JP2018078525A - RF tag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire good communication characteristics corresponding to a communication frequency by forming a planar antenna compatible with a communication frequency of an RF tag for avoidance of an adverse influence of metal and to improve flexibility of the design of an auxiliary antenna without any constraint on a design range of the auxiliary antenna while effectively exhibiting functions of an antenna and a loop circuit which the RF tag itself has.SOLUTION: The RF tag includes: an inlay 10 having an IC chip 11 and an antenna 12; an auxiliary antenna 20 layered under an isolation state from the inlay 10; and a base material 50 having the layered inlay 10 and the auxiliary antenna 20 on. The antenna 12 of the inlay 10 is formed with a loop part 11a in the vicinity to the IC chip 11 and the auxiliary antenna 20 is arranged so that a central position of a side along a resonance axis of the auxiliary antenna 20 opposing to the loop part 11a is positioned in the vicinity to the IC chip 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an RF tag used by being attached to a metal container or metal article such as an aluminum container or a metal casing.

In general, a so-called RF tag having a built-in IC chip in which predetermined information related to an article or object is stored in a readable / writable manner is widely used.
The RF tag is also called an RFID (Radio Frequency Identification) tag, an IC tag, a non-contact tag or the like, and is a so-called inlay in which an electronic circuit including an IC chip and a wireless antenna is sealed and coated with a substrate such as a resin film ( Inlet is an ultra-compact communication terminal formed in the form of a tag (tag). Predetermined information is read / written / read / written wirelessly on the IC chip in the tag by a reading / writing device (reader / writer). (Read-only / write-once / read-write).
Then, by writing predetermined information on such an RF tag and attaching it to an arbitrary article, object, etc., the information recorded on the RF tag is picked up by a reader / writer, and the information recorded on the tag is taken into the article. It is possible to recognize, output, display, update, etc. as the predetermined information regarding.

Such an RF tag can record hundreds of bits to several kilobits of data in an IC chip memory, and can record a sufficient amount of information as information on articles, etc. Since communication can be performed in a non-contact manner, there is no concern about contact wear, scratches, dirt, and the like. Furthermore, since the tag itself can be made non-powered, it can be processed, miniaturized, and thinned according to the object.
By using such an RF tag, various information relating to the article to which the tag is attached, such as the name and identification symbol of the article, contents, components, manager, user, use status, use status, date and time, etc. Various types of information can be recorded, and a wide variety of information, which was impossible with characters and barcodes printed on the label surface, can be read and written accurately simply by attaching a small and thin tag to the article. It becomes possible to do.

By the way, when such an RF tag is attached to, for example, an aluminum container or a metal housing, the RF tag is affected by the conductivity of the metal, and the communication distance is changed or accurate wireless communication is performed. There was a problem that it could not be done. For this reason, if an ordinary general-purpose RF tag is directly attached to a metal article / object, a problem occurs that the tag malfunctions or wireless communication with the reader / writer cannot be performed.
In particular, the radio frequency type RF tag using the high frequency band of the UHF band has a longer communication distance than the electromagnetic induction type using the 135 KHz or 13.56 MHz band, but is caused by absorption or reflection by metal. There was a problem that the communication characteristics were easily damaged.

In Japan, due to the revision of the Radio Law, RF tags will be moved from the 950 MHz band (950-958 MHz: 8 MHz width) of the UHF band used so far to the 920 MHz band (915-930 MHz: 15 MHz width). The available frequency band has been expanded.
Even in such an RF tag using the 920 MHz band after the transition, the above-described influence of the metal is unavoidable, and it is strongly desired to take effective measures.

Here, as means for improving the communication characteristics of the RF tag, it has been proposed to stack a patch antenna formed in a planar shape on the RF tag as an auxiliary antenna (see, for example, Patent Document 1).
Since the communication characteristics of the RF tag depend on the gain due to the antenna size, the antenna size of the RF tag can be substantially increased by further stacking a patch antenna (auxiliary antenna) on the surface of the RF tag. Thus, it is possible to improve communication characteristics by ensuring a large communication distance.

International Publication No. 2010/038813

However, the RF tag provided with the conventionally proposed auxiliary antenna as disclosed in Patent Document 1 is configured such that the planar auxiliary antenna is arranged on a part or all of the RF tag, There has been a problem that the antenna and loop circuit provided in the RF tag are covered with the auxiliary antenna.
The RF tag itself includes an antenna, and a part of the antenna is configured as a loop circuit so that communication can be performed even with the RF tag alone.
However, when the auxiliary antenna is placed over the RF tag, part or all of the antenna and loop circuit of the RF tag are covered with the auxiliary antenna, so that the communication characteristics of the RF tag are not improved and may be damaged. There was a case.

If the antenna of the RF tag is covered by the auxiliary antenna, the surface area (projection area) of the antenna overlaps and is wasted, and the antenna gain is reduced / reduced by that amount. It will not be possible to effectively use existing antenna resources.
In addition, the auxiliary antenna arranged so as to overlap the RF tag is restricted by the shape and configuration of the RF tag to be laminated, and the design range of the antenna is limited, and the design freedom such as the shape and size of the auxiliary antenna is limited. There was also a problem that was restricted.
For this reason, there is a demand for a technique for improving and improving the communication characteristics of the RF tag with the auxiliary antenna, effectively utilizing the antenna included in the RF tag itself, and ensuring the degree of freedom in designing the auxiliary antenna. So far, no effective proposals have been made.

