JP3570512B2 - RFID element for metal body and apparatus for identifying metal body using the same - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an RFID element for a metal body without a battery using an RFID (Radio Frequency Identification) technology and an apparatus for identifying a metal body using the same. More specifically, various metal pipes such as gas pipes, water pipes, sewer pipes, cable pipes, optical fiber pipes, oil transport pipes, chemical transport pipes, and metal objects such as metal objects are laid underground, underground, or above ground. TECHNICAL FIELD The present invention relates to a metal body RFID element for identifying a metal body in a non-contact manner for each type when or after laying, and a metal body identification device using the same.
[0002]
[Prior art]
In complex large-scale plants such as petroleum refining facilities, power generation facilities, shipyards, and chemical factories, many types of metal pipes having almost the same outer diameter are laid underground and above ground. If multiple types of metal pipes need to be laid at once, such as when building a new large plant in a short period of time, make sure that the metal pipes are not accidentally connected to different types. The metal tube itself is provided with an identification symbol or character using a color material such as paint that is difficult to decolorize, and the identification symbol or character is used as reference data to determine the date and time of laying the metal tube, material, size, manufacturer, and inside the tube. The name of the flowing fluid, the piping route, and other necessary data were described in another drawing or form, or were digitized and recorded on a computer. At the time of connection of the metal tube, the drawing, the form or the computer list, and the identification symbol of the metal tube itself were visually identified and collated. Also, when laying the metal pipe, when inspecting, repairing or replacing it, the drawing and the like and the identification code of the metal pipe itself were visually discriminated as in the case of connection, and collated with the history information of the metal pipe. . In addition, information on the results of inspections and the like is also recorded on a form or the like while checking the identification code and the like of the metal tube itself. Such identification and collation work for metal pipes was similarly performed for metal pipes buried underground in cities.
[0003]
[Problems to be solved by the invention]
However, in the conventional method of attaching identification symbols and characters to the metal pipe itself and visually discriminating and collating it, metal pipes laid underground with insufficient lighting equipment or metal pipes laid underground In addition, a considerable amount of time and effort is required for discrimination and collation for a metal tube or the like laid on the ground in a complicated manner, and an identification error may occur.
In order to improve this point, it has been attempted to attach a non-contact type RFID element for a metal body to a metal tube. However, when the metal tube is a magnetic material such as a cast iron tube or a steel tube, the self-inductance of the antenna coil of the RFID element can be increased by attaching the RFID element for a metal body directly or very close to the outer surface of such a tube. Has changed, the resonance frequency of the radio wave transmitted from the external identification device has changed, and the Q value of the antenna coil has been greatly reduced, so that the RFID function cannot be performed.
An object of the present invention is to accurately mount a metal body without changing a resonance frequency for activating an RDID circuit transmitted from an identification device or a Q value of an antenna coil even when integrally mounted on a metal body such as a metal tube. An object of the present invention is to provide an RFID element for a metal body that can be identified and a metal body identification device using the same.
[0004]
[Means for Solving the Problems]
As shown in FIGS. 2 and 6, the invention according to claim 1 is attached to a metal body 20, and is connected to a magnetic material 11 serving as a magnetic core, an antenna coil 12 wound around the magnetic material, and the antenna coil. The RFID circuit 13 has a memory 13f for storing data unique to the metal body, is activated by a radio wave of a specific frequency from the metal body identification device 30, and reads out the radio wave by a data communication command. The RFID device 10 for a metal body configured to read the data from the memory 13f in response to the write command, write data to the memory 13f in response to the write command, and generate a response signal to the identification device 30. , integrally attached to the metal body 20 the outer circumferential surface of the antenna coil 12 is opposed to the outer surface of the metal body 20, the magnetic member 11 as a magnetic core diameter 0. Metal member RFID element soft magnetic powder or the thickness of the metal of ~30μm flakes of 0.1~10μm soft magnetic metal is characterized by being formed by a composite material contained in 10 to 95 wt% plastic It is.
