WO2021145044A1 - Slot antenna for reader/writer of rfid tag, and reader/writer device for rfid tag - Google Patents

Slot antenna for reader/writer of rfid tag, and reader/writer device for rfid tag Download PDF

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Publication number
WO2021145044A1
WO2021145044A1 PCT/JP2020/039832 JP2020039832W WO2021145044A1 WO 2021145044 A1 WO2021145044 A1 WO 2021145044A1 JP 2020039832 W JP2020039832 W JP 2020039832W WO 2021145044 A1 WO2021145044 A1 WO 2021145044A1
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Prior art keywords
antenna
slot
electrode
rfid tag
reader
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PCT/JP2020/039832
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French (fr)
Japanese (ja)
Inventor
詩朗 杉村
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株式会社フェニックスソリューション
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Priority to JP2021527909A priority Critical patent/JP7031924B2/en
Publication of WO2021145044A1 publication Critical patent/WO2021145044A1/en

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • H01Q13/10—Resonant slot antennas

Definitions

  • the present invention relates to a slot antenna for an RFID tag reader / writer and an RFID tag reader / writer device using the slot antenna.
  • Patent Document 1 Japanese Unexamined Patent Publication No. 2004-199226
  • the non-communication area can be reduced, stable communication with the tag can be performed, and the influence on the device installed near the antenna is affected.
  • Disclosed are reader / writer antennas that can be suppressed and RFID systems with such antennas.
  • the reader / writer antenna described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2004-199226) and the RFID system provided with the antenna are the reader / writer antenna composed of a plurality of loop antennas, and each of the plurality of loop antennas is ,
  • the currents are arranged so as to be adjacent to each other at least one loop antenna, and the phases of the currents supplied to at least two adjacent loop antennas are different from each other.
  • Patent Document 2 Japanese Unexamined Patent Publication No. 2009-159240
  • a predetermined wireless IC tag and an antenna are simultaneously used.
  • an antenna built into a housing and a label printer using the antenna which can perform reliable wireless communication only between the antennas.
  • the housing-embedded antenna of Patent Document 2 Japanese Unexamined Patent Publication No. 2009-159240
  • An antenna connected to a writer and arranged in a housing, wherein the antenna is a horn antenna, and the horn antenna is a feeding element, a metal body having a horn shape, and the inside of the horn shape of the metal body. It is characterized by containing a dielectric material filled in the antenna.
  • Patent Document 3 Japanese Unexamined Patent Publication No. 2009-273011
  • a portable RFID reader that appropriately controls gain and directivity without causing an increase in cost, an increase in housing size, or a decrease in reliability. It is disclosed about the writer.
  • the portable RFID reader / writer of Patent Document 3 Japanese Unexamined Patent Publication No. 2009-273011 is a portable RFID reader / writer in which a dipole antenna for transmitting and receiving radio waves to and from an RF tag is provided in a housing.
  • a non-feeding element is provided in at least one of the positions where the Yagi antenna waveguide is formed with respect to the dipole antenna element and the position where the Yagi antenna reflector is formed with respect to the dipole antenna element. It is characterized in that a detachable attachment / detachment mechanism is provided.
  • Patent Document 4 Japanese Unexamined Patent Publication No. 2019-161490 realizes a cavity slot antenna applicable to a small communication terminal such as an RFID tag, and discloses miniaturization and high performance.
  • the antenna device described in Patent Document 4 Japanese Unexamined Patent Publication No. 2019-161490 is arranged via an air layer or a dielectric layer substantially parallel to a substrate having a ground conductor and the ground conductor, and at least a part of the antenna device is refracted.
  • a flat plate-shaped antenna conductor having a closed polygonal slot, a plurality of short-circuit conductors connecting the antenna conductor and the ground conductor, and a plurality of short-circuit conductors arranged in the vicinity of any one of the plurality of short-circuit conductors.
  • the outer peripheral length of the slot is approximately 1 ⁇ to 2 ⁇ , and the width of the slot is 0.005 ⁇ to 0.05 ⁇ .
  • the distance between the plurality of short-circuit conductors is ⁇ / 2 or less, and the distance between the antenna conductor and the ground conductor is 0.005 ⁇ to 0.05 ⁇ .
  • the RFID tag reader / writer may need to communicate with one or a part of the RFID tags and not with the other RFID tags.
  • the RFID tag manufacturing line when an RFID tag is inspected, encoded, and decoded in an assembly line using a belt conveyor or the like, there are non-target RFID tags before and after the target RFID tag. There is. In this case, it is necessary to communicate with the target RFID tag without being affected by the non-target RFID tags existing before and after the target RFID tag.
  • the conventional reader / writer antenna is affected by the non-target RFID tags existing before and after the RFID tag, so that the RFID tag cannot be inspected accurately and efficiently.
  • a reader / writer is inside a housing for storing the product. It is necessary to communicate only with the RFID tag attached to the product.
  • the conventional reader / writer has a problem that if the housing and / or the lid that closes the housing is not shielded, it also communicates with the RFID tag attached to the product outside the housing.
  • the reader / writer antenna described in Patent Document 1 includes a plurality of loop antennas, and it is necessary to adjust the phase between the loop antennas, which causes a problem that the configuration of the antenna and peripheral circuits becomes complicated. Further, the housing-embedded antenna described in Patent Document 2 needs to be provided with a metal body having a horn shape, which also complicates the configuration. Further, the portable RFID reader / writer described in Cited Document 3 also needs to be provided with a director of the Yagi antenna and / or a reflector of the Yagi antenna, which also complicates the configuration.
  • the antenna device described in Patent Document 4 includes a flat plate-shaped antenna conductor having a closed polygonal slot at least partially refracted, so that the direction perpendicular to the plane on which the slot is formed (+ Z direction).
  • the directivity of the radio wave having a rotation in the ⁇ direction is relatively large in the X direction, and the directivity is in the Y direction. Then, there is a problem that the directivity of the radio wave having a rotation in the ⁇ direction is relatively large.
  • An object of the present invention is to suppress the radiation gain of the horizontal plane and the radiation of the horizontal wave in order to prevent the influence of the RFID tag located at a remote position on the horizontal plane, and to radiate the vertical wave uniformly in one direction perpendicular to the antenna surface.
  • a second object of the present invention is to provide an antenna having the above directivity and a reader / writer connected to the antenna, and by arranging the RFID tag in a direction perpendicular to the antenna surface, another RFID in the vicinity thereof. It is an object of the present invention to provide a reader / writer device for RFID tags that can prevent the influence of the above.
  • the slot antenna is a slot antenna for a reader / writer of an RFID tag, and is provided with a first antenna board, a first electrode for slot formation provided on the first antenna board and having a spiral slit, and slot formation.
  • a second antenna for forming a spiral slot which is provided inside the slit of the first antenna for forming a slot and has a predetermined distance from the first electrode for forming a slot, a second antenna substrate facing the first antenna substrate, and a second antenna.
  • a third electrode provided on the antenna substrate and a feeding line for feeding power between the second electrode for slot formation and the third electrode are provided.
  • a slot antenna with a cavity having a slit between the slot-forming first electrode and the slot-forming second electrode as a slot is formed.
  • the slit of the slot antenna has a linear shape, but in the slot antenna that follows one aspect, the slit between the first electrode for slot formation and the second electrode for slot formation has a spiral shape.
  • the radiated radio wave (vertical wave) in the ⁇ direction tends to be large in the plane orthogonal to the longitudinal direction of the slot, and the radiated radio wave tends to be small in the longitudinal direction of the slot.
  • a reader / writer device using a linear slot antenna with a cavity is affected by the RFID tag when the RFID tag is present in a direction perpendicular to the longitudinal direction of the slot.
  • the longitudinal direction of the slit is not fixed in a fixed direction by forming the slit between the slot forming first electrode and the slot forming second electrode into a spiral shape. As a result, the radiation gain in the horizontal plane direction and the radiation of the horizontal wave are suppressed, and the vertical wave is uniformly radiated in the direction perpendicular to the first antenna surface.
  • the slot antenna that follows one aspect efficiently gives only vertical waves to the RFID tag arranged in the direction perpendicular to the first antenna board, and is less susceptible to the influence of RFID tags existing at other positions on the horizontal plane. It works. It is preferable that the first antenna board and the second antenna board face each other, and it is more preferable that the first antenna board and the second antenna board face each other in a parallel state.
  • the horizontal plane means a plane parallel to the first antenna substrate and the second antenna substrate.
  • the slot antenna according to the second invention is a slot antenna according to one aspect, in which the electrical length of the slit of the slot forming first electrode is ⁇ / 2 with the wavelength of the communication frequency as ⁇ , and the slot forming second electrode has.
  • the electrical length may be ⁇ / 4.
  • the resonance frequency of the slot antenna with the communication frequency because the gain of the antenna can be increased.
