JP2007081632A - Radio ic tag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact radio IC tag for minimizing deterioration in the radiation efficiency of an antenna, and that in communication distance by shortening the length and width of the radio IC tag. <P>SOLUTION: An antenna conductor is formed in a meandering shape, thus reducing the outer shape of a packaging substrate to half a conventional one or smaller by miniaturization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless tag that uses electromagnetic waves as a communication medium.

  In recent years, research and development of RFID (Radio Frequency Identification) has been actively conducted as a non-contact automatic recognition technique using electromagnetic waves. RFID is an electromagnetic wave between a small responder (hereinafter also referred to as a wireless IC tag) such as an IC tag or an IC card equipped with a semiconductor memory (IC chip) and a communication antenna, and an interrogator (reader / writer). It is a technology that performs non-contact communication and data communication, and is attracting attention as a next-generation barcode.

  The advantages over bar codes include the large amount of information, the ability to write data, and the long communication distance because an IC chip is used for data communication. The application of the RFID system varies depending on the performance of a chip equipped with a small transponder, the communication method, the frequency band, and the like.

  In order to efficiently radiate the communication antenna mounted on the wireless IC tag, the total length of the antenna conductor is required to be about 1 / 2λ. FIG. 5 is an explanatory diagram of the prior art and shows a conventional antenna configuration configured by a microstrip line. 5A is a top view, FIG. 5B is a cross-sectional view along AA in FIG. 5A, and FIG. 5C is a bottom view. An antenna conductor 11 is disposed on the upper surface of the dielectric 14, and a feeding point 16 and a signal input / output terminal 17 are provided. A ground conductor 15 is disposed on the bottom surface, and a through hole 18 is provided so as to penetrate the antenna conductor 11 and the ground conductor 15.

  The length 12 of the antenna conductor is set to be equivalent to 1 / 2λ at the operating frequency. The antenna conductor width 13 functions as a parameter for setting the radiation efficiency of the antenna. Such an antenna is disclosed in Patent Document 1, for example.

JP 2000-332523 A

  However, in the case of an RFID system using the UHF band (900 MHz), the wavelength λ is about 30 cm, and the length 12 of the antenna conductor when the antenna of the form shown in FIG. 5 is manufactured is about 15 cm. A transponder having an antenna whose antenna conductor has a length of 15 cm is hardly small and has a limited application range. Therefore, if the total length of the wireless IC tag including the antenna is set to 1 / 2λ or less and an attempt is made to reduce the size, the radiation efficiency of the antenna is deteriorated in principle, and as a result, the communication distance is shortened and practically used. It cannot be served.

  The technical problem of the present invention is that the maximum length and the maximum width of a wireless IC tag (mounting substrate) are shortened, and even when the wireless IC tag is small, deterioration of antenna radiation efficiency and communication distance are minimized. It is to provide a wireless IC tag.

  The wireless IC tag of the present invention is composed of an IC chip mounted on a mounting substrate and an antenna conductor connected to the IC chip. By making the antenna conductor shape a meander shape, The mounting board is reduced to about 1 / 5λ, which is 1 / 2λ or less, and the substrate width is about 1 / 30λ.

  In addition, as the antenna conductor, the optimum value of the interval between the linear conductors constituting the meander shape is specified, and the miniaturization is realized without deteriorating the radiation efficiency of the antenna.

  Furthermore, by chamfering the bent part end (edge part) of the linear conductor constituting the meander shape as the antenna conductor, unnecessary radiation at the edge part is suppressed, and the antenna radiation efficiency deteriorates even if it is small in size. Do not configure.

  According to the present invention, there is provided a wireless IC tag in which an IC chip and an antenna conductor connected to the IC chip are mounted on a mounting substrate, and the antenna conductor is formed by continuously bending a linear conductor. A wireless IC tag having a meander shape can be obtained.

  According to the present invention, it is possible to obtain a wireless IC tag characterized in that the antenna conductor is chamfered at a bent portion end portion of the linear conductor.