[0005]
The identification code interrogation signal of the RFID element 10 is transmitted from the external identification device 30 to the RFID element 10. When the antenna coil 12 receives a radio wave of a specific frequency of the interrogation signal, the RFID circuit 13 is activated by electric power generated in the coil 12 by electromagnetic induction. The RFID element 10 that has received the interrogation signal transmits an identification code unique to the metal object to the identification device 30, and the identification device 30 that has received the identification code specifies the metal object. Since the RFID element 10 has the outer peripheral surface of the antenna coil 12 attached to the outer surface of the metal body 20 so as to face the outer surface of the metal body 20, the lines of magnetic force generated and emitted to the coil 12 are directed in the axial direction of the magnetic material 11. Since this direction is substantially parallel to the outer surface of the metal body 20 and most of the magnetic force lines do not pass through the metal body 20, even if the material of the metal body 20 is a ferromagnetic material such as cast iron or steel, it is hard to be affected by this. In addition, since the magnetic material 11 serving as the magnetic core is formed of a composite material of soft magnetic metal powder and plastic or a composite material of soft magnetic metal flake and plastic, an eddy current is generated to lower the resonance characteristics. I won't let you. As a result, the change in the self-inductance of the coil 12 is small, the change in the frequency of the interrogation signal is small, and the decrease in the Q value of the coil 12 is small, so that the RFID element 10 is reliably activated, and Data communication can be performed.
[0006]
The invention according to claim 4 is the invention according to any one of claims 1 to 3 , wherein the metal body 20 is a metal tube, and the magnetic material 11, the antenna coil 12, and the capacitor 13 are covered by the insulating member 16. A portion of the insulating member 16 that is in contact with the metal tube 20 is the RFID element for a metal body formed on the concave surface 16a.
By making the portion of the insulating member 16 in contact with the metal tube 20 concave, the RFID element 10 can be mounted in a stable state.
[0008]
According to a fifth aspect of the present invention, as shown in FIG. 6, a radio wave of a specific frequency is transmitted to the metal body RFID element 10 according to any one of the first to fourth aspects, which is integrally attached to the metal body 20. The RFID circuit 13 of the lever element 10 is activated, data is read / written from / to the memory 13f of the circuit 13 and a response signal from the RFID element 10 is received to identify the metal body 20. It is a device for identifying a metal body.
When a radio wave of a specific frequency is transmitted from the external identification device 30, the radio wave activates the RFID circuit 13 of the RFID element 10, and simultaneously reads and writes data from the memory 13 f of the circuit 13. When the identification device 30 receives the response signal from the RFID element 10, the metal body 20 can be identified.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
(A) Use of RFID Element for Metal Body The metal body identified by the RFID element of the present invention is mainly used in underground such as gas pipes, water pipes, sewer pipes, cable pipes, optical fiber pipes, oil transport pipes, and chemical transport pipes. And various metal pipes laid underground or on the ground. In addition to these metal pipes, the present invention can also be applied to identify metal articles that are laid for a special purpose and need to be inspected, repaired, or replaced at a later date. Examples of the material of the metal tube include ferromagnetic or conductive materials represented by iron tubes, cast iron tubes, copper or copper alloy tubes, corrosion-resistant or heat-resistant alloy tubes, and the like.
(B) Configuration of RFID Element for Metal Body As shown in FIG. 6, the RFID element for metal body 10 is connected to a magnetic material 11 serving as a magnetic core, an antenna coil 12 wound around the magnetic material, and the antenna coil. RFID circuit 13. The RFID circuit 13 has a power supply circuit 13a, a radio frequency (RF) circuit 13b, a modulation circuit 13c, a demodulation circuit 13d, a CPU 13e, and a memory 13f connected to the memory for storing data unique to a metal body. The power supply circuit 13a has a built-in capacitor (not shown), and this capacitor forms a resonance circuit with the antenna coil 12. This capacitor is charged with electric power generated by electromagnetic induction when the antenna coil 12 receives a radio wave having a specific resonance frequency. The power supply circuit 13a rectifies and stabilizes this power and supplies it to the CPU 13e to activate the RFID circuit 13.
[0010]
The memory 13f of the RFID element 10 includes a read only memory (ROM), a random-access memory (RAM), and an electrically erasable programmable only only memory (EEPROM). The stored data is read in response to a read command by data communication, and data is written in response to a write command from the identification device 30.
For example, when the metal body is a metal tube, the following data is stored in the memory 13f of the RFID element.
(A) When mounting an RFID element immediately after manufacturing a metal tube, data such as manufacturing conditions, size, material, and inspection result are stored, which is useful for appropriately delivering the metal tube to a laying site.
(A) When installing an RFID element before laying a metal pipe, data such as the name of the plant to be laid, the place of laying, the order of laying, the name of the fluid flowing through the pipe, and the system of the fluid are stored. Prevention and easy detection of the metal tube during inspection after installation.
(C) After laying the metal tube, write data such as the temperature during use of the metal tube and whether there is any abnormality, and use it for the next inspection and maintenance.
