JP6511623B2 - Auxiliary antenna and RFID system - Google Patents

Description

  The present invention relates to an auxiliary antenna and an RFID system.

  For example, Patent Document 1 includes two coiled conductors facing each other and coupled to each other via a capacitance, and the two coiled conductors are opposed at least at a portion of the outermost circumference and / or the innermost circumference. The resonance is characterized in that the area is wound so as to be larger than the opposing areas in other areas, and the directions of the currents flowing in the respective areas are the same in plan view from one direction. A circuit is disclosed.

WO 2012/014975

It is an object of the present invention to provide an auxiliary antenna and an RFID system for performing communication capable of extending the communication distance of an IC tag.
Another object of the present invention is to provide an auxiliary antenna and an RFID system capable of collectively communicating with a plurality of IC tags.

  The auxiliary antenna according to the present invention is an auxiliary antenna disposed between an IC tag and a communication device that communicates with the IC tag, and is a base material formed of a dielectric and formed in a sheet shape. And a first coil provided on at least one surface of the base material and configured of a conductor, wherein a coil length of the first coil corresponds to a frequency band used for communication of the IC tag It is.

  Preferably, it further comprises a second coil provided on the back surface of the surface provided with the first coil or the same surface among the surfaces of the base material and made of a conductor, and the second coil The coil length is a length corresponding to a frequency band used for communication of the IC tag.

  Preferably, the IC tag is a micro IC tag having a size of 1 mm or less, and the first coil and the second coil are formed in equally spaced spirals having a diameter of 10 mm or less. The frequency band used for IC tag communication is the UHF band, and the lengths of the first coil and the second coil are 1/4 to 3/4 of the wavelength in the frequency band of the UHF band. .

  Preferably, the coil length of the second coil is different from the coil length of the first coil.

Preferably, the first coil or the second coil, of the surfaces of the second base material arranged on the first coil or the second coil and the surface of the second base material. further comprising a third coil arranged on the back surface of the surface provided with the opening area in the third coil, is larger configuration than the opening area of said first coil or said second coil There is.

  Preferably, a plurality of the first coil and the second coil are arranged on a substrate.

  An RFID system according to the present invention is an RFID system configured of an IC tag, a communication device, and an auxiliary antenna, and the IC tag, a communication device that communicates with the IC tag, the IC tag, and And an auxiliary antenna disposed between the communication device and the auxiliary antenna, wherein the auxiliary antenna is formed of a dielectric, and is provided on a sheet-like base material and at least one surface of the base material. And a coil length of the first coil corresponds to a frequency band used for communication of the IC tag.

  Preferably, a plurality of the IC tags are arranged at predetermined intervals, and the first coils are respectively provided at positions facing the arranged IC tags.

According to the present invention, the communication distance of the IC tag can be extended.
Further, according to the present invention, communication can be performed with a plurality of IC tags collectively.

It is a figure which illustrates the outline of RFID system 1 concerning this embodiment. It is a figure explaining the composition of auxiliary antenna 3. FIG. It is a figure explaining the composition of main coil 32 and subcoil 33. As shown in FIG. It is a figure explaining the fine difference of the main coil 32 and the subcoil 33. As shown in FIG. FIG. 7 is a view for explaining a modification 1 of the auxiliary antenna 3; FIG. 10 is a view for explaining a modification 2 of the auxiliary antenna 3; It is a table | surface and graph which show the resonant frequency when changing the winding number (coil length) of a coil regarding a single coil and the arrange | positioned several coil.

First, the background and outline of the present invention will be described.
According to the prior art, the antenna of the communication IC chip of the antenna mounting type is mounted on the IC chip, so the opening area becomes extremely small. Therefore, there is a problem that sufficient transmission and reception sensitivity can not be obtained, and the information transmission distance by the noncontact IC tag can not be made sufficiently large.
Therefore, in view of the problems of the prior art described above, the RFID system 1 according to the present embodiment transmits and receives by installing the main coil and the sub coil resonating at the frequency to be used on the opening surface of the antenna IC chip. An antenna mounted type communication IC chip auxiliary antenna 3 capable of enhancing sensitivity and expanding information transmission is used.

