PDLC Display Domain Design for Low-Afterimage Haze Uniformity

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Solution Overview

Problem

Polymer dispersed liquid crystal displays (PDLCDs) face issues with afterimages due to haze differences between domains, which can persist unless haze differences are eliminated.

Innovation Solution

A PDLCD design with a PDLC layer having liquid crystal droplets of specific sizes (0.8 to 1.5 µm) and thickness (15 to 25 µm), along with a polymer precursor containing specific compounds, is used to minimize haze differences and prevent afterimages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid crystal droplet size and PDLC layer thickness are not controlled within specific ranges, then manufacturing is simpler, but afterimage occurs due to haze differences between domains

Engineering Contradiction:
Improveafterimage reductionVSAvoidliquid crystal droplet size control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by specifying precise ranges for liquid crystal droplet size (0.8 to 1.5 μm) and PDLC layer thickness (15 to 25 μm). By controlling these physical parameters within defined boundaries, the invention achieves uniform haze across domains, reducing afterimage effects while maintaining manufacturability through clear specification limits.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If PDLC layer thickness is increased to improve scattering performance, then light scattering capability improves, but haze differences between domains increase causing afterimage

Engineering Contradiction:
Improvelight scattering capabilityVSAvoidhaze uniformity between domains
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent resolves this contradiction by optimizing the PDLC layer thickness to a specific range (15 to 25 μm). This parameter optimization ensures sufficient light scattering capability while maintaining uniform haze distribution across domains, preventing afterimage formation. The specific thickness range balances scattering performance with domain uniformity.

Inventive Principle:
Principle #35Parameter changes

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 proposed solution effectively reduces afterimages by controlling the size and distribution of liquid crystal droplets, maintaining haze differences below 0.3%, thereby improving the visual clarity and reliability of PDLCDs.

Implementation Method 1

in the absence of an initial potential difference, the scattered state in which incident light is scattered can be controlled

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

by applying a potential difference to the film and aligning the liquid crystal molecules in the same direction as the light direction, the transparent state in which incident light passes without scattering can be controlled

Methodology Applied
Scientific EffectLiquid crystal alignment: Liquid Crystals

Data Source

PatentEP4506751A1Polymer dispersed liquid crystal display with an improved afterimage
Publication Date: 2025.02.12 LIVICON CO LTD
  • EP4506751A1 patent drawingFigure 1
  • EP4506751A1 patent drawingFigure 2(a)~2(c)
  • EP4506751A1 patent drawingFigure 3

AI summary

One embodiment of the present application provide a polymer dispersed liquid crystal display including a first electrode; a second electrode on the first electrode; and a PDLC layer disposed between the first electrode and the second electrode; wherein the PDLC layer includes a liquid crystal droplet and a polymer surrounding the liquid crystal droplet, the liquid crystal droplet has a size in the range of 0.8 to 1.5 µm, the PDLC layer has a thickness in the range of 15 to 25 µm, and wherein the polymer dispersed liquid crystal display has multiple domains driven individually.