JPH0223040Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electromagnetic wave shielding space constituent material that is flexible and has electromagnetic wave shielding properties.

[Conventional technology] In recent years, with the heating of living cells by electromagnetic waves in the medical field, the computerization of office equipment in companies, and the introduction of microcomputers in the measurement field such as outdoor observation, leakage and intrusion of electromagnetic waves have become increasingly important. There is a growing interest in the problem of so-called electromagnetic wave shielding properties.

Conventionally, as a device for forming this type of electromagnetic shielding space, there is, for example, an electromagnetic shielding room. This is a structure formed by surrounding the entire room with metal plates or wire mesh, and is often used when constructing an anechoic chamber.

[Problems to be Solved by the Invention] However, conventional electromagnetic shielding rooms have the problem of high construction costs because they are used exclusively for special purposes. In addition, once constructed, it cannot be easily moved, so it cannot be used in cases where electromagnetic shielding space is required temporarily at any location, such as in the medical and outdoor observation fields, which is extremely inconvenient. There was a problem that.

To deal with this, shielding the electromagnetic waves with metal nets or plates can be considered, but these are not used because they are hard and difficult to work with, and are heavy and pose problems in portability.

On the other hand, in Utility Model Publication No. 44-18565, for example,
A radio wave shield is disclosed that can be shaped like a tent or the like. This radio wave shield is 10~20k
A semiconductive woven fabric consisting of semiconductive filaments having a resistance value of about Ω/cm/strand is coated with conductive filaments having a resistance value of 10 Ω/cm/strand or less in the warp or weft direction of the woven fabric. They are arranged in both the longitudinal and longitudinal directions and at sufficiently small intervals for the wavelengths they are intended to block.

However, this product uses semiconductive filaments, which are synthetic fiber yarns coated with semiconductive paint, and conductive filaments, which are synthetic fiber yarns coated with conductive paint.
There is a drawback in that the conductive paint tends to be missing when the woven fabric is folded. Therefore, tent-shaped electromagnetic wave shielding bodies that are frequently folded and the like deteriorate in shielding performance, have poor durability, and are difficult to be practically applied.

Furthermore, Japanese Patent Publication No. 55-27480 discloses an electromagnetic shielding base material consisting of a sheet made of conductive fibers with metal plating with an average thickness in the range of 0.5 to 3μ on the surface of chemical fibers. .

However, when this product is bent, the plating tends to peel off, and like the above-mentioned product, there is a practical problem in terms of durability.

Furthermore, in Japanese Utility Model Application Publication No. 61-33881, all or part of the threads are made of conductive fibers and heat-fusible fibers, and each thread is arranged almost evenly. A fabric for electromagnetic shielding is disclosed.

However, regarding the spacing of this thread,
No consideration is given to this, and the structure is such that metal threads and non-metal threads are simply arranged at approximately equal intervals in the warp and weft directions. Therefore, it is not known at all what wavelength of electromagnetic waves there is a shielding effect.
It is difficult to reliably prevent leakage and intrusion of electromagnetic waves.

The purpose of this invention is to be easy to install and remove, to be lightweight and easy to move, to prevent deterioration in shielding performance even after repeated bending, and to reliably shield electromagnetic waves according to the wavelength to be shielded. It is an object of the present invention to provide an electromagnetic wave shielding space constituent material capable of forming an electromagnetic wave shielding space capable of preventing leakage and intrusion.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention is made by weaving warps and wefts made of non-metallic fiber yarns and warps and wefts having metal filaments. An electromagnetic wave shielding space construction material comprising a woven fabric and a supporting member that supports the woven fabric to form a space of a predetermined shape, the space a being a distance between metal wires woven into the woven fabric. Electromagnetic waves that are configured by setting the line longitude d and the wavelength λ of the target electromagnetic wave to satisfy the inequality log ₁₀ a/λ≦6.19d/a−3.06 and 0.05≦d/a≦0.32. The object of the present invention is to provide a material for constructing a shielded space.

