JP4223763B2 - Radio wave absorbing member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio wave absorbing member, and more particularly to a sheet-like radio wave absorbing member that can suitably cover an object even if the surface of the object is curved like a cylinder.
[0002]
[Prior art]
In recent years, suppression of unnecessary radio waves has become an important issue in social life due to the remarkable spread of electronic information devices such as mobile phones and personal computers and the diversification of communication technologies.
For example, when you want to eliminate only unnecessary radio waves that are incident directly from a specific radio wave source to the receiving antenna and that are reflected from the wall of the building around the antenna. There is. In such a case, a method is adopted in which a building wall surface serving as a reflection surface is covered with a radio wave absorber to absorb unnecessary radio waves at that portion and reduce incidence on the receiving antenna.
[0003]
Various types of electromagnetic wave absorbers have been proposed in the past, such as pyramid-shaped ones in which carbon is contained in foamed urethane, ferrite tile sintered type, ferrite powder or rubber containing carbon powder or Examples include thin materials such as paints, woven fabrics and nonwoven fabrics using conductive fibers.
[0004]
[Problems to be solved by the invention]
However, each of the conventional wave absorbers provided for construction on the wall surface has a problem that it takes time to construct and a problem that the surface layer structure on which the wave absorber is constructed becomes large.
[0005]
For example, in the case of a radio wave absorber that has a sheet shape and is attached to a wall surface via an adhesive, it takes time to apply the entire surface of the adhesive to the wall surface. In addition, there is concern about peeling due to the change in the adhesive state over time, and it is necessary to further drive screws, anchors, and the like into the wall surface in order to prevent dropping.
In addition, in a panel type radio wave absorber that is relatively smaller than the sheet-like one, it is necessary to assemble the base on which the panel is mounted on the wall surface, so it takes time for construction, and the surface layer structure related to radio wave absorption is large. Become. There is also a problem that it is difficult to mount along a curved surface.
[0006]
An object of the present invention is to solve the above-mentioned problems and provide a radio wave absorbing member that can be easily and satisfactorily installed even if the wall surface to which radio wave absorptivity is to be imparted is curved, and that is excellent in transportability and handling properties There is to do.
[0007]
[Means for Solving the Problems]
As a result of studying the above problems, the present inventors first covered the surface of the radio wave absorber 3 with flexible sheet-like materials 11 and 12 as shown in FIGS. 4 (a) and 4 (b). It came to produce the cushion-shaped electromagnetic wave absorbing member like a cushion or cushion. Due to the flexible cushioning property of this cushion-shaped electromagnetic wave absorbing member, even if the construction target surface is a curved surface, it can be easily and satisfactorily arranged along the curved surface by providing a through hole h and connecting it with a string or the like. It became so.
However, when the actual handleability and workability were examined in more detail, it was found that, for example, when the construction target surface has a large area, problems still need to be improved.
[0008]
For example, when the cushion-shaped electromagnetic wave absorbing member is arranged on a large-area wall surface, main arrangement modes are as follows: (1) A mode in which a relatively small area of the radio wave absorbing member is manufactured and arranged, and (2) (2) A mode in which a relatively large area of the radio wave absorbing member is manufactured and arranged in a small number is conceivable. However, in the arrangement mode {circle around (1)}, since many radio wave absorbing members are arranged side by side like tiles, it takes time to lay them. On the other hand, in the arrangement mode (2), since the radio wave absorbing member is a large mattress that is heavy and difficult to bend, it is difficult to carry and handle.
[0009]
In order to improve the above problems, the present inventors have made the cushion-shaped radio wave absorption member relatively large in area and rolled the entire member by imparting a stab-like or quilted structure to the member. The present invention has been completed by finding that it can be easily wound up into a shape and the transportability and handleability can be improved.
That is, the radio wave absorbing member of the present invention has the following characteristics.
