Electromagnetic wave reflecting member

Abstract

Disclosed is a selectively reflective member which can uniformly reflect only a desired wavelength with high efficiency even in a large area and, at the same time, is highly cost effective. Specifically, there is provided an electromagnetic wave reflecting member that reflects electromagnetic waves with a specific wavelength, the electromagnetic wave reflecting member comprising a first selectively reflective layer that reflects only a clockwise or counterclockwise circularly polarized light component with wavelength λ in incident electromagnetic waves, a phase difference layer, and a second selectively reflective layer that reflects only a clockwise or counterclockwise circularly polarized light component with wavelength λ, provided in that order, the phase difference layer having a retardation satisfying the following equation:

Re={(2n+1)/2±0.2}×λ

wherein Re represents average retardation; λ represents wavelength; and n is an integer of 1 or more.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an electromagnetic wave reflecting member and more specifically to an electromagnetic wave reflecting member that can efficiently and uniformly reflect electromagnetic waves with a specific wavelength falling within a visible to far-infrared light wavelength range.[0003]2. Background Art[0004]Selectively reflective members using cholesteric liquid crystals are known as a member that can selectively reflect a light component with a desired wavelength in a visible light to heat radiation wavelength range. These selectively reflective members can selectively reflect only light (electromagnetic waves) with a desired wavelength and thus are expected to be used, for example, as heat radiation reflecting films or light transparent and heat insulating films that are transparent to visible light and reflect only a heat radiation. In the cholesteric liquid crystal which can realize selective refle...

AI Technical Summary

Benefits of technology

[0024]According to the present invention, the phase difference layer held between the first and second selectively reflective layers that reflect only a clockwise or counterclockwise polarized light component with wavelength λ in electromagnetic waves has an average retardation satisfying the following relationship: Re={(2n+1)/2±0.2}×λ. Accordingly, for example, when a selectively reflective layer that selectively reflects near-infrared light with a wavelength of 1200 nm is used, the average retardation Re of the phase difference layer is 1800 nm at n=1, 3000 nm at n=2, 4200 nm at n=3, and 5400 nm at n=4. Therefore, eve

Problems solved by technology

Cholesteric liquid crystals having a counterclockwise spiral pitch, however, hardly exist in nature, and thus should be chemically synthesized and thus are highly expensive.

Accordingly, this leads to an increase in cost of selectively reflective members comprising a cholesteric liquid crystal film, which reflects a counterclockwise circularly polarized light component, and a cholesteric liquid crystal film, which reflects a clockwise circularly polarized light component, stacked on top of each other.

For this reason, the production of the above laminates on a commercial scale at low cost is difficult.

The casting method,

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