  The present invention has been proposed in order to solve the problems of the conventional techniques as described above, and by forming a planar antenna corresponding to the communication frequency of the RF tag, it is possible to respond to each communication frequency. Good communication characteristics can be obtained, the influence of metal can be effectively avoided and reduced, and the antenna and loop circuit included in the RF tag itself can function effectively while limiting the design range of the auxiliary antenna. An object of the present invention is to provide an RF tag that can improve the degree of freedom in designing an auxiliary antenna without giving a noise.

  In order to achieve the above object, an RF tag according to the present invention includes an inlay having an IC chip and an antenna, an auxiliary antenna stacked in an insulated state from the inlay, and a base on which the stacked inlay and auxiliary antenna are mounted. And is arranged so that the center position of the side along the resonance axis of the auxiliary antenna is located in the vicinity of the IC chip.

According to the present invention, by forming a planar antenna corresponding to the communication frequency of the RF tag, it is possible to obtain good communication characteristics corresponding to each communication frequency, and effectively avoid and reduce the influence of metal. be able to.
According to the present invention, the antenna and loop circuit included in the RF tag itself can be effectively functioned, and the degree of freedom in designing the auxiliary antenna can be increased without limiting the design range of the auxiliary antenna. It becomes possible to improve.
Thereby, for example, a metal-compatible RF tag suitable for an aluminum metal container, a metal housing, or the like can be realized.

It is an external appearance perspective view which shows the RF tag which concerns on one Embodiment of this invention, (a) is the completion state of RF tag, (b) is the state which decomposed | disassembled the surface layer, inlay, auxiliary antenna, and base material which comprise RF tag Is shown. It is a top view which shows the arrangement | positioning relationship of the inlay of the RF tag which concerns on one Embodiment of this invention, and an auxiliary | assistant antenna, (a) is the case where the auxiliary antenna is arrange | positioned facing and spaced apart from the loop circuit part without laminating | stacking with an inlay (B) shows the case where the auxiliary antenna is arranged in contact with and laminated on the loop circuit portion of the inlay, and (c) shows the case of the inlay alone where no auxiliary antenna is arranged. It is a top view which shows the relationship between the inlay of the RF tag which concerns on one Embodiment of this invention, the external dimension of an auxiliary antenna, and the projection area of an antenna, (a) opposes a loop circuit part, without laminating | stacking an auxiliary antenna with an inlay In the case where the auxiliary antennas are arranged apart from each other, (b) shows a case where the auxiliary antenna is arranged so as to be laminated on a part of the inlay. It is explanatory drawing which shows the intensity | strength of the induction current of the antenna of an inlay and an auxiliary antenna corresponding to the arrangement | positioning relationship of the inlay and auxiliary antenna shown in FIG. It is a top view which shows the arrangement | positioning relationship of the inlay of the RF tag and auxiliary antenna which concern on one Embodiment of this invention, and shows the case where the distance between opposing directions of an auxiliary antenna and the loop circuit part of an inlay is varied sequentially. Yes. It is a line graph which shows the communication characteristic (relationship of reading distance and frequency) of RF tag which concerns on one Embodiment of this invention, and shows the case where the distance between opposing directions of an auxiliary antenna and the loop circuit part of an inlay is varied sequentially. Yes. It is a line graph which shows the communication characteristic (relationship between reading distance and frequency) of the RF tag which concerns on one Embodiment of this invention, and has shown the case where a magnet is provided as a base material of RF tag. It is a line graph which shows the communication characteristic (relationship between reading distance and frequency) of the RF tag which concerns on one Embodiment of this invention, and has shown as contrasting the case where it is not provided with the case where a magnet is provided as a base material of RF tag. .

Embodiments of an RF tag according to the present invention will be described below with reference to the drawings.
1A and 1B are external views showing an RF tag according to an embodiment of the present invention, wherein FIG. 1A is a perspective view of the RF tag in a completed state, and FIG. 1B is a surface layer, an inlay, an auxiliary antenna, and the like constituting the RF tag. The perspective view of the state which decomposed | disassembled the base material is shown.
As shown in the figure, the RF tag 1 according to the present embodiment includes an inlay 10 and a planar auxiliary antenna 20 that constitute an RF tag that performs wireless communication, and the inlay 10 and the auxiliary antenna 20. The RF tag 1 is configured to be covered and protected by the surface layer 40 while being mounted on the surface of the substrate 50.

In such an RF tag 1, the antenna 12 of the inlay 10 forms a loop circuit (loop part 11a) in the vicinity of the IC chip 11, and the center position of the side along the resonance axis of the auxiliary antenna 20 is The IC chip 11 is arranged in the vicinity of the IC chip 11.
The auxiliary antenna 20 is arranged so that the center position of the side along the resonance axis of the auxiliary antenna 20 faces the loop portion 11a of the inlay 10 and is located in the vicinity of the IC chip 11. Is preferred.
The IC chip portion of the inlay 10 is the portion to which power is supplied most, and the communication gain by the auxiliary antenna 20 is improved by the effect of the induced current by arranging the center position of the resonance axis of the auxiliary antenna in the vicinity thereof. Will be able to.
Further, by making the auxiliary antenna 20 face the loop portion 11a of the inlay 10, the auxiliary antenna 20 is separated and faced without overlapping the loop portion 11a, thereby improving the communication characteristics of the RF tag 1 as described later. Can do. Even when the inlay 10 is not provided with the loop portion 11a, the center position of the side along the resonance axis of the auxiliary antenna 20 is located in the vicinity of the IC chip 11, thereby improving the communication characteristics due to the effect of the induced current. It becomes possible to make it.

