JP2007243821A - Wireless tag movement detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the slight movement of a wireless tag (object) inside a wide range area without using a coaxial cable and a LAN cable at a very low cost without increasing the number of antennas to be installed. <P>SOLUTION: The movement of the wireless tag is detected by a wireless tag position transmitter 10 comprising a wireless tag reader-writer 11 and a transmitter-receiver 12 (personal computer, for instance), coaxial cables 13 (13a, 13b and 13c), leakage coaxial cables 14 (14a, 14b and 14c), the wireless tags 15 (15a or the like), the wireless tags 16 (16a or the like) and the wireless tags 17 (17a or the like) for emitting the radio waves of 900 MHz band, an information transmission network 18 and a monitoring and controlling system 19, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless tag movement detection system that can detect movement of a wireless tag at low cost by using a leaky coaxial cable as an antenna of a wireless tag reader / writer for detecting the wireless tag.

  In recent years, wireless tags have been widely used. A wireless tag reader / writer is used for reading or writing data of the wireless tag.

  As an antenna for the wireless tag reader / writer, a magnetic loop antenna in which a copper wire is wound in a coil shape on a plane is used for the LF band (124, 135 KHz) and HF (13.45 KHz wavelength 20 m).

  On the other hand, a radio frequency ID (RFID) is widely used recently because a unique ID can be allocated and the ID can be read from a certain distance. A wireless tag reader / writer is used to write and read this ID.

  Radio frequencies are generally 13.56 MHz and 2.45 GHz in Japan, and 13.56 MHz uses an electromagnetic induction method. In the electromagnetic induction system, an IC chip is moved by generating a current in a coiled antenna (an antenna that reacts to a magnetic field component) of a wireless tag with a magnetic field generated by flowing a current through a coil of the wireless tag reader / writer.

  On the other hand, 2.45 GHz uses a microwave system. In the microwave system, a radio tag generates radio waves generated from an antenna of a wireless tag reader / writer (an antenna that reacts mainly to an electric field among electromagnetic waves). The radio waves are received and passed through a dipole antenna to cause a current to flow, and the radio waves are emitted from the IC. Both of these electromagnetic waves mainly react to an electric field.

  In addition, there are roughly the following four types of wireless tags that can be used in Japan at present.

(1) 124 KHz, 135 KHz band (2) 13.56 MHz band (3) 900 MHz band (950 MHz band)
(4) 2.45 GHz band (wavelength of about 13 m)
(5) 300 MHz band (weak radio wave)
The wireless tag of such a frequency band is currently used for various purposes. For example, a system that uses a wireless tag to detect a landslide by the movement of the wireless tag has been proposed.

Such a conventional system will be described below.

  FIG. 15 is a schematic configuration diagram of a conventional wireless tag detection system. Since the transmission output of the tag detection antenna 1k is restricted by regulations of the Radio Law, the communication distance between these antennas and the wireless tag is naturally limited. For this reason, as shown in FIG. 15, the wireless tag 2 and the tag detection antenna 1k are arranged close to each other.

  As shown in FIG. 15, a tag detection antenna 1k is arranged on the slope of a mountain, the tag detection antenna 1k is fixed, and the wireless tag 2 is buried shallowly in the vicinity thereof.

  The above-described wireless tag 2 uses the band (1) or (2) described above.

  When the slope of the mountain collapses, the soil moves as a sign, and when the soil moves, the wireless tag 2 also moves. That is, the movement of the wireless tag 2 means that the wireless tag 2 moves away from the tag detection antenna 1k, and thus the communication distance between the wireless tag 2 and the tag detection antenna 1k is left (because the intensity of the reaching radio wave is weak). The ID code of the wireless tag 2 is not transmitted from the tag detection antenna 1k to a receiver or the like (not shown) at the summit. That is, since the ID code of the wireless tag 2 is not detected, it can be seen that there is a sign of mountain collapse as a result.

  The system of FIG. 16 is a system in which a coaxial cable is connected to a wireless tag reader / writer, this coaxial cable is branched, and a tag detection antenna is connected to each branched coaxial cable.

  In this method, a wireless tag reader / writer 3 is installed on a mountain, a coaxial cable 5 is connected, the coaxial cable 5 is branched by a distributor 6, and coaxial cables 4a, 4b, and 4c are connected.