[0010]
(1) Two flexible sheets are superposed, at least one of the sheets has radio wave transmission, and the radio wave of the following (A) presenting a sheet shape between the two flexible sheets. An absorber is sandwiched between the flexible sheet, the radio wave absorber, and the flexible sheet. The path surrounds the outer peripheral edge of the two flexible sheets and the path across the sheet surface. along, manufactured by sewing to couple the flexible sheet between the two said is subjected, whereby are formed two or more room between the flexible sheet 2 sheets above, each room The electromagnetic wave absorber of the following (A) is accommodated , and the electromagnetic wave absorber is present between the flexible sheets in the sewing part, and the electromagnetic wave absorbers in the individual rooms communicate with each other. , mat-shaped fiber aggregate constituting the electric wave absorber, the sheet side having radio wave transmittance Wherein the fiber density is changed so that successively higher toward the Luo other sheet side, the radio wave absorbing member.
(A) From a mat-like fiber assembly formed by entwining and bonding fibers made of a plurality of types of polar polymers coated with carbon so as to contain at least 5% by weight of various fibers An electromagnetic wave absorber, wherein the fiber density of the fiber assembly changes in the thickness direction.
(2) The radio wave absorbing member according to (1), wherein the material of the flexible sheet having radio wave permeability is a fiber reinforced plastic obtained by reinforcing an organic polymer material with glass fiber.
(3) The radio wave absorption according to (1), wherein the shape of the room when the one sheet surface of the radio wave absorption member is viewed is a square, and the dimensions of the square are 200 mm × 200 mm to 500 mm × 500 mm. Element.
(4) The radio wave absorbing member according to (1), wherein a through hole for passing a string for arranging the radio wave absorbing member is provided on an outer peripheral edge of the radio wave absorbing member.
(5) The radio wave absorbing member according to (4), wherein a part or the entire circumference of the outer peripheral edge including the portion where the through hole is provided is an ear portion in which the flexible sheets are in direct contact with each other.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The radio wave absorbing member according to the present invention has a flexible cushioning property as a whole and has a sheet shape. Hereinafter, of both surfaces of the radio wave absorbing member, a surface on which radio waves should be incident is referred to as a “radio wave incident surface”, and a surface on the opposite side is referred to as a “back surface”.
1A and 1B are schematic views showing an example of the structure of the radio wave absorbing member. FIG. 1A is a view of a radio wave incident surface, and FIG. 1B is an enlarged view of a part of a cross section. . In addition, in FIG.1 (b), since the electromagnetic wave absorber is drawn so that it may not mutually communicate between rooms formed between flexible sheets, this FIG.1 (b) The configuration in which the radio wave absorbers are not in communication with each other is a reference diagram for the present invention, but the configuration other than the configuration can be referred to as a diagram for explaining the present invention. The same applies to FIG. 1B. As shown in these drawings, the radio wave absorbing member includes two flexible sheets 1 and 2 stacked together, and the radio wave absorber 3 of the above (A) in the form of a cushion sheet is accommodated therebetween, As a result, the whole is a sheet-like structure having a flexible cushioning property.
[0016]
Among the flexible sheets 1 and 2, at least one of the sheets has radio wave permeability for the radio wave incident surface. Along the path surrounding the outer periphery of the flexible sheets 1 and 2 (for example, the outer periphery path a shown in FIG. 1A) and the path crossing the sheet surface (for example, the path b shown in FIG. 1A). Sewing (which may be joined as will be described later) 4 for joining the two flexible sheets is performed, so that there are two or more between the two flexible sheets. The room is formed. Hereinafter, the case where sewing is used as the means for forming the room will be described.
[0017]
In the example of FIG. 1, the space between the flexible sheets 1 and 2 is formed into a quilting structure by sewing 4 by stab stitching, and the area shown by hatching is divided into a single room and arranged in six. However, the number of rooms is an example for explanation. In each room, as shown in FIG. 1B, the radio wave absorber 3 of (A) is accommodated. In each room, the mat-like fiber aggregate constituting the radio wave absorber 3 has a fiber density from the radio wave transmitting sheet side toward the other sheet side (that is, from the radio wave incident surface side toward the other side). Are arranged so as to increase sequentially.
[0018]
By adopting the above-described configuration, it is light, highly cushioning, and can be easily attached to the wall surface without impairing the flexible property as the mat-like fiber aggregate that is a feature of the radio wave absorber of (A). A radio wave absorbing member is obtained.
Further, by providing a sashimi-like sewing structure, the portion is more easily bent, the whole member can be easily wound into a roll shape, and transportability and handleability are improved.