  • the electrical length is expressed based on the delay time of the radio wave, not the physical length. In the case of the present invention, the length is expressed between the first antenna board and the second antenna board. When the air layer is used, the electric length is almost the same as the physical length, but when the dielectric layer is formed between the first antenna substrate and the second antenna substrate, the electric length is longer than the physical length. Become.
  • the slot antenna according to the third invention is the slot antenna according to the second invention, in which one end in the longitudinal direction of the second electrode for slot formation is one end in the longitudinal direction of the slit of the first electrode for slot formation. It may be arranged so as to have a predetermined distance from the end portion.
  • the length of the slit between the slot-forming second electrode and the slot-forming first electrode is increased, respectively. It is preferable that the length of the slit of ⁇ / 4 and the first electrode for slot formation alone is ⁇ / 4, because the gain of the antenna can be increased.
  • a metal nut is further fixed at a position corresponding to the second electrode for slot formation of the third electrode to form a slot.
  • a metal bolt may be inserted toward the second electrode for slot formation, and a variable capacitor may be formed between the second electrode for slot formation and the third electrode.
  • the resonance frequency of the slot antenna can be finely adjusted by forming a capacitor between the second electrode for slot formation and the third electrode and adjusting the capacitance value of the capacitor.
  • the RFID tag reader / writer device includes the slot antenna according to the first to fourth aspects and the reader / writer connected to the feeder line of the slot antenna, and is located at a position facing the first antenna substrate. , Communicates with an RFID tag arranged in the direction opposite to the second antenna substrate.
  • the RFID tag reader / writer device faces the first antenna substrate. At this position, it is possible to efficiently communicate with the RFID tag arranged in the direction opposite to the second antenna substrate, and it is not easily affected by the RFID tag existing at another position on the horizontal plane.
  • the RFID tag reader / writer device is used for RFID tag inspection, encoding, and decoding, RFID tag inspection, encoding, and decoding can be performed accurately and efficiently.
  • this reader / writer device when used in a system that automates accounting in a store by reading the RFID tag attached to the product, it is possible to communicate only with the RFID tag placed upward of the slot antenna. It is possible to eliminate or simplify a shield such as a housing for avoiding the influence of RFID tags attached to other products.
  • FIG. 1 is a schematic drawing when the slot antenna 150 is viewed from the horizontal direction
  • FIG. 2 is a schematic drawing when the first antenna substrate 10 is viewed from the direction of the second antenna substrate 50
  • FIG. 3 is a second diagram. It is a schematic drawing which looked at the antenna board 50 from the direction opposite to the 1st antenna board 10.
  • the horizontal direction means a direction parallel to the first antenna board 10 and the second antenna board 50.
  • the slot antenna 150 includes a first antenna board 10 and a second antenna board 50.
  • a slot-forming first electrode 20 having a spiral-shaped slit and a slot-forming first electrode 20 are provided inside the slits for slot formation.
  • a first electrode 20 and a second electrode 30 for forming a spiral slot having a predetermined interval are provided.
  • a third electrode 55 is provided on the surface of the second antenna board 50 opposite to the first antenna board 10.
  • FR-4 normal glass epoxy substrate
  • the slot forming first electrode 20, the slot forming second electrode 30, and the third electrode 55 can be formed by plating and etching a metal such as copper, for example.
  • the SMC connector 80 is arranged at the end of the second antenna board 50, the GND side of the SMC connector 80 is connected to the third electrode 55, and the signal side passes through the strip line 70 (see FIG. 3) and the feeder line 40. It is connected to the second electrode 30 for forming a slot.
  • the first antenna board 10 and the second antenna board 50 are fixed by fixing bolts 90, fixing nuts 100, and spacers 110 so as to be substantially parallel to each other.
  • the space between the first antenna board 10 and the second antenna board 50 is an air layer in this embodiment, a structure in which a dielectric layer is sandwiched between the first antenna board 10 and the second antenna board 50 may be used.
  • the slot antenna 150 is a slot antenna with a cavity having a slit between the slot forming first electrode 20 and the slot forming second electrode 30 as a slot.
  • the length of the slit of the first electrode 20 for slot formation is preferably an electrical length of ⁇ / 2, where the wavelength of the communication frequency of the slot antenna 150 is ⁇ .
  • the length of the second electrode 30 for forming a slot is preferably an electrical length of ⁇ / 4. This is because the resonance frequency of the slot antenna 150 can be matched with the communication frequency by setting the lengths of the slit and the slot in this way.
  • the width of the slit of the slot forming first electrode 20 is about 0.016 ⁇
  • the width of the slot forming second electrode 30 is about 0.003 ⁇ . The electric length is expressed based on the delay time of the radio wave, not the physical length.
  • the slot-forming second electrode 30 has a spiral shape that maintains a predetermined distance from the slot-forming first electrode 20 from the vicinity of the central end of the slot-forming first electrode 20. Is formed in. Therefore, the slot-forming second electrode 30 does not exist near the end of the slot-forming first electrode 20 on the opposite side of the slit. Further, the predetermined interval is about 0.06 ⁇ in this embodiment.
  • the width of the slit of the first electrode 20 for slot formation is preferably in the range of 0.015 ⁇ to 0.022 ⁇ , and the width of the second electrode 30 for slot formation is preferably in the range of 0.002 ⁇ to 0.003 ⁇ . ..
  • a conductive nut 65 connected to the third electrode 55 is fixed to the second antenna substrate 50, and a conductive bolt 60 is inserted. Further, the bolt 60 extends to the vicinity of the first antenna substrate 10 and is located directly above the second electrode 30 for forming a slot (see FIGS. 1 and 2). Therefore, the bolt 60 and the second electrode 30 for slot formation form a capacitor, and the second electrode 30 for slot formation is adjusted by turning the bolt 60 and adjusting the distance between the bolt 60 and the second electrode 30 for slot formation. The capacitance value between the bolt 60 and the bolt 60 (that is, the third electrode 55) can be adjusted. Then, the resonance frequency of the slot antenna 150 can be finely adjusted by adjusting the capacitance value between the slot forming second electrode 30 and the bolt 60 (that is, the third electrode 55).
  • FIG. 4 shows a graph of the measurement results of the directivity of the vertical wave of the slot antenna 150 on the vertical plane.
  • the direction perpendicular to the first antenna substrate 10 and opposite to the second antenna substrate 50 is the + Z axis, and the angle from the + Z axis is ⁇ .
  • FIG. 5 is a schematic explanatory view showing the directivity of the vertical wave of the slot antenna 150 in the horizontal plane direction.
  • the conventional slot antenna with a cavity a linear slit is formed, and the radiated radio wave (vertical wave) in the ⁇ direction is large in the plane orthogonal to the longitudinal direction of the slot, and the radiated radio wave is small in the longitudinal direction of the slot.
  • the slot antenna will be affected by the RFID tag located in the horizontal plane direction orthogonal to the longitudinal direction of the slot.
  • the direction of the slit to which the electric field is applied is formed radially from the center of the spiral, and therefore, as shown in FIG. , There is almost no directivity depending on the direction in the XY plane, and the smaller the angle ⁇ with the + Z axis in all directions, the higher the strength of the radio wave, and the larger the ⁇ , the lower the strength of the radio wave.
  • the slot antenna 150 provided with the spiral slit of the present invention, by arranging the RFID tag 120 of the communication partner in the upward direction of the slot antenna 150, the influence of the RFID tag in the horizontal direction with respect to the RFID tag 120 is exerted. Only vertical waves can be efficiently applied to the RFID tag 120 of the communication partner without receiving the signal.
  • FIG. 6 shows a configuration diagram of a system including the reader / writer device 160 and the RFID tag 120 of the second embodiment.
  • the reader / writer device 160 is composed of a reader / writer 140 and a slot antenna 150, and communicates with an RFID tag 120 including an RFID tag antenna 125.
  • the RFID tag 120 of the communication partner is efficiently affected without being affected by the RFID tag in the horizontal direction. Only vertical waves can be given. For example, when an RFID tag is inspected, encoded, and decoded in an assembly line using a belt conveyor or the like, there are non-target RFID tags before and after the target RFID tag 120.
  • the reader / writer device 160 for RFID tag inspection needs to be able to communicate with the target RFID tag 120 without being affected by the non-target RFID tag.
  • the reader / writer device 160 provided with the slot antenna 150 of the present invention it is possible to communicate with the target RFID tag 120 without being affected by the non-target RFID tag.
  • the first antenna substrate 10 corresponds to the "first antenna substrate”
  • the slot forming first electrode 20 corresponds to the “slot forming first electrode”
  • the slot forming second electrode 30 corresponds to the "slot”.
  • the second antenna substrate 50 corresponds to the "second antenna substrate”
  • the third antenna 55 corresponds to the "third electrode”
  • the feeding line 40 corresponds to the "feeding line”.
  • the RFID tag 120 corresponds to the "RFID tag”
  • the reader / writer 140 corresponds to the "reader / writer”
  • the slot antenna 150 corresponds to the "slot antenna”
  • the bolt 60 for the variable capacitor corresponds to the "bolt”.
  • the nut 65 for the variable capacitor corresponds to the "nut”
  • the reader / writer device 160 corresponds to the "reader / writer device for RFID tag”.