  The tag detection antennas 1k1, 1k2, and 1k3 are connected to the ends of the coaxial cables 4a, 4b, and 4c, and the wireless tags 2a, 2b, and 2c are installed in the vicinity of the respective antennas.

  In this method, the tag detection antennas 1k1, 1k2, and 1k3 are pulled by a coaxial cable, so that the tag detection antennas 1k1, 1k2, and 1k3 are fixed.

  For this reason, for example, when there is a sign of a cliff collapse and the ground moves, the wireless tags 2a, 2b, and 2c move, so that the movement of the wireless tags 2a, 2b, and 2c can be detected.

In FIG. 17, for example, one wireless tag reader / writer 3 is placed at the top of the mountain, coaxial cables 9a, 9b, 9c having a length of several meters are stretched from the wireless tag reader / writer 3, and tag detection is performed at the ends of the coaxial cables 9a, 9b, 9c. The antennas 1k1, 1k2, and 1k3 are connected, and the wireless tags 2a, 2b, and 2c are arranged in the vicinity of the tag detection antennas 1k1, 1k2, and 1k3. ,
Then, one of the piano wires 7a, 7b, and 7c is connected to the wireless tags 2a, 2b, and 2c, and a weight (landslide detection weights 8a, 8b, and 8c) is connected to the other.

  In this way, for example, when a landslide occurs, the weight moves downward as the slope moves, and as a result, the wireless tags 2a, 2b, and 2c are pulled. As a result, the wireless tags 2a, 2b, and 2c leave the tag detection antennas 1k1, 1k2, and 1k3, and it is detected that the wireless tags 2a, 2b, and 2c have moved.

  The system of FIG. 18 uses an intranet LAN cable. Even if the LAN cable is 100 m or 200 m long, there is almost no attenuation.

  By connecting the tag detection antennas 1k1, 1k2, and 1k3 and the cases 11a, 11b, and 11c housing the wireless tag reader / writers 3a, 3b, and 3c to the ends of the LAN cables 10a, 10b, and 10c, the wireless tags 2a, The movement of 2b and 2c is detected by a tag detection antenna and a wireless tag reader / writer in the case and notified to a monitoring center or the like by a LAN cable.

  However, since a large number of cases containing the tag detection antenna 1 and the wireless tag reader / writer 3 are arranged, the cost is increased.

  Moreover, there is JP-A-2005-283337 (Patent Document 1) as a system using a wireless tag.

This patent document states that a wireless tag carried by a competitor ... wirelessly receives and stores time data when passing through the start line, and wirelessly receives time data when passing through the intermediate line. It is memorized and received by radio when passing the goal line.
JP 2005-283337 A

  However, although the method shown in FIG. 15 uses the 124 KHz and 135 KHz bands of (1) or the 13.56 MHz band of (2), the wireless tag 2 has a detection distance of several tens of centimeters and is very short. .

  That is, since the method of FIG. 15 uses the wireless tag 2 and the tag detection antenna with a short detection distance as in (1) or (2) to detect a very wide range of slopes, the tag is used. As many detection antennas as the number of wireless tags are required.

  Further, the movement of the wireless tag cannot be detected unless the tag detection antenna is always fixed. For this reason, it was necessary to carry out construction work for the tag detection antenna. Further, the method of FIG. 15 requires a transmission means for the tag detection antenna.

  Therefore, the system of FIG. 15 has a problem that the equipment cost, the construction cost, etc. become enormous.

  The system shown in FIG. 16 connects the tag detection antenna with a coaxial cable, so that a function of transmitting detection data wirelessly to the tag detection antenna and a large-scale fixing work for the tag detection antenna are not necessary. Also, because the slope is wide, you have to run the coaxial cable for several hundred meters.

  That is, in the coaxial cable, when the line length is about 100 m or 200 m, the signal is attenuated by minus several tens dB. As a result, there is a problem that the movement of the wireless tag 2 cannot be detected.

  The system shown in FIG. 17 shows a landslide, etc., if a weight is moved without a long coaxial cable. However, the installation location of the weight must be carefully examined on site so that it can roll smoothly when there is a landslide. Don't be.

