JP6590131B1 - RFID system - Google Patents

Abstract

An RFID system according to the present invention includes a rack having a metal surface inside a housing, a rack storage device housed inside the housing so as to be insertable / removable, an RFIC element having a pair of terminal electrodes, An RFID tag comprising a radiating element connected to one of the terminal electrodes and a ground conductor connected to the other of the pair of terminal electrodes, and a cable shape wired inside the housing and capable of wireless communication with the RFID tag The RFID system includes a reader / writer antenna. The rack storage device has a tag mounting surface parallel to the insertion / extraction direction. The RFID tag is attached such that the radiating element protrudes from the rack storage device in the insertion / extraction direction, and at least a part of the ground conductor faces the tag attachment surface.

Description

The present invention relates to RFID (Radio-Frequency IDentification) system.

  Conventionally, as this type of RFID system, for example, the RFID system described in Patent Document 1 is known. In Patent Literature 1, an RFID tag is attached to the surface of a rack storage device stored in a server rack, and the RFID tag is read by an identification information reading unit provided in the server rack so as to face the RFID tag. An RFID system is described.

JP 2011-221911 A

  However, in the conventional RFID system, when the surface of the rack storage device is a conductor such as metal, the conductor inhibits wireless communication between the identification information reading unit and the RFID tag, and reads the RFID tag. Things that can't be done can happen.

An object of the present invention is not dependent on the material of the surface of the racking device is to provide an RFID system that can be read more reliably RFID tag.

An RFID system according to the present invention includes:
A rack having a metal surface inside the housing;
Rack storage equipment stored inside the housing so as to be insertable / removable in the insertion / removal direction;
An RFID tag comprising: an RFIC element having a pair of terminal electrodes; a radiating element connected to one of the pair of terminal electrodes; and a ground conductor connected to the other of the pair of terminal electrodes;
A cable-shaped reader / writer antenna wired inside the housing and capable of wireless communication with the RFID tag;
An RFID system comprising:
The rack storage device has a tag mounting surface parallel to the insertion / extraction direction,
The RFID tag is configured such that the radiating element protrudes from the rack storage device in the insertion / extraction direction, and at least a part of the ground conductor is attached to face the tag attachment surface.

The rack storage equipment with an RFID tag according to the present invention is:
Rack storage equipment stored inside the rack so as to be insertable / removable in the insertion / extraction direction;
An RFID tag comprising: an RFIC element having a pair of terminal electrodes; a radiating element connected to one of the pair of terminal electrodes; and a ground conductor connected to the other of the pair of terminal electrodes;
With
The rack storage device has a tag mounting surface parallel to the insertion / extraction direction,
The RFID tag is configured such that the radiating element protrudes from the rack storage device in the insertion / extraction direction, and at least a part of the ground conductor is attached to face the tag attachment surface.

  According to the present invention, the RFID tag can be read more reliably without depending on the surface material of the rack storage device.

It is a perspective view which shows schematic structure of an RFID system provided with the reader / writer apparatus which concerns on this embodiment. It is a front view of the RFID system of FIG. It is a side view which permeate | transmits and shows the inside of the RFID system of FIG. It is a top view which shows an example of an RFID tag. It is a disassembled perspective view which shows an example of a RFIC element. It is a schematic block diagram which shows an example of a reader / writer antenna. It is the schematic of the matching circuit part with which the reader / writer antenna of FIG. 6A is provided. FIG. 6B is a plan view of a matching circuit unit included in the reader / writer antenna of FIG. 6A. It is A1-A1 sectional view taken on the line of FIG. 7A. FIG. 6B is an equivalent circuit diagram of a matching circuit unit included in the reader antenna of FIG. 6A. It is a front view which shows the modification which attached the RFID tag to the bottom face of the rack storage apparatus. It is a front view which shows the modification which attached the RFID tag to the side surface of the rack storage apparatus.

