Cholesteric Liquid Crystal Infrared Reflective Member

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Solution Overview

Problem

Conventional infrared-ray reflective members are not effective in reflecting infrared rays contained in sunlight, which limits their heat insulating efficiency.

Innovation Solution

An infrared-ray reflective member with a selective reflection layer that reflects right-circularly or left-circularly polarized infrared rays, featuring specific reflection bands within the 800 nm to 1900 nm range, allowing efficient reflection of infrared rays while transmitting visible light, utilizing a combination of right-circularly and left-circularly polarized-light selective reflective layers and a λ/2 plate for enhanced reflectance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional infrared-ray reflective members are used, then visible light transmission is maintained, but infrared-ray reflection efficiency is insufficient

Engineering Contradiction:
Improveinfrared-ray reflection efficiencyVSAvoidheat insulating efficiency
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the helical pitch of the cholesteric liquid crystal to match specific infrared wavelengths (first band: 800-1000nm, second band: 1000-1900nm). This parameter optimization enables the selective reflection layer to reflect infrared rays with high efficiency while maintaining visible light transmission, directly resolving the contradiction between insufficient infrared reflection and heat insulating efficiency.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining cholesteric liquid crystal with specific polymers and additives to create a multi-functional coating layer. This composite structure provides both the optical properties needed for infrared reflection and the mechanical properties required for durable heat insulation, simultaneously improving infrared-ray reflection efficiency and heat insulating efficiency.

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If selective reflection layers are added to improve infrared reflection, then device complexity increases

Engineering Contradiction:
Improveinfrared-ray reflection efficiencyVSAvoidlayer structure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single integrated selective reflection layer made of cholesteric liquid crystal. This layer simultaneously provides infrared reflection for both the first radiant energy band (800-1000nm) and the second radiant energy band (1000-1900nm), as well as maintaining visible light transmission. By combining these functions in one layer rather than using separate layers, the patent improves infrared-ray reflection efficiency without proportionally increasing device 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 enables efficient reflection of infrared rays contained in sunlight, improving thermal insulation without hindering visible light transmission, and allows for the use of a wider range of materials for the reflective layers, enhancing reflectance properties.

Implementation Method 1

a selective reflection layer for reflecting an infrared ray of a right-circularly polarized light component or a left-circularly polarized light component

Methodology Applied
Scientific EffectCholesteric liquid crystal selective reflection: Cholesteric Liquid Crystal

Implementation Method 2

reflecting an infrared ray of a right-circularly polarized light component or a left-circularly polarized light component

Methodology Applied
Scientific EffectCircular polarization: Polarisation

Data Source

PatentEP3351980B1Infrared-ray reflective member
Publication Date: 2020.09.30 DAI NIPPON PRINTING CO LTD
  • EP3351980B1 patent drawingFigure 1~3B
  • EP3351980B1 patent drawingFigure 4A~5
  • EP3351980B1 patent drawingFigure 6~7B

AI summary

The present invention is intended for providing an infrared-ray reflective member which efficiently reflects infrared rays (heat rays) contained in sunlight while transmitting visible light rays. The present invention solves the problems by providing an infrared-ray reflective member for transmitting a visible light ray and reflecting an infrared ray having a particular wavelength, comprising an infrared-ray reflective layer having a selective reflection layer for reflecting an infrared ray of a right-circularly polarized light component or a left-circularly polarized light component, characterized in that the infrared-ray reflective layer has a second reflection band corresponding to a second radiant energy band containing a peak located second closest to a short-wavelength side of an infrared range of a spectrum of sunlight on earth, and when a maximum reflectance in the second reflection band is determined at R2 and a wavelength in a long-wavelength side for allowing half-value reflectance of the R2 is determined at λ4, the λ4 is 1250 nm to 1450 nm.