  According to the present invention, when the wavelength of the use frequency of the wireless IC tag is λ, the maximum board width of the mounting board is 1 / 30λ or more and 2 / 30λ or less and the maximum board length is 5 / 30λ or more. , 7 / 30λ or less, a wireless IC tag is obtained.

  According to the present invention, when the wavelength of the use frequency of the wireless IC tag is λ, the antenna conductor is composed of a linear conductor having a width of 1 / 1200λ or more and 3 / 1200λ or less, and the adjacent linear conductors are adjacent to each other. Is formed at intervals of 1 / 1200λ or more and 3 / 1200λ or less, thereby obtaining a wireless IC tag.

  According to the present invention, a wireless IC tag with good antenna characteristics can be obtained even if it is small.

  The present invention reduces the size of the entire wireless IC tag without significantly degrading the antenna characteristics by making the antenna conductor shape a meander shape.

  The shape of the IC chip constituting the present invention and the mounting substrate on which the antenna conductor is mounted can be any shape such as a rectangular shape, a circular shape, or an elliptical shape, but a rectangular shape is preferable in practice. However, since the linear conductor is bent in a meander shape and mounted on the mounting board, the mounting board shape can be freely modified to some extent according to the use and usage form of the wireless IC tag regardless of the above.

  In order to satisfy the conventional antenna performance even when the antenna conductor shape is a meander shape, and to have a size of 1/2 or less of the conventional mounting substrate, the mounting substrate has a maximum substrate length of 5 / 30λ or more 7 / It is preferable that the width is 30λ or less and the maximum substrate width is 1 / 30λ or more and 2 / 30λ or less. Here, the reason why the maximum board length and the maximum board width are described is that the mounting board shape is not necessarily limited to the rectangular shape as described above. That is, in the case of an elliptical shape, the maximum substrate length indicates the length of the major axis, and the maximum substrate width indicates the length of the minor axis.

  In addition, since the antenna conductor is formed on almost the entire surface of the mounting board, the board length and the meander-shaped antenna conductor length, and the board width and the meander-shaped antenna conductor have some differences in practical use. In the case of commercialized products, it is almost the same.

  In addition, the meander shape in the present invention is defined as that arranged with a certain density or more in a certain area while bending a linear body such as a rectangular fold, a zigzag fold, and a waveform. Practically, rectangular folds and spelled folds are preferred.

  However, in order to minimize the area of the antenna mounting surface of the mounting substrate while exhibiting good antenna characteristics, the width of the antenna conductor and the antenna conductor are made a meander shape according to the operating frequency and the desired shape. It is necessary to set the portrait and landscape orientation appropriately.

  Therefore, it is preferable that the width of the antenna conductor is 1 / 1200λ or more and 3 / 1200λ or less and the distance between the antenna conductors is 1 / 1200λ or more and 3 / 1200λ or less for the mounting substrate satisfying the above-described size.

  Hereinafter, embodiments of the present invention will be described using examples.

Example 1
FIG. 1 is a diagram showing an embodiment of the present invention. On a rectangular mounting board 1, a linear conductor is bent in a meander shape, an antenna conductor 2 is arranged, and connected to an IC chip 3 to constitute a wireless IC tag.

  The mounting substrate 1 is made of a glass epoxy substrate having a relative dielectric constant of about 4.2. The IC chip 3 is connected to and mounted on the antenna conductor 2 by wire bonding at the center of the mounting substrate 1. Further, the periphery of the IC chip 3 is resin-sealed and fixed to the mounting substrate 1.

  Further, an antenna short pin conductor 8 is formed on the mounting substrate 1 as an antenna impedance adjustment element. The antenna short pin conductor 8 is formed for impedance matching between the IC chip 3 and the antenna, and supplies high-frequency power from the reader / writer side to the IC chip 3 from the antenna conductor 2 with high efficiency.

  Since the use frequency of the wireless IC tag of the present invention is 953 MHz, the wavelength λ of the use frequency is about 30 cm. In consideration of practical benefits, the substrate length 4 is about 1 / 5λ or 60 mm, and the substrate width 5 is about 1 / 30λ or 10 mm.

