Smart Window Laminate With Conductive Polymer for Low-Voltage LC Driving

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Solution Overview

Problem

Conventional light control laminates for windows have fixed transmittance, leading to issues such as difficulty in visibility at night or daytime glare, increased manufacturing costs due to separate substrates, and high power consumption, along with adhesion issues between liquid crystal and conductive layers.

Innovation Solution

A light control laminate with a conductive polymer layer directly formed on polarizing plates, incorporating a liquid crystal layer composed of a polymerizable monomer and liquid crystal compound, allowing for uniform initial orientation and adhesion without a separate substrate, and operating at low voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate substrate is used to form a conductive layer, then the liquid crystal can be driven, but the manufacturing cost increases and the manufacturing process becomes more complicated

Engineering Contradiction:
Improveliquid crystal driving capabilityVSAvoidmanufacturing cost and process complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the substrate and conductive layer into a single integrated transparent conductive substrate, eliminating the need for separate substrate and conductive layer formation processes. This integration maintains the liquid crystal driving capability while significantly simplifying the manufacturing process and reducing costs.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The transparent conductive substrate serves multiple functions simultaneously: it acts as both the structural substrate and the conductive layer for driving the liquid crystal. This multi-functionality eliminates the need for separate components and reduces manufacturing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a separate substrate is used to form a conductive layer, then the liquid crystal can be driven, but the thickness of the laminate increases

Engineering Contradiction:
Improveliquid crystal driving capabilityVSAvoidlaminate thickness
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

By combining the substrate and conductive layer into a single transparent conductive substrate, the patent eliminates the additional thickness that would result from stacking separate substrate and conductive layer components, thereby reducing the overall laminate thickness while maintaining driving capability.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If a separate substrate is used to form a conductive layer, then the liquid crystal can be driven, but transmittance changes due to phase difference occur

Engineering Contradiction:
Improveliquid crystal driving capabilityVSAvoidlight transmittance
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The integration of substrate and conductive layer into a single transparent conductive substrate eliminates the interfaces between separate layers that cause phase differences and transmittance changes, thereby improving light transmittance while maintaining liquid crystal driving functionality.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If liquid crystal compound without reactive group is used, then the liquid crystal can be driven, but adhesion with conductive layer is poor and sealant is required

Engineering Contradiction:
Improveliquid crystal driving capabilityVSAvoidadhesion between liquid crystal and conductive layer
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent modifies the chemical parameters of the liquid crystal compound by introducing reactive groups (epoxy, hydroxyl, or carboxyl groups) that can chemically bond with the conductive layer. This chemical modification enables direct adhesion without requiring sealants, while the liquid crystal driving capability is preserved.

Inventive Principle:
Principle #35Parameter changes

5Reliability

If polymer dispersed liquid crystal is used, then the liquid crystal can be driven, but the liquid crystal compounds are phase-separated and cannot have constant initial orientation, requiring continuous voltage application

Engineering Contradiction:
Improveliquid crystal driving capabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the compositional parameters by using a specific ratio of liquid crystal compound to polymer (liquid crystal compound: polymer = 95:5 to 5:95 by weight) and incorporating reactive groups that enable uniform distribution and orientation. This prevents phase separation and allows the liquid crystal to maintain constant initial orientation without continuous voltage application, reducing power consumption.

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 laminate provides excellent adhesion, reduced thickness, simplified manufacturing, and lower power consumption, enabling flexible transmittance control without a separate substrate or alignment film.

Implementation Method 1

the first transparent conductive layer and the second transparent conductive layer contain a conductive polymer

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

driven by varying the transmittance by driving the liquid crystal according to the voltage application

Methodology Applied
Scientific EffectLiquid crystal electro-optic effect: Electro-Optic Effects

Implementation Method 3

the liquid crystal layer is a cured product of a liquid crystal layer-forming composition including a polymerizable monomer and a liquid crystal compound

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP4610720A1Light control laminate and smart window including same
Publication Date: 2025.09.03 DONGWOO FINE CHEM CO LTD
  • EP4610720A1 patent drawingFigure 1~2B
  • EP4610720A1 patent drawingFigure 2C~2E
  • EP4610720A1 patent drawing

AI summary

The present disclosure relates to a light control laminate which has excellent adhesion between the liquid crystal and the conductive layer and does not fall off easily so that damage to the laminate can be prevented, which has good cell drivability even at low voltage when implementing the light-transmitting mode even if the liquid crystal layer contains a polymer, which enables normal white to be implemented when no voltage is applied, and which has a significantly reduced thickness and a simplified manufacturing process compared to the conventional light control laminate, a smart window including the same, and an automobile or building window to which the same is applied.