  The system shown in FIG. 18 uses an Ethernet LAN cable instead of a coaxial cable, but is costly because a large number of cases containing expensive tag detection antennas and wireless tag reader / writers are arranged. was there.

  On the other hand, when searching at a distance of several tens of centimeters to several meters, (3) 900 MHz band, (4) 2.45 GHz band, and (5) 300 MHz band are suitable.

  In the case of these wireless tags, since the detection distance is long, it can cover a wide area, but even if the position of the wireless tag in that area moves, the wireless tag continues to be detected because the detection distance is long, A slight movement cannot be detected.

  Furthermore, the 2.45 GHz band of (4) becomes a relatively sharp beam-like detection area from the antenna due to the nature of the microwave band. The 915 MHz band in (3) and the 300 MHz band in (5) are UHF bands, so the detection distance and area are the widest, but they are particularly affected by metals, and the detection distance varies depending on the surrounding environmental conditions. End up.

  Another method is to receive radio waves from a radio tag with at least one radio tag reader, measure the strength of the radio waves, arrival time (radio wave phase), etc., and equalize the distance from the radio tag reader. There may be a method of detecting the position and movement of the wireless tag by performing measurement. However, in order to realize this function, a complicated wireless circuit is built in the wireless tag, and the wireless tag reader is also equipped with a complicated electronic circuit and software that can measure the strength of radio waves, phase difference, etc. There is a need. Since these electronic devices and software are expensive, there is a problem that the entire system becomes very expensive.

  As described above, the conventional methods shown in FIGS. 15, 16, 17, and 18 have a problem in cost.

  Further, the method using a wireless tag with a long detection distance is not suitable for the purpose of detecting a slight movement of an object in a wide area.

  Conversely, if a wireless tag with a small detection distance and area is used, slight movement can be detected by determining whether the wireless tag is detected, but a huge number of antennas are installed to cover the entire area. Need arises.

  Furthermore, the method of emitting radio waves from the wireless tag reader / writer and measuring the position of the wireless tag from the electric field strength and arrival time is expensive.

  Therefore, the present invention can detect a slight movement of a wireless tag (object) in a wide area without using a coaxial cable or a LAN cable, and realizes this at an extremely low cost without increasing the number of antennas to be installed. The purpose is to be able to.

The wireless tag movement detection system of the present invention is a leaky coaxial cable laid in the detection area,
A terminal resistor connected to the leaky coaxial cable, a plurality of wireless tags arranged near the leaky coaxial cable and emitting an ID code upon reception of electromagnetic waves, and supplying a signal to the leaky coaxial cable, A wireless tag reader / writer that decodes an ID code of the wireless tag from a signal transmitted from a leaky coaxial cable, and a device that reads the decoding result of the wireless tag reader / writer and outputs the presence / absence of detection of the wireless tag. To do.

  As described above, according to the present invention, even if a leaky coaxial cable is wound over several hundred meters, the reduction of the leaky coaxial cable is small, and the leaky coaxial cable serves as an antenna to detect a wireless tag. Therefore, even if wireless tags are arranged over a wide range, the cost can be greatly reduced.

  For example, if a leaky coaxial cable and a wireless tag are placed on the slope of a mountain, the ID code of the wireless tag will not be detected on the leaky coaxial cable if there is a landslide, landslide, etc. It can be detected immediately.

An embodiment according to the present invention will be described with reference to the drawings.

  In this embodiment, the movement of the wireless tag is detected by using a leaky coaxial cable for the antenna of the wireless tag reader / writer.

  The frequency band used for the above-described wireless tag will be described first.

  It is assumed that a wireless tag antenna having a frequency band such as 13.56 MHz band, 2.45 GHz band, and 900 MHz band is used.

  In the case of using a 13.56 MHz band wireless tag, the 13.56 MHz band wireless tag reacts mainly to a magnetic field component of electromagnetic waves.

  In addition, 2.45 GHz band and 900 MHz band wireless tags have antennas that react mainly to electric field components of electromagnetic waves. However, the 2.45 MHz band is affected by water attenuation.

  On the other hand, a leaky coaxial cable radiates both vector components of a magnetic field and an electric field as electromagnetic waves. Further, in the very vicinity of the coaxial cable, leakage starts from the electric field component.