  When the antenna conductor was arranged in a meander shape so as to fit on the substrate, and the total length of the antenna conductor 2 was ½λ, and the electric operation was performed as a dipole antenna, it worked well.

  FIG. 3 is a diagram showing a conventional wireless IC tag. The antenna conductor 11 is formed on the mounting substrate 10 and connected to the IC chip 3 in a general dipole wireless IC tag used near 950 MHz. The antenna conductor 11 has a long shape extending around the IC chip 3 and constitutes a dipole antenna.

  The length 12 of the antenna conductor is about 1 / 2λ, that is, 150 mm, and the width 13 of the antenna conductor is 1 / 30λ, that is, 10 mm. In general, the width of the antenna conductor is deeply related to the radiation efficiency of the antenna, and the wider the width, the higher the radiation efficiency.

  The wireless IC tag of the present invention shown in FIG. 1 is compared with the conventional wireless IC tag shown in FIG. The wireless IC tag of the present invention uses a linear conductor to reduce the conductor width to a meander shape so that the external shape of the wireless IC tag (the size of the mounting substrate) is the conventional wireless tag (length: 150 mm). About 1/2 or less (length 60 mm).

(Example 2)
FIG. 2 is a diagram showing an embodiment of the present invention. Although the configuration is the same as that of the wireless IC tag shown in FIG. 1, the meander-shaped antenna conductor edge portion 91 is chamfered to R = 0.5 mm (1 / 600λ). Comparing the shape with the antenna conductor edge portion 9 of FIG. 1, the difference in configuration becomes clear.

  When this radio IC tag was used to perform an electrical operation as a dipole antenna, it operated well and had better antenna characteristics than Example 1.

  By adopting this configuration, unnecessary radiation at the edge portion was suppressed, and deterioration of antenna radiation efficiency was reduced, thereby contributing to further miniaturization.

(Example 3)
FIG. 2 is a diagram showing an embodiment of the present invention. A wireless IC tag having a configuration similar to that used in the second embodiment, wherein the folded length 5a of the antenna conductor is 1 / 30λ, that is, 10 mm, and the length of the wireless tag, that is, the substrate length 4, is 1 / 5λ. That is, a radio frequency IC tag having a thickness of 60 mm, a width 6 of the antenna conductor of 1 / 600λ, that is, 0.5 mm, and a distance 7 between the linear antenna conductors 2 constituting the meander shape was set to 1 / 400λ, ie, 0.75 mm .

  As the folded length 5a of the antenna conductor becomes longer, current cancellation occurs between adjacent linear antenna conductors, and radiation efficiency deteriorates. However, if the folding length 5a is shortened, the substrate length 4 is naturally increased. Accordingly, the radiation efficiency is not deteriorated, and the folded length 5a of the antenna conductor is set to 1 / 30λ, that is, 10 mm in consideration of practical advantages as described above.

  Further, as described above, when the width 6 of the antenna conductor is shortened, the radiation efficiency of the antenna is deteriorated. Furthermore, if the conductor spacing 7 of the linear antenna constituting the meander shape is too close, the radiation efficiency of the antenna is deteriorated.

  As a result of intensive studies, the present inventor has realized that the wavelength λ = 30 cm of the used frequency can be realized and the antenna length can be reduced without deteriorating the radiation efficiency of the antenna when the folded length 5a of the antenna conductor is set to the above-mentioned size. In order to minimize 4, the width 6 of the antenna conductor is 1 / 600λ or 0.5 mm, the conductor spacing 7 of the linear antenna constituting the meander shape is 1 / 400λ or 0.75 mm, and the substrate length 4 ( The conclusion was reached that the length of the wireless tag is most preferably 1 / 5λ or 60 mm. The wireless IC tag having this configuration had a substrate length 4 of 60 mm and a substrate width 5 of 11 mm.

  When this wireless IC tag was electrically operated as a dipole antenna, it operated very well.

Example 4
FIG. 2 is a diagram showing an embodiment of the present invention. A wireless IC tag having the same configuration as that used in the second embodiment, which has a substrate width 5 of 1 / 15λ or 20 mm, a substrate length 4 of 1 / 6λ or 50 mm, and an antenna conductor width 6 of 1 A wireless IC tag having a linear antenna having a meander shape of 1 / 400λ, that is, 0.25 mm and a conductor interval 7 of 1 / 400λ, that is, 0.75 mm was manufactured.