An outline of the RFID system 1 according to the present embodiment will be described.
Hereinafter, the configuration of the embodiment of the present invention will be described with reference to the drawings. The dimensions, materials, and other specific numerical values and the like shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same functions and configurations are denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention are not illustrated. Do.
FIG. 1 is a diagram illustrating an outline of the RFID system 1 according to the present embodiment.
As illustrated in FIG. 1, the RFID system 1 includes an IC tag 10, an auxiliary antenna 3, and a communication device 5.

The IC tag 10 includes a wireless antenna and an IC chip, and can read and write data without contact using electromagnetic waves. For example, the IC tag 10 is a small chip having a side of 3 cm or less, generates its own driving power by an electromagnetic wave, and wirelessly transmits an ID (identification information) written in the chip. The IC tag 10 of this example is a minute semiconductor chip which has a side of 0.5 mm or less and which is driven in the UHF band.
Moreover, in this example, although the case where IC tag 10 is attached to the bottom part of test tube 8 is explained as an example, it is not limited to this. In the present example, 24 test tubes 8 are disposed in the storage rack 9, and an IC tag 10 is attached to each of the test tubes 8.

The auxiliary antenna 3 is disposed between the IC tag 10 and the communication device 5 and extends the communication distance between the IC tag 10 and the communication device 5. The auxiliary antenna 3 is disposed when communication is performed between the IC tag 10 and the communication device 5, and is not always provided between the IC tag 10 and the communication device 5, and the IC tag 10 is not provided. And the communication device 5 is detachable.
The auxiliary antenna 3 is configured to include a substrate 30, a main coil 32, and a sub coil 33.

The communication device 5 includes an IC tag reader / writer 50 and a control device 55. The IC tag reader / writer 50 reads data from the IC tag 10 without contact. In this example, the IC tag reader / writer 50 is described as a reader / writer for performing reading from the IC tag 10 and writing to the IC tag 10, but the present invention is not limited to this. It may be a leader who only The control device 55 controls the operation of the IC tag reader / writer 50, reads the ID from the IC tag 10, and performs data processing using the read ID.
Thus, the RFID system 1 is configured to include the IC tag 10, the auxiliary antenna 3, and the communication device 5.

FIG. 2 is a diagram for explaining the configuration of the auxiliary antenna 3.
As illustrated in FIG. 2A, in the auxiliary antenna 3, the main coil 32 is provided on one surface of the substrate 30, and the sub-coil 33 is provided on the other surface of the substrate 30. The main coil 32 is provided on the surface of the substrate 30 close to the IC tag 10, and the sub coil 33 is provided on the surface close to the IC tag reader / writer 50. The auxiliary antenna 3 of this example includes a plurality of main coils 32 and a plurality of sub coils 33, and each of the plurality of main coils 32 is disposed on the back surface of each of the plurality of sub coils 33.
The main coil 32 is an example of a first coil according to the present invention, and the auxiliary coil 33 is an example of a second coil according to the present invention.

The substrate 30 is a sheet-like member made of a dielectric. For example, the substrate 30 is a sheet-like member made of a transparent synthetic resin. The thickness of the substrate 30 is, for example, 1 mm or less.
The main coil 32 and the sub coil 33 are conductors formed in a spiral shape. For example, the main coil 32 and the sub-coil 33 are linear metals formed in a spiral shape from inside of 1/3 of the center of the coil radius. The main coil 32 and the sub coil 33 in the present example are metal wires formed in a spiral shape at substantially the same line interval from the center of the coil.