  The 900 MHz band wireless tag is not easily affected by water, and a highly efficient dipole antenna or the like can be applied to the tag because of the wavelength relationship. On the other hand, since 13.45 MHz has a long wavelength, only a very low-sized antenna with a very small size can be mounted on the tag. Therefore, the detection distance is greatly limited as compared to 900 MHz. Therefore, in this embodiment, description will be made assuming that the 900 MHz band is used.

<Embodiment 1>
FIG. 1 is a schematic configuration diagram of the wireless tag movement detection system according to the first embodiment. As shown in FIG. 1, the wireless tag movement detection system according to the first embodiment includes a wireless tag position transmitting device 10 including a wireless tag reader / writer 11 and a transmission / reception device 12 (for example, a personal computer) and a coaxial cable 13 (13a, 13b). 13c), the leaky coaxial cable 14 (14a, 14b, 14c), the wireless tags 15 and 15a (15a,...) That radiate 900 MHz radio waves, the wireless tags 16 and 16a, and the wireless tags 17 and 17a. .., And the information transmission network 18 and the supervisory control system 19. The length of the above-described coaxial cable 13 is within a few tens of meters (for example, 10 m to 30 m) in total length. Further, since the leaky coaxial cable 14 has an attenuation of about 10 dB at 1 km, the length of each leaky coaxial cable is several meters to several hundred meters.

  That is, the RFID tag position transmitting device 10 is arranged on the top of a mountain, for example, and a coaxial cable 13a (several meters) is connected to the feeding point of the RFID tag position transmitting device 10 and distributed by the distributor 20, and the coaxial cable 13b. 13c is connected.

  Then, distributors 21 and 22 are connected to the coaxial cables 13b and 13c, and a leak of a predetermined length (for example, 30 meters to 200 meters) is leaked to these distributors 20, 21, and 22 (coaxial connectors for distribution). The coaxial cables 14a, 14b, and 14c are laid on an inclination where the landslide is likely to occur, and the wireless tags 15, 16, and 17 are installed over a wide area in the communication area near the leaky coaxial cable on the slope. The above-described leaky coaxial cable 14 is laid obliquely on a slope, laid sideways, or laid in a bent or straight place.

  As a result, if there is a sign of a landslide such as a landslide on a slope once there is heavy rain, when some tags start to deviate together with the earth and sand, radio waves from the wireless tag leak. The coaxial cable 14 cannot be detected. Therefore, it is possible to detect in advance signs such as landslides.

  Next, the configuration of each unit will be described.

  The response frequency of the above-described wireless tags 15, 16, and 17 is the 900 MHz band. The wireless tags 15, 16, and 17 store unique unique ID codes, and receive the radio waves from the leaky coaxial cable 14 to receive this ID. Fire the code. Further, termination resistors 23a and 23b are connected to the coaxial cables 13c and 13b.

  Furthermore, termination resistors 24, 25, and 26 (50Ω) are connected to the ends of the leaky coaxial cable 14 (14a, 14b, and 14c). That is, the leaky coaxial cable 14 (14a, 14b, 14c) has a standing wave ratio of “1” and a traveling wave is generated.

  As shown in FIG. 2, the leaky coaxial cable 14 is configured by covering an inner conductor with an insulator, covering the insulator with an outer conductor, and covering the outer conductor with a jacket. Furthermore, the support line is covered with a jacket. That is, it has a coaxial cable function for transmitting signals and an antenna function for radiating radio waves in a space along the cable.

  The leaky coaxial cable 14 is connected to a 50Ω termination resistor (one connected to the conductor and the other connected to the support line), and the distributors 20, 21, and 22 are set to 50Ω. Therefore, the standing wave ratio ρ is “1”. Therefore, the radiation is uniform (traveling wave) regardless of the length, as shown in FIG. The leaky coaxial cable 14 is preferably one having an attenuation of about 1 km and about 15 dB.

  Further, the wireless tag reader / writer 11 inputs an ID code via the leaky coaxial cable 14 and the coaxial cable 13 and decodes it.

  In response to an instruction from the monitoring control system 19, the transmission / reception device 12 activates the wireless tag reader / writer 11 and periodically sends a signal to the leaky coaxial cable 14 via the coaxial cable 13 to emit radio waves.

