JP4484066B2 - Water leakage detection method and water leakage detection system - Google Patents

Description

  The present invention relates to an RFID (Radio Frequency Identification) system and a method using the system, and more particularly to a water leakage detection method, a water leakage detection system, and an RFID tag that detect water leakage in a water pipe.

  Distribution pipes that are installed in various buildings and underground are regularly inspected to prevent damage caused by water leaks. This water leakage inspection is performed by a method in which a worker visually checks or palpates the joints of the water pipes one by one in a narrow space where the water pipes are installed. Because it is installed in a dark place with no lighting such as inside the hood, it is not easy to check for water leaks by visual inspection or palpation. There was sex.

  Therefore, various apparatuses and methods have been proposed in order to automate such work that relies on the skill of the worker. For example, Japanese Patent Laid-Open No. 2004-245618 discloses a vibration sensor that can measure sound generated when water leaks from a water pipe, and a frequency separator that separates a signal obtained by the vibration sensor into a plurality of frequency bands. An inverse conversion device that sums only the frequencies necessary for determination out of the single frequency waveform separated by the frequency separator and returns it to the sound waveform, and a characteristic sound waveform and a determination reference value output by the inverse conversion device And a water leakage detection device including a determination device for determining water leakage is disclosed.

JP-A-2004-245618 (page 3-6, FIG. 5)

  However, since the water leakage detection device measures sound generated at the time of water leakage, even if a large amount of water leakage can be detected, it is difficult to detect slight water leakage. In addition, a large-scale device is required to compare the frequency component of the sound generated by the water flow flowing through the water pipe and the frequency of the water leaking sound leaking from the cracks and joints, and the inspection of the water leak is costly. Further, in such a method, when a plurality of water distribution pipes are arranged in a complicated manner, it is difficult to specify in which part the water leakage has occurred.

  The present invention has been made in view of the above-mentioned problems, and its main purpose is to detect water leakage that can be detected easily and reliably even with a slight water leakage without requiring a large-scale device. To provide a detection method, a water leakage detection system, and an RFID tag.

In order to achieve the above object, a water leakage detection method of the present invention includes one or more RFID tags that are installed in the vicinity of a joint of a water distribution pipe and operate in the UHF band or SHF band, and a reader or reader that communicates with the RFID tag. A leak detection method using a writer / writer, wherein the leak is detected based on a change in a communication state between the RFID tag and the reader or the reader / writer due to a leak flowing into the RFID tag from the joint. To do.

  In the present invention, a water absorbing material is disposed on at least a part of the front surface, back surface or front and back surfaces of the RFID tag, and the water absorbing material causes the water leakage to stay on the front surface, back surface or front and back surfaces of the RFID tag. A guide groove is formed on at least one of the front surface and the back surface of the RFID tag, and the guide groove is used to guide the water leakage to the front surface or the back surface of the RFID tag, or on the water pipe installation surface of the RFID tag. A magnetic material is provided, and the soft magnetic material can be configured to suppress the influence of the constituent material of the water pipe or the water inside the water pipe.

Further, the water leakage detection system of the present invention includes at least one RFID tag that is installed in the vicinity of the joint of the water pipe and operates in the UHF band or the SHF band, and a reader or a reader / writer that communicates with the RFID tag. A water leakage detection system comprising: detection of the water leakage based on a change in a communication state between the RFID tag and the reader or the reader / writer due to water leakage flowing into the RFID tag from the joint. is there.

  In the present invention, a configuration in which a water absorbing material that absorbs and retains the leaked water is disposed on at least a part of the front surface, back surface, or front and back surfaces of the RFID tag, on at least one of the front surface or back surface of the RFID tag, A guide groove for guiding the water leakage to the front or back surface of the RFID tag may be formed, or a soft magnetic material may be provided on the water pipe installation surface of the RFID tag. .

  Further, in the present invention, the water leakage determining means for determining that there is water leakage when the reader or the reader / writer cannot communicate with the RFID tag or when the communication state is worse than a predetermined reference state. It can also be set as the structure provided.