An RFID system according to one embodiment of the present invention includes:
A rack having a metal surface inside the housing;
Rack storage equipment stored inside the housing so as to be insertable / removable in the insertion / removal direction;
An RFID tag comprising: an RFIC element having a pair of terminal electrodes; a radiating element connected to one of the pair of terminal electrodes; and a ground conductor connected to the other of the pair of terminal electrodes;
A cable-shaped reader / writer antenna wired inside the housing and capable of wireless communication with the RFID tag;
An RFID system comprising:
The rack storage device has a tag mounting surface parallel to the insertion / extraction direction,
The RFID tag is configured such that the radiating element protrudes from the rack storage device in the insertion / extraction direction, and at least a part of the ground conductor is attached to face the tag attachment surface.

  According to this configuration, even when the tag mounting surface is made of a conductor such as metal, the conductor can be used as a booster antenna, and the gain of the antenna can be improved. That is, according to the above configuration, the RFID tag can be read more reliably without depending on the surface material of the rack storage device.

  The rack may be a server rack having metal surfaces on a plurality of inner surfaces of a rectangular parallelepiped casing.

  The housing stores the plurality of rack storage devices so as to be arranged in a vertical direction perpendicular to the insertion / extraction direction, and the reader / writer antenna has one end connected to a power feeding unit, and the one end A cable-shaped main body having a first conductor extending from one end to the other end, and a second conductor extending from one end to the other end along the first conductor, and the other end of the first conductor And a matching circuit board having a matching circuit portion connected to the other end portion of the second conductor and matching an impedance of the first conductor and an impedance of the second conductor, and the cable-shaped main body portion May be arranged so as to extend in the vertical direction along the inner surface of the housing. According to this configuration, the RFID tags of a plurality of rack storage devices can be read more efficiently by using one reader / writer antenna, and the length of the reader / writer antenna can be further shortened.

  In addition, the RFID tag and the cable-shaped main body may be arranged in the upstream of the insertion / extraction direction inside the housing. According to this configuration, it is possible to read the RFID tags of a plurality of rack storage devices more reliably with one reader / writer antenna.

  The cable-shaped main body may be provided at a position overlapping the radiating element of the RFID tag in a side view as viewed from the lateral direction orthogonal to the insertion / extraction direction and the vertical direction. According to this configuration, it is possible to read the RFID tags of a plurality of rack storage devices more reliably with one reader / writer antenna.

A rack storage device with an RFID tag according to an aspect of the present invention is provided.
Rack storage equipment stored inside the rack so as to be insertable / removable in the insertion / extraction direction;
An RFID tag comprising: an RFIC element having a pair of terminal electrodes; a radiating element connected to one of the pair of terminal electrodes; and a ground conductor connected to the other of the pair of terminal electrodes;
With
The rack storage device has a tag mounting surface parallel to the insertion / extraction direction,
The RFID tag is configured such that the radiating element protrudes from the rack storage device in the insertion / extraction direction, and at least a part of the ground conductor is attached to face the tag attachment surface.

  According to this configuration, even when the tag mounting surface is made of a conductor such as metal, the conductor can be used as a booster antenna, and the gain of the antenna can be improved. That is, according to the above configuration, the RFID tag can be read more reliably without depending on the surface material of the rack storage device.

  Hereinafter, an RFID system and a rack storage device with an RFID tag according to an embodiment will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

  In the following, for convenience of explanation, terms indicating directions such as “up”, “down”, and “lateral” are used assuming a state during normal use. However, these terms are not meant to limit the use state of the RFID system and the rack storage equipment with the RFID tag of the present invention.

(Embodiment)
FIG. 1 is a perspective view illustrating a schematic configuration of an RFID system including a reader / writer device according to the present embodiment. FIG. 2 is a front view of the RFID system of FIG. FIG. 3 is a side view showing the inside of the RFID system of FIG.