  The monitoring control system 19 associates the latitude and longitude (XYZ) and the address with the ID code assigned to each of the wireless tags 15, 16 and 17. The monitoring control system 19 has a geographic information system. That is, it has a function of showing on the map where a landslide occurred.

The operation of the wireless tag movement detection system of the first embodiment configured as described above will be described below. In the present embodiment, a plurality of 900 MHz wireless tags 15 (15a... 16b... 17a...) Are placed in the vicinity of the leaky coaxial cable 14 in a plastic case or the like to detect signs of landslides. It is buried shallowly in the soil and is arranged in the vicinity of the leaky coaxial cable 14 (14a, 14b, 14c. The leaky coaxial cable 14 is also extended and arranged to detect signs of landslides. For example, the remote control system 19 inputs the date and time and transmits the monitoring period to the wireless tag position transmitting device 10 via the information transmission network 18.

    The transmission / reception device 12 of the wireless tag position transmission device 10 receives the input of the monitoring period, and this organization operates the wireless tag reader / writer 11.

  The wireless tag reader / writer 11 periodically outputs a signal having a frequency of 900 MHZ band to the coaxial cable 13a with the activation.

  This signal is distributed by the distributor 20 and transmitted from the distributor 20 to the coaxial cables 13b and 13c.

  The coaxial cables 13b and 13c are provided with distributors 21 and 22, and signals are transmitted from the distributors to the leaky coaxial cables 14a, 14b and 14c. With this signal, the leaky coaxial cable 14 uniformly radiates radio waves to the outside.

  Each of the wireless tags 15, 16, and 17 generates an electric current in the coil by this radio wave and emits an ID code stored in an IC or the like. This ID code is captured by the leaky coaxial cable 14 (14a, 14b, 14c), sent to the wireless tag reader / writer via the distributor and the coaxial cable, and decoded, and the wireless tag reader / writer 13 receives the ID code and the leaky coaxial cable. 14 is sent to the transmission / reception device 12 together with the number 14, and the transmission / reception device 12 transmits the data to the monitoring control system 19 in a predetermined communication format.

  The monitoring control system 19 receives this ID code and the number of the leaky coaxial cable 14 and displays them on the screen. Thereby, the monitoring control system 19 side (also referred to as a monitoring center) can grasp that all the wireless tags are not moving.

(When landslide occurs)
For example, when it rains and the inclination slightly moves, the wireless tags 15, 16, and 17 move as the earth and sand move.

  For example, when the wireless tag 15a moves away from the detection distance of the leaky coaxial cable 14a with the movement of the earth and sand, the ID code (for example, ID12345) from the wireless tag 15a is not detected in the leaky coaxial cable 14a.

  That is, the wireless tag reader / writer cannot read the ID code of the wireless tag 15ac. The detection data of the leaky coaxial cable 14a is transmitted to the monitoring control system 19 via the information transmission network 18 by the transmission / reception device 12.

  The supervisory control system 19 determines whether or not the ID code of the wireless tag 15a near the leaky coaxial cable 14a no longer exists. When the ID 12345 no longer exists, the wireless tag position corresponding to this ID 12345 The geographical coordinates XYZ (previously stored in correspondence with the ID code in the memory) are read, and the location name corresponding to XYZ (previously stored in correspondence with the ID code) is displayed on the screen, and the map Is displayed on the screen, the vicinity of the place is displayed by color, and an alarm is generated (see FIG. 4).

  Therefore, it is possible to capture the precursory phenomenon of full-scale landslides by simply installing inexpensive leaky coaxial cables and wireless tags without arranging a large number of expensive tag detection antennas as in the past. There are advantages.

  Here, the description is supplemented with respect to the relationship between the distance from the source of the electromagnetic wave transmitted from the antenna and the intensity of the electromagnetic wave.

と微分の形で書き表すことができる。 If the charge amount at a place P that is a distance r away from a length 1 electric dipole in the source of a certain space is q (t) (t is time), the rate of change in the charge amount is current.

And can be expressed in the form of differentiation.

