JP2002151944A - Master station antenna for rf id system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master station antenna with high reception sensitivity that can provide a service even to RF ID(Radio Frequency Identification) tags located over a wide range/at a remote distance. SOLUTION: Placing a torus conductor plate 2c at a prescribed position in front of the master station reception antenna 2b for the RF ID system increases the electric field strength around the reception antenna 2b so as to increase the input to the reception antenna 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a base station antenna of an RFID system.

[0002]

2. Description of the Related Art Conventionally, as a technique for recognizing various kinds of information using an optical reader, a bar code system is most widely used. A system using a barcode can perform various management of the product by expressing the number of a product or part, a product name, a price, and other information by a one-dimensional or two-dimensional barcode, and can perform various management of the product. It is also used in POS (point-of-sale information management) systems such as inventory management, process management, entry / exit management, and stores. Barcodes have the advantage that they can be used easily, but they have the disadvantage that the amount of information that can be stored is relatively small, and that some information cannot be rewritten or added. On the other hand, as a non-contact type individual identification system using radio waves, an RFID (Radio Frequency Iden) using a transponder (transceiver) generally called a tag (RFID tag) is used.
tification) system, for example, tag (non-contact ID)
Tag) is embedded in tableware and trays to perform automatic payment processing in the cafeteria, and a system applied to ski lift lift tickets and the like. An RFID system generally includes one tag (transponder), a reader or reader / writer of a master station, and one computer or information processing system. FIG.
Shows an example of a tag (hereinafter, referred to as an RFID tag) applied to the above-described RFID system. FIG. 1A is a plan sectional view showing the structure of the RFID tag, and FIG. Is a side sectional view. In the RFID tag 1 in this example, a circular concave portion is provided in the center of a disk-shaped resin holder 1c, and an IC chip 1b containing an electronic element and an antenna coil 1a are provided at the bottom in the concave portion. The upper part is covered with a resin mold 1d so as to be flat. Conventionally, the RFID tag 1 having such a planar shape has been used by being attached to or embedded in an individual to be identified.

[0003]