  As described above, in the present invention, the RFID tag that operates in a high frequency band such as the UHF band and the SHF band is easily affected by water. Since an RFID tag that operates in a high frequency band is installed and the presence or absence of water leakage is determined based on changes in the communication state between the RFID tag and the reader or reader / writer, a large-scale device is not required. Water leakage can be detected using the RFID system. Further, the RFID tag is about several millimeters to several centimeters, and the communication state sufficiently changes even with a single drop of water, so that even a slight water leak can be detected easily and reliably.

  According to the water leakage detection method, the water leakage detection system, and the RFID tag of the present invention, even a slight water leak can be detected easily and reliably without requiring a large-scale device.

  The reason for this is that RFID tags that operate in high frequency bands (preferably 2.45 GHz) such as UHF band and SHF band are susceptible to water, and water leaks occur near the joints of distribution pipes. This is because an RFID tag that operates in the high frequency band is installed in an easy place, and the presence or absence of water leakage is determined based on a change in the communication state between the RFID tag and the reader or reader / writer.

  Further, the RFID tag is about several mm to several cm, and even a single drop of water sufficiently changes the communication state, so that even a slight water leak can be detected. In addition, an absorbing material that absorbs and retains leaked water is disposed on at least a part of the front or back surface of the RFID tag, or leaked water is placed on at least one of the front or back surface of the RFID tag. Because it is possible to improve the detection accuracy by providing guide grooves on the front or back surface, or by disposing the soft magnetic material on the distribution pipe installation surface of the RFID tag to suppress the influence of water inside the distribution pipe. is there.

  As described above, conventionally, inspection of water leaks in water distribution pipes has been performed by visual inspection or palpation, but it is not easy to detect water leaks in water pipes in narrow and dark places. Thus, an apparatus for automatically detecting a water leak is disclosed in Patent Document 1 or the like, but it is difficult for a conventional apparatus to detect a slight water leak. There was a problem that could not be identified.

  In recent years, an RFID system that performs data communication between a tag having an IC chip and a reader or a reader / writer has been used for various purposes. This RFID system has different communicable distances depending on the frequency band to be used, and operates in a short wave band of about 13.56 MHz, and operates in a high frequency band such as UHF band and SHF band. An RFID tag that operates in a high frequency band is characterized by a long communication distance. However, since this frequency band is absorbed by water, it is susceptible to the influence of water.

  For this reason, an RFID tag that operates in a high frequency band such as the UHF band or the SHF band is not normally used for applications that operate near water. However, in the present invention, an RFID tag that operates in the high frequency band affects the influence of water. Utilizing the disadvantage of being easily received, the RFID tag is installed in a place where water leakage is likely to occur, such as a joint of a water distribution pipe, and the change in the communication state between the RFID tag and the reader or reader / writer (communication distance The presence or absence of water leakage can be determined on the basis of a decrease, a shift in the resonance frequency, or communication failure. The specific configuration will be described below with reference to the drawings.

  First, a water leakage detection method, a water leakage detection system, and an RFID tag according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram schematically illustrating a configuration of a water leakage detection system according to the present embodiment, and FIG. 2 is a diagram illustrating a structure of a tag according to the present embodiment. Moreover, FIG. 3 is a figure which shows typically the state which installed the tag of a present Example in the water pipe, and FIG. 4 is a figure which shows typically the state which the water leak generate | occur | produced. 5 to 8 are diagrams showing variations of the tag of this embodiment.

  As shown in FIG. 1, the water leakage detection system 1 of the present embodiment includes one or more tags 2 that perform data communication in a high frequency band (preferably near 2.45 GHz) such as a UHF band or an SHF band, and a reader or reader. / Writer (hereinafter referred to as reader / writer 6). The tag 2 includes an antenna 3 that constitutes a resonance circuit and an IC chip 5 that stores information, and the reader / writer 6 includes an antenna 7 that communicates with the tag 2 and a communication circuit 8a that converts transmission / reception signals. And a control unit 8 such as an arithmetic processing circuit 8b for decoding transmission / reception signals. The tag 2 is driven using a built-in power source or a power source supplied from the reader / writer 6.