となる。これらの式は極座標に基づいて表記されており、ｅｒ、ｅθ、ｅΦは各々ｅ方向、θ方向、Φ方向単位ベクトルである。またｃは空間中の電磁波の伝搬速度である。 When there is a minute dipole facing the z-axis direction at the origin, the electric field E (t) and magnetic field H (t) of the minute dipole at the point P shown in FIG.

It becomes. These expressions are expressed based on polar coordinates, and er, eθ, and eΦ are e-direction, θ-direction, and Φ-direction unit vectors, respectively. C is the propagation speed of electromagnetic waves in space.

  In these equations, the term proportional to r-3 is a term that creates an electrostatic magnetic field, and in the case of an electric dipole, it exists only in the electric field.

となる。方向単位ベクトルは直交しているので、遠方界では電界と磁界は直交し、波の進行方向に電界・磁界の成分がない。

となる。 The term r-2 is a term that generates an induction electromagnetic field. The r-1 term is a term that creates a radiation field. If it is far enough, the electrostatic term and the induction term are much smaller than the radiation term. Therefore, the electric field / magnetic field (far field) in a place sufficiently away from the dipole is

It becomes. Since the direction unit vectors are orthogonal, the electric field and the magnetic field are orthogonal in the far field, and there is no electric / magnetic field component in the wave traveling direction.

It becomes.

Here, the ratio ξ between the far electric field and the magnetic field is called wave impedance, and is expressed by the following equation.

  From [Equation 6] and [Equation 7], in the near field region, the wave impedance ξ increases as the distance r from the wave field becomes shorter. Therefore, in the near field region (Fresnel region), the electric field component of the electromagnetic field is strong, It can be said that the magnetic field component becomes stronger in the far field region (Fraun for Far region).

<Other embodiments>
In the first embodiment, signs such as large landslides and landslides are detected using a plurality of leaky coaxial cables, but as shown in FIG. 6, one RFID tag reader / writer 11 (transmitter / receiver is not shown) is used. One end of the coaxial cable 13a is connected, a connector (feeding point) is connected to the other end of the coaxial cable 13a, a leaky coaxial cable 14a is connected to the connector, the slope is turned sideways, and a wireless tag is located nearby. May be arranged.

  In this way, if there is a landslide or landslide, the wireless tag 15 (15a, 15b, 15c) moves downward, so the ID of the wireless tag cannot be immediately detected, so a sign of a landslide can be detected in a wide area. .

  In addition, as shown in FIG. 7, there is a method of reducing the leakage attenuation amount of the leaky coaxial cable as the distance from the transmitter / receiver increases. A leaky coaxial cable 30 produced with a leakage reduction amount of A section of 40 dB, a leakage attenuation amount of B section of 30 dB, and a leakage attenuation amount of C section of 20 dB was connected to the wireless tag reader / writer 11 via the coaxial cable 11. Is. The leaky coaxial cable 30 is disposed laterally on the slope.

  Since the leaky coaxial cable 30 is divided in this way and each has a different leak attenuation amount, the detection distance of the wireless tag can be made constant regardless of the distance from the transmitter (the length of the leaky coaxial cable). . On the other hand, there are cases where slopes have trees or rocks, and all wireless tags cannot be placed on the leaky coaxial cable in a uniform proximity. In such a case, if the attenuation amount of the section of the leaky coaxial cable 30 is changed according to the environment of the slope, the detection distance between the leaky cable and the wireless tag can be changed for each section.

  FIG. 8 shows a single leaky coaxial cable distributed by a distributor. Since it is possible to arrange a large number of leaky coaxial cables in a wide area by the distributor, it is suitable for detecting a wide area in detail.

  Further, FIG. 9 is a view in which a 900 MHz wireless tag 15 and a 13.56 MHz wireless tag 29 are fixed in the case 28 and embedded in the vicinity of the leaky coaxial cable.

  A coaxial cable 11 is connected to the leaky coaxial cable 14a, and a 900 MHz band wireless tag reader / writer 11 and a 13.56 MHz band wireless reader / writer 31 are connected to the coaxial cable 11.

  The wireless tag in the 900 MHz band has a detection distance of about 1 m to 2 m, and 13.56 MHz is a detection distance of several centimeters.