[0011]
The shape of the magnetic material 11 serving as the magnetic core of the antenna coil 12 is a solid plate, column, or prism. Examples of the magnetic material 11 include a soft magnetic metal powder or a composite material of flake and plastic. Here, carbonyl iron powder or reduced iron powder is used for the soft magnetic metal powder, and iron, permalloy, an amorphous alloy, etc. are refined by atomizing the flakes of the soft magnetic metal to obtain the soft magnetic metal powder. After molding, flakes obtained by mechanically flattening the soft magnetic metal powder are used.
[0012]
As a method of manufacturing a soft magnetic metal and plastic composite material, a mixture of soft magnetic metal powder or flakes and a plastic powder such as nylon resin, polyethylene resin, acrylic resin, and vinyl chloride resin is kneaded, and this kneaded material is mixed. A suitable method is to pelletize and then injection mold into a predetermined shape. In this case, if a magnetic field is applied in the magnetic direction during the injection of the mixture to align the soft magnetic metals, the characteristics as the RFID element are further improved. The mixture of the soft magnetic metal powder or the flake and the plastic powder may be formed into a plate by a roll and then cut into strips, compression-molded, or cast into a mold. In any of the above methods, the characteristics are improved by applying a magnetic field to align the soft magnetic metals.
[0013]
When the soft magnetic metal is a powder, its diameter is preferably in the range of 0.1 to 30 μm, and more preferably in the range of 0.3 to 5 μm. When the soft magnetic metal is a flake, its thickness is preferably in the range of 0.1 to 10 μm, and more preferably in the range of 0.3 to 5 μm. When the diameter of the soft magnetic metal powder is smaller than the above range, the powder is easily oxidized, and when the diameter is too large, there is a problem that the loss due to eddy current increases. The mixing ratio of the soft magnetic metal to the plastic is preferably 10 to 95% by weight, more preferably 40 to 90% by weight. The rest is plastic. If the content of the soft magnetic metal is less than the above range, there is a problem that the magnetic permeability is too low. If the content exceeds the above range, there is a problem that the soft magnetic metals come into direct contact with each other and the magnetic material 11 becomes conductive, resulting in a large loss. . The antenna coil 12 wound around the magnetic material is a conductive wire made of copper, copper alloy (Cu-Cr, Cu-Be, Cu-Zn), aluminum, or the like having excellent conductivity. It is preferable that this conductive wire is covered with an insulating film.
[0014]
When the metal body is made of a ferromagnetic material such as iron or cast iron, the electromagnetic shielding member 14 shown in FIGS. 1 and 5 avoids the electromagnetic influence from such a metal body and reduces the resonance characteristics of the resonance circuit of the RFID element. Is used to further improve. For this purpose, the electromagnetic shielding material needs to have a larger area than the magnetic material. Further, it is preferable that the electromagnetic shielding material is provided at a slight distance from the surface of the metal body, the outer peripheral surface of the antenna coil, and the surface of the magnetic material so as not to come into direct contact with them. Further, the electromagnetic shielding material is a nonmagnetic and conductive plate material or thin film such as high-purity aluminum, high-purity copper or copper alloy.
When this electromagnetic shielding material is used, the size of the magnetic material and the antenna coil, the number of coil turns, and the capacitance of the capacitor are selected so that a predetermined resonance frequency is obtained in a state where the electromagnetic shielding material is present. When this electromagnetic shielding material is interposed between the outer peripheral surface of the coil and the metal body, the magnetic lines of force coming out of the magnetic material at the time of resonance that are going to pass through the metal body are placed on the electromagnetic shielding material having high conductivity. pass. Since the electromagnetic shielding material is non-magnetic and conductive, the hysteresis loss is extremely small and eddy current loss hardly occurs. As a result, even if the metal body is a ferromagnetic body, it does not affect the resonance circuit, and the antenna coil is electromagnetically cut off from the metal body, so that a change in the self-inductance of the coil and a decrease in the Q value are completely prevented. it can.