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Abstract

[Problem] To provide an antenna for an RFID reader/writer configured so that, in order to prevent the influence of an RFID tag in a position separated on the horizontal plane, the antenna suppresses radiation of horizontal waves and radiation gain in a horizontal plane, and uniformly radiates vertical waves in one direction that is vertical relative to the antenna surface. Further, to provide a reader/writer device comprising the antenna. [Solution] A slot antenna 150 is for a reader/writer 140 of an RFID tag 120, the slot antenna 150 comprising: a first antenna substrate 10; a first electrode 20 for slot forming which is provided on the first antenna substrate 10 and has a spiral-shaped slit; a spiral-shaped second electrode 30 for slot forming which is provided inside of the slit of the first electrode 20 and is at a prescribed gap from a first electrode 10; a second antenna substrate 50 facing the first antenna substrate 10; a third electrode 55 provided on the second antenna substrate; and a power supply line 40 which supplies power between the second electrode 30 for slot forming and the third electrode 55.

Description

ＲＦＩＤタグのリーダライタ用のスロットアンテナ、および、ＲＦＩＤタグ用リーダライタ装置Slot antenna for RFID tag reader / writer and RFID tag reader / writer device
　本発明は、ＲＦＩＤタグのリーダライタ用のスロットアンテナ、および、スロットアンテナを用いたＲＦＩＤタグ用リーダライタ装置に関する。 The present invention relates to a slot antenna for an RFID tag reader / writer and an RFID tag reader / writer device using the slot antenna.
　例えば、特許文献１（特開２００４－１９９２２６号公報）には、交信不可能エリアを減少させ、タグとの安定した交信を行うことができ、かつ、アンテナ近傍に設置される機器への影響を抑制することができるリーダ／ライタアンテナ及び該アンテナを備えたＲＦＩＤシステムについて開示されている。
　特許文献１（特開２００４－１９９２２６号公報）記載のリーダ／ライタアンテナ及び該アンテナを備えたＲＦＩＤシステムは、複数のループアンテナにより構成されるリーダ／ライタアンテナにおいて、前記複数のループアンテナの各々は、他の少なくとも一つのループアンテナと相隣り合うように配置され、少なくとも相隣り合う２つのループアンテナに供給される電流の位相が相異なるものである。 For example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2004-199226), the non-communication area can be reduced, stable communication with the tag can be performed, and the influence on the device installed near the antenna is affected. Disclosed are reader / writer antennas that can be suppressed and RFID systems with such antennas.
The reader / writer antenna described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2004-199226) and the RFID system provided with the antenna are the reader / writer antenna composed of a plurality of loop antennas, and each of the plurality of loop antennas is , The currents are arranged so as to be adjacent to each other at least one loop antenna, and the phases of the currents supplied to at least two adjacent loop antennas are different from each other.
　また、特許文献２（特開２００９－１５９２４０号公報）には、ラベルプリンタなどの筐体内にて無線ＩＣタグとの双方向通信を行う際に、同時に所定の１つの無線ＩＣタグとアンテナとの間のみで確実な無線通信を実施することのできる、筐体組み込み用のアンテナと、それを用いたラベルプリンタについて開示されている。
　特許文献２（特開２００９－１５９２４０号公報）の筐体組み込み用アンテナは、双方向の無線通信により、無線ＩＣタグの記憶領域に格納された情報の読み出しおよび書き込みを非接触にて行うＲＦＩＤリーダライタに接続される、筐体内に配置されたアンテナであって、前記アンテナがホーンアンテナであり、前記ホーンアンテナが、給電素子と、ホーン形状を有する金属体と、前記金属体のホーン形状の内部に充填された誘電体とを含むことを特徴とするものである。 Further, in Patent Document 2 (Japanese Unexamined Patent Publication No. 2009-159240), when bidirectional communication with a wireless IC tag is performed in a housing such as a label printer, a predetermined wireless IC tag and an antenna are simultaneously used. Disclosed are an antenna built into a housing and a label printer using the antenna, which can perform reliable wireless communication only between the antennas.
The housing-embedded antenna of Patent Document 2 (Japanese Unexamined Patent Publication No. 2009-159240) is an RFID reader that reads and writes information stored in the storage area of a wireless IC tag in a non-contact manner by bidirectional wireless communication. An antenna connected to a writer and arranged in a housing, wherein the antenna is a horn antenna, and the horn antenna is a feeding element, a metal body having a horn shape, and the inside of the horn shape of the metal body. It is characterized by containing a dielectric material filled in the antenna.
　また、特許文献３（特開２００９－２７３０１１号公報）には、コストの増大や筐体サイズの大型化や信頼性の低下を招くことなく、利得や指向性を適切に制御する携帯型ＲＦＩＤリーダライタについて開示されている。
　特許文献３（特開２００９－２７３０１１号公報）の携帯型ＲＦＩＤリーダライタは、筐体にＲＦタグとの間で電波を送受信するダイポールアンテナが設けられている携帯型ＲＦＩＤリーダライタであって、 前記筐体に、前記ダイポールアンテナのエレメントに対して八木アンテナの導波器を形成する位置及び前記ダイポールアンテナのエレメントに対して八木アンテナの反射器を形成する位置のうち少なくともいずれかに無給電素子を着脱可能な着脱機構が設けられていることを特徴とするものである。 Further, in Patent Document 3 (Japanese Unexamined Patent Publication No. 2009-273011), a portable RFID reader that appropriately controls gain and directivity without causing an increase in cost, an increase in housing size, or a decrease in reliability. It is disclosed about the writer.
The portable RFID reader / writer of Patent Document 3 (Japanese Unexamined Patent Publication No. 2009-273011) is a portable RFID reader / writer in which a dipole antenna for transmitting and receiving radio waves to and from an RF tag is provided in a housing. A non-feeding element is provided in at least one of the positions where the Yagi antenna waveguide is formed with respect to the dipole antenna element and the position where the Yagi antenna reflector is formed with respect to the dipole antenna element. It is characterized in that a detachable attachment / detachment mechanism is provided.
　さらに、特許文献４（特開２０１９－１６１４９０号公報）には、ＲＦＩＤタグ等の小型の通信端末に適用可能なキャビティスロットアンテナを実現し、小型化及び高性能化について開示されている。
　特許文献４（特開２０１９－１６１４９０号公報）記載のアンテナ装置は、 グランド導体を有する基板と、前記グランド導体と略平行に空気層又は誘電体層を介して配置され、少なくとも一部が屈折した閉多角形状のスロットを有する平板状のアンテナ導体と、前記アンテナ導体と前記グランド導体とを接続する複数の短絡導体と、前記複数の短絡導体のうちのいずれかの短絡導体の近傍に配置され、前記アンテナ導体に給電する給電導体と、を有し、使用する周波数の波長をλとしたとき、前記スロットの外周の長さは略１λ～２λ、前記スロットの幅は０．００５λ～０．０５λであり、前記複数の短絡導体の間隔はλ／２以下であり、前記アンテナ導体と前記グランド導体との間の距離は、０．００５λ～０．０５λである。 Further, Patent Document 4 (Japanese Unexamined Patent Publication No. 2019-161490) realizes a cavity slot antenna applicable to a small communication terminal such as an RFID tag, and discloses miniaturization and high performance.
The antenna device described in Patent Document 4 (Japanese Unexamined Patent Publication No. 2019-161490) is arranged via an air layer or a dielectric layer substantially parallel to a substrate having a ground conductor and the ground conductor, and at least a part of the antenna device is refracted. A flat plate-shaped antenna conductor having a closed polygonal slot, a plurality of short-circuit conductors connecting the antenna conductor and the ground conductor, and a plurality of short-circuit conductors arranged in the vicinity of any one of the plurality of short-circuit conductors. When a feeding conductor that feeds the antenna conductor is provided and the wavelength of the frequency used is λ, the outer peripheral length of the slot is approximately 1λ to 2λ, and the width of the slot is 0.005λ to 0.05λ. The distance between the plurality of short-circuit conductors is λ / 2 or less, and the distance between the antenna conductor and the ground conductor is 0.005λ to 0.05λ.
特開２００４－１９９２２６号公報Japanese Unexamined Patent Publication No. 2004-199226 特開２００９－１５９２４０号公報JP-A-2009-159240 特開２００９－２７３０１１号公報Japanese Unexamined Patent Publication No. 2009-273011 特開２０１９－１６１４９０号公報JP-A-2019-161490
　ＲＦＩＤタグ用リーダライタは、複数のＲＦＩＤタグが周囲に存在する環境において、そのうちの１つ、または一部のＲＦＩＤタグと通信し、他のＲＦＩＤタグとは通信しないことが必要な場合がある。
　例えば、ＲＦＩＤタグの製造ラインにおいて、ＲＦＩＤタグをベルトコンベア等を用いて流れ作業で検査、およびエンコード、デコードをする場合には、対象となるＲＦＩＤタグの前後に対象外のＲＦＩＤタグが存在している。この場合、対象となるＲＦＩＤタグの前後に存在する対象外のＲＦＩＤタグの影響を受けることなく対象となるＲＦＩＤタグと通信を行う必要がある。しかし、従来の、リーダライタ用アンテナではＲＦＩＤタグの前後に存在する対象外のＲＦＩＤタグの影響を受けるため、ＲＦＩＤタグの検査を正確に、かつ効率的に行うことができなかった。 In an environment where a plurality of RFID tags are present, the RFID tag reader / writer may need to communicate with one or a part of the RFID tags and not with the other RFID tags.