  When such a case containing two types of wireless tags is placed near the leaky coaxial cable, the case moves several centimeters when the slope moves several centimeters, and the ID code radio wave of the 13.56 GHz wireless tag 29 is leaked from the coaxial cable. Then it will not be caught. That is, since the ID code of the wireless tag is not detected by the 13.56 GHz wireless tag reader / writer 31, it can be seen that the slope has moved slightly.

  Furthermore, if it moves greatly, the ID code from the 900 MHz wireless tag 15 cannot be captured by the leaky coaxial cable. That is, since the 900 MHz wireless tag reader / writer 11 does not detect the ID code of the wireless tag, it can be seen that the slope has moved greatly.

  Further, when two types of wireless tag readers are prepared as shown in FIG. 9, leaky coaxial cables having different attenuation amounts are connected for each section. For example, a wireless tag of 15.56 MHz may be arranged in the section A, and a wireless tag of 900 MHz may be arranged in the section B. In this way, it is possible to distinguish and detect a place where a finely moving place is desired and a place where a large moving place is detected.

<Example>
FIG. 10 is a system configuration diagram for detecting, with a leaky coaxial cable, what kind of luggage has been carried and stored by storing the wireless tag in the packing box.

  In the system of FIG. 10, leaking coaxial cables 14a and 14b are arranged in a warehouse at a relay point of a delivery company or near a belt conveyor, and the leaking coaxial cables are connected to the coaxial cables 13a and 13b by distributors 20, 21, and 22, respectively. 13c, the wireless reader / writer 11 reads the ID code of the wireless tag, sends this ID code to the supervisory control system 40 via the information transmission network 18, and the supervisory control system 40 determines what package from the received ID code. It detects what has come or what has been brought.

  That is, when the supervisory control system 40 receives the ID code and the content data of the package in advance and receives the ID code through the leaky coaxial cable, the content data is searched using the ID code as a key.

  In FIG. 11, a wireless tag is attached to the substrate 43 to detect what substrate has entered or removed from the unit.

  The circuit board 43 is generally assigned a circuit name and number, and in maintenance inspection and the like, the number and circuit name are confirmed and taken in and out of the unit. However, mistakes are likely to occur if there are many circuit boards.

  Therefore, in the box composed of the three-stage units shown in FIG. 11, a leaky coaxial cable is put on the lower edge of each unit. However, the end is connected.

  In FIG. 11, a coaxial cable 13a is connected to a wireless tag reader / writer 11 from a feeding point (connector), a distributor 20 is connected to the coaxial cable 13a, and a leaky coaxial cable 14a and a coaxial cable 13b are connected to the distributor 20. .

  Further, the distributor 21 is connected to the coaxial cable 13b, and the leaky coaxial cable 14b and the coaxial cable 13c are connected to the distributor 21. Further, the distributor 22 is connected to the coaxial cable 13 c, and the leaky coaxial cable 14 c is connected to the distributor 22.

  That is, the transmitter / receiver 12 is operated to transmit radio waves from the wireless tag reader / writer 11 to the leaky coaxial cable via the coaxial cable, and the ID is detected from the wireless tag attached to each substrate 43 (43a, 43b...). Let the leaky coaxial cable catch the cord.

  The RFID tag reader / writer decodes these ID codes and sends them to the transmission / reception device 12. The transmission / reception device 12 compares the received ID code with the ID of the substrate stored in advance as a key. , Display what is stored.

  If the substrate 43 is pulled out, what is pulled out is displayed using the ID code as a key.

  In addition, the transmission / reception device includes a table that stores the number of the place where the board of each unit of the box enters and the type of the board, and when the board is replaced, the ID code detected by the leaky coaxial cable as a key, The board type corresponding to this ID code is read, and if it differs from the table type, an error is immediately notified.

  Also, the ID code detected by the leaky coaxial cable can be sent to the monitoring center via the network and used for maintenance management.

  In addition, as shown in FIG. 12, the leaky coaxial cable 14a is put on the wall surface in the tunnel, and the wireless tag 2 is attached to the wall surface near the leaky coaxial cable 14a to detect the peeling of the wall in the tunnel. May be. That is, when the wall is peeled off, the wireless tag falls, so that the leaky coaxial cable cannot capture the ID of the wireless tag.

  This is transmitted by the wireless tag position detection device to the monitoring center via the network.

