JP5205884B2 - IC tag reader / writer and method for arranging multiple antenna units - Google Patents

Description

  The present invention relates to a reader / writer for an IC tag and a method for arranging a plurality of antenna units.

  An RFID (Radio Frequency Identification) tag (IC tag, wireless tag) may be used in a position detection system that detects a two-dimensional position of a moving object.

As described above, there are two typical methods for detecting a two-dimensional position of a moving object using an RFID tag.
(1) A method of embedding tags each having a unique ID in a plane, causing a reader / writer attached to a moving object to read the position of the tag, and transmitting the tag from the reader / writer to the position collection system by appropriate communication means;
(2) A method in which a number of tags attached to a moving object are detected by a reader / writer embedded in a plane, and the position of the reader / writer that has detected the tag is transmitted from the reader / writer to the position collection system.

  In the former method (1), it is necessary for a moving object or person to be equipped with a wireless tag reader / writer (see Patent Document 1), and the position data is transmitted to the position collection system by another wireless device or the like. There is a need. In addition, moving objects and people need to be equipped with a power source for activating tags scattered on a plane. On the other hand, since the tag itself is generally cheaper than a reader / writer, even if a large number of small-sized tags are embedded in a plane in order to improve the position detection accuracy, no significant cost problem arises.

  In the latter method (2), a moving object or person only needs to be equipped with a tag. However, in order to realize accurate position detection, it is necessary to embed a large number of readers / writers (generally more expensive than tags) in a plane. Therefore, various methods have been devised that can stably install a large number of readers / writers (see Patent Documents 2 and 3). FIG. 3 is a schematic block diagram of the position detection system of Patent Document 3 that realizes the method (2) and stably installs a number of readers / writers. In this system, a large number of antenna units 104 communicating with the IC tag 120 are controlled by a small number of control circuit units 101. However, in this system, since a large number of antenna units 104 are controlled by a small number of control circuit units 101, each antenna is accessed in a time-sharing manner, and there is little opportunity to try to acquire an ID in the IC tag 120, that is, a reaction There is a disadvantage that the speed is slow.

  FIG. 4 is an antenna arrangement diagram of a plurality of reader / writers arranged two-dimensionally in the position detection RFID device described in Patent Document 2 as a conventional technique. In a plurality of reader / writers of the RFID device, a circuit unit 202 equipped with a control circuit unit is connected to 16 modulation / demodulation circuit units 208 via a signal transmission path 206 for serial digital signal communication, and each of the modulation / demodulation circuit units 208 is an antenna. 204 is connected. The circuit unit 202 and the antenna 204 interface with a serial digital signal. Although there are standards using radio waves of various frequencies for RFID, for example, when using a frequency of 13.56 MHz band, the communicable distance between the tag and the reader / writer antenna is short. If antennas are laid out as shown in FIG. 4, the antennas that can detect the tag are limited, so that the position can be easily detected.

  The circuit unit 202 attempts to access sequentially while designating the addresses 0x0 to 0xF (hexadecimal) of the modulation / demodulation circuit unit 208. The time required for acquiring the ID of one IC tag is determined by one antenna 204 and modulation / demodulation circuit unit 208, and when the time is T, the tag on the upper surface of the antenna laid as shown in FIG. 4 is detected. It takes a maximum time of 16T.

  FIG. 5 is an antenna arrangement diagram of a plurality of reader / writers for position detection described in Patent Document 2 in a wider range than FIG. The antenna layout shown in FIG. 5 is a collection of 4 units with the antenna layout of FIG. 4 as one unit. In the layout diagram of FIG. 5, it can be detected at which position of the 8 × 8 divided 64 locations the tag is located. In this example, in order to eliminate interference of adjacent antennas, the four circuit units 202 are synchronized, and access to the IC tag is tried in order from address 0. 5 shows access by the antenna 204 attached to the modulation / demodulation circuit 208 at address 0, and FIG. 6 shows access by the antenna 204 attached to the modulation / demodulation circuit 208 at address 1. If the number of modulation / demodulation circuit units 208 (of the antenna 204) controlled by the control circuit unit included in one circuit unit 202 is increased, the number of control circuit units can be reduced and the cost can be reduced. However, the IC tag detection time increases accordingly.

