more dichroic dyes. The optical device is characterized in that it exhibits a wide absorption band that is greater than 175 nm within a visible wavelength range of 400-700 nm, has a clear state transmission equal to or above 30% and a dark state transmission equal to or below 40%.