  The RFID system according to the present embodiment is a system for managing a plurality of rack storage devices stored inside a server rack installed in a data center using RFID tags. According to this system, for example, even when the rack storage device is offline, the rack storage device can be managed by reading the information of the RFID tag.

  As shown in FIGS. 1 to 3, an RFID system 1 according to this embodiment includes a server rack 2 that is an example of a rack, a rack storage device 3 that is stored in the server rack 2, and a cable-shaped reader / writer antenna 4. And.

  The server rack 2 has a metal surface on the inner side of the casing 21 serving as an outer shell. In the present embodiment, the server rack 2 has metal surfaces on a plurality of inner surfaces of a rectangular parallelepiped casing 21. More specifically, the housing 21 has an upper inner surface 21A, a lower inner surface 21B, and left and right inner surfaces 21C and 21D made of metal. In the present embodiment, the front surface (the right side in FIG. 3) and the back surface (the left side in FIG. 3) of the housing 21 are open surfaces, but, for example, an openable / closable door may be provided.

  The rack storage device 3 is a device that is housed inside the housing 21 of the server rack 2 so as to be insertable / removable in the insertion / removal direction X. In the present embodiment, a plurality of rack storage devices 3 are stored in the casing 21 so as to be arranged in the vertical direction Z perpendicular to the insertion / extraction direction X. Each rack storage device 3 is supported at the bottom by a pair of rails (not shown) provided so as to extend in the insertion / extraction direction X, for example. In addition, metal pillars 21 </ b> E and 21 </ b> F extending in the vertical direction Z are provided on the left and right inner side surfaces 21 </ b> C and 21 </ b> D of the housing 21. Each rack storage device 3 is fixed to the metal pillars 21E and 21F by fastening members such as bolts. The interval between the rack storage devices 3 adjacent to each other in the vertical direction Z is, for example, 5 cm.

  Each rack storage device 3 has a tag attachment surface 3A parallel to the insertion / extraction direction X. The tag attachment surface 3A is made of a conductor such as metal. The RFID tag 5 is attached in parallel to the insertion / extraction direction X on the tag attachment surface 3A. For example, device information and position information of the rack storage device 3 are stored in the RFID tag 5.

  The reader / writer antenna 4 is wired inside the casing 21 and configured to be able to wirelessly communicate with the RFID tag 5. The reader / writer antenna 4 includes a cable-like main body 41, a communication module 42 connected to one end of the cable-like main body 41, and a matching circuit board 43 connected to the other end of the cable-like main body 41. ing.

  The cable-shaped main body 41 is disposed so as to extend in the vertical direction Z along the inner side surface 21 </ b> C of the housing 21. The matching circuit board 43 is attached to the upper inner surface 21 </ b> A of the housing 21. The communication module 42 includes an antenna for external communication (not shown), transmits information of the RFID tag 5 read through the cable-shaped main body 41 to the external device, and receives information received from the external device as the cable-shaped main body 41. Through the RFID tag 5. The RFID tag 5 and the cable-shaped main body 41 are arranged to be biased to the upstream side in the insertion / extraction direction X (the right side in FIG. 3) inside the housing 21.

  In this embodiment, the server rack 2 and the reader / writer antenna 4 constitute a “reader / writer device” that wirelessly communicates with the RFID tag 5 to read and write information to the RFID tag 5.

  FIG. 4 is a plan view showing an example of the RFID tag 5. As shown in FIG. 4, the RFID tag 5 includes an RFIC (Radio-Frequency Integrated Circuit) element 51 having a pair of terminal electrodes 51a and 51b, a radiation element 52 connected to one terminal electrode 51a, and the other terminal. And a ground conductor 53 connected to the electrode 51b.