In the present embodiment, the auxiliary antenna 20 has a convex portion 21 at the center position of the side along the resonance axis of the auxiliary antenna 20 facing the loop portion 11 a of the inlay 10, and the convex portion 21 is formed on the IC chip 11. It arrange | positions so that it may be located in the vicinity.
In particular, as shown in FIGS. 2A and 3A, the auxiliary antenna 20 is arranged in parallel on the inlay 10 and the projection surface without contacting the antenna 12 of the inlay 10. .

Specifically, as shown in FIGS. 1A and 1B, the RF tag 1 according to the present embodiment includes an inlay 10 including an IC chip 11 and an antenna 12, and is insulated from the inlay 10. A planar auxiliary antenna 20 arranged on the same plane, a base layer 50 on which the inlay 10 and the auxiliary antenna 20 are arranged and mounted, and a base material 50 that functions as a dielectric constant adjusting layer for the mounted inlay 10. And a surface layer 40 serving as a cover that covers the inlay 10 and the auxiliary antenna 20 mounted on the base material 50.
The auxiliary antenna 20 is formed in a predetermined shape and size corresponding to the communication frequency of the inlay 10, and the auxiliary antenna 20 is disposed at a predetermined position with respect to the inlay 10 ( 2 (a) and FIG. 3 (a)), it is mounted on the base material 50.
Hereinafter, each part will be described in detail.

[Inlay]
The inlay 10 constitutes an RF tag that reads, writes, and reads and writes predetermined information wirelessly with a reader / writer (reading / writing device) (not shown). For example, the inlay 10 is a read-only type or a write-once type. , Read / write type.
Specifically, the inlay 10 includes an IC chip 11 and an antenna 12 that is electrically connected to and connected to the IC chip 11, and the IC chip 11 and the antenna 12 serve as a base material such as PET resin. After being mounted and formed on one sealing film 13 formed in step 1, the other sealing film 13 is overlaid and sealed and protected in a state of being sandwiched between the two sealing films 13 Has been.
In this embodiment, a rectangular inlay 10 is used in which an IC chip 11 and an antenna 12 extending on both sides of the IC chip 11 are sandwiched and sealed with a rectangular sealing film 13.

The IC chip 11 is formed of a semiconductor chip such as a memory, and can record data of, for example, several hundred bits to several kilobits.
A loop-shaped circuit conductor is connected to the IC chip 11 so as to surround the periphery of the chip to form a loop portion (loop circuit) 11a. The IC chip 11 is connected to the left and right sides of the IC chip 11 via the loop portion 11a. An antenna 12 is connected.
Data read / written (data call / registration / deletion / update, etc.) is performed by wireless communication with the reader / writer (not shown) via the antenna 12 and the auxiliary antenna 20 described later, and the data recorded in the IC chip 11 is recorded. Has come to be recognized.
As data recorded on the IC chip 11, for example, arbitrary data such as product identification code, name, weight, content, manufacturer / seller name, manufacturing location, date of manufacture, expiration date, etc. can be recorded. Yes, it can be rewritten.

The antenna 12 has a predetermined shape and size (length, length, etc.) by etching a metal thin film such as a conductive ink or a conductive aluminum vapor deposition film on the surface of one sealing film 13 serving as a base material. (Area).
Here, the length of the antenna 12 in the longitudinal direction extending to the left and right sides of the IC chip 11 is an integral number of the wavelength of the radio frequency of the inlay 10, for example, approximately 1/2 or approximately 1/4 of the wavelength of the radio frequency. It is formed so that it may become the length. In the inlay 10 according to the present embodiment, the antenna 12 is bent twice at approximately right angles in the longitudinal direction extending to the left and right sides of the IC chip 11, so that both ends in the longitudinal direction of the antenna 12 face each other toward the loop portion 11a. It is formed in a saddle shape that extends to a predetermined antenna length.
In the antenna 12 according to this embodiment, the central portion of the metal thin film is formed in a hollow / punched shape in which the metal thin film does not exist along the longitudinal direction from the vicinity of the IC chip 11 to both end portions in the longitudinal direction. The conductive portion of the antenna 12 is formed in a circular / loop shape. Thereby, the distance of the conductive part of the antenna 12 is ensured, and a predetermined antenna length can be obtained.

The sealing film 13 is made of a flexible film material such as polyethylene, polyethylene terephthalate (PET), polypropylene, polyimide, polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS), and the like. It is preferable that the IC chip 11 and the antenna 12 to be sealed are made of transparent PET resin or the like that is visible from the outside.
Moreover, the film surface of the single side | surface side of the sealing film 13 can be equipped with the adhesion layer and the contact bonding layer so that it can affix on a base material or an article | item.
The sealing film 13 may be sealed in a state where the IC chip 11 and the antenna 12 are sandwiched between the two sealing films 13, or the single sealing film 13 is folded to form an IC chip. 11 and the antenna 12 can be sandwiched and sealed.

As a communication frequency band used in the inlay 10, the RF tag 1 of the present embodiment targets a 920 MHz band (915-930 MHz: 15 MHz width) belonging to a so-called UHF band.
As frequency bands generally used in RF tags, there are several types of frequency bands such as a band of 135 kHz or less, a 13.56 MHz band, an 860 M to 960 MHz band belonging to the UHF band, and a 2.45 GHz band. The communication distance that enables wireless communication varies depending on the frequency band used, and the optimum antenna length and the wiring pattern vary depending on the frequency band.