[0019]
In the present invention, it is important to select and use the radio wave absorber (A) from among various radio wave absorbers conventionally used.
The radio wave absorber of the above (A) is formed by entwining and bonding fibers 31 made of a plurality of types of polar polymers coated with carbon 32, as shown in FIG. Mat-like fiber assembly. Each of the fibers of each thickness is contained in an amount of 5% by weight or more, whereby the radio wave absorption band is widened and the radio wave absorption rate in each band is good. Further, as shown in FIG. 1B (similar to FIG. 4B), radio wave absorption is performed between the flexible sheets 1 and 2 so that the fiber density of the mat-like fiber aggregate changes in the thickness direction. The body 3 is arranged. In FIG. 1B, the density change in several steps is depicted because of the expression by hatching, but the number of change steps is not limited, and the change may be continuous (stepless). The fiber density may be changed so that radio waves are absorbed most effectively.
[0020]
By changing the fiber density of the mat-like fiber assembly in the thickness direction, the reflection of the radio wave on the radio wave incident surface is reduced, and the radio wave is easily taken into the radio wave absorber. It can absorb well. Due to this effect, other radio wave absorbers require a reflector (metal plate) on the back side, whereas the radio wave absorber in (A) above does not require a reflector on the back side, and is flexible. The mat-like fiber aggregate having a high cushioning property can be used as it is.
[0021]
The electromagnetic wave absorber (A) used in the present invention is described in detail in Japanese Patent Publication No. 6-32417, and reference may be made to the fiber material, thickness, carbon coating, manufacturing method, and the like.
[0022]
The radio wave absorbing member has a cushion sheet shape as a whole, and there is no limitation on the outer shape and area of the sheet, but the present invention has a problem in handling when attached to a construction target surface having a large area. In view of this point, the usefulness appears remarkably when the sheet surface of the radio wave absorbing member has a relatively large area. The outer shape of the entire sheet of the member is preferably a square (square, rectangular) from the viewpoint of easy cutting and processing, but depending on the application, such as the shape of the construction target surface, a triangle, a polygon, An arbitrary shape such as a circle may be used.
[0023]
There is no limitation on the outer shape and dimensions of the entire sheet of the electromagnetic wave absorbing member. For example, a rectangular sheet of about (500 mm × 500 mm) to (2000 mm × 2000 mm) may be used, and the width may be about 300 mm to 1000 mm. About a length direction, you may provide as a state which wound long enough.
Moreover, although there is no restriction | limiting in the total thickness of the said electromagnetic wave absorption member, From the normal thickness of said (A), about 20-50 mm is a preferable thickness.
[0024]
The flexible sheet should just have the flexibility of the grade which does not impair the softness | flexibility and cushioning property of the electromagnetic wave absorber of said (A). Furthermore, if you use a material with the desired properties such as waterproofness and airtightness, it is possible to prevent foreign substances such as water, dust, and exhaust gas from entering the radio wave absorber, thereby suppressing the deterioration of radio wave absorption capability. You can also.
Of the two flexible sheets sandwiching the radio wave absorber, at least one sheet is assumed to have radio wave permeability. Also, both sheets may have radio wave permeability, or a radio wave incident surface and a back surface may be clearly distinguished by using a flexible laminate sheet including a metal foil layer or the like as a back side sheet. . When a material that does not have radio wave transmission is used for the back side sheet, color separation may be performed so that the front and back sides can be easily distinguished.
It is important that the sheet used for the radio wave incident surface does not reflect radio waves as much as possible on the sheet surface (interface with air). The flexible sheet not only allows radio waves to pass but also absorbs radio waves. It may have properties.
[0025]
Any material may be used for the flexible sheet, but it is possible to use an organic polymer that has radio wave permeability and is excellent in water resistance, weather resistance, mechanical strength, workability, and the like. Materials. Among organic polymer materials, acrylic resin, polyvinyl chloride resin, unsaturated polyester resin, polyethylene resin, polypropylene resin, polyvinylidene chloride, polycarbonate, or FRP (fiber reinforced plastic) reinforced with glass fiber are preferable. Etc.
Moreover, you may add a flame retardant etc. to an organic polymer material in the range which does not reduce the said characteristic.