  For example, when the position of an IC tag included in a person's shoe sole is detected by a large number of readers / writers embedded in the floor, the success of the ID acquisition operation of the large number of readers / writers embedded in the floor is very rare. It can be inferred that most operate without tag responses.

Patent Document 1 discloses a position detection system in which an IC tag is installed on a floor or the like, and a mobile body is equipped with an IC tag reader / writer and a wireless communication means to perform position detection. This mobile body needs to be provided with an IC tag reader / writer and wireless communication means that require electric power. In the IC tag reader / writer disclosed in Patent Document 2, the control circuit unit in the circuit unit and the modulation / demodulation circuit unit in the antenna unit are connected via a transmission line. It can be said that the IC tag reader / writer has a high degree of freedom in the positional relationship between the control circuit section and the modem circuit section. However, as described above, when a plurality of antenna units are connected to the circuit unit, there is a problem that it takes time to attempt ID acquisition with all antennas. Further, the IC tag reader / writer disclosed in Patent Document 3 communicates with each of a plurality of ID tags with one antenna unit.
JP 2006-194893 A JP 2006-60763 A JP 2006-172303 A

  The present invention provides an IC tag reader / writer that increases the reaction speed by increasing the ID acquisition opportunity of the tag without lowering the accuracy of the detection position while taking advantage of the fact that the moving object only needs to have a tag. provide.

The present invention has been made to achieve the above object. An IC tag reader / writer according to claim 1 of the present invention is provided.
An antenna unit including an antenna and a modulation / demodulation circuit unit, and a circuit unit including a control circuit unit, and a plurality of antenna units are connected to one circuit unit,
The antenna unit and the circuit unit are readers / writers for IC tags that interface with serial digital signals and control communication with a control circuit unit,
A position on a plane where a plurality of antenna units are arranged is defined by orthogonal X-axis and Y-axis, and the first antenna unit for detecting the position of the IC tag is located on the first layer parallel to the plane. The second layer that is spread and parallel to the plane has a size that is N times (N is a natural number) in the X-axis direction and M times (M is a natural number) in the Y-axis direction, compared to the size of the first antenna unit. A plurality of second antenna units for obtaining the ID of the IC tag are arranged,
N pieces of first antenna units in the X-axis direction and M pieces in the Y-axis direction are arranged inside the plane of the second antenna unit ,
Only when a plurality of the second antenna units in the second layer attempt to acquire an ID of an IC tag and an ID of the IC tag is acquired, the detailed position is detected by the first antenna unit of the first layer. Is done .

An IC tag reader / writer according to claim 2 of the present invention is provided.
2. The IC tag reader according to claim 1, wherein a plurality of antennas of the second antenna unit are arranged so as not to overlap with the antenna of the first antenna unit in the vertical direction of the plane.・ It is a writer.

The method for detecting the position of an IC tag according to claim 3 according to the present invention comprises:
An antenna unit including an antenna and a modulation / demodulation circuit unit, and a circuit unit including a control circuit unit, and a plurality of antenna units are connected to one circuit unit,
The antenna unit and the circuit unit are a method of detecting the position of an IC tag using an IC tag reader / writer that interfaces with a serial digital signal and controls communication with a control circuit unit,
The position on the plane where the plurality of antenna units are arranged is defined by the orthogonal X axis and Y axis, and the first antenna unit for detecting the position of the IC tag is spread on the first layer parallel to the plane. The second layer parallel to the plane has a size N times (N is a natural number) in the X-axis direction and M times (M is a natural number) in the Y-axis direction, compared to the size of the first antenna unit. , Arranging a plurality of second antenna units for obtaining the ID of the IC tag,
N pieces of first antenna units in the X-axis direction and M pieces in the Y-axis direction are arranged inside the plane of the second antenna unit,
Only when a plurality of the second antenna units in the second layer attempt to acquire an ID of an IC tag and an ID of the IC tag is acquired, the detailed position is detected by the first antenna unit of the first layer. Is done.