  As shown in FIG. 2, the tag 2 has an antenna 3 (preferably operated in the UHF band or SHF band) on a base material 4 made of a deformable plastic film having a size of several mm × several cm. A dipole antenna) and an IC chip 5 are arranged, and the antenna 3 and the IC chip 5 are connected.

  Note that the structure of FIG. 2 is an example, and the structure and shape of the antenna 3 are not particularly limited. For example, FIG. 2 shows a dipole antenna in which two antenna elements are arranged in a straight line as the antenna 3, but any antenna that can operate in a frequency band such as the UHF band or the SHF band may be used. Of the two antenna elements of the dipole antenna, the monopole antenna that is a mirror image by dropping the GND side onto the casing, and the two dipole antennas are arranged in a cross shape with a 90 ° phase shift and circularly polarized A turn-style antenna that radiates waves may be used. In FIG. 2, the antenna 3 and the IC chip 5 are exposed, but the entire tag 2 may be protected by a film or the like.

  And the tag 2 of the said structure is installed in the place where the water leak of a water pipe tends to produce. For example, as shown in FIG. 3, the tag 2 is fixed in the vicinity of the connection portion between the pipe 9 and the joint 10 using an adhesive or an adhesive tape. The installation location of the tag 2 is arbitrary, and the tag 2 may be installed so as to contact the joint 10 or may be installed so as to straddle the pipe 9 and the joint 10. The number of tags 2 is also arbitrary, and the tags 2 may be installed at a plurality of locations, or a plurality of tags 2 may be installed at each connection location.

  Here, when water leakage does not occur, when the antenna 7 of the reader / writer 6 (preferably a handy type reader / writer that is easy to carry) is held over the tag 2, the tag 2 and the reader / writer 6 are connected. Data communication is normally performed between them, but when water leaks, if the leaked water 11 covers at least part of the antenna 3 of the tag 2 as shown in FIG. As a result, electromagnetic waves are absorbed and the communication distance is shortened, or the leaked water 11 causes the impedance of the antenna 3 to change and the resonance frequency to shift, thereby deteriorating the communication state and causing troubles such as communication failure. To do.

  Therefore, based on the change in the communication state between the tag 2 and the reader / writer 6, it can be determined that there is no water leakage if the communication state is normal and that water leakage has occurred if the communication state is abnormal. Therefore, water leakage can be detected easily and reliably. In addition, since the reader / writer 6 can identify each tag 2 when a plurality of tags 2 are installed, if a table that associates the tag 2 with the installation location is provided in advance, a location where water leakage has occurred Can also be identified.

  The water leakage state shown in FIG. 4 is merely an example, and it is sufficient that the leaked water 11 spreads over at least a part of the front surface or the back surface of the antenna 3 of the tag 2, and the tag 2 of this embodiment is as described above. Since it is a small size of several millimeters to several centimeters, the communication state can be sufficiently changed even with a single drop of water leakage. Further, the inspector himself / herself may determine the presence or absence of water leakage. For example, a determination unit is provided in the control unit 8 of the reader / writer 6, and the communication is impossible when the communication is impossible or the communication state is worse than a predetermined reference state. A configuration may be adopted in which it is determined that there is a leak and the inspector is notified by a lamp or the like.

  In addition, when water leaks little by little from the connection point of the water distribution pipe, the water accumulates below the water distribution pipe. In FIG. 3, the tag 2 is installed at the bottom of the water distribution pipe (here, the pipe 9). 3 Since it is not possible to specify from which position water drops at a vertical connection point on the right side, there is a possibility that water leakage cannot be detected depending on the installation location of the tag 2. Therefore, in such a case, as shown in FIG. 5, the tag 2 can be installed so as to cover the entire circumference of the water distribution pipe (here, the joint 10). As a method of covering the entire circumference of the water pipe, the length of the tag 2 may be longer than the outer circumference of the water pipe, and the tag 2 may be wound around the water pipe. A ring-shaped tag 2 that is substantially equal to the outer surface of the water pipe may be formed, and the tag 2 may be fitted from one end of the water pipe.