The main coil 32 of the present example has the same shape as the sub coil 33, and is disposed at mutually opposing positions.
The main coil 32 and the sub-coil 33 arranged in this way are disposed on the opening face of the antenna mounting type IC tag 10, so that they resonate with incoming radio waves from the outside and a large electromotive force is generated on the antenna of the IC tag 10. While being generated, radio waves from the antenna of the IC tag 10 can be efficiently oscillated to the outside, the transmission / reception sensitivity of the antenna of the IC tag 10 can be increased, and the information transmission distance by the IC tag 10 can be increased. This is because the main coil 32 and the sub coil 33 have a much larger aperture area as compared with the antenna of the IC tag 10.

The coil length of the main coil 32 and the sub-coil 33 formed in a spiral can be varied by the number of turns, and can be tuned to a wavelength as required.
Further, the main coil 32 and the sub coil 33 are formed of a conductor on the dielectric substrate 30, and the coil length can be shortened compared to the dielectric constant of the substrate 30.

Further, as illustrated in FIG. 2, by stacking and arranging the main coil 32 and the sub coil 33, high density magnetic flux can be obtained.
By electrically coupling the high Q antenna coil of the IC tag 10 on a space curve through which the center line of the main coil 32 and the sub coil 33 passes, the conductor diameter of the main coil 32 and the sub coil 33 is substantially increased. The Q of the coil can be improved to sharpen the resonance characteristic as a whole, and the transmission / reception sensitivity at the used frequency can be further enhanced.

FIG. 3 is a diagram for explaining the configuration of the main coil 32 and the sub coil 33. As shown in FIG.
The diameter w of the metal wire forming the main coil 32 and the sub coil 33 is 0.15 mm to 0.25 mm, and the number of turns Tn of the main coil 32 and the sub coil 33 is 6.2 to 6.4. As a result, the coil diameter D of the main coil 32 and the sub coil 33 becomes 9 mm or less, and a large number can be arranged on the surface of the substrate 30.

FIG. 4 is a diagram for explaining a minute difference in coil lengths of the main coil 32 and the sub coil 33. As shown in FIG.
The coil lengths of the main coil 32 and the sub coil 33 in this example are both 1/4 to 3/4 of the wavelength in the UHF band, but the coil lengths of the main coil 32 and the sub coil 33 are slightly It is preferable to make them different. The coil lengths of the main coil 32 and the sub coil 33 may be 1/2 to 1/4 of the wavelength in the UHF band. Since the coil length of the main coil 32 is slightly different from the coil length of the opposing sub coil 33, the frequency band can be expanded as illustrated in FIG. For example, the difference in coil length between the main coil 32 and the sub coil 33 is 0.6% or more and 2.0% or less. The difference in coil length between the main coil 32 and the sub coil 33 in this example is 1.01%. The main coil 32 and the sub coil 33 may be provided on the same surface of the substrate 30 as shown in this figure, or may be provided on different surfaces as shown in FIG.

As illustrated in FIG. 1, between the antenna 51 of the IC tag reader / writer 50 and the plurality of test tubes 8 stored in the storage rack 9, the auxiliary antenna 3 in which a plurality of main coils 32 and sub coils 33 are arranged is Deploy. Each of the plurality of main coils 32 regularly arranged on the plane of the substrate 30 faces the IC tag 10 attached to the tip of the test tube 8 in close proximity. The communication distance between the IC tag reader / writer 50 and the IC tag 10 attached to the test tube 8 is expanded by the auxiliary antenna 3 arranged in this manner. As a result, the IC tag reader / writer 50 can simultaneously read out from the IC tag 10 attached to each of the plurality of test tubes 8.
That is, by the extension of the communication distance, the increase of the aperture area, and the high density of the main coil 32 and the sub coil 33 in the auxiliary antenna 3, the batch reading of the plurality of IC tags 10 is performed while maintaining the minuteness of the IC tag 10. Is realized.