  By using the present invention, it is inexpensive to perform quick position detection without losing accuracy while taking advantage of a general IC tag reader / writer that only requires a simple IC tag to be attached to a moving object or person. Can be done with any device.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
Among the specific methods for detecting the two-dimensional position of a moving object using an RFID tag, “(2) a reader / writer embedded with a number of tags attached to a moving object on a plane is provided. The reader / writer for an IC tag for realizing "a method for detecting and transmitting the position of a reader / writer from which a tag has been detected from a reader / writer to a position collection system", in particular, as shown in FIGS. The antenna (unit) is further improved. Specifically, the antennas are arranged in multiple layers so as to overlap each other so that one position can be detected by a plurality of antennas.

  FIG. 1A is a schematic plan layout view of an IC tag reader / writer according to a first embodiment of the present invention. In the IC tag reader / writer according to the first embodiment, the antenna unit 4 shown in FIGS. 1 (2) and (3) is arranged as follows.

That is, when the position on the plane where a plurality of antenna units are arranged is defined by the orthogonal X-axis and Y-axis, and the minimum detection accuracy of the IC tag is the unit length, N and M are integers, In the first layer (lower layer) parallel to the plane, an antenna unit 4 (see FIG. 1 (2)) having an antenna whose X-axis direction is a unit length and whose Y-axis direction is M times the unit length. N are arranged. Next, in the second layer (upper layer) parallel to the plane, the antenna unit 4 having an antenna whose Y axis is a unit length and whose X axis direction is N times the unit length (see FIG. 1 (3)). M) are arranged.

  In the IC tag reader / writer according to the first embodiment, as in the reader / writer shown in FIG. 4, the circuit unit 2 equipped with the control circuit unit has a signal transmission path 6 for performing serial digital signal communication. The modulation / demodulation circuit unit 8 is connected to the antenna unit 4. The circuit unit 2 and the antenna unit 4 interface with a serial digital signal.

  In the IC tag reader / writer provided with the antenna as described above, in the ID acquisition operation of the IC tag 20 including the antenna 14 and the modulation / demodulation circuit unit 18, the example shown in FIG. Then, ID acquisition by the antenna unit 4 to which addresses 0, 1, 2, and 3 are attached is repeated.

  Since most of the ID acquisition operations are assumed to have no tag response, the determination of the presence or absence of the IC tag in the arrangement shown in FIG. Only when there is a tag response, the position x in the X-axis direction is first stored, and this time, in the example of FIG. 1 (1), the antenna units with addresses 4, 5, 6, and 7 are attached. ID acquisition by 4 is performed, and the position y of the Y axis is specified. In this way, the position (x, y) of the IC tag 20 can be specified.

  In the IC tag reader / writer according to the first embodiment shown in FIG. 1 (1), the detection accuracy is the same as that of the prior art shown in FIG. 4, but the number of antenna units (readers / writers) to be laid down is the same. Is one-half, and the time until the presence / absence of a tag response is determined is one-fourth.

[Second Embodiment]
FIG. 2 is a schematic plan layout view of an IC tag reader / writer according to a second embodiment of the present invention. The IC tag reader / writer according to the second embodiment is substantially the same as the IC tag reader / writer according to the first embodiment. Therefore, the same parts are denoted by the same reference numerals, description thereof will be omitted, and differences between the two will be mainly described.

  First, the antenna unit 4- (1) having a size that determines the accuracy of position detection of the IC tag 20 is spread on the first layer (lower layer) parallel to the plane on which the plurality of antenna units are arranged. Next, the second layer (upper layer) parallel to the plane on which the plurality of antenna units are arranged has a size that is N times in the X-axis direction and M times in the Y-axis direction compared to the size of the antenna unit in the first layer The antenna unit 4- (2) is spread. In the second-layer antenna unit 4- (2), N first-layer antenna units 4- (1) having N pieces in the X-axis direction and M pieces in the Y-axis direction are arranged.