  Further, when the tag 2 is fixed to the water distribution pipe with an adhesive or an adhesive tape, the tag 2 must be fixed by inserting a hand into a narrow space, and it may be difficult to work depending on the arrangement of the water distribution pipe. Therefore, for example, as shown in FIG. 6, the tag 2 is processed into an arc shape (for example, “C” shape) having a half or more circumference according to the shape of the water distribution pipe, and the tag 2 is formed from the side surface of the water distribution pipe. It can also be a structure to be inserted. In this case, in order to prevent the tag 2 from being easily detached after being inserted into the water distribution pipe, for example, the base material 4 is formed of a plastic having an appropriate thickness, or a spring material or the like is disposed inside the base material 4. For example, it is preferable to provide appropriate flexibility.

  Moreover, in FIG. 3 thru | or FIG. 6, although the tag 2 was installed in the outer peripheral direction of a water pipe, the installation direction of the tag 2 is also arbitrary, for example, as shown in FIG. 7, a water pipe (here pipe 9) and You may arrange | position so that the length of the tag 2 may correspond, and may arrange | position diagonally.

  In the above description, the influence of water leaking from the joint of the water distribution pipe is shown. However, when the thickness of the pipe 9 or the joint 10 is thin, the communication of the tag 2 is caused by the water flowing through the pipe 9 or the joint 10. It is also possible that the state changes. Therefore, when the thickness of the pipe 9 or the joint 10 is thin, the base material 4 of the tag 2 is made thicker, or as shown in FIG. By separating the antenna 3 of the tag 2 from the water pipe (preferably about 3 to 5 mm), the influence of the water flowing inside can be suppressed.

  The spacer 12 can be formed using an arbitrary material. However, for example, when plastic (dielectric constant 2 to 3) or rubber is used, the dielectric constant of the spacer 12 increases, and as a result, the loss caused by the spacer 12 itself. Therefore, it is preferable to use porous plastics (dielectric constant 1.1 to 1.2) such as urethane foam in which bubbles are mixed, porous rubber, or the like.

  As described above, according to the configuration of the present embodiment, the tag 2 that operates in a high frequency band (preferably near 2.45 GHz) such as the UHF band or the SHF band is installed in a place where water leakage is likely to occur, such as a connection portion of a water pipe. And since the presence or absence of water leak is determined based on the change of a communication state, water leak can be detected easily and reliably.

  Next, a water leakage detection method, a water leakage detection system, and an RFID tag according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 12 are diagrams schematically showing the structure of the tag of this embodiment.

  In the first embodiment described above, the tag 2 in which the antenna 3 and the IC chip 5 are arranged on the base material 4 or the tag 2 in which the spacer 12 is arranged at the lower part of the base material 4 is used. Since the constituent material of the tag 2 usually has a property of easily repelling water, when the amount of water leakage is small, the leaked water may not stay on the front and back surfaces of the antenna 3 and the communication state may not change. In addition, if water leaks occur continuously, it is possible to detect water leaks at any time, but if water leaks occur intermittently, There is a possibility that water leaks cannot be detected even after inspection. Therefore, in this embodiment, the leaked water can be held on the front surface or the back surface of the tag 2 so that even a slight water leak or an intermittent water leak can be reliably detected.

  More specifically, as shown in FIG. 9 (a), the tag 2 of this embodiment has a UHF band or SHF on a base material 4 made of a plastic film or the like that can be deformed according to the shape of the water distribution pipe. An antenna 3 that operates in a high-frequency band such as a band (preferably near 2.45 GHz) and an IC chip 5 are arranged, and a surface of the antenna 3 and the IC chip 5 has a water-absorbing material such as a sponge (water-absorbing material 13). Is called). In the tag 2 having such a water absorbing material 13, the water leaked from the connecting portion of the water pipe is absorbed and held by the water absorbing material 13, so even a slight water leak or an intermittent water leak is sure. Can be detected.