In FIG. 13, a leaky coaxial cable is placed on the railing of the bridge, and a wireless tag is attached in the vicinity thereof.

  In FIG. 14, a wireless tag is attached to the wall of a building, the inside of the building, etc., and a leaky coaxial cable is put around this.

  When the wireless tag (15, 16, 17) is dropped or displaced, the ID code of the wireless tag cannot be captured by the leaky coaxial cable. The wireless tag position transmission device 10 (including the wireless tag reader / writer and the transmission / reception device) transmits this to the monitoring center 48 via the network.

  At the monitoring center 48, the wall can be peeled off and the signs of internal collapse can be seen immediately, so the residents can be advised to evacuate immediately or can be instructed to maintain the entire building.

1 is a schematic configuration diagram of a wireless tag movement detection system according to a first embodiment. It is explanatory drawing of a leaky coaxial cable. It is explanatory drawing when terminating resistance is attached to the leaky coaxial cable. It is explanatory drawing explaining the screen of a monitoring control system. It is explanatory drawing explaining the relationship between the distance from the transmission source of the electromagnetic waves transmitted from an antenna, and the intensity | strength of electromagnetic waves. It is a block diagram of the radio | wireless tag movement detection system of other embodiment (single type). It is a block diagram of the radio | wireless tag movement detection system of other embodiment (grading type). It is a block diagram of the radio | wireless tag movement detection system of other embodiment (branch type). 1 is a configuration diagram of a wireless tag movement detection system in which a 900 MHz wireless tag 15 and a 13.56 MHz wireless tag 29 are fixed in a case 28 and embedded in the vicinity of a leaky coaxial cable. It is a block diagram when a radio | wireless tag movement detection system is used for a belt conveyor. It is a block diagram when a radio | wireless tag movement detection system is used for the box which accommodated the board | substrate. It is a block diagram when a wireless tag movement detection system is used in a tunnel. It is a block diagram when a wireless tag movement detection system is used for a bridge. It is a block diagram when a wireless tag movement detection system is used in a building. It is a schematic block diagram of the conventional radio | wireless tag detection system. FIG. 2 is a schematic configuration diagram of a conventional wireless tag movement detection system in which a coaxial cable is connected to a wireless tag reader / writer, the coaxial cable is branched, and a tag detection antenna is connected to each branched coaxial cable. It is a schematic block diagram of the conventional wireless tag movement detection system which connected the weight to the wireless tag. 1 is a schematic configuration diagram of a wireless tag movement detection system using an intranet LAN cable. FIG.

Explanation of symbols

11 wireless tag reader / writer 12 transmission / reception device 13 coaxial cable 14 leaking coaxial cable 15 wireless tag 16 wireless tag 17 wireless tag 19 monitoring control system 1

Claims (7)

A leaky coaxial cable laid in the detection area;
A terminating resistor connected to the leaky coaxial cable;
A plurality of wireless tags arranged near the leaky coaxial cable and emitting ID codes upon reception of electromagnetic waves;
A wireless tag reader / writer for supplying a signal to the leaky coaxial cable and decoding an ID code of the wireless tag from a signal transmitted from the leaky coaxial cable;
An apparatus for detecting movement of a wireless tag, comprising: an apparatus for reading a result of decoding by the wireless tag reader / writer and outputting whether or not the wireless tag is detected. The wireless tag is
The wireless tag movement detection system according to claim 1, further comprising an antenna that reacts to at least one of an electric field and a magnetic field of the electromagnetic wave.   3. The wireless tag movement detection system according to claim 1, wherein the wireless tag reader / writer and the leaky coaxial cable are connected to each other by a coaxial cable.   4. The radio tag according to claim 1, wherein the coaxial cables are connected to each other by a plurality of distributors, and the leaky coaxial cables are respectively connected to the distributors and installed in the detection area. Movement detection system.   The leaky coaxial cable is provided over a plurality of sections, and leaky coaxial cables having different signal attenuation rates are connected to the sections. Wireless tag movement detection system. The frequency band to which the antenna of the wireless tag responds is
6. The RFID tag movement detection system according to claim 1, wherein the RFID tag movement detection system is in a 900 MHz band. 7. The wireless tag movement detection system according to claim 1, wherein the detection area is a mountain slope, an inside of a structure, or a substrate.

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