  As shown in FIG. 1, the RFID tag 5 has a radiating element 52 protruding from the rack storage device 3 in the insertion / extraction direction X, and at least a part of the ground conductor 53 is tag mounting surface 3A as shown by a dotted line in FIG. It is attached so that it may face. As shown in FIG. 3, the cable-shaped main body 41 is provided at a position overlapping the radiation element 52 of the RFID tag 5 in a side view as viewed from the lateral direction Y orthogonal to the insertion / extraction direction X and the vertical direction Z. Yes. Further, as shown in FIG. 2, the cable-shaped main body 41 is provided at a position that does not overlap the RFID tag 5 in a front view as viewed from the insertion / extraction direction X.

  FIG. 5 is an exploded perspective view showing an example of the RFIC element 51. The RFIC element 51 is, for example, an RFIC element corresponding to a communication frequency in the 900 MHz band, that is, the UHF band. In the present embodiment, the RFIC element 51 includes a multilayer substrate 51A, an RFIC chip 51B and a matching circuit 51C built in the multilayer substrate 51A.

  In the present embodiment, the multilayer substrate 51A is constituted by three stacked sheet-like insulating layers 51Aa, 51Ab, and 51Ac. In FIG. 5, a pair of terminal electrodes 51a and 51b are provided on the upper surface of the uppermost insulating layer 51Aa with a space therebetween.

  In the insulating layer 51Ab located in the middle in FIG. 5, the first coil pattern 51Ca is provided at a position facing one terminal electrode 51a, and the second coil pattern 51Cb is located at a position facing the other terminal electrode 51b. Is provided. One end of the first coil pattern 51Ca is connected to one terminal electrode 51a via an interlayer connection conductor, and the other end of the first coil pattern 51Ca is connected to the other end of the second coil pattern 51Cb. One end of the second coil pattern 51Cb is connected to the other terminal electrode 51b via an interlayer connection conductor. A through hole H1 into which the RFIC chip 51B is inserted is provided between the first coil pattern 51Ca and the second coil pattern 51Cb.

  In the lowermost insulating layer 51Ac in FIG. 5, a third coil pattern 51Cc is provided at a position facing the first coil pattern 51Ca, and a fourth coil pattern 51Cd is positioned at a position facing the second coil pattern 51Cb. Is provided. An RFIC chip 51B is mounted between the third coil pattern 51Cc and the fourth coil pattern 51Cd. One end of the third coil pattern 51Cc is connected to one end of the first coil pattern 51Ca via an interlayer connection conductor, and the other end of the third coil pattern 51Cc is connected to one input / output terminal of the RFIC chip 51B. Yes. One end of the fourth coil pattern 51Cd is connected to one end of the second coil pattern 51Cb via an interlayer connection conductor, and the other end of the fourth coil pattern 51Cd is connected to the other input / output terminal of the RFIC chip 51B. Yes.

  In the present embodiment, the matching circuit 51C includes a first coil pattern 51Ca, a second coil pattern 51Cb, a third coil pattern 51Cc, a fourth coil pattern 51Cd, and each interlayer connection conductor. The matching circuit 51C functions to match impedance between the RFIC chip 51B, the radiating element 52, and the ground conductor 53. When the radiating element 52 and the ground conductor 53 functioning as an antenna receive a high-frequency signal from the outside, the RFIC chip 51B is activated by receiving a current induced by the reception. The activated RFIC chip 51B generates a high-frequency signal and outputs the generated signal to the outside as a radio wave via the radiating element 52 and the ground conductor 53.

  As shown in FIG. 4, the radiating element 52 and the ground conductor 53 are partially formed in a meander shape. Thereby, the length in the longitudinal direction can be compressed while maintaining the overall electrical length. In the present embodiment, the end 53a of the ground conductor 53 is configured to be capable of capacitive coupling with the tag mounting surface 3A of the rack storage device 3 respectively. The radiating element 52 is designed to have an electrical length longer than that of the ground conductor 53. The present invention is not limited to this, and the ground conductor 53 may be designed to have an electrical length longer than that of the radiating element 52.