[0026]
The structure of the flexible sheet may be a woven fabric (knitted fabric) made of fibers or a single membrane obtained by extrusion, etc., and the fabric (knitted fabric) is impregnated and coated with a plastic material. It may be. What is necessary is just to determine these suitably according to requirements, such as airtightness.
[0027]
The thickness of the flexible sheet may be determined according to flexibility, mechanical strength, weight, radio wave transmissivity when used on the radio wave incident surface side, and is generally 0.2 mm to 2.0 mm in general. The degree is a preferred thickness range.
[0028]
As shown in FIG. 1B, the thickness of the two flexible sheets may be equal to the front and back, and the degree of unevenness caused by sewing may be equal to the front and back, as shown in FIG. 3A. Alternatively, one thickness may be made thinner than the other, and unevenness may be mainly generated on the thinner side by sewing.
In FIG. 3A, the radio wave absorber is drawn so as not to communicate with each other between the rooms formed between the flexible sheets. The configuration in which the radio wave absorbers are not in communication with each other is a reference diagram for the present invention, but the configuration other than the configuration can be referred to as a diagram for explaining the present invention. Hereinafter, the same applies to FIG.
[0029]
As an internal structure of the radio wave absorbing member, as a reference example, as shown in FIG. 1 (b), a mode in which a radio wave absorber is separately accommodated in each room formed by sewing (that is, radio wave absorption in the sewing portion). As an embodiment of the present invention, as shown in FIG. 3 (b), there is a radio wave absorber between the flexible sheets in the sewn portion 6, and the individual chambers A mode in which the radio wave absorbers are in communication with each other is exemplified.
In particular, in the embodiment shown in FIG. 3B, two flexible sheets and a radio wave absorber are prepared as sheets of sizes for manufacturing purposes, respectively (flexible sheet / radio wave absorber / flexible This is a preferable structure because the radio wave absorbing member can be easily obtained by simply superimposing the three layers so as to form a sheet, and then performing sewing as shown in FIG.
[0030]
The shape of each room formed by sewing (that is, the sewing pattern) is not limited, but in addition to the lattice-like sewing pattern in which rectangular rooms are arranged in a matrix as shown in FIG. Sewing patterns that are closely arranged, sewing patterns in which one or more other shaped rooms are repeatedly arranged, radial sewing patterns, striped sewing patterns, or sewing patterns in which these patterns are combined Can be mentioned. Among these, a sewing pattern in which squares and triangles are arranged is preferable because the pattern can be formed by linear sewing and the direction of bending is practical in three directions and four directions. For example, various sewing patterns may be employed depending on the application and required bending.
In sewing, a sealing process using an adhesive that also serves as a waterproofing process for the seam may be performed.
[0031]
When the shape of the room is a square, the size of one square is preferably about 200 mm × 200 mm to 500 mm × 500 mm, and a square and a rectangle may be arbitrarily determined from these ranges. In consideration of the bendability in actual use and the point of securing the width of the radio wave absorbing portion, a dimension of about 300 mm × 300 mm to 400 mm × 400 mm is particularly preferable.
Even when the shape of the room is a shape other than the rectangular shape, the sewing pattern may be set to have an equivalent area with reference to the dimensions in the case of the rectangular shape.
[0032]
As a means for forming a room between the flexible sheet two, is an aspect of the present invention, in addition to sewing with thread, as a reference example, as shown in the portion 4a of FIGS. 3 (a) Bonding without using a thread (for example, bonding by an adhesive, bonding by thermocompression bonding, bonding by ultrasonic waves, bonding by high-frequency heating), and the like. The joining may be a process in which a radio wave absorber is sandwiched between two flexible sheets.
The thread used for sewing has a strength that can withstand the sewing structure itself, and preferably has weather resistance and flame retardancy. From these points, a thread composed of cotton thread, polyester, nylon, and polynosic is preferable.
[0033]
In order to facilitate attachment to the wall surface, various attachment structures may be further added to the radio wave absorbing member. As a specific example, as shown to Fig.1 (a), you may provide the through-hole 5 for letting a string etc. pass in the outer periphery of the said electromagnetic wave absorption member.