For example, in an RFID tag manufacturing line, when an RFID tag is inspected, encoded, and decoded in an assembly line using a belt conveyor or the like, there are non-target RFID tags before and after the target RFID tag. There is. In this case, it is necessary to communicate with the target RFID tag without being affected by the non-target RFID tags existing before and after the target RFID tag. However, the conventional reader / writer antenna is affected by the non-target RFID tags existing before and after the RFID tag, so that the RFID tag cannot be inspected accurately and efficiently.
　また、最近、商品に付されたＲＦＩＤタグを読み取ることにより、店舗における会計を自動化するシステムが使われはじめているが、この会計システムにおいては、リーダライタは、商品を収納する筐体の中にある商品に付されたＲＦＩＤタグのみと通信する必要がある。
　しかし、従来のリーダライタでは、筐体および／または筐体を閉じるふたをシールドしなければ、筐体の外にある商品に付されたＲＦＩＤタグとも通信してしまうとの課題があった。 Recently, a system that automates accounting in a store by reading an RFID tag attached to a product has begun to be used. In this accounting system, a reader / writer is inside a housing for storing the product. It is necessary to communicate only with the RFID tag attached to the product.
However, the conventional reader / writer has a problem that if the housing and / or the lid that closes the housing is not shielded, it also communicates with the RFID tag attached to the product outside the housing.
　特許文献１に記載のリーダ／ライタアンテナは複数のループアンテナを備え、かつ、それらのループアンテナの間の位相を調整する必要があり、アンテナおよび周辺回路の構成が複雑になるとの課題がある。
　また、特許文献２に記載の筐体組み込み用アンテナではホーン形状を有する金属体を備える必要があり、やはり構成が複雑になる。
　また、引用文献３に記載の携帯型ＲＦＩＤリーダライタの場合も、八木アンテナの導波器および／または八木アンテナの反射器を備える必要があり、やはり構成が複雑になる。 The reader / writer antenna described in Patent Document 1 includes a plurality of loop antennas, and it is necessary to adjust the phase between the loop antennas, which causes a problem that the configuration of the antenna and peripheral circuits becomes complicated.
Further, the housing-embedded antenna described in Patent Document 2 needs to be provided with a metal body having a horn shape, which also complicates the configuration.
Further, the portable RFID reader / writer described in Cited Document 3 also needs to be provided with a director of the Yagi antenna and / or a reflector of the Yagi antenna, which also complicates the configuration.
　一方、特許文献４に記載のアンテナ装置は、少なくとも一部が屈折した閉多角形状のスロットを有する平板状のアンテナ導体を備えることによって、スロットの形成されている面に垂直な方向（＋Ｚ方向）に指向性を持たせたものであるが、図３、図７、図８等に記載されているように、Ｘ方向ではφ方向の回転を持つ電波の指向性が比較的大きく、またＹ方向ではθ方向の回転を持つ電波の指向性が比較的大きいとの課題がある。 On the other hand, the antenna device described in Patent Document 4 includes a flat plate-shaped antenna conductor having a closed polygonal slot at least partially refracted, so that the direction perpendicular to the plane on which the slot is formed (+ Z direction). However, as shown in FIGS. 3, 7, 8, 8 and the like, the directivity of the radio wave having a rotation in the φ direction is relatively large in the X direction, and the directivity is in the Y direction. Then, there is a problem that the directivity of the radio wave having a rotation in the θ direction is relatively large.
　本発明の目的は、水平面上で離れた位置にあるＲＦＩＤタグの影響を防ぐために、水平面の放射利得と水平波の放射とを抑え、垂直波をアンテナ面に垂直な一方向に均一に放射する、ＲＦＩＤタグのリーダライタ用のスロットアンテナを提供することにある。
　本発明の第２の目的は、上記指向性を備えたアンテナと、アンテナに接続されたリーダライタとを備え、アンテナ面に垂直な方向にＲＦＩＤタグを配置することによって、近傍にある別のＲＦＩＤの影響を防ぐことのできるＲＦＩＤタグ用リーダライタ装置を提供することにある。 An object of the present invention is to suppress the radiation gain of the horizontal plane and the radiation of the horizontal wave in order to prevent the influence of the RFID tag located at a remote position on the horizontal plane, and to radiate the vertical wave uniformly in one direction perpendicular to the antenna surface. , To provide slot antennas for RFID tag reader / writer.
A second object of the present invention is to provide an antenna having the above directivity and a reader / writer connected to the antenna, and by arranging the RFID tag in a direction perpendicular to the antenna surface, another RFID in the vicinity thereof. It is an object of the present invention to provide a reader / writer device for RFID tags that can prevent the influence of the above.
　（１）
　一局面に従うスロットアンテナは、ＲＦＩＤタグのリーダライタ用のスロットアンテナであって、第１アンテナ基板と、第１アンテナ基板に設けられ、スパイラル状のスリットを有するスロット形成用第１電極と、スロット形成用第１電極のスリットの内部に設けられ、スロット形成用第１電極と所定の間隔を有するスパイラル状のスロット形成用第２電極と、第１アンテナ基板に対向する第２アンテナ基板と、第２アンテナ基板に設けられる第３電極と、スロット形成用第２電極と第３電極との間に給電する給電線と、を備える。 (1)
The slot antenna according to one aspect is a slot antenna for a reader / writer of an RFID tag, and is provided with a first antenna board, a first electrode for slot formation provided on the first antenna board and having a spiral slit, and slot formation. A second antenna for forming a spiral slot, which is provided inside the slit of the first antenna for forming a slot and has a predetermined distance from the first electrode for forming a slot, a second antenna substrate facing the first antenna substrate, and a second antenna. A third electrode provided on the antenna substrate and a feeding line for feeding power between the second electrode for slot formation and the third electrode are provided.
　この場合、スロット形成用第１電極とスロット形成用第２電極の間のスリットをスロットとするキャビティ付きのスロットアンテナが形成される。通常、スロットアンテナのスリットは直線形状であるが、一局面に従うスロットアンテナでは、スロット形成用第１電極とスロット形成用第２電極との間のスリットがスパイラル状になっている。
　キャビティ付きで直線形状のスロットアンテナの場合、スロットの長手方向に直交する面内においてθ方向の放射電波（垂直波）が大きく、スロットの長手方向は放射電波が小さい傾向がある。したがって、キャビティ付きで直線形状のスロットアンテナを用いたリーダライタ装置はスロットの長手方向に対して垂直な方向にＲＦＩＤタグが存在する場合、このＲＦＩＤタグの影響を受ける。
　これに対して、一局面に従うスロットアンテナでは、スロット形成用第１電極とスロット形成用第２電極との間のスリットをスパイラル状とすることによって、スリットの長手方向が一定の方向に固定されず、その結果、水平面方向の放射利得と水平波の放射とを抑え、垂直波を第１アンテナ面に垂直な方向に均一に放射する。そして、一局面に従うスロットアンテナは、第１アンテナ基板に垂直な方向に配置されたＲＦＩＤタグに効率よく垂直波のみを与え、水平面上でその他の位置に存在するＲＦＩＤタグの影響を受けにくいとの効果を奏する。
　なお、第１アンテナ基板と、第２アンテナ基板とは、対向することが好ましく、平行な状態で対向することが、より好ましい。
　本明細書において、水平面とは第１アンテナ基板および第２アンテナ基板に平行な面を意味する。 In this case, a slot antenna with a cavity having a slit between the slot-forming first electrode and the slot-forming second electrode as a slot is formed. Normally, the slit of the slot antenna has a linear shape, but in the slot antenna that follows one aspect, the slit between the first electrode for slot formation and the second electrode for slot formation has a spiral shape.
In the case of a linear slot antenna with a cavity, the radiated radio wave (vertical wave) in the θ direction tends to be large in the plane orthogonal to the longitudinal direction of the slot, and the radiated radio wave tends to be small in the longitudinal direction of the slot. Therefore, a reader / writer device using a linear slot antenna with a cavity is affected by the RFID tag when the RFID tag is present in a direction perpendicular to the longitudinal direction of the slot.
On the other hand, in the slot antenna that follows one aspect, the longitudinal direction of the slit is not fixed in a fixed direction by forming the slit between the slot forming first electrode and the slot forming second electrode into a spiral shape. As a result, the radiation gain in the horizontal plane direction and the radiation of the horizontal wave are suppressed, and the vertical wave is uniformly radiated in the direction perpendicular to the first antenna surface. The slot antenna that follows one aspect efficiently gives only vertical waves to the RFID tag arranged in the direction perpendicular to the first antenna board, and is less susceptible to the influence of RFID tags existing at other positions on the horizontal plane. It works.
