JP4290267B2 - Radio wave shielding device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is primarily structures information in digital signal is exchanged, it is intended to relate to the preferred wave shielding device using such facilities.
[0002]
[Prior art]
With the development of communication devices, high-speed signal exchange is actively performed, including ISDN and LAN. For example, in facilities where these devices are used or researched, in order to prevent radio waves from leaking outside, or to prevent malfunction due to excessive radio waves entering from outside, There is a shield room that actively blocks leakage. In such a shield room, the frequency range of radio waves to be shielded is determined in advance.
[0003]
By the way, even in such a shield room, there is a possibility that unnecessary radio waves may be taken in through this cable or an opening through which the cable passes when the outside is communicated with a cable or the like for signal exchange. Therefore, in such a shield room, a radio wave shielding device is installed on a wall surface or the like. FIG. 2 shows a conventional radio wave shielding device 2 installed in the shield room 1, and FIG. 3 shows the radio wave shielding device 2 in an enlarged manner.
[0004]
The radio wave shielding device 2 is generally called a line filter, and is interposed in the middle of the signal line to prevent unnecessary radio waves from entering the shield room 1 by riding on the signal line. it can. Such a radio wave shielding device 2 includes a box-like casing 4 formed entirely of a metal plate, and electronic components such as a capacitor and a coil (not shown) housed in the casing 4.
[0005]
In order to attach the radio wave shielding device 2 to the wall surface 3 of the shield room 1, first, a lower hole 5 is formed in the wall surface 3, and the distal end side of the metal cable 6 led from the inside of the shield room is inserted into the lower hole 5. Then, the other metal cable 7 is connected on the lower surface side of the metal casing 4 while being connected to an appropriate terminal of the radio wave shielding device 2.
In order to attach such a radio wave shielding device 2 to the shield room 1, the periphery of the pilot hole 5 is completely covered with the metal casing 4, and between the mounting flange 8 provided on the outer surface of the metal casing 4 and the wall surface 3. By inserting the screw 9, the screw 9 is tightly attached so that no gap is generated between the screw 9 and the wall surface 3.
[0006]
According to such a radio wave shielding device 2, when a weak electric signal such as a communication line is drawn into the shield room 1, even if an extra radio wave enters the signal line, it attenuates before the extra radio wave enters. Can be made.
On the other hand, as shown in FIG. 4, a communication system using an optical fiber cable 10 is also known. Here, the optical fiber cable 10 communicates between the electronic devices inside and outside the shield room 1 with an optical signal, and the optical fiber cable 10 is inserted into a metal pipe 11 penetrating the wall surface 3. According to such a communication system, since an electric signal is not multiplied on the optical fiber cable 10, the invasion or leakage of the radio wave by the signal line does not occur.
[0007]
[Problems to be solved by the invention]
By the way, in the above-described radio wave shielding device 2, it is not possible to attenuate at least the frequency band of the signal to be used. If the frequency band to be used is attenuated, a problem occurs in the exchange of information.
In other words, this means that the radio wave shielding device 2 takes in jamming radio waves in substantially the same frequency band as the signals used in the shield room 1.
[0008]
On the other hand, in the communication system using the optical fiber cable 10, there is a problem that the optical fiber 10 connecting the devices inside and outside the shield room 1 becomes a factor of high cost, and it is difficult to route the cable 10 and the workability is remarkably impaired. Have.
In view of such a situation, the present invention can effectively prevent unnecessary radio waves from entering or leaking, can transmit only necessary signals, and has good handling and installation workability. It is an object of the present invention to provide a radio wave shielding device that can be implemented at low cost.
[0010]
[Means for Solving the Problems]
In order to achieve such an object, a radio wave shielding device according to the present invention is attached to a wall surface of a shield room, and a space in a metal casing that shields intrusion of external radio waves is divided into a first room and a second room by a metal partition plate. And a waveguide is installed in the middle of the partition plate, and photoelectric converters are accommodated in the first chamber and the second chamber, respectively. It is characterized in that information transmission means between the devices is passed through the waveguide.
[0011]
According to the present invention as described above, even if radio waves flying in the atmosphere enter, the radio waves can be blocked by the waveguide. In addition, leakage of radio waves from the shield room can be prevented by this waveguide. In addition, since the information is sent by a transmission means such as an optical fiber cable that communicates between the photoelectric converters, the signal to be transmitted is a digital signal even if extra radio waves are carried over the metal cable from the outside. If there is, the excess radio wave is cut when converted into an optical signal by the photoelectric converter, and the radio wave is not multiplied after being converted into the optical signal.
[0012]
The transmission means may use infrared rays. According to such a configuration, a transmission cable can be eliminated between the photoelectric converters .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a radio wave shielding apparatus according to an embodiment of the present invention and a communication system using the shielding apparatus.
The radio wave shielding device 40 includes a box-shaped metal casing 12 formed of a metal plate, and a metal partition plate 15 that defines the inside of the casing 12 into a first chamber 13 and a second chamber 14. A metal pipe 16 is attached as a waveguide through the substantial center of the partition plate 15. A photoelectric converter 17 is accommodated in the first chamber 13 and a photoelectric converter 18 is accommodated in the second chamber 14. The photoelectric converters 17 and 18 are connected by an optical fiber cable 19. .