SUMMARY OF THE INVENTION RFID as described above
The system has an advantage that it can store a larger amount of information than a barcode and can be configured to be rewritable. In addition, there is an advantage that it can read through substances such as dust, paint, mud, plastic, and wood, has high reading accuracy, and is difficult to forge. On the other hand, barcodes are cheaper than RFID tags,
There is an advantage that it can be easily used. However, barcodes have the disadvantage that they cannot be read unless the surface of the reading unit on the reader side matches the surface of the barcode, and the RFID tag also requires a reader or reader / writer in the direction of its antenna. There is a disadvantage that data cannot be sent and received. Therefore, there is a problem that both cannot be used for an object whose identification target surface is not constant. Further, when the power radiated from the transmission antenna of the master station is fixed, the antenna having the highest possible reception sensitivity (master station side)
It has been desired from the RFID system because the service can be provided to a wider / longer distance tag. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an antenna with high reception sensitivity (master station side) capable of providing a service to tags in a wider range and a longer distance. Is to do.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a master station antenna for an RFID system, and an object of the present invention is to dispose an annular conductor plate at a predetermined position in front of a receiving antenna. This is achieved by increasing the electric field strength near the receiving antenna and increasing the receiving input of the receiving antenna.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiments described below,
A structure provided with two RFID tags composed of one antenna and one IC chip (or silicon chip) on the slave station side, or a structure provided with an RFID tag composed of two antennas and one IC chip Will be described as an “RFID unit”. Further, the two antennas of the RFID unit will be referred to as an “antenna module” for explanation. The slave station-side RFID unit according to the present invention includes an antenna module including two antennas for both power reception and data transmission and reception, and one or two IC chips having a memory capable of rewriting information. And
For example, by adopting an antenna structure in which two rectangular or elliptical antennas having a curved surface shape of a sphere are arranged in an orthogonal direction along a spherical surface, radio waves from almost all directions viewed from the center of the sphere can be transmitted. In addition to being able to receive, radio waves can be emitted in almost all directions. Also, RFID
As a package of the unit, for example, a structure formed in a ball shape is used, and the two antennas are arranged on any one of the surface portion, the inner wall portion, and the hollow portion. As a simple and inexpensive configuration of the RFID unit, two sealed RFID tags each including one antenna and one IC chip are used, and these RFID tags are used.
By attaching the D tag to the surface of the ball-shaped structure, an RFID unit capable of transmitting and receiving radio waves in almost all directions is realized. Also, the master station (reading device) side of the RFID unit having two RFID tags transmits, for example, a transmission stop command to the RFID tag that first receives a response to the inquiry, and transmits the command to the other RFID tag. By receiving the response data, an RFID system can be constructed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows an example of the structure of the antenna module of the slave station-side RFID unit according to the present invention. The antenna module 11M according to the present invention includes two antennas 11 having the same shape. In each of the antennas 11, the antenna lines in the longitudinal direction and in the transverse direction together form the curvature of the arc of the sphere 20,
In the present embodiment, two antennas 11 are arranged along two semicircular arcs whose semicircular surfaces form an angle of 90 degrees with each other. For example, as shown in FIG.
Along the circumference of 0, a bendable thin plate antenna is laid so as to intersect in the orthogonal direction on the same hemisphere, so that the antenna from almost all directions including the convex side and the concave side is provided. It has an antenna structure that can receive radio waves and radiate radio waves in almost all directions. The length of the antenna 11 in the longitudinal direction is preferably half the length of the circumference when the antenna 11 is laid along the circumference of the sphere 20 as described above, but may be less than that. Further, the length in the short direction is preferably as long as the longitudinal direction from the viewpoint of transmission and reception of radio waves, but it is only necessary that transmission and reception of radio waves in approximately 180 degrees can be performed. A shorter length that does not occur as much as possible is preferable. 3 (A) to 3 (C) show the slave station side RFI.
FIG. 3 is a schematic diagram showing the configuration of the arrangement configuration of the antenna module of the D unit, where positions where the longitudinal center lines of the antenna 11 are arranged are indicated by reference numerals A1 to A5, and semicircular surfaces are indicated by reference numerals SC1 to SC5. ing. In both arrangements, the surface of the semicircle forms an angle of 90 degrees, and FIG.
FIG. 3B shows an example in which two antennas are arranged on semicircular portions A1 and A2 on the same hemisphere so that arc portions intersect, as shown in FIG. FIG. 3 (C) shows an example of the arrangement on the semicircular portion A3 on the opposite hemispherical surface side.
Shows an example in which two antennas are arranged along each of the semicircular portions A4 and A5 when rotated by 90 degrees around a line connecting the end points of the semicircles. As described above, if two antennas having a circular arc shape whose longitudinal direction has a length of substantially a semicircle have an antenna structure in which the center of the circular arc is the same and the plane of the circular arc is arranged at an angle of 90 degrees, Transmission and reception of radio waves in almost all directions are possible. As an ID chip, a chip using radio waves in the LF band to the UHF band, or a chip using radio waves of a high frequency (microwave band) is applied. Which chip to use is determined by the field to which it is applied.For example, in the case of comprehensive management from the product manufacturing stage to distribution and sales, use a transponder element that can transmit at a long distance. Is preferred. In addition, it is good also as a form which connects an antenna of the shape mentioned above to one IC chip, without providing an IC chip corresponding to an antenna,
Alternatively, a configuration may be adopted in which a hemispherical antenna in which a coil is spirally wound along a hemispherical surface is used, and the RFID unit is configured with one antenna. However, in order to make the configuration inexpensive, it is preferable to connect each antenna to each IC chip. As shown below, the RFID circuit is attached or embedded in a sticker having an adhesive surface. (Hereinafter referred to as “seal-type RFID”) is most preferable.