The above-mentioned cloth needs to have flexibility so that it can be formed into an arbitrary shape when assembled and folded when removed.

In order to shield electromagnetic waves, the above-mentioned cloth is a woven cloth made of general non-metallic fibers, with metal filaments arranged at appropriate intervals in both the warp and weft. For example, a woven fabric made of conductive core yarn (Japanese Unexamined Patent Publication No. 76357/1989) or a membrane-like cloth made of conductive thin wires and glass fibers and treated with a flexible material to keep them secret are used. .

The support member is made of a pipe, a joint, a wire, etc., and supports the cloth to realize a house-shaped, triangular-shaped, semicylindrical-shaped, etc.-shaped shielded space. The form of the shielded space is determined depending on its purpose; for example, in the case of outdoor use, the roof is triangular in consideration of rain and snow. In addition, in the case of indoor use,
The shape is a rectangular parallelepiped and the internal capacity is large.

Note that when leakage or intrusion of electromagnetic waves from the bottom of the shielded space becomes a problem, the bottom is also covered with the cloth.

[Operation] In the above configuration, the spacing and wire diameter of the metal filaments are determined according to the wavelength of the electromagnetic waves to be shielded according to the above two inequalities, so that appropriate shielding can be performed.

Furthermore, since the electromagnetic wave shielding cloth is woven with metal filaments together with non-metallic fibers, the properties of non-metallic fibers as general fibers are utilized to provide sufficient flexibility. Therefore, during assembly, it is easy to realize a predetermined shape framed by the support member, and it is also easy to disassemble and remove, and moreover, it is foldable and easy to carry.

Furthermore, since the present invention incorporates metal filaments, the conductive parts do not become missing or peel, compared to those coated with conductive paint or plated with metal. Therefore, even if it is frequently bent, the shielding performance will not deteriorate. That is, the electromagnetic wave shielding space constituent material of the present invention has sufficient durability against bending, etc., not only in terms of mechanical strength but also in terms of electromagnetic wave shielding performance.

Furthermore, unlike prefabricated houses, etc., the components are made of cloth and supporting members, so they are inexpensive and lightweight, and can be quickly assembled and disassembled at any location. Therefore, a shielded space with a large volume can be realized even indoors with narrow entrances and exits where it is difficult to carry in materials, remote areas in the mountains, etc.

Furthermore, the fabric itself has an electromagnetic wave shielding function, eliminating the need for metal plates, etc., and significantly reducing the weight of the components. Therefore, transportation becomes easy when used outdoors.

[Example] An example of the present invention will be described with reference to the drawings.

FIG. 1 shows a partially cutaway perspective view of an embodiment of an electromagnetic wave shielding tent to which the electromagnetic wave shielding space constructing material of the present invention is applied, and FIG. 2 shows an enlarged view of the portion viewed from arrow A.

The tent shown in these figures is an example of a house-shaped tent, and has a pipe 11 and a joint 1.
A frame 1 assembled by supporting members consisting of 2
0, and an electromagnetic wave shielding cloth 20 attached thereto.

The electromagnetic wave shielding cloth 20 is cut to correspond to an appropriate surface of the frame 10, and a plurality of sheets constitute one set.
When installing, each cut portion is connected to each other by appropriate means such as a string, but in this embodiment, a metal fastener 22 is attached to prevent leakage and intrusion of electromagnetic waves.

Moreover, since the cloth 20 can be cut,
The entrance/exit 21 can be provided at any position.
In this case, it is desirable to attach metal fasteners 22 to the peripheral edges of the entrance and exit to prevent leakage and intrusion of electromagnetic waves.

In this embodiment, as the electromagnetic wave shielding cloth 20,
As shown in Fig. 3, a fabric is used which is formed by blending warp 1 and weft 2 made of non-metallic fiber yarns used in general fabrics with warp 3 and weft 4 made of metal filaments. .

