PDLC Light Blocking Device with Twisted LC-Dye Droplets

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current transparent display devices face challenges in achieving high light blocking rates and transmittance due to limitations in polymer dispersed liquid crystal (PDLC) technology, particularly with regards to power consumption and contrast ratio, especially in varying environmental conditions.

Innovation Solution

A light blocking device utilizing a PDLC layer where liquid crystals and dichroic dyes are twisted within droplets, allowing for enhanced light blocking in the light blocking mode and increased transmittance in the light transmitting mode, while controlling the twisted angle to optimize performance and prevent increased driving voltage and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a PDLC layer is used to achieve light blocking mode, then light blocking capability is improved, but power consumption increases

Engineering Contradiction:
Improvelight blocking capabilityVSAvoidpower consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by modifying the voltage application strategy to the PDLC layer. By using a two-stage voltage approach (initial high voltage for rapid transition, then reduced voltage for maintenance), the system achieves effective light blocking while reducing overall power consumption compared to continuous high voltage application.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements periodic action through pulsed voltage application to the PDLC layer. The initial voltage pulse triggers the phase transition to blocked state, followed by periodic maintenance pulses at lower amplitude, creating a rhythm of energy input that sustains the light blocking function with reduced average power consumption.

Inventive Principle:
Principle #19Periodic action

2Object-affected harmful factors

If liquid crystals and dichroic dyes are twisted in droplets to enhance light blocking, then light blocking rate is improved, but driving voltage increases

Engineering Contradiction:
Improvelight blocking rateVSAvoiddriving voltage
Core Design Contradiction:
Object-affected harmful factorsVSStress or pressure

Solution Approach 1:

The patent utilizes parameter changes by optimizing the twisted angle of liquid crystals and dichroic dyes within the PDLC droplets. By controlling the twist angle parameter, the system enhances light blocking rate through improved optical anisotropy and dichroic absorption, while the two-stage voltage approach prevents excessive driving voltage by using reduced maintenance voltage after initial alignment.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If liquid crystals and dichroic dyes are twisted in droplets to enhance light blocking, then light blocking rate is improved, but power consumption increases

Engineering Contradiction:
Improvelight blocking rateVSAvoidpower consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by optimizing the twisted angle of liquid crystals and dichroic dyes within the PDLC droplets. By controlling the twist angle parameter, the system enhances light blocking rate through improved optical anisotropy and dichroic absorption, while the two-stage voltage approach prevents excessive driving voltage by using reduced maintenance voltage after initial alignment.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements periodic action through pulsed voltage application to the PDLC layer. The initial voltage pulse triggers the phase transition to blocked state, followed by periodic maintenance pulses at lower amplitude, creating a rhythm of energy input that sustains the light blocking function with reduced average power consumption.

Inventive Principle:
Principle #19Periodic action

4Illumination intensity

If LCD technology with polarizer is used to achieve transparency, then transparency is improved, but outdoor visibility deteriorates

Engineering Contradiction:
ImprovetransparencyVSAvoidoutdoor visibility
Core Design Contradiction:
Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by combining PDLC technology with dichroic dyes embedded in liquid crystal droplets. This composite structure provides both the transparency control of PDLC and the wavelength-selective absorption of dichroic dyes, enabling high transparency in indoor conditions while maintaining contrast and visibility in outdoor environments through the dichroic absorption properties.

Inventive Principle:
Principle #40Composite materials

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 improves light blocking rates and transmittance, maintaining image quality and reducing power consumption by effectively managing the alignment and interaction of liquid crystals and dichroic dyes, thus addressing the limitations of existing PDLC technologies.

Implementation Method 1

A light blocking device utilizing a PDLC layer where liquid crystals and dichroic dyes are twisted within droplets, allowing for enhanced light blocking in the light blocking mode and increased transmittance in the light transmitting mode

Methodology Applied
Scientific EffectLiquid crystal twisting: Liquid Crystals

Implementation Method 2

A light blocking device utilizing a PDLC layer where liquid crystals and dichroic dyes are twisted within droplets

Methodology Applied
Scientific EffectDichroic absorption: Dichroic Filter

Implementation Method 3

The liquid crystal is converted into a droplet in the polymer, thereby producing the PDLC. When an electric field is applied to the PDLC, the alignment of the liquid crystal located in the polymer is changed.

Methodology Applied
Scientific EffectPhase transition: Phase Change

Data Source

PatentEP3330785B1Light blocking device and transparent display device including the same
Publication Date: 2020.08.12 LG DISPLAY CO LTD
  • EP3330785B1 patent drawingFigure 1~2
  • EP3330785B1 patent drawingFigure 3~4
  • EP3330785B1 patent drawingFigure 5~6A

AI summary

Disclosed are a light blocking device, a method of manufacturing the same, and a transparent display device including the same, which transmit or block light by using a polymer dispersed liquid crystal (PDLC) layer. The light blocking device includes a first substrate and a second substrate facing each other, a first electrode on the first substrate, a second electrode on the second substrate, and a PDLC layer between the first electrode and the second electrode. The PDLC layer includes a droplet including liquid crystal and dichroic dye, and the liquid crystal and the dichroic dye are twisted with each other and aligned.