By passing the string through the through hole, the string can be easily bound along the curved surface of the cylinder. It is preferable to appropriately reinforce the through-holes by means of rounded eyes or thickening.
Moreover, it is good also as an ear | edge part by making two flexible sheets of the site | part which forms this through-hole directly contact | adhere. The ear portion may be extended to the outside from the outer shape of the sheet, and may be an ear portion for attachment having a sufficiently wide area for the through hole. The position of the ear portion may be a part or all of the outer periphery, and may be appropriately determined so that the radio wave absorbing member can be fixed.
[0034]
By directly adhering the flexible sheets to each other around the outer peripheral edge of the member, the internal radio wave absorber can be sealed, but the sealing structure is achieved by bonding and joining the flexible sheets. Alternatively, the end face may be covered with a sealing tape.
[0035]
Advertisements and arbitrary characters / patterns may be printed on the surface of the flexible sheet, especially the part that becomes the radio wave incident surface. As a display board while absorbing radio waves, it is used for public, government, and consumer use. It will be useful.
[0036]
Since the radio wave absorbing member can be easily fixed by a string when the construction target surface is a wide curved surface, particularly a cylindrical curved surface, the advantage appears remarkably. For example, some ships are equipped with artillery and turrets for defense and security purposes, and may have to act so that they are not detected by the opponent's radar.
The radio wave absorbing member of the present invention is particularly useful for such radar countermeasures in ships. That is, since the main body of the gun is a cylindrical curved surface, the member can be easily fixed by being wound around the surface of the main body of the gun with a string, and can be easily arranged along the curved surface of the turret. In addition, since the internal radio wave absorber is protected by the flexible sheet, it is possible to suppress deterioration of the characteristics of the internal radio wave absorber due to a sea breeze or the like even when used on the ocean for a long time.
[0037]
【Example】
In this example, a radio wave absorber having the quilting structure shown in FIG. 3B was actually manufactured by sandwiching the radio wave absorber of (A) above using a surface-treated Tetoron canvas.
[0038]
The electromagnetic wave absorber of the above (A) is a fiber made of a polar polymer having a fiber diameter of 1000 (denier) of 70% by weight, a fiber diameter of 120 (denier) of 15% by weight, and a wire diameter of 50 (denier). 70 entwined in a proportion of 15% by weight ones (denier), Telecommunications incident side 0.03 g / cm ³ specific gravity as wave absorber mat-shaped fiber assembly such that the rear surface side 0.06 g / cm ³ Next, an adhesive was sprayed to bond and fix the fibers, and a carbon paint was sprayed to form. Here, denier is a unit representing the thickness of silk yarn, nylon yarn, etc., and one denier is 450 meters in length and 0.05 grams in mass.
The obtained radio wave absorber has a rectangular flat plate shape with a thickness of 25 mm and an outer shape of 900 mm × 1800 mm.
[0039]
Both of the flexible sheets are two-sided flat Tetoron canvas (trade name: New Superstar 2001, disaster prevention product certification number F05030, manufactured by KANBO PRAS) with fluorine antifouling treatment on the surface, The thickness is 0.46 mm and the weight is 550 g / m ² . The external shape is 1000 mm × 1900 mm.
[0040]
As shown in FIG. 3B, a three-layer structure (flexible sheet 1 / wave absorber 3 / flexible sheet 2) is formed, and a lattice pattern is sewn with a thread made of polyester and having a thickness of 1 mm. gave.
[0041]
The sewing pattern was a lattice-like pattern with a pitch of 300 mm so that a square room with a side of 300 mm was partitioned, and a side edge portion with a width of 50 mm was secured over the entire circumference. With this sewing pattern, a radio wave absorbing member in which square rooms with sides of 300 mm were arranged in 3 rows × 6 columns was obtained.
The sealing structure of the outer peripheral edge was obtained by sandwiching the adhesive polymer between the flexible sheets and thermally welding it.
Further, through holes having a diameter of 8 mm were formed in this side edge portion in accordance with the four corners and the pitch of the sewing pattern of 300 mm.