Next, an example in which the above-mentioned antenna structure is formed by using two child station side seal type RFIDs will be described.
First, the configuration of the seal type RFID will be described. FIG.
(A) and (B) show an example of a configuration of a seal-type RFID used in an embodiment of the present invention in a plan view and a sectional view. The seal type RFID 10 has a configuration in which a rectangular or elliptical antenna 11 serving both power reception and data reception / transmission and an IC chip 12 having a built-in electronic element are mounted on the adhesive layer 13 b of the container 13. It has become. In this example, as shown in FIG. 4B, the antenna 1 is provided through a protective coating 13c made of a non-conductive member.
1 and the IC chip 12 are embedded between two layers (13a, 13d). Lower layer 13d of adhesive layer 13b
Is a release liner, which is released when used by adhering to a ball-shaped structure constituting a package of an RFID unit. The antenna unit is attached by, for example, printing conductive ink in a required shape. In this example, an antenna in which a coil is wound in an elliptical shape is taken as an example, but an antenna in which a coil is wound in a rectangular shape, or an antenna in which antenna wires are arranged on a straight line as shown in FIG. Alternatively, the shapes of the antenna and the seal can be appropriately changed.
When an RFID unit is configured using the seal type RFID 10 as described above, for example, as shown in FIG. 6, a ball-shaped structure 20 is packaged, and two seals are formed so as to intersect in the orthogonal direction on the spherical surface. When the type RFID 10 is arranged and laid along a curved surface, the antenna has the above-described antenna structure, and can receive radio waves from almost all directions viewed from the center and radiate radio waves in almost all directions. The RFID unit 30 capable of performing the above can be realized. In addition, the above-mentioned seal type RFID 1
If the ball-shaped structure 20 to which the “0” is stuck is provided inside a package 21 having a predetermined shape as shown in FIG. 7, an RFID unit 30 having an arbitrary shape can be realized. The member of the seal type RFID 10 may be a member having a high transmittance of radio waves in the frequency band used for transmitting and receiving signals, but it is preferable to use, for example, inexpensive styrene foam.

Next, the configuration of the master station (information processing apparatus) that performs processing such as reading / writing of the slave unit RFID unit will be described. For example, as shown in FIG. 8, the master station side read / write device 2 of the RFID unit
a, 2b, amplifier 3, FSK (Frequency Shift Keyin
g) It comprises a demodulator 4, an excitation drive 5, a control CPU 6, and the like. An annular conductor plate 2c is provided at a predetermined position in front of the receiving antenna 2b,
The electric field strength in the vicinity is increased to increase the reception input of the reception antenna 2b. In the present invention,
The slave station-side RFID unit includes two RFIDs (tags) having transmission / reception area portions in directions different from each other.
Since the same data is stored in the storage units of two RFID tags, two responses are generated in response to an inquiry (interrogation radio wave). Therefore, in the data reading process, only one response data needs to be processed.

In such a configuration, the RFI according to the present invention
Next, the operation of the master station receiving antenna 2b of the D unit will be described. First, a Yagi antenna structure is adopted as the receiving antenna 2b, and the concentric circular Fresnel zones of the received radio wave are shielded every other by the annular conductor plate 2c so as to remove the anti-phase electric field. When a receiving antenna having such an arrangement is used, a receiving antenna having as high a receiving sensitivity as possible (master station side) can be realized when the power radiated from the transmitting antenna of the master station is constant. Because we can provide services for tags of
By simply improving the receiving antenna of the master station, the slave station can provide the RFID system more widely without any modification.

Next, an example of the operation of the control CPU (or its host computer) in the master station read / write device of the RFID unit according to the present invention will be described with reference to the flowchart of FIG. The control CPU in the read / write device of the RFID unit transmits an inquiry signal for reading on a carrier wave (step S1). On the RFID unit side, necessary power is generated by the carrier wave, the power is used for writing / reading and transmission of data, and ID information is transmitted as a response signal via an antenna. In this example, the RFID unit is provided with two RFIDs (tags), and response signals having the same content are transmitted by independent operations. The control CPU of the read / write device determines whether or not a response to the inquiry has been received (step S2). When the response has been received, one of the RFIDs (for example, the RFID which first responded) has been received. A transmission stop command is sent to the user (steps S3 and S4). And the other RFID
(Step S5), and performs information processing such as identification processing using the response data (step S6). As described above, in the master station read / write device of the RFID unit, at the time of the read process, when the response to the inquiry is received, the transmission to one of the RFIDs (in this example, the RFID which received the response first) is stopped. A step (or a circuit) for transmitting a command may be provided, and there is no need to change the identification processing on the device side or the interface with the RFID.