  The RFIC element 51, the radiating element 52, and the ground conductor 53 are provided on the base material 54. The base material 54 is a rectangular thin plate and has a uniform thickness. In the present embodiment, the end portion 52 a of the radiating element 52 and the end portion 53 a of the ground conductor 53 are both configured to be capable of capacitive coupling via the tag mounting surface 3 </ b> A of the rack storage device 3 and the base material 54. The base material 54 is made of a dielectric material having a low dielectric constant with a relative dielectric constant of 10 or less, for example. The substrate 54 is made of a flexible dielectric material such as polyethylene terephthalate (PET), fluorine resin, urethane resin, paper, and the like.

  FIG. 6A is a schematic configuration diagram illustrating an example of the reader / writer antenna 4. 6B is a schematic diagram of a matching circuit unit included in the reader / writer antenna 4 of FIG. 6A. FIG. 7A is a plan view of a matching circuit unit included in the reader / writer antenna 4 of FIG. 6A. 7B is a cross-sectional view taken along line A1-A1 of FIG. 7A. FIG. 7C is an equivalent circuit diagram of the matching circuit unit included in the reader / writer antenna 4 of FIG. 6A.

  As shown in FIG. 6A, the reader / writer antenna 4 includes a cable-shaped main body portion 41 formed of a coaxial cable. The cable-shaped main body 41 includes an inner conductor 44 that is an example of a first conductor, and an outer conductor 45 that is an example of a second conductor provided along the inner conductor 44. The inner conductor 44 is a linear conductor having one end connected to the power feeding unit 46 and extending from one end to the other end. The power feeding unit 46 is built in the communication module 42 shown in FIGS. The external conductor 45 is a tubular conductor extending from one end to the other end along the internal conductor 44 so as to cover the internal conductor 44 via an insulator (not shown).

  Further, as shown in FIG. 6A, the reader / writer antenna 4 includes a matching circuit portion 47 provided at one end portion of the cable-shaped main body portion 41 and a position of the external conductor 45 at a position away from one end portion of the cable-shaped main body portion 41. And a magnetic body 48 provided along the outer peripheral surface.

  As shown in FIG. 6B, the matching circuit unit 47 is connected to the other end portion of the inner conductor 44 and the other end portion of the outer conductor 45 so as to match the impedance of the inner conductor 44 and the impedance of the outer conductor 45. It functions.

  As shown in FIGS. 7A and 7B, the matching circuit unit 47 includes a planar first conductor layer 471 connected to the internal conductor 44, a via-hole conductor 472, and a planar first electrode that is an example of an “electrode pattern”. 2 conductor layers 473. The first conductor layer 471 and the second conductor layer 473 have a width wider than the outer diameter of the outer conductor 45 and extend along the extending direction of the inner conductor 44. The first conductor layer 471 and the second conductor layer 473 are provided so as to face each other via the insulator 474 and are connected to each other by two via-hole conductors 472. The second conductor layer 473 is formed to have a longer length in the extending direction of the cable-shaped main body 41 than the first conductor layer 471. Thus, a part of the second conductor layer 473 and the outer conductor 45 are provided so as to face each other with the insulator 474 interposed therebetween. In FIG. 7B, in order to illustrate both the via-hole conductor 472 and the inner conductor 44 in cross-section, as shown by the line A1-A1 in FIG.

  The inner conductor 44 is electrically connected to the first conductor layer 471. The first conductor layer 471 is electrically connected to the second conductor layer 473 through two via-hole conductors 472. The second conductor layer 473 is connected to the outer conductor 45 by capacitive coupling having a capacitor component 475 through the insulator 474. That is, as shown in FIG. 7C, the inner conductor 44 and the outer conductor 45 are connected via a matching circuit unit 47 having a capacitor component 475 and an inductor component 476.