It is preferable that the first antenna board and the second antenna board face each other, and it is more preferable that the first antenna board and the second antenna board face each other in a parallel state.
In the present specification, the horizontal plane means a plane parallel to the first antenna substrate and the second antenna substrate.
　（２）
　第２の発明にかかるスロットアンテナは、一局面に従うスロットアンテナにおいて、スロット形成用第１電極のスリットの電気長が、通信周波数の波長をλとしてλ／２であり、スロット形成用第２電極の電気長がλ／４であってもよい。 (2)
The slot antenna according to the second invention is a slot antenna according to one aspect, in which the electrical length of the slit of the slot forming first electrode is λ / 2 with the wavelength of the communication frequency as λ, and the slot forming second electrode has. The electrical length may be λ / 4.
　この場合、スロットアンテナの共振周波数を通信周波数と合わせることで、アンテナの利得を上げることができ、好ましい。
　なお、電気長とは、長さを、物理的な長さではなく電波の遅延時間を基準に表したものであって、本発明の場合、第１アンテナ基板と第２アンテナ基板との間を空気層とした場合は電気長は物理的な長さとほぼ同一であるが、第１アンテナ基板と第２アンテナ基板との間を誘電体層とした場合には電気長は物理的な長さより長くなる。 In this case, it is preferable to match the resonance frequency of the slot antenna with the communication frequency because the gain of the antenna can be increased.
The electrical length is expressed based on the delay time of the radio wave, not the physical length. In the case of the present invention, the length is expressed between the first antenna board and the second antenna board. When the air layer is used, the electric length is almost the same as the physical length, but when the dielectric layer is formed between the first antenna substrate and the second antenna substrate, the electric length is longer than the physical length. Become.
　（３）
　第３の発明にかかるスロットアンテナは、第２の発明にかかるスロットアンテナにおいて、スロット形成用第２電極の長手方向の一方の端部が、スロット形成用第１電極のスリットの長手方向の一方の端部と所定の間隔となるように配置されてもよい。 (3)
The slot antenna according to the third invention is the slot antenna according to the second invention, in which one end in the longitudinal direction of the second electrode for slot formation is one end in the longitudinal direction of the slit of the first electrode for slot formation. It may be arranged so as to have a predetermined distance from the end portion.
　この場合、スロット形成用第２電極をスロット形成用第１電極のスリットの端部に寄せることにより、それぞれ、スロット形成用第２電極とスロット形成用第１電極との間のスリットの長さをλ／４、スロット形成用第１電極単独のスリットの長さをλ／４とすることにより、アンテナの利得を上げることができて、好ましい。 In this case, by moving the slot-forming second electrode closer to the end of the slit of the slot-forming first electrode, the length of the slit between the slot-forming second electrode and the slot-forming first electrode is increased, respectively. It is preferable that the length of the slit of λ / 4 and the first electrode for slot formation alone is λ / 4, because the gain of the antenna can be increased.
　（４）
　第４の発明にかかるスロットアンテナは、一局面から第３の発明にかかるスロットアンテナにおいて、さらに、第３電極の、スロット形成用第２電極に対応する位置に金属のナットが固定され、スロット形成用第２電極に向けて金属のボルトが挿入されて、スロット形成用第２電極と第３電極との間に可変キャパシタが形成されてもよい。 (4)
In the slot antenna according to the fourth invention, in the slot antenna according to the first aspect to the third invention, a metal nut is further fixed at a position corresponding to the second electrode for slot formation of the third electrode to form a slot. A metal bolt may be inserted toward the second electrode for slot formation, and a variable capacitor may be formed between the second electrode for slot formation and the third electrode.
　この場合、スロット形成用第２電極と第３電極との間にキャパシタを形成し、キャパシタの容量値を調整することで、スロットアンテナの共振周波数を微調することができる。 In this case, the resonance frequency of the slot antenna can be finely adjusted by forming a capacitor between the second electrode for slot formation and the third electrode and adjusting the capacitance value of the capacitor.
　（５）
　他の局面にかかるＲＦＩＤタグ用リーダライタ装置は、一局面から第４の発明にかかるスロットアンテナと、スロットアンテナの給電線に接続されたリーダライタとを備え、第１アンテナ基板に対向する位置で、前記第２アンテナ基板と反対の方向に配置されるＲＦＩＤタグと通信する。 (5)
The RFID tag reader / writer device according to the other aspect includes the slot antenna according to the first to fourth aspects and the reader / writer connected to the feeder line of the slot antenna, and is located at a position facing the first antenna substrate. , Communicates with an RFID tag arranged in the direction opposite to the second antenna substrate.
　この場合、スロットアンテナは水平面方向の放射利得と水平波の放射を抑え、垂直波をアンテナ面に垂直な方向に均一に放射することから、ＲＦＩＤタグ用リーダライタ装置は、第１アンテナ基板に対向する位置で、前記第２アンテナ基板と反対の方向に配置されるＲＦＩＤタグと効率よく通信することができ、水平面上でその他の位置に存在するＲＦＩＤタグの影響を受けにくい。
　そして、ＲＦＩＤタグ用リーダライタ装置をＲＦＩＤタグの検査、およびエンコード、デコードに用いた場合、正確でかつ効率よく、ＲＦＩＤタグの検査、およびエンコード、デコードを行うことができる。
　また、商品に付されたＲＦＩＤタグを読み取ることにより、店舗における会計を自動化するシステムにこのリーダライタ装置を用いた場合には、スロットアンテナの上方向に配置されたＲＦＩＤタグとのみ通信することができ、他の商品に付されたＲＦＩＤタグの影響を避けるための筐体などのシールドを不要とする、または簡易なものとすることができる。 In this case, since the slot antenna suppresses the radiation gain in the horizontal plane direction and the radiation of the horizontal wave and radiates the vertical wave uniformly in the direction perpendicular to the antenna surface, the RFID tag reader / writer device faces the first antenna substrate. At this position, it is possible to efficiently communicate with the RFID tag arranged in the direction opposite to the second antenna substrate, and it is not easily affected by the RFID tag existing at another position on the horizontal plane.
When the RFID tag reader / writer device is used for RFID tag inspection, encoding, and decoding, RFID tag inspection, encoding, and decoding can be performed accurately and efficiently.
In addition, when this reader / writer device is used in a system that automates accounting in a store by reading the RFID tag attached to the product, it is possible to communicate only with the RFID tag placed upward of the slot antenna. It is possible to eliminate or simplify a shield such as a housing for avoiding the influence of RFID tags attached to other products.
スロットアンテナを水平方向から見た模式的図面である。It is a schematic drawing which looked at the slot antenna from the horizontal direction. 第１アンテナ基板を第２アンテナ基板の方向から見た模式的図面である。It is a schematic drawing which looked at the 1st antenna board from the direction of the 2nd antenna board. 第２アンテナ基板を第１アンテナ基板と反対の方向から見た模式的図面である。It is a schematic drawing which looked at the 2nd antenna board from the direction opposite to the 1st antenna board. スロットアンテナのＹＺ面内の指向性の測定結果を示すグラフである。It is a graph which shows the measurement result of the directivity in the YZ plane of a slot antenna. スロットアンテナの水平方向の指向性を示す模式的説明図である。It is a schematic explanatory drawing which shows the directivity in the horizontal direction of a slot antenna. リーダライタ装置とＲＦＩＤタグからなるシステムの構成図である。It is a block diagram of the system which consists of a reader / writer device and an RFID tag.
　以下、図面を参照しつつ、本発明の実施形態について説明する。以下の説明では、同一の部品には同一の符号を付す。また、同符号の場合には、それらの名称および機能も同一である。したがって、それらについての詳細な説明は繰り返さないものとする。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Moreover, in the case of the same code, their names and functions are also the same. Therefore, the detailed description of them will not be repeated.
［第１の実施形態］
　図１はスロットアンテナ１５０を水平方向から見たときの模式的図面であり、図２は第１アンテナ基板１０を第２アンテナ基板５０の方向から見た模式的図面であり、図３は第２アンテナ基板５０を第１アンテナ基板１０と反対の方向から見た模式的図面である。なお、水平方向とは、第１アンテナ基板１０および第２アンテナ基板５０と平行な方向を意味する。 [First Embodiment]
FIG. 1 is a schematic drawing when the slot antenna 150 is viewed from the horizontal direction, FIG. 2 is a schematic drawing when the first antenna substrate 10 is viewed from the direction of the second antenna substrate 50, and FIG. 3 is a second diagram. It is a schematic drawing which looked at the antenna board 50 from the direction opposite to the 1st antenna board 10. The horizontal direction means a direction parallel to the first antenna board 10 and the second antenna board 50.