In Japan, due to the revision of the Radio Law, RF tags will be shifted from the 950 MHz band (950-958 MHz: 8 MHz width) used so far to the 920 MHz band (915-930 MHz: 15 MHz width). The available frequency band has been expanded.
Therefore, in the present embodiment, the inlay 10 can be reduced in size, and the auxiliary antenna 20 described later is formed in a predetermined size, so that the UHF band in which the wavelength is short and the antenna can be reduced is targeted. Specifically, for the 920 MHz band, good communication characteristics are obtained in the 920 MHz band.
However, as long as there is no restriction on the size of the inlay 10 or the auxiliary antenna 20, the technical idea according to the present invention can be applied to frequency bands other than the 920 MHz band and the UHF band.

[Auxiliary antenna]
The auxiliary antenna 20 functions as an extra antenna for improving / adjusting the communication characteristics of the inlay 10 described above, and is mounted on the base material 50 as shown in FIG. It consists of the planar conductive member arrange | positioned on the same plane, and is in the insulated state with the inlay 10 resin-sealed by the sealing film 13.
That is, the entire inlay 10 is resin-sealed by the sealing film 13 and is physically insulated from the auxiliary antenna 20 made of a conductive member.

Since the auxiliary antenna 20 is disposed in the vicinity of the inlay 10, the auxiliary antenna 20 and the IC chip 11 of the inlay 10 are disposed to face each other via the sealing film 13. An electrical connection is made by the ring.
Thus, the auxiliary antenna 20 is disposed on the inlay 10 so as to face each other on the same plane, so that the antenna 12 and the auxiliary antenna 20 of the inlay 10 constitute a two-dimensional antenna, and the auxiliary antenna 20 serves as a booster for communication radio waves. Thus, the communication characteristics of the inlay 10 are adjusted and improved.

The auxiliary antenna 20 has a predetermined shape and size (length, area) by etching a metal thin film such as a conductive ink or a conductive aluminum vapor-deposited film on the surface of a film serving as a base material such as PET resin. It can be formed by molding.
FIG. 2 is a plan view of the auxiliary antenna according to the present embodiment. FIG. 2A is a diagram in which the auxiliary antenna is disposed so as to face and separate from the loop circuit portion without being laminated with the inlay, and FIG. When the auxiliary antenna is arranged in contact with and laminated on the loop circuit portion of the inlay, (c) shows the case of the inlay alone without the auxiliary antenna.
As shown in FIGS. 4A and 4B, in the present embodiment, the auxiliary antenna 20 is formed in a rectangular / planar shape with long sides and short sides substantially the same as the long sides and short sides of the inlay 10. It has come to be.

The auxiliary antenna 20 is formed such that the length in the longitudinal direction is an integral multiple of the wavelength of the radio frequency of the inlay 10 or a length that is a fraction of an integer, for example, approximately ½ of the wavelength of the radio frequency. .
The length of the long side (longitudinal direction) of the auxiliary antenna 20 is an integral multiple of the wavelength of the communication radio wave or 1 / integer (1/2, 1/4, 1/8...) According to the principle of the patch antenna. By doing so, alignment can be achieved. The overall size (length) of the RF tag 1 is substantially defined by the length of the auxiliary antenna 20. For example, if the length of the auxiliary antenna 20 is ½ wavelength, the RF tag 1 The overall size (length) is approximately ½ wavelength or slightly longer (longer).
In this respect, it is not preferable that the total length of the tag is too long (too large) due to the nature of the RF tag that is required to be downsized.

Therefore, in the present embodiment, the size of the auxiliary antenna 20 is the length of the long side (longitudinal direction) or the total length of the three adjacent short sides / long sides / short sides. For example, it is formed so as to have a length of about half of the wavelength of the radio frequency.
With such a configuration, the auxiliary antenna 20 can obtain good communication characteristics as an antenna having a length approximately half the wavelength of the radio frequency of the inlay 10.
Specifically, for example, when the communication frequency of the target inlay 10 is 920 MHz, λ≈326.0 mm and λ / 2≈163.0 mm. Accordingly, the auxiliary antenna 20 is formed such that the length of the long side or the total length of the three sides including both the short sides adjacent to the long side is about 163.0 mm.

In general, the inlay is configured as two layers (UHF tag) of the PET layer serving as an antenna and a base material, or three layers as an impedance adjustment antenna under the PET layer.
For this reason, also in the inlay 10 according to the present embodiment, the structure of the PET layer interposed between the auxiliary antenna 20 that is a conductor and the antenna 12 of the inlay 10 has a wavelength shortening effect. The wavelength will be shortened. The relative dielectric constant of PET is about “4”.
For this reason, the length of the long side of the auxiliary antenna 20 in this embodiment, or the length of the three sides of the long side and the adjacent short sides is also an approximate value, and the length is, for example, a value of approximately λ / 2. This is sufficient, and the length may vary depending on changes in communication characteristics depending on the material and dielectric constant of the base material 50 of the RF tag 1, the usage environment, usage mode, and the like of the tag.

