JP2007258924A - Antenna for radio tag and management system for article using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio tag antenna the characteristic of which is broadbanded to enhance the performance, and to provide a management system for articles using the same. <P>SOLUTION: The radio tag antenna for making communication with a radio tag provided with a plurality of input ports forms its antenna pattern by shifting frequencies at which a return loss value of the antenna is a minimum. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radio tag antenna and an article management system using the antenna.

  The wireless tag includes an IC chip that holds and processes data and an antenna unit that communicates with the interrogator. There are wireless tags that use radio waves of various frequencies for communication with the interrogator, and applications that take advantage of their characteristics are provided and proposed. As a general reader / writer, a patch antenna is frequently used because it can be easily reduced in size and weight, has a relatively high gain, and has good directivity. However, the patch antenna has a drawback that the frequency band is narrow and loss due to dielectric loss increases as the frequency increases.

Therefore, for example, to increase the bandwidth of the patch antenna, for example, it has a plurality of patch antenna elements arranged at a predetermined interval in the E plane direction of a radio wave to be transmitted and received, and the resonance frequency of each patch antenna element And a patch antenna is proposed in which at least one of the patch antenna elements is bent in the E plane. (For example, refer to Patent Document 1).
JP 2001-298319 A

  Even when the patch antenna as described above is applied as a tag antenna, it is not easy to have a sufficiently wide band in communication with the stacked wireless tags.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radio tag antenna whose tag antenna characteristics are widened to improve performance and an article management system using the same.

  According to one aspect of the present invention, a wireless tag antenna for communicating with a wireless tag having a plurality of input ports, wherein a plurality of antenna patterns are arranged so as to shift a frequency at which a return loss value of the antenna is minimized. An antenna for a wireless tag, characterized in that is formed.

  According to another aspect of the present invention, there is provided a wireless tag antenna for communicating with a wireless tag having a plurality of input ports, wherein the frequency for optimizing the matching with the wireless tag is different. There is provided an antenna for a radio tag characterized by having a plurality of antennas.

  The power input to each port is combined and supplied to the wireless tag.

  The plurality of antennas share a part of the antenna.

  ADVANTAGE OF THE INVENTION According to this invention, the antenna management system which used the antenna for radio tags which aimed at the performance improvement by broadening the characteristic of the tag antenna, and an article | item using this is obtained.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram showing the configuration of radio tag antennas 20 and 30 and a radio tag 10 according to an embodiment of the present invention, FIG. 2 is a schematic block diagram showing the configuration of the radio tag, and FIG. 3 is a reader / writer. The schematic block diagram which shows the structure of is shown, respectively.

  The wireless tag 10 is a kind of wireless data carrier that is affixed to an article or a delivery item, and is an independent component in which a tag antenna that can be transmitted and received and an IC chip are integrally formed on a substrate. The IC chip 40 rectifies and stabilizes the modulated radio waves received by the tag antennas 20 and 30, thereby demodulating the modulated radio waves and sending them to the control unit. The demodulator 22, the modulator 23 that modulates the data sent from the controller and sends it to the tag antenna, the data demodulated by the demodulator 22 is written to the memory, and the transmission data is read from the memory and sent to the modulator 23. A control unit 24 and a memory 25 are provided.

  The memory 25 includes a wireless ID area that stores a unique wireless ID assigned and set by the manufacturer at the manufacturing stage of the wireless tag, and a user area in which a user can write arbitrary data. In the user area, a unique tracking management code such as an article or a delivery item to which the wireless tag is attached is recorded.

  A delivery item or the like to which such a wireless tag is attached is placed on a reading table of a wireless tag reader that reads the wireless tag, for example.

  The wireless tag reader includes a wireless tag antenna, and reads memory data of the wireless tag in the communication area of the wireless tag antenna in a non-contact manner.

  As shown in FIG. 3, the wireless tag reader 50 is connected to a host device such as a personal computer, for example, an interface unit 51 that exchanges data, a CPU 52 that controls communication with the wireless tag and hardware to be connected, operation A control unit 55 including a ROM 53 storing a program, a RAM 54 storing data temporarily, a modulation unit 56 that modulates data supplied from the control unit 55 into a modulation signal suitable for wireless communication, and a modulation signal From a transmission amplifier 57 that amplifies and radiates as a radio wave from a transmission / reception antenna, a reception amplifier 58 that amplifies a radio signal received by the antenna unit, and a demodulation unit 59 that demodulates data from the amplified radio signal and applies the data to the control unit It is configured.

  When communicating with a wireless tag, the carrier signal is first modulated by the transmitter and transmitted as a power radio signal from the transmission antenna, and then the data to be transmitted is superimposed on the power radio signal. The signal is modulated by the unit and transmitted from the transmission antenna.

  In this specification, the UHF band will be described as an example. The wireless tag 10 according to the present embodiment includes a plurality of input ports. For example, a device having two ports can be referred to as a dual port type. The power from the antenna is input to each port, and the combined power is supplied to the wireless tag.