  When this wireless IC tag was electrically operated as a dipole antenna, it operated well.

(Example 5)
FIG. 2 is a diagram showing an embodiment of the present invention. The wireless IC tag has the same configuration as that used in the second embodiment. The board width 5 is 1 / 30λ or 10 mm, the board length 4 is 7 / 30λ or 70 mm, and the antenna conductor width 6 is 1 A wireless IC tag was manufactured with / 400λ or 0.75 mm, and the conductor interval 7 of the linear antenna conductor constituting the meander shape was 1 / 1200λ or 0.25 mm.

  When this wireless IC tag was electrically operated as a dipole antenna, it operated well.

(Example 6)
FIG. 4 is an explanatory diagram of a communication distance measurement experiment. The interrogator 101 communicates with the wireless IC tag 103 via the interrogator antenna 102. The output of the interrogator 101 is 24.5 dBM, and the antenna gain of the interrogator antenna 102 is 6 dBi. Further, the wireless IC tag 103 and the interrogator 101 are arranged at an interval of a distance r and perform communication.

  The distance r was measured using the conventional general wireless IC tag shown in FIG. 3 as the wireless IC tag and the wireless IC tag used in Examples 1 to 3 of the present invention.

  The communication distance of the conventional wireless IC tag is 1.3 m, whereas the communication distance when the wireless IC tags of Examples 1 to 5 are used is 0.9 to 1.2 m. Although the communication distance is slightly shorter than the conventional wireless IC tag, it can be seen that there is no problem in practical use.

  With the above-described configuration, an RFID system using a small wireless IC tag having a size approximately half that of the conventional size can be configured, and the system can be designed unprecedented.

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to these embodiments, and the present invention is not limited to the scope of the present invention. Included in the invention. That is, it goes without saying that the present invention also includes various variations and modifications that would be obvious to those skilled in the art.

  With the wireless IC tag of the present invention, the degree of freedom of RFID system design is increased, and an RFID system with a wide range of application can be constructed at a low price.

The figure which shows the Example of this invention. The figure which shows the Example of this invention. The figure which shows the conventional radio | wireless IC tag. Explanatory drawing of a communication distance measurement experiment. FIG. 5 (a) is a top view, FIG. 5 (b) is an AA sectional view of FIG. 5 (a), and FIG. 5 (c) is a bottom view.

Explanation of symbols

1,10 Mounting substrate 2,11 Antenna conductor 3 IC chip 4 Substrate length 5 Substrate width 5a Antenna conductor folding length 6,13 Antenna conductor width 7 Conductor spacing 8 Antenna short pin conductors 9, 91 Antenna conductor edge 12 Antenna Conductor length 101 Interrogator 102 Interrogator antenna 103 Wireless IC tag 14 Dielectric 15 Ground conductor 16 Feed point 17 Signal input / output terminal 18 Through hole r Distance

Claims (4)

  A wireless IC tag comprising an IC chip and an antenna conductor connected to the IC chip mounted on a mounting substrate, wherein the antenna conductor has a meander shape formed by continuously bending a linear conductor. A featured wireless IC tag.   2. The wireless IC tag according to claim 1, wherein the antenna conductor is chamfered at a bent end portion of the linear conductor.   When the wavelength of the use frequency of the wireless IC tag is λ, the maximum board width of the mounting board is 1 / 30λ or more and 2 / 30λ or less, and the maximum board length is 5 / 30λ or more and 7 / 30λ or less. The wireless IC tag according to claim 1, wherein the wireless IC tag is provided.   When the wavelength of the use frequency of the wireless IC tag is λ, the antenna conductor is a linear conductor having a width of 1 / 1200λ or more and 3 / 1200λ or less, and each adjacent linear conductor is 1 / 1200λ or more and 3 The wireless IC tag according to any one of claims 1 to 3, wherein the wireless IC tag is formed at an interval of / 1200λ or less.

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