In the present embodiment, the auxiliary antenna 12 formed in the shape and dimensions as described above is located in the vicinity of the IC chip 11, particularly on the resonance axis of the auxiliary antenna 20 facing the loop portion 11 a of the inlay 10 described above. The center position of the side along the side is arranged so as to be positioned in the vicinity of the IC chip 11.
In the present embodiment, as shown in FIGS. 2A and 2B, the auxiliary antenna 20 protrudes at the center position of the side along the resonance axis of the auxiliary antenna 20 that faces the loop portion 11 a of the inlay 10. A portion 21 is formed, and the convex portion 21 is disposed in the vicinity of the IC chip 11.
Furthermore, in this embodiment, as shown in FIG. 2A, the auxiliary antenna 20 including the convex portion 21 is arranged in parallel on the inlay 10 and the projection surface without contacting the antenna 12 of the inlay 10. It has come to be.

When the auxiliary antenna 20 comes into contact with or is stacked on the inlay 10, particularly when the auxiliary antenna 20 is disposed so as to overlap the loop portion 11 a or the IC chip 11 of the inlay 10, the conductive member that forms the auxiliary antenna 20 The communication characteristics of the IC chip 11 may be impaired.
That is, a loop circuit is formed in the vicinity of the IC chip 11 of the inlay 10 (the loop portion 11a). The loop portion 11a has a purpose of matching impedance and performs communication using a magnetic field component. It is necessary to prevent the magnetic field component from being disturbed by the conductor of the auxiliary antenna 20.

In addition, when the auxiliary antenna 20 is disposed so as to overlap the inlay 10, the antenna 12 including the loop portion 11 a of the inlay 10 overlaps the auxiliary antenna 20, so that the surface area (projected area) as the antenna is the inlay 10 and the auxiliary antenna 20. The antenna resources provided in the inlay 10 are wasted, and the antenna gain is reduced accordingly.
Furthermore, if the auxiliary antenna 20 is arranged so as to overlap the inlay 10, the design range of the auxiliary antenna 20 is limited due to the restrictions of the antenna 12 and the loop portion 11a of the inlay 10, and the shape and size of the auxiliary antenna are limited. The degree of freedom of design is limited.
On the other hand, if the auxiliary antenna 20 and the inlay 10 are too far apart, electrical connection by so-called capacitor coupling via the sealing film 13 becomes insufficient, and good communication characteristics cannot be obtained.

Therefore, in the present embodiment, one long side (longitudinal direction) of the auxiliary antenna 12 is disposed so as to face the loop portion 11a of the inlay 10 with a predetermined interval (distance), and the loop portion of the auxiliary antenna 20 The center position of the long side opposite to 11a, that is, the center position of the long side along the resonance axis of the auxiliary antenna 20 is arranged in the vicinity of the IC chip 11.
Specifically, in the auxiliary antenna 20 according to the present embodiment, as shown in FIG. 2A, a convex portion 21 is formed at the center position of the long side facing the loop portion 11a of the inlay 10, The convex portions 21 are arranged in the vicinity of the IC chip 11 so as to face each other with a predetermined distance.

Therefore, as shown in FIG. 2A, the auxiliary antenna 20 is arranged at a predetermined interval without the antenna portion including the convex portion 21 contacting the antenna 12 including the loop portion 11a of the inlay 10. The antenna resource 20 and the antenna 12 of the inlay 10 are arranged in parallel without overlapping antenna resources on the projection plane.
At this time, the sealing film 13 covering the entire inlay 10 overlaps a part of the auxiliary antenna 20, and the auxiliary antenna 20 and the IC chip 11 of the inlay 10 are arranged to face each other via the sealing film 13, Electrical connection is made by capacitor coupling.
With such an arrangement, the antenna area of both the auxiliary antenna 20 and the antenna 12 of the inlay 10 can be utilized as much as possible, thereby increasing the antenna gain to the maximum.

Here, the convex portion 21 formed on the auxiliary antenna 20 is set in shape and size with reference to the size of the inlay 10 to be used. The antenna 20 is formed in a size (width and height) such that the conductive members of the antenna 20 do not overlap.
Specifically, the convex portion 21 of the auxiliary antenna 20 is based on the width of the loop portion 11a of the IC chip 11 of the inlay 10, and the conductor of the auxiliary antenna 20 including the convex portion 21 is connected to the IC chip 11 and the loop portion. The convex portion 21 is formed so as not to overlap with 11a and to have a length substantially the same as the width in the longitudinal direction of the loop portion 11a.

FIG. 3 shows the relationship between the external dimensions of the inlay 10 and the auxiliary antenna 20 and the projected area of the antenna portion.
First, FIG. 3A shows a case where the auxiliary antenna 20 is not stacked on the inlay 10 and is arranged in parallel so as to face and separate from the loop portion 11a. In this case, the external dimensions of the auxiliary antenna 20 are, for example, the width (length in the longitudinal direction) of the auxiliary antenna 20: 105 mm, the height (length in the short direction): 11 mm, the width of the convex portion 21: 23 mm, and the height. The antenna portion of the antenna 12 including the loop portion 11a of the inlay 10 and the antenna portion of the auxiliary antenna 20 has a projection area of 2014 mm ² .
On the other hand, FIG. 3B shows a case where the auxiliary antenna 20 is disposed so as to be laminated on a part of the inlay 10. In this case, the external dimensions of the auxiliary antenna 20 are, for example, the width of the auxiliary antenna 20: 105 mm, the height: 13 mm, the width of the convex portion 21: 25 mm, and the height Δ2 mm, and the antenna 12 including the loop portion 11 a of the inlay 10. The antenna portion of the auxiliary antenna 20 has a projection area of 1755 mm ² .