Next, an example of a system to which the RFID unit according to the present invention is applied will be described. FIG. 10 shows an example of a system in which a "basket" (or a pallet) 2 loaded with products is transported by a transport means such as a conveyor 3, and the products are sorted and shipped according to delivery destinations and product types. Although a general system uses a barcode, the system cannot be used when a container such as a "cage" or the like in which the surface of the barcode is not constant is used. For example, in agricultural cooperatives, generally, goods such as cucumber, apples, and oranges are put in a "basket" 2 and transported on a conveyor 3 to carry out shipping work manually. In the past, information such as information that has been deleted has been managed manually and has not been mechanized.
Therefore, if the RFID unit of the present invention is used and an ID tag reading device (or reading / writing device) 4 is provided, a system for reading and managing data such as which agricultural cooperative and who has shipped it can be constructed at low cost. can do. For example, by simply throwing a ball-shaped RFID unit (ball-shaped RFID unit about the size of a golf ball) 30 into which a distribution route has been written in advance, into the leading “basket” (or pallet) 2, the reading device 4 It is possible to realize a system that can read data such as who shipped it and where it is handled by the agricultural cooperative. Also, if the RFID unit is taken out of the "car" 2, it can be reused. With such a usage form, introduction of the RFID system is very simple and operation is easy. In the above-described embodiment, the RFID unit is described as an example of a passive type that obtains operating power from energy emitted by a reader, but may be an active type with a built-in battery. Further, the RFID unit having no mounting section has been described as an example, but a unit configuration having a mounting section may be adopted.

[0012]

As described above, according to the present invention, the power radiated from the transmitting antenna of the master station is made constant,
Even without specially increasing the transmission output, a receiving antenna with high receiving sensitivity (master station side) can be realized, and services can be provided to tags over a wider range and a longer distance. Only by doing so, the slave station can provide the RFID system in a wider range without special modification.

[Brief description of the drawings]

1A and 1B are a plan view and a side sectional view illustrating a structure of a general RFID tag.

FIG. 2 is a perspective view showing an example of the structure of the antenna module of the RFID unit according to the present invention.

FIG. 3 is a schematic diagram illustrating an example of an arrangement configuration of an antenna module of an RFID unit according to the present invention.

FIG. 4 is a seal type RFID used in an embodiment of the present invention.
3A and 3B are a plan structural view and a cross-sectional structural view showing an example of the configuration of FIG.

FIG. 5 is a seal type RFID used in an embodiment of the present invention.
FIG. 6 is a plan view showing another example of the configuration of FIG.

FIG. 6 is a perspective view showing an example of a configuration of an RFID unit according to the present invention.

FIG. 7 is a perspective view showing another example of the configuration of the RFID unit according to the present invention.

FIG. 8 is a diagram showing an example of a system configuration on a master station side according to the present invention.

FIG. 9 is a flowchart for explaining an operation example on the reading device side of the RFID unit according to the present invention.

FIG. 10 is a schematic diagram showing an example of a system to which the RFID unit according to the present invention is applied.

[Explanation of symbols]

 2b Receiving antenna 2c Annular conductor plate 10 Sealed RFID 11 Transmitting / receiving antenna 11M Antenna module 12 IC chip 20 Ball-shaped structure 30 RFID unit

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5B058 CA17 5J020 AA00 AA03 BA02 BA03 BC02 BC09 DA02 5J046 AA04 QA03

Claims (3)

[Claims] 1. A master station antenna for an RFID system, wherein an annular conductor plate is disposed at a predetermined position in front of a receiving antenna to increase the electric field intensity near the receiving antenna, and A master station antenna for an RFID system, wherein the number of inputs is increased. 2. The master station antenna of the RFID system according to claim 1, wherein the receiving antenna has a Yagi antenna structure. 3. The parent of the RFID system according to claim 1, wherein the annular conductor plate shields every other concentric Fresnel zone of the received radio wave to remove an anti-phase electric field. Station antenna.