　スロットアンテナ１５０は、第１アンテナ基板１０と第２アンテナ基板５０とを備える。第１アンテナ基板１０の第２アンテナ基板５０側の面には、スパイラル状のスリットを有するスロット形成用第１電極２０と、スロット形成用第１電極２０のスリットの内部に設けられ、スロット形成用第１電極２０と所定の間隔を有するスパイラル状のスロット形成用第２電極３０とを備える。第２アンテナ基板５０の第１アンテナ基板１０と反対側の面には、第３電極５５を備える。
　第１アンテナ基板１０と第２アンテナ基板５０とは、例えば、通常のガラスエポキシ基板（ＦＲ－４）を使用することができる。また、スロット形成用第１電極２０、スロット形成用第２電極３０、および第３電極５５は、例えば、銅などの金属をメッキし、エッチングすることで形成することができる。 The slot antenna 150 includes a first antenna board 10 and a second antenna board 50. On the surface of the first antenna substrate 10 on the side of the second antenna substrate 50, a slot-forming first electrode 20 having a spiral-shaped slit and a slot-forming first electrode 20 are provided inside the slits for slot formation. A first electrode 20 and a second electrode 30 for forming a spiral slot having a predetermined interval are provided. A third electrode 55 is provided on the surface of the second antenna board 50 opposite to the first antenna board 10.
As the first antenna substrate 10 and the second antenna substrate 50, for example, a normal glass epoxy substrate (FR-4) can be used. Further, the slot forming first electrode 20, the slot forming second electrode 30, and the third electrode 55 can be formed by plating and etching a metal such as copper, for example.
　第２アンテナ基板５０の端部にはＳＭＣコネクタ８０が配置され、ＳＭＣコネクタ８０のＧＮＤ側は第３電極５５に接続され、信号側はストリップライン７０（図３参照）、給電線４０を経由してスロット形成用第２電極３０に接続される。
　第１アンテナ基板１０と第２アンテナ基板５０は固定用ボルト９０、固定用ナット１００、およびスペーサ１１０で互いにほぼ平行になるように固定されている。第１アンテナ基板１０と第２アンテナ基板５０の間は本実施形態では空気層であるが、第１アンテナ基板１０と第２アンテナ基板５０の間に誘電体層を挟んだ構造としてもよい。
　スロットアンテナ１５０は、スロット形成用第１電極２０とスロット形成用第２電極３０の間のスリットをスロットとするキャビティ付きのスロットアンテナである。 The SMC connector 80 is arranged at the end of the second antenna board 50, the GND side of the SMC connector 80 is connected to the third electrode 55, and the signal side passes through the strip line 70 (see FIG. 3) and the feeder line 40. It is connected to the second electrode 30 for forming a slot.
The first antenna board 10 and the second antenna board 50 are fixed by fixing bolts 90, fixing nuts 100, and spacers 110 so as to be substantially parallel to each other. Although the space between the first antenna board 10 and the second antenna board 50 is an air layer in this embodiment, a structure in which a dielectric layer is sandwiched between the first antenna board 10 and the second antenna board 50 may be used.
The slot antenna 150 is a slot antenna with a cavity having a slit between the slot forming first electrode 20 and the slot forming second electrode 30 as a slot.
　スロット形成用第１電極２０のスリットの長さは、スロットアンテナ１５０の通信周波数の波長をλとして、電気長λ／２とするのが好ましい。また、スロット形成用第２電極３０の長さは電気長λ／４とするのが好ましい。これは、スリットおよびスロットの長さをこのように設定することによって、スロットアンテナ１５０の共振周波数を通信周波数と一致させることができるからである。また、本実施形態ではスロット形成用第１電極２０のスリットの幅は、約０．０１６λ、スロット形成用第２電極３０の幅は、約０．００３λである。
　なお、電気長とは、長さを、物理的な長さではなく電波の遅延時間を基準に表したものである。本発明の場合、第１アンテナ基板１０と第２アンテナ基板５０との間を空気層とした場合は電気長は物理的な長さとほぼ同一であるが、第１アンテナ基板１０と第２アンテナ基板５０との間を誘電体層とした場合には電気長は物理的な長さより長くなる。
　スロット形成用第２電極３０は図２に示したように、スロット形成用第１電極２０のスリットの中心側の端部付近からスロット形成用第１電極２０と所定の間隔を保持してスパイラル状に形成されている。したがって、スロット形成用第１電極２０のスリットの反対側の端部付近にはスロット形成用第２電極３０は存在しない。また、所定の間隔は本実施形態では約０．０６λである。
　なお、スロット形成用第１電極２０のスリットの幅は、０．０１５λから０．０２２λの範囲、スロット形成用第２電極３０の幅は、０．００２λから０．００３λの範囲であることが好ましい。 The length of the slit of the first electrode 20 for slot formation is preferably an electrical length of λ / 2, where the wavelength of the communication frequency of the slot antenna 150 is λ. Further, the length of the second electrode 30 for forming a slot is preferably an electrical length of λ / 4. This is because the resonance frequency of the slot antenna 150 can be matched with the communication frequency by setting the lengths of the slit and the slot in this way. Further, in the present embodiment, the width of the slit of the slot forming first electrode 20 is about 0.016λ, and the width of the slot forming second electrode 30 is about 0.003λ.
The electric length is expressed based on the delay time of the radio wave, not the physical length. In the case of the present invention, when the air layer is formed between the first antenna board 10 and the second antenna board 50, the electrical length is almost the same as the physical length, but the first antenna board 10 and the second antenna board When the dielectric layer is formed between 50 and 50, the electric length is longer than the physical length.
As shown in FIG. 2, the slot-forming second electrode 30 has a spiral shape that maintains a predetermined distance from the slot-forming first electrode 20 from the vicinity of the central end of the slot-forming first electrode 20. Is formed in. Therefore, the slot-forming second electrode 30 does not exist near the end of the slot-forming first electrode 20 on the opposite side of the slit. Further, the predetermined interval is about 0.06λ in this embodiment.
The width of the slit of the first electrode 20 for slot formation is preferably in the range of 0.015λ to 0.022λ, and the width of the second electrode 30 for slot formation is preferably in the range of 0.002λ to 0.003λ. ..
　図１から図３に示すように、第２アンテナ基板５０には第３電極５５に接続された導電性のナット６５が固定され、導電性のボルト６０が差し込まれている。さらにボルト６０は第１アンテナ基板１０の近傍まで伸びて、スロット形成用第２電極３０の直上に位置している（図１、図２参照）。したがって、ボルト６０とスロット形成用第２電極３０とはキャパシタを構成し、ボルト６０を回し、ボルト６０とスロット形成用第２電極３０との間隔を調整することによって、スロット形成用第２電極３０とボルト６０（すなわち第３電極５５）との間の容量値を調整することができる。そして、スロット形成用第２電極３０とボルト６０（すなわち第３電極５５）との間の容量値を調整することによって、スロットアンテナ１５０の共振周波数を微調することができる。 As shown in FIGS. 1 to 3, a conductive nut 65 connected to the third electrode 55 is fixed to the second antenna substrate 50, and a conductive bolt 60 is inserted. Further, the bolt 60 extends to the vicinity of the first antenna substrate 10 and is located directly above the second electrode 30 for forming a slot (see FIGS. 1 and 2). Therefore, the bolt 60 and the second electrode 30 for slot formation form a capacitor, and the second electrode 30 for slot formation is adjusted by turning the bolt 60 and adjusting the distance between the bolt 60 and the second electrode 30 for slot formation. The capacitance value between the bolt 60 and the bolt 60 (that is, the third electrode 55) can be adjusted. Then, the resonance frequency of the slot antenna 150 can be finely adjusted by adjusting the capacitance value between the slot forming second electrode 30 and the bolt 60 (that is, the third electrode 55).
　図４にスロットアンテナ１５０の垂直波の垂直面での指向性の測定結果のグラフを示す。図４においては、第１アンテナ基板１０に垂直で、第２アンテナ基板５０と反対の方向を＋Ｚ軸とし、＋Ｚ軸からの角度をθとしている。スロットアンテナ１５０は＋Ｚ軸方向において電波の強度が最大となり、θ＝３０度で－１ｄＢ、θ＝６０度で－５ｄＢ、θ＝９０度（±Ｙ軸方向）では－１４ｄＢ以上減衰している。
　したがって、例えばＲＦＩＤタグをベルトコンベア等を用いて流れ作業で検査、およびエンコード、デコードをする場合、＋Ｚ軸方向（スロットアンテナ１５０の真上）にＲＦＩＤタグを置くことにより、対象のＲＦＩＤタグ１２０とは良好な通信特性を示し、対象でないＲＦＩＤタグ（例えばθ＝６０度方向にあるＲＦＩＤタグ）に対しては、その影響を最小限とすることができる。 FIG. 4 shows a graph of the measurement results of the directivity of the vertical wave of the slot antenna 150 on the vertical plane. In FIG. 4, the direction perpendicular to the first antenna substrate 10 and opposite to the second antenna substrate 50 is the + Z axis, and the angle from the + Z axis is θ. The strength of the radio wave of the slot antenna 150 is maximized in the + Z-axis direction, and is attenuated by -1 dB at θ = 30 degrees, -5 dB at θ = 60 degrees, and -14 dB or more at θ = 90 degrees (± Y-axis direction).
Therefore, for example, when the RFID tag is inspected, encoded, and decoded by the flow work using a belt conveyor or the like, the RFID tag is placed in the + Z axis direction (directly above the slot antenna 150) to obtain the target RFID tag 120. Shows good communication characteristics, and its influence can be minimized for RFID tags that are not targeted (for example, RFID tags in the direction of θ = 60 degrees).