As described above, the auxiliary antenna 20 is arranged in parallel on the projection surface and the inlay 10 without contacting / stacking the antenna 12 including the loop portion 11a of the inlay 10 and the auxiliary antenna 20 including the convex portion 21. The projected area with the antenna 12 of the inlay 10 including the loop portion 11a can be secured as wide as possible.
In the example shown in FIG. 3, the projected area of the antenna portion of the inlay 10 and the auxiliary antenna 20 is 2014 mm ² −1755 mm ² = 259 mm in the parallel arrangement shown in (a) and the stacked arrangement shown in (b). An area difference of ² will occur.

Due to the difference in area between the antenna portions of the inlay 10 and the auxiliary antenna 20, the parallel arrangement (FIG. 3A) that can ensure a large and large projected area, compared with the case of the stacked arrangement that reduces the projected area, The antenna gain can be increased or improved by the area difference, and better communication characteristics can be obtained.
Furthermore, the inlay 10 and the auxiliary antenna 20 that are arranged to face each other are arranged to be separated from each other with a predetermined distance. The distance between the inlay 10 and the auxiliary antenna 20 and the communication characteristics will be described later with reference to FIGS.

Note that the current that flows through the auxiliary antenna 20 when data is read from and written to the inlay 10 flows only in the peripheral portion of the planar auxiliary antenna 20 (skin effect).
Therefore, if the auxiliary antenna 20 has the above-described size and shape, the planar portion can be formed in, for example, a mesh shape or a lattice shape.
By forming the auxiliary antenna 20 in a mesh shape or the like in this manner, the function as an antenna is not impaired by the skin effect, and the area of the entire conductor portion of the auxiliary antenna 20 can be reduced. Conductive materials such as conductive ink to be formed can be saved, and the cost of the RF tag 1 can be further reduced.

[Base material]
The base material 50 is a member that functions as a dielectric constant adjusting layer for the mounted inlay 10 as well as a base material layer on which the inlay 10 and the auxiliary antenna 20 described above are mounted.
In the present embodiment, the inlay 10 and the auxiliary antenna 20 have a plate shape that is slightly larger than the outer shape of the inlay 10 and the auxiliary antenna 20 arranged in parallel so that the inlay 10 and the auxiliary antenna 20 can be arranged and mounted on the same plane without protruding. -It is formed in a planar shape.

Specifically, the auxiliary antenna 20 and the inlay 10 are arranged in parallel on the same plane on one surface side (the upper surface side in FIG. 1) of the base material 50. Then, one surface (upper surface) of the base material 50 on which the inlay 10 and the auxiliary antenna 20 are mounted is covered and coated with a surface layer 40 serving as a cover member. As a result, the inlay 10 and the auxiliary antenna 20 are sealed in a state where they are arranged in parallel and are sandwiched between the base material 50 and the surface layer 40, and are protected from the outside.
The surface layer 40 is a sheet-like member that is adhered and adhered to one surface of the base material 50 on which the inlay 10 and the auxiliary antenna 20 are mounted. For example, paper, synthetic paper, polyethylene, polyethylene terephthalate (PET), polypropylene, polyimide, and the like. It can be formed of a flexible sheet material or film material made of the above resin.

On the other hand, on the other surface side (the lower surface side in FIG. 1) of the base material 50, although not particularly shown, an adhesive material made of, for example, a double-sided tape (adhesive tape) or a plate-like magnet is provided. It is attached and attached to the surface of a metal article to be attached by the adhesive force of the material and the magnetic force of the magnet.
Thus, the RF tag 1 is placed and fixed on the surface of the metal article so that the base material 50 is affixed and fixed to the surface to be attached and is not easily dropped off or peeled off.

Here, as such a base material 50 according to the present embodiment, for example, it can be formed of a crosslinked polyolefin foam such as foamed polyethylene or foamed polypropylene.
Moreover, the base material 50 can also be comprised by the single strip | belt-shaped member formed with the above crosslinked polyolefin foams, and the base material 50 is piled up by superimposing a plurality of (for example, two layers) strip-shaped members. Can also be configured.

Furthermore, the magnet for attachment to the metal object mentioned above can also be comprised as a part of base material 50 (refer FIG. 7, 8 mentioned later).
The magnet used as the base material 50 is a magnet that can be attached and attached by magnetic force to the metal to be attached to the RF tag 1 in a plate shape or a belt shape having a predetermined size and thickness corresponding to the base material 50. It can be formed and laminated and pasted on a substrate 50 made of resin or the like.

Moreover, the base material 50 as described above is mounted on the base material 50 by being formed so as to have a predetermined dielectric constant that adjusts the communication characteristics of the inlay 10 arranged in parallel with the auxiliary antenna 20. It can function as a dielectric constant adjusting layer for the laminated inlay 10.
For example, the base material 50 can be formed as a dielectric constant adjusting layer having a relative dielectric constant suitable for communication specification of the inlay 10 by being formed with a predetermined thickness by a predetermined member.

Thus, since the base material 50 has a predetermined relative dielectric constant and thickness, the influence from the metal to which the RF tag 1 is attached can be avoided and absorbed by the base material 50, and the communication of the RF tag 1 can be avoided. As a characteristic, a good communication distance as described later can be obtained.
Accordingly, in consideration of various conditions such as the type and communication characteristics of the inlay 10 to be used, the article in which the RF tag 1 is used, the use environment, the use frequency band, and the like, an appropriate material and thickness are selected as the base material 50. By selecting and exchanging only 50, it becomes possible to use the RF tag 1 for different articles or to correspond to different communication frequencies.

