JPH0580180B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tightly coupled wireless transmission method, and more particularly, to a tightly coupled wireless transmission method for transmitting and receiving information signals wirelessly within a limited space. It is something.

[Prior Art] Conventionally, wireless terminal equipment of a computer system in an office has been implemented using an antenna method as shown in FIG.

That is, when transmitting and receiving data wirelessly between the central device 1 and the terminal devices 11 and 21 forming the wireless system 100, the wireless device 2 and antenna 3 are connected to the central device 1, and the wireless device 11 and the antenna 3 are connected to the central device 1. Machine 1
2 and an antenna 13 are connected, and data is transmitted and received by propagation of radio waves between the antenna 3 and the antenna 13.

Further, a radio device 22 and an antenna 23 are also connected to the terminal device 21, and the antenna 3 and the antenna 23 are connected to the terminal device 21.
Data is now sent and received by the propagation of radio waves between the two.

In addition, in the case of FIG. 5, in addition to the above-mentioned radio system 100, another radio system 200 is also provided, which includes a system consisting of a radio device 2' and an antenna 3', and a system consisting of a radio device 12' and an antenna 13'. It is being

[Problems to be Solved by the Invention] However, in the case of the conventional antenna system shown in Fig. 5 above, the radio waves radiated from the antenna reach the whole room or even the neighboring room due to spatial propagation, so If there is another wireless system in the room or in an adjacent room, and the two wireless systems 100 and 200 use the same carrier frequency, the radio waves radiated from the antenna of one wireless system will be transmitted to the other wireless system. It becomes an interference radio wave.

Therefore, it is necessary to take measures such as changing the carrier frequency in one radio system or providing electrical shielding between the two radio systems, which poses problems in terms of effective use of radio frequencies and economic efficiency.

In addition, when installing the above-mentioned radio system as a weak radio station that does not require a license, there is a restriction that the electric field strength must not exceed 54 dBμV/m at a point 3 meters away from the antenna, so it is especially important to keep the electric field strength at a specified level. It is necessary to maintain stable characteristics, but it is actually quite difficult to achieve this with conventional antenna systems.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, to allow multiple radio systems using the same carrier frequency to coexist within a limited space, and to enable the entire device to be installed within a limited space. An object of the present invention is to provide a tightly coupled wireless transmission method that can maintain the limited electric field strength as a weak wireless station even if it is placed in a wide place such as covering the entire area of the country.

[Means for solving the problem] The gist of the present invention is to tightly couple a cable hidden by an object that transmits an electromagnetic field and a coupler placed on the opposite side of the cable to the object. ,
In the tightly coupled wireless transmission method for transmitting and receiving information signals wirelessly between the cable and the coupler,
A magnetizable substance is provided on the cable side, and a magnet is provided in the coupler.

[Example] Hereinafter, an example of the present invention will be described in detail using FIGS. 1 to 4.

This invention can be used as a computer in the office.
In FIG. 1 showing an embodiment of the present invention applied to a wireless system, a radio device 32 is connected to a central device 31, and radio devices 42 and 52 are connected to a terminal device 41 and a terminal device 51, respectively. ,
A cable 33 that generates an electromagnetic field is connected to the radio device 32, and couplers 43 and 53 that detect the electromagnetic field are connected to the radio devices 42 and 52, respectively.

The cable 33 is of a tightly coupled type in which the electromagnetic field level is at the required level in the immediate vicinity of the cable 33, and the electromagnetic field level is minute at a certain distance from the cable 33. For example, as shown in FIG. It is an induced magnetic field generating type having propagation characteristics such that the relationship between the separation distance R from the cable P and the electric field strength E is E=10log(1/R ² ).

Each of the couplers 43 and 53 is a radial type with low radiation efficiency, or a non-radiative type such as an inductive coupling type or an electrostatic coupling type.

A cable 33 connected to the radio 32 is laid under a carpet on the office floor, and a coupler connected to the radios 42 and 52 is placed directly above the cable 33 on the carpet. 4
3 and 53 are placed, and the couplers 43 and 53 are closely coupled to the cable 33. In addition, the code 34
is the terminating resistor.

Therefore, in the radio device 32, a carrier wave of a predetermined frequency is modulated by the output data of the central device 31, and
The modulated high frequency signal is supplied to the cable 33, and an electromagnetic field is generated from the cable 33.

Then, by detecting the electromagnetic field by the couplers 43, 53, a modulated high frequency signal is obtained in the couplers 43, 53, and the modulated high frequency signal is supplied to the radio devices 42, 52, radio device 42,
The data is demodulated at 52, and the demodulated data is supplied to the terminal devices 41, 51.

An example of the connection state between the cable 33 and the couplers 43 and 53 is shown in FIG. 2, using the cable 33 and the coupler 43 as an example.

That is, a coupler 43 placed on a carpet 61 laid on the floor 60 covering the cable 33 laid on the surface of the office floor 60 connects a cable 43a whose one end is connected to the radio device 42 described above. have,
It has a coil 43b provided at the other end of this cable 43a, and magnets 43c and 43d,
The other end of the cable 43a, the coil 43b, the magnet 4
Case 43 where 3c and 43d are integrally molded
It consists of e.

Further, the connection state between the cable 33 and the coupler 53 is also the same as described above.

At least one of the members constituting the cable 33
For example, the high-frequency signal conductor of the cable 33 is at least partially formed of a magnetizable material such as iron, and the magnets 43c and 53d of the couplers 43 and 53 are The position of the coil 43b in the couplers 43, 53 is maintained directly above the cable 33 due to the attractive force on the portion formed by the substance.

Note that the magnetic fields generated by the magnets 43c and 43d are DC magnetic fields, and the electromagnetic field used between the coil 43b and the cable 33 is an AC magnetic field.
There is no need to worry about the effects of c and 43d on tightly coupled wireless transmission.