　図５は、スロットアンテナ１５０の垂直波の水平面方向での指向性を示す模式的説明図である。図５では＋Ｚ軸との角度θ＝０度（＋Ｚ軸方向）、３０度、６０度、９０度（ＸＹ平面）の方向の電波の強度がＸＹ平面内の方向によってどのように変化するかを示している。
　従来のキャビティ付きのスロットアンテナでは、直線状のスリットが形成されており、スロットの長手方向に直交する面内においてθ方向の放射電波（垂直波）が大きく、スロットの長手方向は放射電波が小さい傾向がある。この場合、スロットアンテナは、水平面方向で、スロットの長手方向に直交する方向に位置するＲＦＩＤタグの影響を受けることになる。
　これに対して、本発明のスパイラル状のスリットを備えたスロットアンテナ１５０では、電界が印加されるスリットの向きがスパイラルの中心から放射線状に形成されており、このため、図５に示すように、ＸＹ平面内の方向による指向性はほとんどなく、すべての方向において＋Ｚ軸との角度θが小さい方が電波の強度が大きく、θが大きくなると電波の強度が小さくなっている。
　したがって、本発明のスパイラル状のスリットを備えたスロットアンテナ１５０では通信相手のＲＦＩＤタグ１２０をスロットアンテナ１５０の上方向に配置することにより、ＲＦＩＤタグ１２０に対して水平方向にあるＲＦＩＤタグの影響を受けることなく、通信相手のＲＦＩＤタグ１２０に効率よく垂直波のみを与えることができる。 FIG. 5 is a schematic explanatory view showing the directivity of the vertical wave of the slot antenna 150 in the horizontal plane direction. In FIG. 5, how the intensity of radio waves in the directions of angles θ = 0 degrees (+ Z axis direction), 30 degrees, 60 degrees, and 90 degrees (XY plane) with the + Z axis changes depending on the direction in the XY plane is shown. Shown.
In the conventional slot antenna with a cavity, a linear slit is formed, and the radiated radio wave (vertical wave) in the θ direction is large in the plane orthogonal to the longitudinal direction of the slot, and the radiated radio wave is small in the longitudinal direction of the slot. Tend. In this case, the slot antenna will be affected by the RFID tag located in the horizontal plane direction orthogonal to the longitudinal direction of the slot.
On the other hand, in the slot antenna 150 provided with the spiral slit of the present invention, the direction of the slit to which the electric field is applied is formed radially from the center of the spiral, and therefore, as shown in FIG. , There is almost no directivity depending on the direction in the XY plane, and the smaller the angle θ with the + Z axis in all directions, the higher the strength of the radio wave, and the larger the θ, the lower the strength of the radio wave.
Therefore, in the slot antenna 150 provided with the spiral slit of the present invention, by arranging the RFID tag 120 of the communication partner in the upward direction of the slot antenna 150, the influence of the RFID tag in the horizontal direction with respect to the RFID tag 120 is exerted. Only vertical waves can be efficiently applied to the RFID tag 120 of the communication partner without receiving the signal.
［第２の実施形態］
　図６に、第２の実施形態のリーダライタ装置１６０とＲＦＩＤタグ１２０とからなるシステムの構成図を示す。
　リーダライタ装置１６０はリーダライタ１４０とスロットアンテナ１５０とから構成され、ＲＦＩＤタグアンテナ１２５を備えたＲＦＩＤタグ１２０と通信する。そして、第２の実施形態のリーダライタ装置１６０ではＲＦＩＤタグ１２０をスロットアンテナ１５０の上方向に配置することにより水平方向にあるＲＦＩＤタグの影響を受けることなく、通信相手のＲＦＩＤタグ１２０に効率よく垂直波のみを与えることができる。
　例えば、ＲＦＩＤタグを、ベルトコンベア等を用いて流れ作業で検査、およびエンコード、デコードをする場合には、対象となるＲＦＩＤタグ１２０の前後に対象外のＲＦＩＤタグが存在している。そして、ＲＦＩＤタグ検査用のリーダライタ装置１６０は、対象外のＲＦＩＤタグの影響を受けることなく、対象となるＲＦＩＤタグ１２０と通信できることが必要である。
　このような場合に、本願発明のスロットアンテナ１５０を備えたリーダライタ装置１６０を用いることで、対象外のＲＦＩＤタグの影響を受けることなく、対象となるＲＦＩＤタグ１２０と通信することができる。 [Second Embodiment]
FIG. 6 shows a configuration diagram of a system including the reader / writer device 160 and the RFID tag 120 of the second embodiment.
The reader / writer device 160 is composed of a reader / writer 140 and a slot antenna 150, and communicates with an RFID tag 120 including an RFID tag antenna 125. Then, in the reader / writer device 160 of the second embodiment, by arranging the RFID tag 120 in the upward direction of the slot antenna 150, the RFID tag 120 of the communication partner is efficiently affected without being affected by the RFID tag in the horizontal direction. Only vertical waves can be given.
For example, when an RFID tag is inspected, encoded, and decoded in an assembly line using a belt conveyor or the like, there are non-target RFID tags before and after the target RFID tag 120. Then, the reader / writer device 160 for RFID tag inspection needs to be able to communicate with the target RFID tag 120 without being affected by the non-target RFID tag.
In such a case, by using the reader / writer device 160 provided with the slot antenna 150 of the present invention, it is possible to communicate with the target RFID tag 120 without being affected by the non-target RFID tag.
　また、最近、商品に付されたＲＦＩＤタグを読み取ることにより、店舗における会計を自動化するシステムが使われはじめている。この会計システムにおいては、商品を収納する筐体の中にある商品に付されたＲＦＩＤタグのみと通信する必要がある。しかし、商品に付されたＲＦＩＤタグを読み取るリーダライタ装置の近辺には、別の商品に付されたＲＦＩＤタグが存在しており、従来のリーダライタでは、筐体および／またはふたをシールドすることにより、筐体の外にある商品に付されたＲＦＩＤタグとの通信を妨害することが必要であった。
　これに対して、本願発明のスロットアンテナ１５０を用いたリーダライタ装置１６０ではスロットアンテナ１５０の上方向に配置されたＲＦＩＤタグ１２０とのみ通信することができるため、筐体および／または筐体を閉じるふたのシールドをなくする、またはより簡易なものにすることができる。 Recently, a system that automates accounting in stores by reading RFID tags attached to products has begun to be used. In this accounting system, it is necessary to communicate only with the RFID tag attached to the product in the housing for storing the product. However, in the vicinity of the reader / writer device that reads the RFID tag attached to the product, there is an RFID tag attached to another product, and in the conventional reader / writer, the housing and / or the lid is shielded. Therefore, it was necessary to interfere with the communication with the RFID tag attached to the product outside the housing.
On the other hand, in the reader / writer device 160 using the slot antenna 150 of the present invention, since it is possible to communicate only with the RFID tag 120 arranged in the upward direction of the slot antenna 150, the housing and / or the housing is closed. The shield on the lid can be removed or made simpler.
　本発明において、第１アンテナ基板１０が『第１アンテナ基板』に相当し、スロット形成用第１電極２０が『スロット形成用第１電極』に相当し、スロット形成用第２電極３０が『スロット形成用第２電極』に相当し、第２アンテナ基板５０が『第２アンテナ基板』に相当し、第３電極５５が『第３電極』に相当し、給電線４０が『給電線』に相当し、ＲＦＩＤタグ１２０が『ＲＦＩＤタグ』に相当し、リーダライタ１４０が『リーダライタ』に相当し、スロットアンテナ１５０が『スロットアンテナ』に相当し、可変キャパシタ用のボルト６０が『ボルト』に相当し、可変キャパシタ用のナット６５が『ナット』に相当し、リーダライタ装置１６０が『ＲＦＩＤタグ用リーダライタ装置』に相当する。 In the present invention, the first antenna substrate 10 corresponds to the "first antenna substrate", the slot forming first electrode 20 corresponds to the "slot forming first electrode", and the slot forming second electrode 30 corresponds to the "slot". The second antenna substrate 50 corresponds to the "second antenna substrate", the third antenna 55 corresponds to the "third electrode", and the feeding line 40 corresponds to the "feeding line". However, the RFID tag 120 corresponds to the "RFID tag", the reader / writer 140 corresponds to the "reader / writer", the slot antenna 150 corresponds to the "slot antenna", and the bolt 60 for the variable capacitor corresponds to the "bolt". However, the nut 65 for the variable capacitor corresponds to the "nut", and the reader / writer device 160 corresponds to the "reader / writer device for RFID tag".
　本発明の好ましい実施形態は上記の通りであるが、本発明はそれだけに制限されない。本発明の精神と範囲から逸脱することのない様々な実施形態が他になされることは理解されよう。さらに、本実施形態において、本発明の構成による作用および効果を述べているが、これら作用および効果は、一例であり、本発明を限定するものではない。 The preferred embodiment of the present invention is as described above, but the present invention is not limited thereto. It will be appreciated that various embodiments are made that do not deviate from the spirit and scope of the present invention. Further, in the present embodiment, the actions and effects according to the constitution of the present invention are described, but these actions and effects are examples and do not limit the present invention.
　　　１０　第１アンテナ基板
　　　２０　スロット形成用第１電極
　　　３０　スロット形成用第２電極
　　　４０　給電線
　　　５０　第２アンテナ基板
　　　５５　第３電極
　　　６０　可変キャパシタ用ボルト
　　　６５　可変キャパシタ用ナット
　　　７０　ストリップライン
　　　８０　ＳＭＣコネクタ
　　　９０　固定用ボルト
　　１００　固定用ナット
　　１１０　スペーサ
　　１２０　ＲＦＩＤタグ
　　１２５　ＲＦＩＤタグアンテナ
　　１３０　電波の放射方向
　　１４０　リーダライタ
　　１５０　スロットアンテナ
　　１６０　リーダライタ装置