  The water-absorbing material 13 may be any material that can absorb water and hold it for a certain period of time. For example, the water-absorbing material 13 can absorb water by a capillary phenomenon such as a filter, paper, or cotton with an appropriately sized hole or gap. A material that can be sucked in or a material that gels by absorbing moisture can be used.

  In FIG. 9A, the entire surface of the tag 2 is covered with the water absorbing material 13, but when the tag 2 is not protected by a film or the like, the IC chip 5 remains wet with water. There is a risk of damage. In such a case, as shown in FIG. 9 (b), the water absorbing material 13 is disposed only on the upper portion of the antenna 3, or as shown in FIG. 9 (c), the water absorbing material is provided only on the upper portion of one antenna 3. It is good also as a structure which arrange | positions the water absorbing material 13 in at least one part of the surface of the tag 2, such as arrange | positioning 13. FIG.

  In FIG. 9, the water absorbing material 13 is disposed on the surface of the tag 2, but the communication state changes even if water is present in the lower part of the antenna 3, so that as shown in FIG. The water absorbing material 13 can also be disposed on the back surface (lower layer of the base material 4). In this case as well, the water absorbing material 13 may be disposed on at least a part of the back surface of the tag 2 such that the water absorbing material 13 is disposed only on the lower layer of the one antenna 3. Further, in order to facilitate the work of fixing the tag 2 having the water absorbing material 13 disposed on the front surface or the back surface to the water distribution pipe, as shown in FIG. 10B, the back surface of the tag 2 (in FIG. The adhesive 14 may be provided in advance on the back surface.

  Moreover, in FIG.9 and FIG.10, although the water absorbing material 13 has been arrange | positioned to one of the surface of the tag 2, or the back surface, in order to improve the water absorption effect, as shown in FIG. A part of the water absorbing material 13 may be disposed, or as shown in FIG. 12, at least a part of the periphery of the tag 2 may be covered with the water absorbing material 13.

  As described above, according to the configuration of the present embodiment, the tag 2 that operates in a high frequency band (preferably near 2.45 GHz) such as the UHF band or the SHF band is installed in a place where water leakage is likely to occur, such as a connection portion of a water pipe. In addition, since the water absorbing material 13 is disposed on at least a part of the front surface or the back surface of the tag 2, the leaked water can be retained on the front surface or the back surface of the tag 2. Even intermittent water leaks can be reliably detected.

  Next, a water leakage detection method, a water leakage detection system, and an RFID tag according to a third embodiment of the present invention will be described with reference to FIGS. 13 to 15 are diagrams schematically showing the structure of the tag of this embodiment.

  In the second embodiment described above, the water absorbing material 13 is disposed on at least one of the front surface and the back surface of the tag 2, but it is sufficient that the leaked water can be reliably guided to the upper surface or the lower surface of the antenna 3 of the tag 2. Therefore, for example, as shown in FIG. 13, a guide groove 15 can be provided on the back surface of the substrate 4. In this structure, the leaked water is guided to the lower part of the antenna 3 along the guide groove 15 and stays inside the guide groove 15 due to surface tension, so that even a slight water leak can be detected efficiently. It becomes possible.

  The shape, depth and direction of the guide groove 15 are not particularly limited. For example, the guide groove 15 may be formed along the longitudinal direction of the tag 2 as shown in FIG. As shown, when the protective material 16 is formed on the surface of the tag 2, the guide groove 15 may be provided in the protective material 16 on the upper surface of the tag 2, or the guide groove 15 is provided on both the front surface and the back surface. May be. 13 to 15, the guide groove 15 is formed in one direction, but a lattice-shaped guide groove 15 may be provided, or a guide groove 15 having a curved or bent shape may be provided.

  As described above, according to the configuration of the present embodiment, the tag 2 that operates in a high frequency band (preferably near 2.45 GHz) such as the UHF band or the SHF band is installed in a place where water leakage is likely to occur, such as a connection portion of a water pipe. In addition, since the guide groove 15 is formed on at least one of the front surface and the back surface of the tag 2, the leaked water can be guided to the front surface or the back surface of the tag 2, and slight water leakage or intermittent Even a water leak can be reliably detected.

