Cholesteric Liquid Crystal Infrared Reflective Plate

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Solution Overview

Problem

Existing infrared-light reflective technologies face challenges in achieving high heat-shielding capability without relying on costly and difficult-to-produce λ/2 plates, and they often struggle with incomplete reflection of light at oblique angles and surface temperature issues due to the use of metallic films or infrared-absorbing dyes.

Innovation Solution

A laminated structure comprising a substrate with at least four light-reflective layers of fixed cholesteric liquid crystal phase, where adjacent layers have opposite optical rotations and specific reflection center wavelengths, allowing for broadened selective reflectivity and high heat-shielding capability without the need for λ/2 plates, and an easy-adhesion layer for improved durability and adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a metallic film is used for heat shielding, then reflectivity is improved, but production cost increases and radio disturbance occurs

Engineering Contradiction:

Improveheat shielding capabilityVSAvoidproduction cost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent replaces expensive metallic films with a cost-effective cholesteric liquid crystal composition that can be applied through simple coating methods. The liquid crystal layer provides comparable or superior heat shielding performance without the high production costs associated with vacuum deposition of metallic films.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes metallic films (which block electromagnetic waves including radio waves) with a cholesteric liquid crystal-based optical system that selectively reflects infrared light through its helical structure, allowing radio waves to pass through unimpeded while maintaining heat shielding capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If a metallic film is used for heat shielding, then reflectivity is improved, but radio disturbance occurs

Engineering Contradiction:

Improveheat shielding capabilityVSAvoidradio disturbance

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The cholesteric liquid crystal layer is designed with specific local optical properties - it selectively reflects infrared wavelengths (heat radiation) while being transparent to radio waves and other electromagnetic frequencies. This localized spectral selectivity allows heat shielding without radio disturbance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes the unique optical parameters of cholesteric liquid crystals, specifically their helical pitch and refractive index anisotropy, to create wavelength-selective reflection. By controlling these parameters, the system reflects infrared light while transmitting radio waves, resolving the contradiction between heat shielding and radio communication.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If infrared-absorbing dye is used, then heat absorption is improved, but surface temperature rises and heat-shielding capability lowers

Engineering Contradiction:

Improveinfrared absorptionVSAvoidfilm surface temperature

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

Instead of absorbing infrared radiation and converting it to heat (which raises surface temperature), the cholesteric liquid crystal layer reflects infrared radiation back to its source. This converts the potentially harmful heat absorption into beneficial heat reflection, maintaining low surface temperature while achieving effective heat shielding.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces the thermal mechanism of infrared-absorbing dyes (which convert radiation to heat) with an optical mechanism based on selective reflection. The cholesteric liquid crystal's helical structure reflects infrared wavelengths directly without converting them to thermal energy, thus avoiding surface temperature rise.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Loss of energy

If λ/2 plate is used to improve reflection, then production cost increases and adaptability decreases

Engineering Contradiction:

Improvereflection efficiencyVSAvoidmaterial selection flexibility

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The cholesteric liquid crystal layer serves multiple functions simultaneously: it provides wavelength-selective reflection, maintains optical clarity, and can be applied to various substrates without requiring special λ/2 plates. This multi-functionality eliminates the need for separate retardation components and expands material selection flexibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the functions of the λ/2 plate and the reflective layer into a single integrated cholesteric liquid crystal system. The liquid crystal layer inherently provides both the retardation effect and the selective reflection, eliminating the need for separate components and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 the reflectivity and heat-shielding capabilities of the infrared-light reflective plate, particularly in the 700nm to 1300nm range, while maintaining high visible light transmittance and preventing yellowish coloration, thus providing effective sunlight shielding for buildings and vehicles.

Implementation Method 1

a light-reflective layer formed of a fixed cholesteric liquid-crystal phase, wherein adjacent two light-reflective layers have opposite optical rotations to each other... reflecting an infrared-light of a wavelength equal to or longer than 700nm

Methodology Applied

Scientific EffectSelective reflection: Reflection

Implementation Method 2

at least four light-reflective layers... formed of a fixed cholesteric liquid crystal phase

Methodology Applied

Scientific EffectCholesteric liquid crystal phase: Cholesteric Liquid Crystal

Data Source

PatentEP2442162B1Infrared light reflecting plate and laminated glass

Publication Date: 2021.07.21 FUJIFILM CORP

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AI summary

To provide an infrared-light reflective plate having the improved selective reflectivity characteristics. Disclosed is an infrared-light reflective plate reflecting an infrared-light of equal to or longer than 700nm comprising a substrate, and, on at least one of surfaces of the substrate, at least four light-reflective layers, X1, X2, X3 and X4, formed of a fixed cholesteric liquid crystal phase, and disposed in this order from the substrate, wherein the reflection center wavelengths of the light-reflective layers X1 and X2 are same with each other and are λ1 (nm), and the two layers reflect circularly-polarized light in opposite directions; the reflection center wavelengths of the light-reflective layers X3 and X4 are same with each other and are λ2 (nm), and the two layers reflect circularly-polarized light in opposite directions; and λ1<λ2 is satisfied.