  In such an IC tag reader / writer, first, the larger antenna unit 4- (2) in the second layer tries to obtain the ID of the IC tag 20 roughly. Only when the ID of the IC tag is acquired, the detailed position is detected by the smaller antenna unit 4- (1) in the first layer. By doing in this way, time until detailed position detection of an IC tag can be shortened more.

  In an IC tag reader / writer, an antenna is often formed as a pattern on a circuit board such as an epoxy resin. With such a circuit board, a pattern can be formed on the front and back of the double-sided board.

  Furthermore, if it is a multilayer substrate, an antenna having three or more layers can be formed.

1 is a schematic plan layout view of an IC tag reader / writer according to a first embodiment of the present invention. FIG. 5 is a schematic plan layout view of an IC tag reader / writer according to a second embodiment of the present invention. It is a block diagram of the reader / writer for IC tags of a prior art. It is an antenna arrangement diagram of a plurality of readers / writers arranged two-dimensionally in a conventional position detection RFID device. FIG. 5 is an antenna arrangement diagram of a plurality of readers / writers for position detection according to the prior art in a wider range than FIG. 4. FIG. 5 is an antenna arrangement diagram of a plurality of readers / writers for position detection according to the prior art in a wider range than FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Circuit unit, 4 ... Antenna unit, 6 ... Transmission path, 8 ... Modulation / demodulation circuit unit, 14 ... Antenna, 18 ... Modulation / demodulation circuit unit, 20 ... IC tag.

Claims (3)

An antenna unit including an antenna and a modulation / demodulation circuit unit, and a circuit unit including a control circuit unit, and a plurality of antenna units are connected to one circuit unit,
The antenna unit and the circuit unit are readers / writers for IC tags that interface with serial digital signals and control communication with a control circuit unit,
A position on a plane where a plurality of antenna units are arranged is defined by orthogonal X-axis and Y-axis, and the first antenna unit for detecting the position of the IC tag is located on the first layer parallel to the plane. The second layer that is spread and parallel to the plane has a size that is N times (N is a natural number) in the X-axis direction and M times (M is a natural number) in the Y-axis direction, compared to the size of the first antenna unit. A plurality of second antenna units for obtaining the ID of the IC tag are arranged,
N pieces of first antenna units in the X-axis direction and M pieces in the Y-axis direction are arranged inside the plane of the second antenna unit,
Only when a plurality of the second antenna units in the second layer attempt to acquire an ID of an IC tag and an ID of the IC tag is acquired, the detailed position is detected by the first antenna unit of the first layer. A reader / writer for an IC tag, wherein   2. The IC tag reader according to claim 1, wherein a plurality of antennas of the second antenna unit are arranged so as not to overlap with the antenna of the first antenna unit in the vertical direction of the plane. ·lighter. An antenna unit including an antenna and a modulation / demodulation circuit unit, and a circuit unit including a control circuit unit, and a plurality of antenna units are connected to one circuit unit,
The antenna unit and the circuit unit are a method of detecting the position of an IC tag using an IC tag reader / writer that interfaces with a serial digital signal and controls communication with a control circuit unit,
The position on the plane where the plurality of antenna units are arranged is defined by the orthogonal X axis and Y axis, and the first antenna unit for detecting the position of the IC tag is spread on the first layer parallel to the plane. The second layer parallel to the plane has a size N times (N is a natural number) in the X-axis direction and M times (M is a natural number) in the Y-axis direction, compared to the size of the first antenna unit. , Arranging a plurality of second antenna units for obtaining the ID of the IC tag,
N pieces of first antenna units in the X-axis direction and M pieces in the Y-axis direction are arranged inside the plane of the second antenna unit,
Only when a plurality of the second antenna units in the second layer attempt to acquire an ID of an IC tag and an ID of the IC tag is acquired, the detailed position is detected by the first antenna unit of the first layer. A method for detecting the position of an IC tag, wherein:

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