  Of the plurality of main coils 32 and sub coils 33 arranged on the same plane, the coil lengths of the main coil 32 and sub coil 33 (that is, coils surrounded by other coils) disposed at the center, It may be shorter by 0.8% to 2.2% than the main coil 32 and the sub coil 33 disposed at the peripheral portion. This is because, as shown in FIG. 7, a coil surrounded by another coil is shifted in resonance frequency due to the influence of another coil in proximity. In other words, the plurality of main coils 32 and sub-coils 33 arranged on the same plane may have different coil lengths according to the number of adjacent other coils. Alternatively, all the coil lengths may be made uniform by surrounding the outer peripheries of the plurality of arranged main coils 32 and sub coils 33 with metal (for example, a looped metal wire with a notch).

[Modification 1]
Next, modifications of the above embodiment will be described.
FIG. 5 is a view for explaining a modification 1 of the auxiliary antenna 3.
As illustrated in FIG. 5, in the auxiliary antenna 3, the number of sub-coils 33 and the number of main coils 32 opposed to this across the substrate 30 may be 1: n. That is, the plurality of main coils 32 may be disposed to be opposed to one sub coil 33.

[Modification 2]
FIG. 6 is a view for explaining a modification 2 of the auxiliary antenna 3.
As illustrated in FIG. 6, three or more layers of three or more coils 42 having different opening areas may be stacked. In this case, the open area of the coil 42 is preferably arranged to be gradually larger. This makes it possible to gradually increase the aperture area of the antenna. The coils 42 are made of the same material and line width as the main coil 32 or the sub coil 33. Also, the plurality of coils 42 are held by the plurality of substrates 40.

[Other modifications]
Moreover, although the form which makes the main coil 32 and the subcoil 33 mutually oppose was demonstrated in the said embodiment, it is good also as only the main coil 32. FIG. This is because the communication distance can be extended with only one coil.

1 RFID System 3 Auxiliary Antenna 30 Substrate 32 Main Coil 33 Secondary Coil 5 Communication Device 10 IC Tag 40 Substrate 42 Coil

Claims (7)

An auxiliary antenna disposed between an IC tag and a communication device that communicates with the IC tag,
A substrate made of a dielectric and formed into a sheet;
A first coil provided on at least one surface of the substrate and made of a conductor;
The coil length of the first coil is 1/4 to 3/4 of the wavelength in the frequency band used for the communication of the IC tag , and the first coil is 1/1 from the center of the radius of the coil. An auxiliary antenna formed in a spiral from the inside of three . It further has a second coil provided on the back surface of the surface on which the first coil is provided, or the same surface among the surfaces of the base material, and made of a conductor,
The coil length of the second coil is 1/4 to 3/4 of the wavelength in the frequency band used for communication of the IC tag , and the second coil is 1/1 / from the center of the coil radius. The auxiliary antenna according to claim 1, wherein the auxiliary antenna is formed in a spiral shape from inside of three . The auxiliary antenna according to claim 2, wherein a coil length of the second coil is different from a coil length of the first coil. A second base material disposed to be stacked on the first coil or the second coil;
And a third coil disposed on the back surface of the surface on which the first coil or the second coil is provided among the surfaces of the second base material,
The auxiliary antenna according to claim 3, wherein an opening area of the third coil is larger than an opening area of the first coil or the second coil. The auxiliary antenna according to claim 4, wherein a plurality of the first coil and the second coil are arranged on a substrate. An RFID system consisting of an IC tag, a communication device, and an auxiliary antenna,
IC tag,
A communication device for communicating with the IC tag;
And an auxiliary antenna disposed between the IC tag and the communication device.
The auxiliary antenna is
A substrate made of a dielectric and formed into a sheet;
A first coil provided on at least one surface of the substrate and made of a conductor;
The coil length of the first coil is 1/4 to 3/4 of the wavelength in the frequency band used for the communication of the IC tag , and the first coil is 1/1 from the center of the radius of the coil. An RFID system that is formed in a spiral from inside of three . The plurality of IC tags are arranged at predetermined intervals,
The RFID system according to claim 6, wherein the first coil is provided at a position facing each of the arranged IC tags.

Images