  Next, a water leakage detection method, a water leakage detection system, and an RFID tag according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 16 is a diagram schematically showing the structure of the tag of this example, and FIG. 17 is a diagram schematically showing the structure of the soft magnetic material.

  In the above-described embodiment, the tag 2 is fixed to the water distribution pipe alone or via the spacer 12 or the water absorbing material 13, but when the water distribution pipe is formed of a metal material such as iron, the tag is caused by eddy current flowing in the metal material. 2 may not operate or the communication distance may be reduced, and water leakage may not be reliably detected. In addition, when the distance between the water flowing inside the water distribution pipe and the tag 2 is short, the communication state may change due to absorption of electromagnetic waves by the internal water or a shift in resonance frequency.

  Therefore, in this embodiment, for example, as shown in FIG. 16A, a soft magnetic material 17 is disposed on the back surface of the base 4 of the tag 2 having the same structure as that of the first embodiment. As shown in (b), a soft magnetic material 17 is disposed on the back surface of the water absorbing material 13 of the tag 2 having the same structure as that of the second embodiment, and the metal material constituting the water distribution pipe or the water inside the water distribution pipe is used. The effect can be suppressed. In FIG. 16, the soft magnetic material 17 is disposed below the base material 4 or the absorber 13, but the soft magnetic material 17 is applied to the tag 2 having any structure shown in the first to third embodiments. Can be arranged.

  The soft magnetic material 17 is made of a general soft magnetic material or a soft magnetic material manufactured using the method described in the prior application of the present inventor (Japanese Patent Laid-Open No. 2002-215321). However, in order to reduce loss, it is also possible to use a composite of extremely fine soft magnetic metal powder and plastic or rubber.

  This very fine soft magnetic powder is linked in a chain form due to spontaneous magnetization, and the soft magnetic powder is combined with plastic or rubber and extended in one direction as shown in FIG. When a direct-current magnetic field is applied to the film coated with the suspended ink, the chained powder aggregates are aligned in the extended direction as shown in FIG. When a magnetic field is applied in the direction in which the material is extended, the magnetic flux in the extended direction can be increased by passing the aggregate of the chain-like powder. On the other hand, in the direction orthogonal to the extended direction, the powder is not connected, so the magnetic permeability is low, and since the powder is fine, there is no influence of the eddy current flowing inside the powder. Accordingly, if the powder content is adjusted so that the powder is not connected to each other in the direction orthogonal to the magnetization direction, it can be used even at a high frequency exceeding 40 MHz.

  As described above, according to the configuration of the present embodiment, the tag 2 that operates in a high frequency band (preferably near 2.45 GHz) such as the UHF band or the SHF band is installed in a place where water leakage is likely to occur, such as a connection portion of a water pipe. And since the soft magnetic material 17 is arrange | positioned on the back surface of the tag 2, even if it is a case where a water distribution pipe is comprised with the metal material, a water leak can be detected reliably.

  In the second embodiment, the water absorbing material 13 is disposed on the tag 2, and in the third embodiment, the guide groove 15 is provided on the tag 2, but the water absorbing material 13 is disposed on one surface by combining these. It is also possible to provide a combination such as providing the guide groove 15 on the other surface, and further disposing the soft magnetic material 17 shown in the fourth embodiment.

  In each of the above embodiments, the tag 2 that operates in the UHF band or the SHF band is used. However, the tag 2 according to the present invention only needs to change its communication state depending on the presence or absence of water, and operates in the water absorption band. Any tag can be used.

  Further, in each of the above embodiments, the structure of the tag 2 or the reader / writer 6 is characterized, but in order to efficiently guide the leaked water to the front surface or the back surface of the tag 2, A guide groove may be provided on the path between the tag 2 and the joint of the water pipe.

  In the present invention, since the communication state changes depending on the presence or absence of water, the tag 2 and the antenna 7 of the reader / writer 6 are opposed to each other with the water pipe interposed therebetween, and it is detected whether water is flowing in the water pipe. It can be applied to systems.