As the non-metallic fiber thread, either natural fiber or artificial fiber can be used depending on the use of the electromagnetic wave shielding fabric. For example, cotton, nylon, glass fiber, etc. can be used alone or in appropriate combinations.

As the metal wire, a metal wire such as aluminum or copper, or a twisted wire made of one or more metal wires can be used. In addition, depending on the application, a combination of metal wires and non-metal wires, metal fibers, or carbon fibers may also be used. Therefore, the metal wire in this specification includes not only metal but also a conductor such as carbon.

The warp 3 and weft 4 made of the metal filaments are
Each interval a and wire diameter d are determined by the inequality log ₁₀ a/λ≦6.19d/a−3.06 …(1) and 0.05≦d/a≦0.32 …(2) Set to satisfy.

In addition, within the above range, metal filaments having different wire diameters may be used and woven at different intervals in the warp direction and the weft direction.

Further, the warps 1 and 3 and the wefts 2 and 4 are woven at predetermined intervals. That is, in this embodiment, the warp 1 and the warp 3 include two warp threads for the former and one warp thread for the latter.
They are arranged in parallel at equal intervals, forming the basic lattice of the sutra. On the other hand, the weft yarns 2 and 4 are alternately arranged in parallel at equal intervals to form a basic weft lattice. These basic lattices are woven so as to be arranged at equal intervals.

The diameter and interval of each of the warp threads 3 and the weft threads 4, which are made of metal filaments, are determined by the wavelength λ of the target electromagnetic wave. For example, for warp thread 4, if metal wires with a wire diameter of 0.13 mm are arranged in parallel every 0.7 mm, the wavelength will be 100 mm or more (frequency 3 GHz or less)
When an electromagnetic wave is incident, the amount of transmission of a polarized wave component parallel to the metal wire can be suppressed to -40 dB or less.

Although this shielding property is not as good as that of a metal plate, it poses no problem for general use.
It is fully effective.

The effect on electromagnetic waves of the tent of the embodiment constructed using the electromagnetic shielding cloth constructed as described above will be explained with reference to the drawings.

In addition, in the above-mentioned example, metal wires are woven into both sides, but in order to simplify the explanation, here, as a theoretical model of the present invention, metal wires are woven into both sides.
Assume that an electric field E having only polarization components parallel to the grating is incident on a grating made up of an infinite number of metal wires 5 arranged in the longitudinal direction, as shown in Figure B.

In FIG. 4A, if the characteristic impedance of the medium in which the grating exists is Z0, the grating can be equivalently represented by a four-terminal circuit. An example of this is shown in FIG.

In the equivalent circuit shown in Figure 5, the reactance
Xa and Xb are determined as shown in Equations 3 and 4 as functions of the lattice spacing a, the incident electric field wavelength λ, the wire diameter d of the metal filament, the electric field incident angle θ, and the dielectric constant εγ of the medium.

These formulas are from MITRadiation Laboratory Series vol 10
“Waveguide hand book”P286 McGRAW
-HILL BOOK COMPANY, INC., 1951, and is well known.

Xb=Z0a cosθ/λ〓(πd/a) ² ...(4) However, λ〓=λ・ε ^-1/2 〓 Here, M in the third equation above is, M={m ² +2ma/λ 〓sinθ −(a cosθ/λ〓) ² } ^-1/2 −|m| ^-1 .

Now, if the normalized impedances of Xa and Xb are respectively =Za/Z0 and =Zb/Z0, the transmitted power ratio Pt is given by the fifth equation.

Using Equation 5 above, the transmitted power ratio Pt when an electromagnetic wave having an electric field component E in the direction of the metal wires is incident from the normal direction of the lattice plane in the air is
When the relationship with log ₁₀ (a/λ) is expressed using d/a as a parameter, the relationship shown in FIG. 6 is obtained.