[Case]
The RF tag 1 according to the present embodiment described above can be used in a state of being sandwiched and sealed by the base material 50 and the surface layer 40 as shown in FIG. Can be stored in a predetermined housing (case) for use.
Although not particularly illustrated, the housing may have any configuration as long as it is a storage unit / protection unit capable of storing the inlay 10 and the auxiliary antenna 20 arranged in parallel inside. For example, it can be composed of a synthetic resin or metal case having an internal space in which the inlay 10 and the auxiliary antenna 20 sandwiched and sealed between the base material 50 and the surface layer 40 can be stored.

By protecting the inlay 10 and the auxiliary antenna 20 with such a casing, the weather resistance, heat resistance, and waterproofness of the RF tag 1 are improved.
In addition, when the inlay 10 and the auxiliary antenna 20 are housed and protected in the housing, part or all of the base material 50 and the surface layer 40 can be omitted.
In this case, the storage part, the lid member, and the like that constitute the housing function as the base material 50 and the surface layer 40.
In this case, the main body of the housing, the lid member, and the like also serve as the dielectric constant adjusting layer performed by the base material 50 described above.

[Communication characteristics]
Next, communication characteristics of the RF tag 1 according to this embodiment configured as described above will be described with reference to FIGS.
FIG. 4 is an explanatory diagram showing the intensity of the induced current flowing through the antenna 12 and the auxiliary antenna 20 of the inlay 10 corresponding to the positional relationship between the inlay 10 and the auxiliary antenna 20 shown in FIG.
As shown in the figure, first, when the inlay 10 and the auxiliary antenna 20 are arranged in parallel so as to be spaced apart from each other and opposed to each other on the projection plane without being contacted / stacked, the current flows through the antenna 12 and the auxiliary antenna 20 of the inlay 10. It can be seen that the induced current is 11 A / m (ampere / meter) or more.

On the other hand, when the auxiliary antenna 20 is arranged in parallel by contacting and contacting the opposite side of the loop portion 11a of the inlay 10, the induced current flowing through the antenna 12 and the auxiliary antenna 20 of the inlay 10 is 11 A / m or less, which is the same. Even when arranged in parallel, it can be seen that the induced current flowing through the antenna portion is reduced as compared with the case where the inlay 10 and the auxiliary antenna 20 are arranged apart from each other without being in contact with each other.
Furthermore, when the inlay 10 is arranged alone without the auxiliary antenna 20, the induced current flowing through the antenna 12 of the inlay 10 is about 9 A / m, compared to the case with the auxiliary antenna 20, It can be seen that the induced current is greatly reduced.

As described above, by providing the auxiliary antenna 20, the induced current of the antenna portion of the RF tag 1 including the antenna 12 of the inlay 10 is greatly increased, but further, the inlay 10 and the auxiliary antenna 20 are not brought into contact with each other. It can be seen that the induced current of the antenna portion can be further increased by arranging them in parallel in such a state.
Therefore, the RF tag 1 in which the inlay 10 and the auxiliary antenna 20 according to the present embodiment are spaced apart and arranged in parallel secures a large induced current in the antenna portion, and improves and increases the antenna gain, thereby providing good communication characteristics. Can be obtained.

Next, the separation distance between the inlay 10 and the auxiliary antenna 20 that are opposed to each other with a predetermined distance as described above and the communication characteristics thereof will be described with reference to FIGS.
FIG. 5 is a diagram schematically illustrating a case where the distance between the opposing portions of the auxiliary antenna 20 inlay 10 and the loop portion 11a is sequentially changed, and the distance between the opposing portions is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, and 6 mm from the top. Is increased.
FIG. 6 is a broken line showing communication characteristics (relationship between read distance and frequency) of the RF tag 1 when the distance between the opposing portions of the auxiliary antenna 20 inlay 10 and the loop portion 11a is sequentially changed corresponding to FIG. It is a graph.

As shown in these drawings, the auxiliary antenna 20 and the inlay 10 that are arranged in parallel have a communication distance (reading distance) as the distance between the loop portion 11a of the opposing inlay 10 and the convex portion 21 of the auxiliary antenna 20 is shorter. It can be seen that the communication frequency band that can be handled is widened.
In particular, as shown in FIG. 6, when the distance between the loop portion 11a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 is in the range of 1 mm to 5 mm, the reading distance is 4 to 10 m or more, and a sufficient communication distance is obtained. You can see that
Therefore, the separation distance between the inlay 10 and the auxiliary antenna 20 is preferably set in the range of 1 mm to 5 mm, and preferably in the range of at least less than 6 mm and within 5 mm.

As shown in FIG. 6, when the distance between the loop portion 11a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 is 0 mm, that is, the convex portion 21 is in contact with or in contact with the loop portion 11a. Even in this case, a communication distance close to that when the separation distance is 1 mm is obtained.
However, in this case, since the corresponding band of the communication frequency is narrowed, it is more preferable that the separation distance is about 1 mm.
Therefore, the distance between the inlay 10 and the auxiliary antenna 20 is preferably set to a range of at least 0 mm or more.

FIG. 7 shows communication characteristics (reading distance and frequency) of the RF tag 1 when the base material 50 (see FIG. 1) of the RF tag 1 is provided with a magnet for sticking / attaching to a metal plate as a metal object. This is a line graph showing the relationship.
FIG. 8 is a graph comparing the communication characteristics of the RF tag 1 with and without the magnet as the base member 50 of the RF tag 1 corresponding to FIG.