It is a figure which shows typically the structure of the water leak detection system which concerns on 1st Example of this invention. It is a figure which shows the structure of the tag which concerns on 1st Example of this invention. It is a figure which shows typically the installation state of the tag which concerns on 1st Example of this invention. It is a figure which shows typically the installation state (at the time of water leakage) of the tag which concerns on 1st Example of this invention. It is a figure which shows the variation of the tag which concerns on 1st Example of this invention. It is a figure which shows the variation of the tag which concerns on 1st Example of this invention. It is a figure which shows the variation of the tag which concerns on 1st Example of this invention. It is a figure which shows the variation of the tag which concerns on 1st Example of this invention. It is a figure which shows the structure of the tag which concerns on 2nd Example of this invention. It is a figure which shows the variation of the tag which concerns on 2nd Example of this invention. It is a figure which shows the variation of the tag which concerns on 2nd Example of this invention. It is a figure which shows the variation of the tag which concerns on 2nd Example of this invention. It is a figure which shows the structure of the tag which concerns on 3rd Example of this invention. It is a figure which shows the variation of the tag which concerns on the 3rd Example of this invention. It is a figure which shows the variation of the tag which concerns on the 3rd Example of this invention. It is a figure which shows the structure of the tag which concerns on the 4th Example of this invention. It is a figure which shows typically the manufacturing method and sectional structure of the soft-magnetic material which concern on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water leak detection system 2 Tag 3 Antenna 5 IC chip 6 Reader / writer 7 Antenna 8 Control part 8a Communication circuit 8b Arithmetic processing circuit 9 Pipe 10 Joint 11 Leaked water 12 Spacer 13 Water absorption material 14 Adhesive material 15 Guide groove 16 Protection material 17 Soft magnetic materials

Claims (9)

A water leakage detection method using one or more RFID tags installed in the vicinity of a joint of a water distribution pipe and operating in a UHF band or an SHF band, and a reader or a reader / writer that communicates with the RFID tag,
A water leak detection method, comprising: detecting the water leak based on a change in a communication state between the RFID tag and the reader or the reader / writer due to water leaking into the RFID tag from the joint.   The water-absorbing material is disposed on at least a part of the front surface, the back surface, or the front and back surfaces of the RFID tag, and the leaked water is retained on the front surface, the back surface, or the front and back surfaces of the RFID tag. The water leakage detection method according to 1.   The water leakage detection method according to claim 1, wherein a guide groove is formed on at least one of a front surface and a back surface of the RFID tag, and the water leakage is guided to the front surface or the back surface of the RFID tag by the guide groove.   2. A soft magnetic material is disposed on the surface of the RFID tag to which the water pipe is installed, and the soft magnetic material suppresses the influence of the constituent material of the water pipe or the water inside the water pipe. The water leakage detection method as described in any one of thru | or 3. A leak detection system comprising at least one RFID tag that operates in the UHF band or SHF band and is installed in the vicinity of a joint of a water pipe and a reader or a reader / writer that communicates with the RFID tag,
A water leakage detection system capable of detecting the water leakage based on a change in a communication state between the RFID tag and the reader or the reader / writer due to water leakage flowing into the RFID tag from the joint.   6. The water leakage detection system according to claim 5, wherein a water absorbing material that absorbs and retains the water leakage is disposed on at least a part of the front surface, back surface, or front and back surfaces of the RFID tag.   The water leakage detection system according to claim 5, wherein a guide groove for guiding the water leakage to the front surface or the back surface of the RFID tag is formed on at least one of the front surface or the back surface of the RFID tag.   The water leakage detection system according to any one of claims 5 to 7, wherein a soft magnetic material is disposed on the water pipe installation surface of the RFID tag.   The reader or the writer is provided with a water leakage determination unit that determines that there is water leakage when communication with the RFID tag is not possible or when the communication state is worse than a predetermined reference state. Item 9. The water leakage detection system according to any one of Items 5 to 8.

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