PDLC and GHLC Composite Light Control for Transparent Displays
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Solution Overview
Problem
Current transparent display devices face challenges in achieving high transmittance ratios in transparent mode and high light shielding ratios in light shielding mode, particularly due to issues with dichroic dyes absorption and scattering efficiency, which affect visibility and contrast ratios.
Innovation Solution
A light controlling apparatus utilizing multiple liquid crystal layers, including a polymer dispersed liquid crystal (PDLC) layer and a guest-host liquid crystal (GHLC) layer, with dichroic dyes, where the layers are arranged to minimize light absorption in transparent mode and maximize light scattering or absorption in light shielding mode, using alignment films and substrates to control the orientation of liquid crystals and dichroic dyes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single PDLC layer is used, then the device can scatter or transmit light without polarizing plates, but the transmittance ratio in transparent mode is insufficient
Solution Approach 1:
The patent combines PDLC layer and GHLC layer into a composite liquid crystal system. The PDLC layer provides light scattering capability while the GHLC layer with dichroic dyes enhances light absorption and color control. This composite structure achieves high transmittance ratio in transparent mode by coordinating the complementary functions of both layers, resolving the contradiction between transmittance performance and structural complexity.
Solution Approach 2:
The liquid crystal system is segmented into functionally distinct layers: PDLC layer for light scattering control and GHLC layer for light absorption and color filtering. Each layer is optimized for its specific function, allowing the overall system to achieve superior transmittance ratio without requiring polarizing plates, thus resolving the technical contradiction.
2Illumination intensity
If dichroic dyes are added to enhance light shielding, then light shielding ratio improves, but light absorption increases reducing transmittance in transparent mode
Solution Approach 1:
The patent applies different material properties to different layers: PDLC layer focuses on light scattering with minimal absorption, while GHLC layer contains dichroic dyes for selective light absorption. By localizing the absorption function to specific regions (GHLC layer), the system achieves high light shielding ratio when needed while maintaining high transmittance in transparent mode, resolving the energy loss contradiction.
Solution Approach 2:
The liquid crystal system dynamically switches between transparent and light shielding modes by applying voltage. In transparent mode, the dichroic dyes in GHLC layer are oriented to minimize absorption, while in light shielding mode, they are oriented to maximize absorption. This dynamic control resolves the contradiction between light shielding ratio and light absorption by allowing the system to adapt its properties based on operational requirements.
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 transmittance ratios in transparent mode while achieving high light shielding ratios in light shielding mode, improving visibility and contrast, and reduces the need for polarizing plates, thereby simplifying the manufacturing process and reducing costs.
Implementation Method 1
If an electric field is applied to the polymer dispersed liquid crystal (PDLC), arrangement of liquid crystals arranged in the polymer is varied. Therefore, the polymer dispersed liquid crystal (PDLC) layer may scatter or transmit light which is externally incident.
Implementation Method 2
using alignment films and substrates to control the orientation of liquid crystals and dichroic dyes
Data Source
AI summary
A light controlling apparatus, a method of fabricating the light controlling apparatus, and a transparent display device including the light controlling apparatus are disclosed, in which light may be transmitted or shielded using a polymer dispersed liquid crystal (PDLC) layer and a guest-host liquid crystal (GHLC) layer, where the guest-host liquid crystal layer includes dichroic dyes. The 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 polymer dispersed liquid crystal (PDLC) layer and a guest-host liquid crystal (GHLC) layer between the first electrode and the second electrode, wherein the PDLC layer includes first liquid crystals having droplets, and the GHLC layer includes second liquid crystals and dichroic dyes.