Cholesteric Liquid Crystal Light Control for Transparent Displays
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Solution Overview
Problem
Transparent display devices based on LCD and OLED technologies face issues such as reduced transparency due to polarizing plates, high power consumption, and poor contrast ratios in various lighting environments, particularly in outdoor settings.
Innovation Solution
A light controlling apparatus using cholesteric liquid crystals that transition between a focal conic state for light shielding and a homeotropic state for transparency, incorporating dichroic dyes and refractive index matching layers to enhance light shielding and transmittance ratios without separate power consumption, and designed to reflect infrared or ultraviolet wavelengths rather than visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LCD technology is applied to transparent display devices, then the display can be realized with thin profile and low power consumption, but transparency is deteriorated by the polarizing plate
Solution Approach 1:
The patent removes the polarizing plate from the LCD structure, extracting the component that causes transparency deterioration while retaining the LCD's low power consumption benefits. The liquid crystal layer alone is used to control light transmission and reflection.
Solution Approach 2:
The patent changes the optical parameters of the liquid crystal layer by applying different voltages to switch between transparent and reflective states, enabling the display to control light transmission without requiring polarizing plates.
2Illumination intensity
If OLED technology is applied to transparent display devices, then no polarizing plate is needed, but power consumption is higher than LCD and true black display is difficult
Solution Approach 1:
The patent replaces the active light emission mechanism of OLED with a passive light reflection mechanism using liquid crystals. Instead of generating light through electrical excitation of organic materials, the system uses voltage-controlled liquid crystal orientation to reflect or transmit ambient light, significantly reducing power consumption.
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 achieves a high light shielding ratio in light shielding mode while maintaining a high transmittance ratio in transparent mode, reducing power consumption and manufacturing costs, and improving visibility and contrast ratios across different lighting conditions.
Implementation Method 1
a liquid crystal layer between the first electrode and the second electrode, the liquid crystal layer including cholesteric liquid crystals
Implementation Method 2
the cholesteric liquid crystals have a focal conic state in a light shielding mode in case where no voltage is applied
Implementation Method 3
and have a homeotropic state in a transparent mode in case where a voltage is applied
Implementation Method 4
applying cholesteric liquid crystals that reflect light of an infrared wavelength range and an ultraviolet wavelength range
Implementation Method 5
wherein the cholesteric liquid crystals are arranged randomly in a light shielding mode to scatter incident light
Implementation Method 6
a light controlling apparatus of which a light-shielding ratio is high in a light-shielding mode by using a liquid crystal layer that includes dichroic dyes
Implementation Method 7
a light controlling apparatus that includes refractive index matching layers to increase a transmittance ratio by reducing a refractive index difference
Data Source
AI summary
A light controlling apparatus includes first and second substrates facing each other; a first electrode on the first substrate; a second electrode on the second substrate; and a liquid crystal layer between the first electrode and the second electrode, the liquid crystal layer including cholesteric liquid crystals, wherein the cholesteric liquid crystals have a focal conic state in a light shielding mode in case where no voltage is applied, and have a homeotropic state in a transparent mode in case where a voltage is applied.