First, as shown in FIG. 7, when a magnet is provided as the base material 50 of the RF tag 1, the distance between the loop portion 11 a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 is the same as in the case of FIG. 6 described above. When the distance is 1 mm, the reading distance is 10 m or more, and it can be seen that a sufficient communication distance is obtained.
Further, in this case, when the separation distance between the loop portion 11a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 is 0 mm, a communication distance close to that when the separation distance is 1 mm is obtained. As in the case, the available communication frequency band becomes narrower.
For this reason, it can be seen that the distance between the loop portion 11a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 should be about 1 mm.

Next, as shown in FIG. 8, in the case where a magnet is not provided as the base material 50 of the RF tag 1 shown in FIG. 7, the band of the communication frequency that can be handled fluctuates. It can be seen that almost the same results as those obtained are obtained.
In particular, when the distance between the loop portion 11a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 is 1 mm, the reading distance is almost 12 m, and it can be seen that a longer communication distance is obtained.
As described above, according to the RF tag 1 according to the present embodiment, the loop portion 11a of the inlay 10 and the convex portion 21 of the auxiliary antenna 20 are arranged in parallel at a predetermined distance so that the base of the RF tag 1 can be obtained. Even when a magnet is provided as the material 50, a sufficient communication distance that is substantially the same as when no magnet is provided is ensured, and good communication characteristics of the RF tag 1 can be obtained.

As described above, according to the RF tag 1 of the present embodiment, the communication characteristics of the inlay 10 are optimized in accordance with the frequency band by the auxiliary antenna 20 arranged in parallel with the inlay 10 on the same plane. By setting / adjusting to an appropriate state, good communication characteristics corresponding to each communication frequency can be obtained, and the influence of metal can be effectively avoided / reduced.
According to the present embodiment, the auxiliary antenna 20 of the RF tag 1 is arranged opposite to and spaced from the loop portion 11a of the inlay 10 with a predetermined interval (distance), so that the auxiliary antenna 20 is placed in the inlay 10. The auxiliary antenna 20 and the antenna 12 of the inlay 10 are arranged in parallel without overlapping on the projection plane without contacting / stacking the antenna 12 including the loop portion 11a.

As a result, a part or all of the inlay 10 is covered by the auxiliary antenna 20 so that the electrical characteristics of the inlay 10 are not affected, and the antenna areas of both the auxiliary antenna 20 and the antenna 12 of the inlay 10 are not affected. Can be made as wide as possible, and the antenna gain can be maximized.
Further, the auxiliary antenna 20 can extend the design range of the antenna without being restricted by the antenna 12 of the inlay 10 and the loop portion 11a.
Therefore, in the RF tag 1 according to this embodiment, the antenna 12 and the loop circuit 11a included in the RF tag 1 itself can be effectively and maximally functioned, and the degree of freedom in designing the auxiliary antenna 20 is improved. Therefore, the auxiliary antenna 20 that is optimal for the inlay 10 to be used can be designed and adjusted, and a metal-compatible RF tag that can provide good communication characteristics can be realized.

  As mentioned above, although preferred embodiment was shown and demonstrated about the RF tag and metal container of this invention, RF tag which concerns on this invention is not limited only to embodiment mentioned above, Various in the range of this invention It goes without saying that changes can be made.

For example, in the above-described embodiment, as an article / object to be used with the RF tag according to the present invention attached, for example, an aluminum metal container or a metal housing is assumed. Articles and objects that can be used are not limited to aluminum metal containers or metal housings.
That is, the RF tag according to the present invention is applied to any article / object as long as it is an article / object in which an RF tag is used and predetermined information / data is read / written via a reader / writer. can do. For example, except for aluminum metal containers and metal casings, it is suitably used for any metal objects and objects such as metal heaters, electrical appliances, tableware, cooking utensils, furniture, furniture, containers, automobiles, etc. be able to.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as a metal-compatible RF tag that is used by being attached to any article or object such as an aluminum metal container or a metal housing.

DESCRIPTION OF SYMBOLS 1 RF tag 10 Inlay 11 IC chip 11a Loop part 12 Antenna 13 Sealing film 20 Auxiliary antenna 21 Convex part 40 Surface layer 50 Base material

Claims (5)

An inlay with an IC chip and an antenna;
An auxiliary antenna laminated in an insulated state with the inlay;
A substrate on which the laminated inlay and auxiliary antenna are mounted, and
The RF tag, wherein a center position of a side along a resonance axis of the auxiliary antenna is disposed in the vicinity of the IC chip. The inlay antenna forms a loop circuit in the vicinity of the IC chip,
2. The RF tag according to claim 1, wherein the auxiliary antenna is arranged so that a center position of a side along a resonance axis of the auxiliary antenna facing the loop circuit is located in the vicinity of the IC chip. . The auxiliary antenna has a convex portion at the center position of the side along the resonance axis of the auxiliary antenna facing the loop circuit, and is arranged so that the convex portion is located in the vicinity of the IC chip. The RF tag according to claim 2, wherein: The RF tag according to any one of claims 1 to 3, wherein the auxiliary antenna is arranged in parallel on the projection surface without contacting the antenna of the inlay. 4. The RF tag according to claim 2, wherein a center position of a side along a resonance axis of the auxiliary antenna is arranged so as to be separated within 5 mm from the loop circuit of the inlay. 5.