In one embodiment of the invention described above, for the transmission of data from the central device 31 to the terminal devices 41, 51, the electromagnetic field generated from the cable 33 is transferred to the cable 33 on which the couplers 43, 53 are placed.
The minimum level required to be detected by the couplers 43, 53 only in the very vicinity of the cable 33 is sufficient, and the level may be low at a certain distance from the cable 33.

In addition, when using the cable 33 having the propagation characteristics shown in FIG. 3, by placing the couplers 43 and 53 at a position of R=10 mm where the electric field strength is 100 dBμV/m, for example, Combiner 4
3, 53 from the central device 31 to the terminal device 4
1, 51, and the electric field strength is 20dBμV/for example at the position of R = 1000mm.
Since the frequency is as small as m, the electromagnetic field generated from the cable 33 does not interfere with another radio system using the same carrier frequency.

Conversely, even when data is transmitted from the terminal device 41 side or the terminal device 51 side toward the central device 31, the propagation characteristics of the electromagnetic field generated from the couplers 43 and 53 have a tendency similar to that shown in Fig. 3. By setting the carrier frequency to 1, there will be no interference with another radio system using the same carrier frequency as described above.

In this case, even if the frequencies of the signals transmitted from the radios 42 and 52 are the same, interference can be prevented by controlling appropriately so that the signals are not transmitted from both at the same time.

FIG. 4 is an explanatory diagram of couplers 43 and 53 in which Velcro tape (trade name) 43f is attached to the surface facing the cable that generates the electromagnetic field. Note that the magnets 43c and 43d explained in FIG. 2 are omitted.

When the carpet is a textile fabric, when the magic tape 43f is placed on the fibers of the carpet, it bites into the fibers and is caught on the fibers.
It will not peel off easily.

Therefore, by attaching a magic tape 43f to the surface of the coupler facing the cable as shown in FIG. It can be securely fixed in the upper position.

In any of the above cases, the coupler or terminal device is equipped with a light source such as a light emitting diode or an appropriate sound source, and when the level of the electromagnetic field detected by the coupler is near the maximum value, a signal to that effect is provided. By providing a light or sound notification, the location directly above the cable where the coupler should be placed can be easily and reliably found.

Note that the tightly coupled wireless transmission method according to the present invention includes:
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit thereof.

For example, the cable that generates the electromagnetic field is not limited to the type that generates an induced electric field, but may also be of the type that generates an electrostatic field, the type that generates a surface wave electric field, or the type that generates a radiated electric field. Further, this cable does not necessarily have to be of a tightly coupled type as a whole, and a general coaxial cable or a pair cable may be inserted in the part where a coupler is not placed.

Further, the coil provided in the coupler may be replaced with a micro dipole, a micro loop, an electric field generating probe, etc., which have low radiation efficiency.

Furthermore, when a magnet is provided in the coupler, on the cable side, instead of forming at least a part of at least one of the members constituting the cable from a magnetizable material, a magnetizable member is arranged in parallel with the cable. It's okay.

Furthermore, the cable can be hidden by any object that transmits the electromagnetic field, such as not only carpet but also tiles, wood boards, concrete, plastic boards, cloth, etc. Of course, the location where the cable is laid and the coupler is installed is not limited to the floor, but may also be a wall, ceiling, or the like.

Furthermore, it goes without saying that the present invention can be applied not only to the case of sending and receiving data, but also to the case of sending and receiving signals such as audio signals and image signals.

[Effects of the Invention] As described above, according to the present invention, the electromagnetic field generated from the cable does not interfere with other wireless systems, so the same carrier frequency can be used within one room or building. A plurality of radio systems can coexist, and frequencies can be used effectively, and there is no need to provide special radio wave shielding means on the walls of buildings, making it economical.

Furthermore, not only can multiple wireless systems using the same carrier frequency coexist within a limited space, but even if the entire device is placed in a wide area such as indoors or throughout a building, A tightly coupled wireless transmission method that can maintain the limited electric field strength as a weak wireless station can be achieved.

Furthermore, the structure of the present invention in which a magnetizable substance is provided on the cable side and a magnet is provided in the coupler allows the coupler to be placed in the best position relative to the cable for tight coupling even if the cable is hidden. Wireless transmission can be performed. As a result, it is possible to build a system without exposing the cables to the public, and the aesthetics of the office room are improved.
It will greatly contribute to the promotion of OA.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device used in a tightly coupled wireless transmission method showing one embodiment of the present invention, and FIG.
3 is a characteristic curve diagram showing an example of the propagation characteristics of the electromagnetic field generated from the cable; FIG. 4 is a sectional view showing another example of the coupler; FIG. 5 is a block diagram showing an example of a device used in a conventional tightly coupled wireless transmission method. 31...Central device, 32, 42, 52...Radio device, 33...Cable, 34...Terminal resistor, 4
1, 51... terminal device, 43, 53... coupler,
60...floor, 61...carpet, 43a...cable, 43b...coil, 43c, 43d...
Magnet, 43e...case, 43f...magic tape.

Claims (1)

[Claims] 1. A cable hidden by an object that transmits an electromagnetic field and a coupler placed on the opposite side of the cable with respect to the object are closely coupled, and between the cable and the coupler A close-coupled wireless transmission method for transmitting and receiving information signals wirelessly, characterized in that a magnetizable substance is provided on the cable side and a magnet is provided in the coupler. 2. A member according to claim 1, characterized in that a member for locking or fixing the coupler to the object that transmits the electromagnetic field is provided on the surface of the coupler that faces the cable through the object that transmits the electromagnetic field. Tightly coupled wireless transmission method.