  The RFID tag antenna according to the embodiment of the present invention includes a first antenna 20 and a second antenna 30, and antenna patterns are formed by shifting the frequency at which the return loss value of the antenna is minimized. FIG. 4 is a diagram for explaining the characteristics of the first antenna 20 and the second antenna 30 which are antennas for wireless tags. In the first antenna 20, the frequency at which the return loss value is approximately −20 dB is around 900 MHz. On the other hand, in the second antenna 30, the frequency at which the return loss value is approximately −20 dB is around 950 MHz. The frequency which becomes a return loss value of both is shifted by about 50 MHz. As a result, the combined return loss value is about −27 dB as the minimum at around 925 MHz. Thus, in the embodiment of the present invention, the first antenna 20 and the second antenna 30 have different frequencies for optimizing matching with the wireless tag 10.

  As shown in FIG. 1, it is preferable that the first antenna 20 and the second antenna 30 are disposed so as to face each other with the wireless tag 10 interposed therebetween. The first antenna 20 and the second antenna 30 can be formed by, for example, a planar patch antenna, and by making the total length slightly different from each other, it is possible to make a difference between the characteristics of the two. In FIG. 1, the first antenna 20 and the second antenna 30 have lengths a, b, c, d, e, and f, respectively. In this case, by making the lengths of the respective antennas different so that a + b + c ≠ d + e + f, the antenna pattern can be formed by shifting the frequency at which the antenna return loss value is minimized.

  FIG. 5 is a schematic view showing the configuration of another embodiment of the present invention, and FIG. 6 is an enlarged schematic view showing the pattern of the IC chip portion in an easy-to-understand manner. The first antenna portion A and the second antenna portion B share a ground C in the IC chip, and form antennas having different overall lengths. The first antenna portion A is a portion indicated by a right oblique line in FIG. 6, and the second antenna portion B is a portion indicated by a left oblique line in FIG. By adopting such a configuration, even when the grounds of the IC chips are close to each other, it is possible to easily create an antenna pattern by shifting the frequency at which the antenna return loss value is minimized.

  Next, an article management system using the RFID tag antenna according to the present invention will be described. As shown in FIG. 7, this article management system is an example of a courier service which is individual delivery of an article. The parcel delivery service is a transportation service that delivers relatively small packages such as small packages and documents to each house. Courier service is characterized by rapid delivery from the shipper's doorway to the destination doorway.

The client brings an envelope, in which documents are enclosed, and an RFID tag having a plurality of input ports attached thereto, to the collection place. At the collection / delivery place, envelopes with wireless tags are collected in a single bag. Tag information is read from the envelope packed in a bag by a wireless tag reader incorporating the wireless tag antenna according to the present invention. Even if the envelope and the envelope are in close contact with each other, the tag antenna can be read smoothly because the tag antenna has a wide band. The read tag information is sent to the computer center, and data management is performed as tag location information, tag ID master, and information master, for example.

  Next, the bags put together in one bag are brought into processing centers in various places, where the tag information is read again by the wireless tag reader, and the data is sent to the computer center.

These bags are transported to the next collection / delivery place, sorted by destination and means of transport, and then delivered to the final destination. When delivery of the delivery is completed, information indicating completion is sent to the computer center.

  Since a unique ID is given to the delivery item by attaching a wireless tag, not only the requester but also the receiving side accesses the computer center to track where the delivery item is currently located. be able to.

  As described above, in the past, attempts have been made to increase the bandwidth by sacrificing the gain of the antenna. However, according to the present embodiment, the performance of the tag antenna is improved by increasing the bandwidth of the tag antenna without sacrificing the gain. Can be achieved.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a schematic diagram illustrating a configuration of a radio tag antenna and a radio tag according to an embodiment of the present invention. It is a schematic block diagram which shows the structure of a wireless tag. It is a schematic block diagram which shows the structure of a reader / writer. It is a figure explaining the characteristic of the antenna for RFID tags concerning the embodiment of the present invention. It is the schematic which shows the structure of other embodiment of this invention. It is the schematic which expanded the pattern of the chip | tip part. 1 is a configuration diagram illustrating an article management system according to an embodiment of the present invention.

Explanation of symbols

  10 ... wireless tag, 20 ... first antenna, 30 ... second antenna.

Claims (6)

  A wireless tag antenna for communicating with a wireless tag having a plurality of input ports, wherein a plurality of antenna patterns are formed so as to shift a frequency at which a return loss value of the antenna is minimized. RFID tag antenna.   A wireless tag antenna for communicating with a wireless tag having a plurality of input ports, the antenna having a plurality of antennas so as to have different frequencies for optimizing matching with the wireless tag Antenna for wireless tag.   3. The wireless tag antenna according to claim 1, wherein the power input to each port is combined and supplied to the wireless tag.   The wireless tag antenna according to claim 1 or 2, wherein the plurality of antennas share a part of the antenna.   3. The radio tag antenna according to claim 1, wherein the number of the input ports is two.   An article management system to which an RFID tag having a plurality of input ports is attached, wherein the RFID tag antenna according to any one of claims 1 to 5 is used. .