In the same figure, for example, log ₁₀ (a/λ)=-2,
It can be seen that when d/a=0.2, Pt is approximately -40 dB. This is the attenuation that appears when an electric field with a frequency of 3 GHz, which has only polarization components parallel to the grating, is perpendicularly incident on a grating with a grating spacing of a = 1.0 mm and a diameter of metal wires of d = 0.2 mm. It's the amount.

From this Figure 6, find the region where the transmitted power ratio is -40 dB or less, with d/a on the horizontal axis and log ₁₀ on the vertical axis.
If (a/λ) is taken and expressed, it becomes the shaded area shown in FIG. The straight line in the figure is a least squares approximation curve of the boundary, and is expressed by Equation 6.

log ₁₀ a/λ=6.19d/a-3.06...(6) Therefore, in this example, the warp and weft of the woven fabric are
Since the metal wires are incorporated with a wire diameter and spacing that satisfy the first and second equations for the wavelength λ of the electromagnetic waves to be shielded, they are effective against electric fields that are biased in any direction. , it is possible to provide electromagnetic wave shielding characteristics due to the same effect as described above.

In addition, since the electromagnetic wave shielding cloth of the present example is constructed by interweaving ordinary fibers and metal filaments, the increase in weight is small and dyeing is easy.

In addition, the electromagnetic wave shielding cloth of this example takes advantage of the characteristics of ordinary fibers and can maintain sufficiently high flexibility, so it can be applied to spatial forms with large curvature, and can be used in various forms. Can be used for tents.

Furthermore, the electromagnetic wave shielding fabric according to the invention of this embodiment has the wire diameter and arrangement interval of the metal filaments set to the first
By selecting such that the formula and the second formula are satisfied, a sufficiently high shielding effect against arbitrary electromagnetic waves can be obtained. In this case, since the metal filaments and general fibers are interwoven, the mutual spacing between the metal filaments can be accurately maintained, unlike a fabric made of only metal filaments. Therefore, it acts on the target electromagnetic waves over a wide area of the entire woven fabric.

[Effects of the invention] As explained above, the present invention is easy to install and remove, is lightweight and easy to move, and can form an electromagnetic wave shielding space at low cost. It has the effect of reliably shielding electromagnetic waves.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of an embodiment of an electromagnetic wave shielding tent to which the electromagnetic wave shielding space constructing material of the present invention is applied, Fig. 2 is an enlarged view of the portion viewed from arrow A, and Fig. 3 is a diagram according to the present invention. FIG. 4A is a front view showing a theoretical model for explaining the operation of the electromagnetic wave shielding fabric, FIG. 4B is a sectional view thereof, and FIG. 5 is a partial enlarged view of an embodiment of the electromagnetic shielding fabric. Figure 6 is _a circuit diagram showing the equivalent circuit of the lattice according to the theoretical model of The graph, Figure 7, is based on the area where the transmitted power ratio is -40 dB or less from Figure 6 above, and the horizontal axis shows d/a,
This is a graph showing log ₁₀ (a/λ) on the vertical axis. 1, 3... Warp, 2, 4... Weft, 10... Skeleton, 11... Pipe, 12... Joint, 20
...Electromagnetic shielding cloth, 21...Entrance/exit, 22...Fusuna.

Claims (1)

[Claims for Utility Model Registration] A woven fabric formed by blending warps and wefts made of non-metallic fiber yarns and warps and wefts having metal filaments, and a woven fabric formed by supporting the woven fabric into a predetermined shape. an electromagnetic wave shielding space constituting material comprising a supporting member forming a space, wherein the distance a and the wire diameter d of the metal wires woven into the woven fabric are determined by the inequality log ₁₀ with respect to the wavelength λ of the target electromagnetic wave. An electromagnetic wave shielding space constituent material configured to satisfy a/λ≦6.19d/a-3.06 and 0.05≦d/a≦0.32.