[0042]
As a result of evaluating the mounting / removing workability and the mounting state of the radio wave absorbing member, it is possible to easily attach / remove a flat wall surface by hooking a through hole on a hook provided on the wall surface. Also, it was possible to easily wrap a cylindrical column using a rope. In addition, it can be attached with an adhesive while well following the unevenness of the wall surface and the curvature of the cylinder.
When this radio wave absorbing member was attached to a cylinder and radio waves having a frequency of 5.8 GHz were incident at an incident angle of 30 ° by the arch method, the radio wave absorption amount was 20 dB or more, and it was found that the radio wave absorption characteristics were good.
In addition, this electromagnetic wave absorbing member can be wound in a roll shape despite its relatively large overall dimensions (1000 mm × 1900 mm), and is easy to transport, store and handle to the construction site. It was confirmed that it was good.
[0043]
【The invention's effect】
As described above, the radio wave absorbing member according to the present invention can be easily and satisfactorily arranged even when the wall surface to which radio wave absorptivity is to be imparted is curved, and is excellent in transportability and handling properties.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of the structure of a radio wave absorber according to the present invention. FIG. 1A is a view of the radio wave incident surface, and FIG. 1B is an enlarged view of a part of the XX cross section of FIG. In addition, in FIG.1 (b), since the electromagnetic wave absorber is drawn so that it may not mutually communicate between rooms formed between flexible sheets, this FIG.1 (b) The configuration in which the radio wave absorbers are not in communication with each other is a reference diagram for the present invention, but the configuration other than the configuration can be referred to as a diagram for explaining the present invention.
FIG. 2 is an enlarged schematic view showing a structure of a mat-like fiber assembly constituting a radio wave absorber.
FIG. 3 is a cross-sectional view showing another example of the structure of the radio wave absorber according to the present invention. In FIG. 3A, the radio wave absorber is drawn so as not to communicate with each other between the rooms formed between the flexible sheets. The configuration in which the radio wave absorbers are not in communication with each other is a reference diagram for the present invention, but the configuration other than the configuration can be referred to as a diagram for explaining the present invention.
FIG. 4 shows the structure of a cushion-shaped radio wave absorbing member invented by the present inventors to solve the conventional problems (however, the radio wave absorbing member of the present invention has problems solved). FIG. FIG. 4A is a view of the plate surface of the radio wave absorbing member, and FIG. 4B is a YY cross-sectional view of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flexible sheet 2 Flexible sheet 3 Electric wave absorber 4 Sewing

Claims (5)

Two flexible sheets are stacked, at least one of the sheets has radio wave permeability,
Between the two flexible sheets, a sheet-like radio wave absorber (A) shown below is sandwiched to form a three-layer structure of a flexible sheet, a radio wave absorber, and a flexible sheet. ,
Along a path across the path and the seat surface surrounding the outer peripheral edge of the flexible sheet of two said, made sewing coupling a flexible sheet between the two said is subjected, whereby said two variable Two or more rooms are formed between the flexible sheets,
Each room contains the following wave absorber (A) , and the wave absorber is also present between the flexible sheets in the sewing part. The mat-like fiber aggregates that are in communication with each other and that constitute the radio wave absorber change such that the fiber density sequentially increases from the radio wave transmitting sheet side toward the other sheet side. An electromagnetic wave absorbing member.
(A) From a mat-like fiber assembly formed by entwining and bonding fibers made of a plurality of types of polar polymers coated with carbon so as to contain at least 5% by weight of various fibers An electromagnetic wave absorber, wherein the fiber density of the fiber assembly changes in the thickness direction. The radio wave absorbing member according to claim 1, wherein the material of the flexible sheet having radio wave permeability is a fiber reinforced plastic obtained by reinforcing an organic polymer material with glass fiber.   The radio wave absorbing member according to claim 1, wherein the shape of the room when the one sheet surface of the radio wave absorbing member is viewed is a square, and the dimensions of the square are 200 mm × 200 mm to 500 mm × 500 mm.   The radio wave absorbing member according to claim 1, wherein a through hole for passing a string for arranging the radio wave absorbing member is provided on an outer peripheral edge of the radio wave absorbing member. The radio wave absorbing member according to claim 4 , wherein a part or the entire circumference of the outer peripheral edge including the portion where the through hole is provided is an ear part formed by directly adhering the flexible sheets.

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