[0015]
As shown in FIGS. 1 to 4, the magnetic material 11, the antenna coil 12, the RFID circuit 13, and the like of the present invention are exposed to direct sunlight, wind and rain, placed in a high-temperature and high-humidity environment, or buried in the ground. For this reason, it is preferable that the insulating member 16 is covered with the insulating member 16 having excellent airtightness, watertightness, and weather resistance. The insulating member 16 is preferably made of plastic such as polypropylene, nylon, polyester, vinyl chloride, vinyl acetate, ABS, polyethylene, and epoxy resin, which can be easily processed and mass-produced. The magnetic material, the antenna coil, the RFID circuit, etc. may be sealed in a plastic case, but the injection molded plastic body is more durable when laid for a long time, and the electrical characteristics are improved. Is not changed. When the metal body is made of a magnetic material and no electromagnetic shielding material is provided, it is preferable to injection-mold the plastic body so that the distance between the outer peripheral surface of the antenna coil and the outer surface of the metal body is 60 mm or more. This is because the plastic between the magnetic material and the metal body functions as an electromagnetic shielding material. When the metal body is a metal tube, it is preferable that the portion of the plastic body or the plastic body that is in contact with the metal tube has a concave surface 16a (FIG. 1) because the RFID element 10 can be stably mounted. When the RFID element is mounted on a metal tube having a single diameter, the concave surface is most preferably a curved surface having the same radius of curvature as the outer peripheral surface of the metal tube when the RFID element is mounted. When attaching the RFID element to a plurality of types of metal tubes having different diameters, it is preferable that the concave surface has a versatile V-shaped cross section (FIG. 1) which can be used in common without changing the shape.
[0016]
(C) Method of Attaching RFID Element for Metal Body to Metal Body In the invention according to claim 1, the outer peripheral surface of the antenna coil 12 faces the outer surface of the metal body 20 as shown in FIG. , The RFID element 10 is integrally attached to the metal body 20. The RFID element may be directly adhered to the outer surface of the metal body with an adhesive, or may be attached by a screwing means such as a screw. When the metal body is a metal tube, after the RFID element is brought into contact with the outer peripheral surface of the metal tube, an adhesive tape 19 is wrapped around the RFID element 10 as shown in FIGS. A belt (not shown) may be provided on the RFID element and the belt may be integrated by tightening and fixing the belt. Alternatively, although not shown, a strong permanent magnet may be fixed to a portion of the insulating member which is in contact with the metal body, and the insulating member may be bonded by this magnetic force.
[0017]
When the axial direction X of the antenna coil 12 is vertical as shown in FIG. 3, the RFID element 10 is attached to the side surface of the metal tube 20 in parallel to the tangent to the outer peripheral surface of the metal tube. That is, the antenna coil 12 is disposed so that the axial direction thereof is perpendicular to the axial direction of the metal tube 20. FIG. 5 shows an equivalent circuit at this time. In addition, as shown in FIG. 4, when the antenna coil 12 is arranged so that the axial direction X is horizontal and parallel to the axial direction of the metal tube 20, the RFID element 10 is mounted on the surface of the metal tube 20. 3 and 4, broken arrows indicate lines of magnetic force radiated at the time of resonance.
[0019]
(D) Configuration of Metal Object Identification Device and Method of Identifying Metal Object Using This Device As shown in FIG. 6, the metal object identification device 30 is a handy type RFID controller, and includes a transmitting / receiving antenna 31 and a battery. A power supply circuit 32, a radio frequency (RF) circuit 33, a modulation circuit 34, and a demodulation circuit 35 are provided. Further, the identification device 30 has a CPU 36, a memory 37 connected thereto, a display 38, and an input device 39.
An example of a method of identifying a metal body to which the RFID element 10 is attached by the identification device 30 configured as described above will be described. In this example, the metal body is a steel pipe laid in a plant factory, and the RFID element 10 is attached as shown in FIG. Returning to FIG. 6, data unique to the steel pipe (identification code, pipe size, pipe material, name of fluid flowing through the pipe, etc.) is stored in the memory 13f of the RFID element 10 in advance. The identification code interrogation signal is transmitted from the transmission / reception antenna 31 of the identification device 30 to the antenna coil 12 of the RFID element 10 by radio waves of a specific frequency. This interrogation signal is a binary digital signal. This digital signal is emitted from a signal generator (not shown) of the identification device 30 and is modulated by the modulation circuit 34. The RF circuit 33 amplifies the modulated signal and transmits the amplified signal from the antenna 31. This modulation includes, for example, ASK (amplitude modulation), FSK (frequency modulation) or PSK (phase modulation).
[0020]
The radio waves of the transmitted interrogation signal are received by the antenna coil 12 without changing the frequency by the electromagnetic shielding member 14 (FIG. 1) provided between the outer peripheral surface of the antenna coil 12 of the RFID element 10 and the steel pipe 20. You. By this reception, the electric power generated by the electromagnetic induction is charged in the capacitor of the power supply circuit 13a. The power supply circuit 13a rectifies and stabilizes this power, supplies it to the CPU 13e, and activates the RFID circuit 13. Next, the RF circuit 13b of the RFID circuit 13 fetches only the signal necessary for demodulation, and the demodulation circuit 13d reproduces the original digital signal interrogation signal. The data such as the material and the name of the fluid flowing through the pipe are transmitted to the identification device 30. The transmission of this data is performed by modulating the binarized identification code by the modulation circuit 13c of the RFID circuit 13, amplifying it by the RF circuit 13b, and transmitting the amplified data from the antenna coil 12.