  The magnetic body 48 is made of ferrite, for example. As shown in FIG. 6A, the magnetic body 48 functions to divide the reader / writer antenna 4 into a radiation unit 61 that performs wireless communication with the RFID tag 5 and a non-radiation unit 62 that does not communicate with the RFID tag 5. To do. That is, the radiating portion 61 extends from one end portion of the cable-shaped main body portion 41 to the magnetic body 48. The non-radiating portion 62 extends from the magnetic body 48 to the other end portion of the cable-shaped main body portion 41. The non-radiating part 62 functions as a shield member. The other end portion of the cable-shaped main body portion 41 is connected to the power feeding portion 46. The outer conductor 45 is connected to the ground so as to be electrically stable.

  Note that the reader / writer antenna 4 is an antenna using a standing wave generated in the external conductor 45, and is not a loop antenna using a so-called induction magnetic field. The detection area (radio wave area) of the reader / writer antenna 4 is limited to about 1 m. Further, even if there is a metal body or a magnetic body in the vicinity of the reader / writer antenna 4, the frequency characteristics do not change greatly. Further, even if the reader / writer antenna 4 is bent, interference between the bent portions does not occur. For this reason, the reader / writer antenna 4 can be relatively freely arranged two-dimensionally or three-dimensionally. Since the reader / writer antenna 4 is formed in a cable shape, the detection range of the reader / writer antenna 4 can be adjusted according to the length of the reader / writer antenna 4.

  Further, the matching circuit unit 47 is provided on the matching circuit board 43 shown in FIGS. As shown in FIG. 7B, the matching circuit board 43 has a second conductor layer 473 that is an electrode pattern formed on the facing surface OS that faces the external conductor 45 via the insulator 474. The matching circuit board 43 is directly or indirectly attached to the upper inner surface 21A via a spacer so that the second conductor layer 473 intersects the upper inner surface 21A of the casing 21 which is a metal surface. For example, the matching circuit board 43 is attached to the upper inner surface 21A in which the angle formed by the second conductor layer 473 with respect to the upper inner surface 21A is in the range of 45 degrees to 135 degrees. In the present embodiment, the matching circuit board 43 is attached to the upper inner surface 21A so that the second conductor layer 473 is orthogonal or substantially orthogonal to the upper inner surface 21A.

  In addition, the second conductor layer 473 is provided at a predetermined distance or more away from a metal surface different from the upper inner surface 21A to which the matching circuit board 43 is attached. For example, when a metal door is provided on the front surface (right side in FIG. 3) of the housing 21, the second conductor layer 473 is provided 5 cm or more away from the door.

  According to the present embodiment, since the matching circuit board 43 is attached to the upper inner surface 21A so that the second conductor layer 473 intersects the upper inner surface 21A that is a metal surface, the second conductor layer 473 and the upper inner surface 21A are attached. It is possible to further reduce the facing area. Thereby, it can suppress that a capacitive component arises between the 2nd conductor layer 473 and 21 A of upper side inner surfaces. As a result, it is possible to suppress a decrease in antenna characteristics of the reader / writer antenna 4.

  Further, according to the present embodiment, since the matching circuit board 43 is attached to the upper inner surface 21A so that the second conductor layer 473 is orthogonal or substantially orthogonal to the upper inner surface 21A, the second conductor layer 473 and the upper inner surface It is possible to further suppress the generation of a capacitive component with respect to 21A. As a result, the deterioration of the antenna characteristics of the reader / writer antenna 4 can be further suppressed.

  In addition, according to the present embodiment, the cable-shaped main body 41 is disposed so as to extend in the vertical direction Z along the inner side surface 21C of the housing 21, and the matching circuit board 43 is disposed on the upper inner surface 21A of the housing 21 or It is attached to the lower inner surface 21B. According to this configuration, the plurality of RFID tags 5 arranged in the housing 21 can be efficiently read by the single reader / writer antenna 4, and the length of the reader / writer antenna 4 can be further shortened.

  Further, according to the present embodiment, the second conductor layer 473 is provided at a predetermined distance or more away from the metal surface different from the upper inner surface 21A to which the matching circuit board 43 is attached. The influence received from a metal surface can be suppressed. As a result, the deterioration of the antenna characteristics of the reader / writer antenna 4 can be further suppressed.