[0015]
Here, the photoelectric converters 17 and 18 are, for example, optical transceivers, and signals are exchanged as digital signals.
On the other hand, the electronic device in the shield room 20 and the photoelectric converter 17 are connected by a metal cable 21, and the photoelectric converter 18 and an electronic device not shown are connected by a metal cable 22. Therefore, in this embodiment, an electrical signal emitted from an electronic device in the shield room 20 is converted into an optical signal by the photoelectric converter 17, converted into an electrical signal again by the photoelectric converter 18, and then not shown. Supplied to electronic equipment.
[0016]
By the way, in this embodiment, the optical fiber cable 19 is inserted into a metal pipe 16 that is attached to penetrate the partition plate 15.
Therefore, in this embodiment, even if radio waves flying in the atmosphere try to enter from the opening 25 formed in the partition plate 15, that is, the opening of the pipe, the pipe acts as a waveguide. Can be attenuated. In this case, the length of the pipe 16 is preferably at least three times the diameter of the cross-sectional area, and it is known that the pipe 16 can be effectively attenuated.
[0017]
Such a radio wave shielding device 40 is normally installed outside the wall surface 23 constituting the shield room 20, but even when installed inside the wall surface 23, the same operational effects can be achieved.
Further, in order to attach the metal casing 12 to the wall surface 23, a mounting flange 33 or the like may be provided on the outer surface of the casing, and a screw 34 may be inserted into the mounting flange 33 and fixed to the wall surface 23 with these screws 34. In this case, it is necessary to fix it tightly so that no gap is generated between the wall 23 and the wall 23. In addition to this, a short pipe 26 extending from the metal casing 12 is inserted into the lower hole 30 of the wall surface 23 through which the metal cable 21 is inserted, and the thread provided on the short pipe is connected to the shield room 20 side. You may fix with the nut 31. FIG.
[0018]
As described above, according to the present embodiment, the exchange of signals between the electronic devices inside and outside the shield room 20 is output from electricity to light and further from light to electricity, so that the optical fiber cable 19 interposed in the middle is output. With the transmission means, it is possible to output without putting extra radio waves. Even if radio waves flying in the atmosphere through the opening 25 of the pipe 16 through which the optical fiber cable 19 passes may enter the shield room 20, the radio waves can be attenuated by the metal pipe 16.
[0019]
Furthermore, the length of the optical fiber cable 19 to be used may be short. In addition, according to the communication system using such a radio wave shielding device 40, only an appropriate signal can be transmitted without being affected by an extra signal, and an extra signal can be introduced into the shield room. Absent. In addition, a radio wave shielding device of the traditional can be incorporated into the shield room in signal in the frequency band that can not be shielded in view of the attenuation band of the shielded room.
[0020]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the optical fiber cable 19 is used as the signal transmission means. However, the transmission means is not limited to the optical fiber cable, and can be transmitted by infrared rays called optical radio. In this case, no cable is required. In addition, it is only necessary that the path of the infrared ray is inside the pipe 16, so that radio waves in the atmosphere can be shielded.
[0021]
In addition, the waveguide that penetrates and is attached to the partition plate 15 is not limited to the metal pipe 16, and may be a waveguide having a square cross section. Further, it is known that the length L of the rectangular waveguide is good if the length is at least three times the maximum dimension of the cross section.
Thus, the shape of the waveguide can be rectangular or other shapes.
[0022]
【The invention's effect】
As described above, according to the radio wave shielding device of the present invention, even if various interference radio waves try to enter from outside through the air, they can be shielded by the waveguide. Moreover, even if an extra radio wave is carried from outside via a metal cable, it can be blocked when the radio wave is converted into an optical signal. Therefore, a signal that causes a malfunction does not enter the shield room. On the contrary, radio waves including information are not leaked from the shield room. Further, when an optical fiber cable is used as a transmission means, it is sufficient to use a very short length, so that it can be produced at low cost. Furthermore, since the end of the optical fiber cable is not exposed to the outside, handling is convenient. In addition, if infrared rays are used as the transmission means, a cable is not required, and thus the size is reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a radio wave shielding device according to an embodiment of the present invention.
FIG. 2 is a perspective view of a conventional radio wave shielding device installed in a shield room.
FIG. 3 is a schematic cross-sectional view of the conventional radio wave shielding apparatus shown in FIG.
FIG. 4 is a schematic sectional view showing another conventional communication system.
[Explanation of symbols]
11 Radio wave shielding device 12 Metal casing 13 First chamber 14 Second chamber 15 Partition plate 16 Pipes 17 and 18 Photoelectric converter 19 Optical fiber cable 20 Shield rooms 21 and 22 Metal cable

Claims (3)

A space inside the metal casing, which is attached to the wall surface of the shield room and shields the invasion of external radio waves, is divided into a first room and a second room by a metal partition plate, and in the middle of this partition plate A waveguide is inserted through the photoelectric converter, and photoelectric converters are accommodated in the first chamber and the second chamber, respectively, and information transmission means between the photoelectric converters is passed through the waveguide. A radio wave shielding device characterized by the above.    2. The radio wave shielding apparatus according to claim 1, wherein the transmission means is an optical fiber cable.    2. The radio wave shielding apparatus according to claim 1, wherein the transmission means is infrared rays.

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