[0021]
Next, in the identification device 30 that has received the data, the information specific to the steel pipe can be confirmed on the display 38. Here, when the steel pipe is inspected and the result is written into the memory 13f of the RFID element 10, the data of the inspection result is inputted from the input device 39 and the identification device 30 is transmitted to the RFID element 10 in the same manner as when the identification code is transmitted. Send. The data of the inspection result is written into the memory 13f of the RFID element 10 and is used as a reference for the next inspection.
[0022]
【The invention's effect】
As described above, the RFID element for a metal body according to the present invention has a structure in which the outer peripheral surface of the antenna coil is attached to the metal body so as to face the outer surface of the metal body such as a metal tube, and the magnetic material serving as a magnetic core is formed of a soft magnetic metal. Since it is formed of a composite material of powder or flakes and plastic, the resonance frequency of the RFID element and the Q value of the coil do not change even if they are integrally attached to the metal body, and the metal body can be reliably identified. As a result, the RFID element of the present invention is attached to each metal pipe in a plant factory where various kinds of metal pipes are intricate, the interrogation signal is transmitted by the identification device, and the metal pipe is laid or inspected while checking with the response signal. For example, connection or inspection of a metal tube due to a mistake can be prevented. If the status of the metal tube is written in the memory of the RFID element at the time of inspection or the like, the history of the metal tube can be read out and confirmed later from the memory of the RFID element by the identification device.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing how an RFID element is attached to a metal body.
FIG. 2 is a sectional view showing another attachment state of the RFID element to a metal body.
FIG. 3 is a perspective view showing a state of attachment of the RFID element corresponding to FIG. 1 to a metal body.
FIG. 4 is a perspective view showing a state of attachment of the RFID element corresponding to FIG. 2 to a metal body.
FIG. 5 is a diagram showing an equivalent circuit of the metal element RFID element of the present invention.
FIG. 6 is a circuit configuration diagram of the metal body RFID element and the metal body identification device of the present invention.
[Explanation of symbols]
10 RFID element for metal body 11 Magnetic material (magnetic core)
12 antenna coil 13 RFID circuit 13f memory 16 insulating member 16a concave surface 20 metal body (metal tube)
30 Metal body identification device

Claims (5)

A magnetic material (11) attached to a metal body (20) and serving as a magnetic core, an antenna coil (12) wound around the magnetic material, and an RFID circuit (13) connected to the antenna coil, wherein the RFID The circuit (13) has a memory (13f) for storing data unique to the metal body, is activated by a radio wave of a specific frequency from the metal body identification device (30), and responds to a read command by data communication of the radio wave. Read data from the memory (13f) and write data to the memory (13f) in response to a write command, and generate a response signal to the identification device (30). An RFID element (10),
An outer peripheral surface of the antenna coil (12) is integrally attached to the metal body (20) so as to face an outer surface of the metal body (20),
The magnetic material (11) serving as the magnetic core contained 10 to 95% by weight of soft magnetic metal powder or 0.1 to 10 μm thick soft magnetic metal flakes having a diameter of 0.1 to 30 μm in plastic. An RFID element for a metal body, which is formed of a composite material. The RFID element for a metal body according to claim 1 , wherein the metal body (20) is a metal tube, and the axial direction of the antenna coil (12) is arranged perpendicular to the axial direction of the metal tube (20). The RFID for a metal body according to claim 1 or 2 , wherein the metal body (20) is a metal tube, and the axial direction of the antenna coil (12) is arranged parallel to the axial direction of the metal tube (20). element. The metal body (20) is a metal tube, and the magnetic material (11), the antenna coil (12), and the RFID circuit (13) are covered by an insulating member (16), and the insulating member (16) The RFID element for a metal body according to any one of claims 1 to 3, wherein a portion in contact with the metal tube (20) is formed in a concave surface (16a). The RFID circuit (13) of the element (10) by transmitting a radio wave of a specific frequency to the metal element RFID element (10) according to any one of claims 1 to 4, which is integrally attached to the metal element (20). ) And reads / writes data from / to the memory (13f) of the circuit (13), receives a response signal from the RFID element (10), and identifies the metal body (20). The configured metal body identification device.

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