  In addition, according to the present embodiment, the RFID tag 5 is attached such that the radiating element 52 protrudes from the rack storage device 3 in the insertion / extraction direction X, and at least a part of the ground conductor 53 faces the tag attachment surface 3A. ing. According to this configuration, even when the tag attachment surface 3A is made of a conductor such as metal, the conductor can be used as a booster antenna, and the gain of the antenna can be improved. That is, according to the above configuration, the RFID tag 5 can be read more reliably without depending on the material of the surface of the rack storage device 3. In addition, since the RFID tag 5 is not attached to the front or back surface of the rack storage device 3 in which a normal interface is provided, it is possible to suppress a reduction in the visibility of the interface, and it does not hinder the connection of wiring to the interface.

  In addition, according to the present embodiment, the RFID tag 5 and the cable-shaped main body 41 are arranged in the upstream of the insertion / extraction direction X inside the housing 21. According to this configuration, the RFID tags 5 of the plurality of rack storage devices 3 can be read more reliably by the single reader / writer antenna 4.

  Further, according to the present embodiment, the cable-shaped main body 41 is provided at a position overlapping the radiating element 52 of the RFID tag 5 in a side view as viewed from the lateral direction orthogonal to the insertion / extraction direction X and the vertical direction Z. ing. According to this configuration, the RFID tags 5 of the plurality of rack storage devices 3 can be read more reliably by the single reader / writer antenna 4.

  In addition, this invention is not limited to the said embodiment, It can implement in another various aspect. For example, in the above description, the matching circuit board 43 is attached to the upper inner surface 21A of the casing 21, but the present invention is not limited to this. The matching circuit board 43 may be attached to the lower inner surface 21 </ b> B of the housing 21. Further, the matching circuit board 43 may be attached to the inner side surfaces 21 </ b> C and 21 </ b> D of the housing 21. Further, the matching circuit board 43 is not limited to being attached to the inner surface of the housing 21, and may be attached to a metal surface provided in the housing 21. For example, when the server rack 2 has a metal partition, the matching circuit board 43 may be attached to the partition. The “metal surface” is not limited to a flat surface, and may be a mesh surface, for example.

  In the above description, the matching circuit board 43 is attached so that its longitudinal direction is along the upper inner surface 21A as shown in FIG. 1, but the present invention is not limited to this. For example, the matching circuit board 43 may be attached such that the short side direction is along the upper inner surface 21A.

  In the above description, the plurality of rack storage devices 3 are arranged in the vertical direction Z, but the present invention is not limited to this. For example, the plurality of rack storage devices 3 may be arranged in the horizontal direction Y. In this case, the cable-shaped main body 41 may be attached to the inner surface of the housing 21 so as to extend in the lateral direction Y.

  In the above description, the tag mounting surface 3A of the rack storage device 3 is made of a conductor such as metal, but the present invention is not limited to this. For example, the tag attachment surface 3A may be a surface in which a conductor such as metal is coated with a resin. Note that when the tag attachment surface 3A is made of a conductor and the RFID tag 5 is directly attached to the tag attachment surface 3A, the characteristics of the antenna can be improved and the information reading accuracy of the RFID tag 5 can be increased. it can.

  In the above description, as shown in FIGS. 1 to 3, the tag mounting surface 3A of the rack storage device 3 is the top surface of the rack storage device 3, but the present invention is not limited to this. The tag attachment surface 3A of the rack storage device 3 may be a surface parallel to the insertion / extraction direction X. For example, as shown in FIG. 8, the tag attachment surface 3A is the bottom surface of the rack storage device 3, and the RFID tag 5 may be attached to the bottom surface. For example, as illustrated in FIG. 9, the tag attachment surface 3 </ b> A is a side surface of the rack storage device 3, and the RFID tag 5 may be attached to the side surface. In this case, if the cable-shaped main body 41 is positioned on the extension line in the extending direction of the RFID tag 5, it becomes difficult for the cable-shaped main body 41 to read information on the RFID tag 5. For this reason, it is preferable to provide the cable-shaped main body 41 at a position that does not overlap the RFID tag 5 in a front view as viewed from the insertion / extraction direction X.