 
  10 1st antenna board 20 1st electrode for slot formation 30 2nd electrode for slot formation 40 Feed line 50 2nd antenna board 55 3rd electrode 60 Variable capacitor bolt 65 Variable capacitor nut 70 Strip line 80 SMC connector 90 For fixing Bolt 100 Fixing nut 110 Spacer 120 RFID tag 125 RFID tag Antenna 130 Radio wave radiation direction 140 Reader / writer 150 Slot antenna 160 Reader / writer device

Claims (5)

  1. 　第１アンテナ基板と、
    　前記第１アンテナ基板に設けられ、スパイラル状のスリットを有するスロット形成用第１電極と、
    　前記スロット形成用第１電極のスリットの内部に設けられ、前記スロット形成用第１電極と所定の間隔を有するスパイラル状のスロット形成用第２電極と、
    　前記第１アンテナ基板に対向する第２アンテナ基板と、
    　前記第２アンテナ基板に設けられる第３電極と、
    　前記スロット形成用第２電極と前記第３電極との間に給電する給電線と、を備える、
    　ＲＦＩＤタグのリーダライタ用のスロットアンテナ。     1st antenna board and
    A first electrode for forming a slot, which is provided on the first antenna substrate and has a spiral slit,
    A spiral second electrode for forming a slot, which is provided inside the slit of the first electrode for forming a slot and has a predetermined distance from the first electrode for forming a slot, and a second electrode for forming a spiral.
    The second antenna board facing the first antenna board and
    The third electrode provided on the second antenna substrate and
    A feeding line for feeding power between the slot-forming second electrode and the third electrode is provided.
    Slot antenna for RFID tag reader / writer.
  2. 　前記スロット形成用第１電極のスリットの電気長が、通信周波数の波長をλとして、λ／２であり、前記スロット形成用第２電極の電気長がλ／４である、請求項１に記載のスロットアンテナ。 The first aspect of claim 1, wherein the electric length of the slit of the first electrode for slot formation is λ / 2, where the wavelength of the communication frequency is λ, and the electric length of the second electrode for slot formation is λ / 4. Slot antenna.
  3. 　前記スロット形成用第２電極の長手方向の一方の端部は、前記スロット形成用第１電極のスリットの長手方向の一方の端部と前記所定の間隔となるように配置される、請求項２に記載のスロットアンテナ。 2. Claim 2 that one end in the longitudinal direction of the second electrode for slot formation is arranged so as to be at the predetermined distance from one end in the longitudinal direction of the slit of the first electrode for slot formation. The slot antenna described in.
  4. 　さらに、前記第３電極の、前記スロット形成用第２電極に対応する位置に金属のナットが固定され、前記スロット形成用第２電極に向けて金属のボルトが挿入されて、前記スロット形成用第２電極と前記第３電極との間に可変キャパシタが形成される、請求項１から３のいずれか１項に記載のスロットアンテナ。 Further, a metal nut is fixed at a position of the third electrode corresponding to the slot forming second electrode, and a metal bolt is inserted toward the slot forming second electrode to form the slot forming first electrode. The slot antenna according to any one of claims 1 to 3, wherein a variable capacitor is formed between the two electrodes and the third electrode.
  5. 　請求項１から４のいずれか１項に記載のスロットアンテナと、
    　前記給電線に接続されたリーダライタと、を備え、
    　前記第１アンテナ基板に対向する位置で、前記第２アンテナ基板と反対の方向に配置されるＲＦＩＤタグと通信する、ＲＦＩＤタグ用リーダライタ装置。

     
          The slot antenna according to any one of claims 1 to 4,
    A reader / writer connected to the feeder is provided.
    An RFID tag reader / writer device that communicates with an RFID tag arranged in a direction opposite to that of the second antenna board at a position facing the first antenna board.
PCT/JP2020/039832 2020-01-17 2020-10-23 Slot antenna for reader/writer of rfid tag, and reader/writer device for rfid tag WO2021145044A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI795083B (en) * 2021-11-19 2023-03-01 國立雲林科技大學 Circularly polarized slot antenna used in outdoor large event rfid system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008028872A (en) * 2006-07-24 2008-02-07 Hoko Denshi Kk Slot spiral antenna, square-shaped slot spiral antenna, and adjustment method thereof
JP2008236046A (en) * 2007-03-16 2008-10-02 Yagi Antenna Co Ltd Small slot antenna
JP2014533454A (en) * 2011-09-30 2014-12-11 グーグル インコーポレイテッド Computer antenna with conductive chassis (inventor: Ajay Chandra Venkata Gummalla)

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008028872A (en) * 2006-07-24 2008-02-07 Hoko Denshi Kk Slot spiral antenna, square-shaped slot spiral antenna, and adjustment method thereof
JP2008236046A (en) * 2007-03-16 2008-10-02 Yagi Antenna Co Ltd Small slot antenna
JP2014533454A (en) * 2011-09-30 2014-12-11 グーグル インコーポレイテッド Computer antenna with conductive chassis (inventor: Ajay Chandra Venkata Gummalla)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI795083B (en) * 2021-11-19 2023-03-01 國立雲林科技大學 Circularly polarized slot antenna used in outdoor large event rfid system

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JPWO2021145044A1 (en) 2021-07-22

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