  In the above description, the cable-shaped main body 41 of the reader / writer antenna 4 is formed of a coaxial cable, but the present invention is not limited to this. For example, the cable-shaped main body 41 is provided along a strip-shaped insulator, a strip-shaped first conductor provided along one main surface of the insulator, and the other main surface of the insulator. You may be comprised with a flat cable provided with a strip | belt-shaped 2nd conductor.

  While the invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.

  According to the present invention, since the RFID tag can be read more reliably without depending on the material of the surface of the rack storage device, for example, a plurality of racks can be stored inside a server rack installed in the data center. This is useful for RFID systems that manage devices using RFID tags.

DESCRIPTION OF SYMBOLS 1 RFID system 2 Server rack 3 Rack storage equipment 3A Tag attachment surface 4 Reader / writer antenna 5 RFID tag 21 Case 21A Upper inner surface 21B Lower inner surface 21C, 21D Inner surface 21E, 21F Metal pillar 41 Cable-shaped main body 42 Communication module 43 Matching circuit board 44 Inner conductor (first conductor)
45 Outer conductor (second conductor)
46 Power feeding section 47 Matching circuit section 48 Magnetic body 51 RFIC element 51a, 51b Terminal electrode 51A Multilayer substrate 51Aa, 51Ab, 51Ac Insulating layer 51B RFIC chip 51C Matching circuit 51Ca First coil pattern 51Cb Second coil pattern 51Cc Third coil pattern 51Cd Fourth coil pattern 52 Radiating element 52a End portion 53 Ground conductor 53a End portion 54 Base material 61 Radiating portion 62 Non-radiating portion 471 First conductor layer 472 Via-hole conductor 473 Second conductor layer (electrode pattern)
474 Insulator 475 Capacitor component 476 Inductor component H1 Through hole

Claims (3)

A rack having a metal surface inside the housing;
Rack storage equipment stored inside the housing so as to be insertable / removable in the insertion / removal direction;
An RFID tag comprising: an RFIC element having a pair of terminal electrodes; a radiating element connected to one of the pair of terminal electrodes; and a ground conductor connected to the other of the pair of terminal electrodes;
A cable-shaped reader / writer antenna wired inside the housing and capable of wireless communication with the RFID tag;
An RFID system comprising:
The rack storage device has a tag mounting surface parallel to the insertion / extraction direction,
The RFID tag is attached so that the radiating element protrudes from the rack storage device in the insertion / extraction direction, and at least a part of the ground conductor faces the tag attachment surface ,
In the housing, a plurality of the rack storage devices are stored so as to be arranged in a vertical direction perpendicular to the insertion / extraction direction,
The reader / writer antenna is
A cable having one end connected to a power feeding portion, a first conductor extending from the one end to the other end, and a second conductor extending from the one end to the other end along the first conductor. A main body,
A matching circuit board connected to the other end portion of the first conductor and the other end portion of the second conductor and having a matching circuit portion for matching the impedance of the first conductor and the impedance of the second conductor; Prepared,
The cable-shaped main body is disposed so as to extend in the vertical direction along the inner surface of the housing,
The RFID tag and the cable-shaped main body portion are arranged to be biased toward the upstream side in the insertion / extraction direction inside the housing,
RFID system.   The RFID system according to claim 1, wherein the rack is a server rack having metal surfaces on a plurality of inner surfaces of a rectangular parallelepiped housing. The cable-like main body, in a side view as viewed from a lateral direction orthogonal to the insertion direction and the vertical direction, the is provided in the overlap with the radiating element position of the RFID tag, to claim 1 or 2 The described RFID system.

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