WO2006126275A1

WO2006126275A1 - Ic tag system

Info

Publication number: WO2006126275A1
Application number: PCT/JP2005/009756
Authority: WO
Inventors: Hiroshi Tachi; Yuzuru Fujita
Original assignee: Hitachi Ulsi Systems Co., Ltd.
Priority date: 2005-05-27
Filing date: 2005-05-27
Publication date: 2006-11-30

Abstract

In an IC tag system provided with, for instance, an IC tag (201a) which operates in a band of 2.45GHz, and a reader/writer antenna, a length (L) of an antenna (203a) of the IC tag (201a), which is normally approximately 60mm, is shortened to approximately 5mm. A small reader/writer antenna (type [3]) having a size of, for instance, approximately a 1.2mm square, is used, corresponding to the shortened antenna length. By combining such small IC tag (201a) with a small reader/writer antenna, systems such as a system for controlling a small component by mounting the IC tag (201a) on the component, and a high resolution location detecting system for detecting the IC tag (201a) by the small reader/writer antenna by mounting the IC tag (201a) at high density can be provided.

Description

Specification

IC tag system

Technical field

[0001] The present invention relates to an IC tag system, and more particularly to a technology effective when applied to a passive IC tag system of 2.45 GHz band.

Background art

According to a study by the present inventor, the following technologies can be considered for the technology of the IC tag system.

[0003] The IC tag system is configured by a device called an IC tag and a reader / writer, for example. An IC tag refers to a small device equipped with a storage medium, wireless communication function and antenna. The IC tag is sometimes called a “wireless tag”, “electronic tag”, or “RFID (Radio Frequency Identification) tag”. For example, there are various shapes such as a coin type with a diameter of about 2 cm, a stick type with a length of about 5 cm, a label type and a card type with a cash card level.

[0004] Such an IC tag includes information in its storage medium. The information can be read wirelessly using a reader / writer. In recent years, for example, attempts have been made to perform process management using an IC tag in a product assembly process, or to manage products using an IC tag instead of a barcode.

[0005] By the way, IC tags are roughly classified into active types and passive types because of the difference in power supply method. Active type IC tags obtain the power required for operation by mounting batteries. On the other hand, a noisy IC tag does not have a battery or the like, and obtains power necessary for operation through wireless communication with a reader / writer. In other words, radio waves that are also sent by the reader / writer force are converted into electric power and used as radio wave energy that can be used only as a signal.

[0006] Note that the frequency band of radio waves used for communication between an IC tag and a reader / writer is determined by standards. One example is the 13.56MHz band using the electromagnetic induction system and the 2.45GHz band using the microwave system. Among them, the 2.45 GHz band standard is defined in ISO 18000-4, which is an international standard. 2.45 GHz band power Waves have a communication distance of, for example, about lm, which is longer than the 13.56 MHz band. Recently, there are also 950 MHz radio waves, which are divided into UHF bands, as frequency bands that can extend the communication distance to several meters.

Disclosure of the invention

Problems to be solved by the invention

[0007] By the way, as a result of the study of the present inventor by the technology of the IC tag system as described above, the following became clear.

[0008] For example, in the passive type IC tag system using the radio wave communication method such as the UHF band and the microwave band as described above, it is generally required that the communication distance between the reader / writer side antenna and the IC tag is long. It has been. This is nothing but the purpose of widening the spatial position where communication stability can be obtained and expanding the stable operation range of the system. For this reason, a general IC tag system generally uses a multi-element patch antenna with high gain on the reader / writer side. In addition, the antenna on the IC tag side is also sized appropriately for the wavelength of the radio wave used, and generally has a physical length of about half the wavelength.

[0009] When such a shape design with priority on communication distance is performed, it is difficult to reduce the size of the IC tag system. For example, a 2.45 GHz microwave band IC tag requires an antenna of about 5 cm to 6 cm, which is half the wavelength of about 12 cm. The corresponding antenna on the side of the reader / writer must be at least 10 cm in size.

[0010] However, if the size of the antenna is increased in this way, the spatial resolution for identifying the IC tag is decreased. That is, for example, when it is desired to use an IC tag as a position sensor, a spatial resolution of 5 cm to less than 6 cm cannot be realized.

Accordingly, an object of the present invention is to provide an IC tag system including a miniaturized IC tag and an IC tag detection means. Another object of the present invention is to provide an IC tag system capable of improving the spatial resolution when an IC tag is used as a position sensor.

[0012] The above and other objects and novel features of the present invention will be described and described in the present specification. It will become clear from the accompanying drawings.

Means for solving the problem

[0013] Among the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

[0014] An IC tag system according to the present invention includes an IC tag having an antenna and a reader / writer antenna for performing wireless communication with the IC tag. In this wireless communication, the UHF band (30 OMHz to 3GHz) or higher frequency band is used. The antenna of the IC tag is a dipole antenna with a length of 1Z6 or less of the wavelength corresponding to the frequency band to be used. The maximum size of the reader / writer antenna is also 1Z6 of this wavelength. The size is as follows.

[0015] IC tag systems with a frequency band above the UHF band are usually used to extend the communication distance. As a side effect, the antenna size of the IC tag and reader / writer increases, making it difficult to reduce the size. It has become. However, if the size of the antenna of the IC tag is made much smaller than the size that is normally said to be appropriate (1Z2 wavelength), the communication distance is sacrificed. It has been found that communication is possible by using a small size reader / writer antenna according to the size.

[0016] Therefore, by actively utilizing such a phenomenon, for example, a system including an IC tag and a reader / writer antenna reduced to about 1Z6 or less of the wavelength as described above is constructed. Thus, for example, a system that mounts IC tags on small parts and manages the parts, or mounts multiple IC tags on a certain object at high density, and uses this for reader / writers By detecting with an antenna, it is possible to realize a system that detects the position with high resolution.

In such a system, the antenna of the IC tag is desirably a so-called folded dipole antenna in which the two terminals are electrically connected by the antenna. Is preferably a so-called patch antenna that is a planar antenna. In addition, the size of the antenna of the IC tag or the size of the reader / writer antenna described above is preferably set to a wavelength of lZio or less in order to further reduce the size. In addition, the existing frequency band is 2.45 GHz band rather than 900 MHz band. Because the length is short, it can be downsized.

[0018] Further, when the IC tag system of the present invention is applied as a position detection system as described above, for example, each of a plurality of IC tags is mounted at a specific position of one detection target, and the detection target When the reader / writer antenna is arranged in the space near the object, the system is configured to specify the positional relationship between the detection target object and the reader / writer antenna. To identify this positional relationship, it is only necessary to determine which IC tag has responded to the reader / writer antenna.

In such a case, depending on the positional relationship between the plurality of IC tags and the reader / writer antenna, responses are made simultaneously from the plurality of IC tags to the reader / writer antenna, and individual IC tags cannot be identified. A situation is possible. Therefore, the IC tag system may be provided with a so-called congestion control function for receiving responses from such a plurality of IC tags and specifying the individual IC tags. This makes it possible to further increase the resolution of position detection.

[0020] In addition, when the frequency band of 45 GHz is used, the size of the reader / writer antenna is 2 cm or less based on the wavelength of 1Z6 or less. This size is almost the same as, for example, the sense of the size of a human finger. By installing this on the finger, a user-friendly palpation type position detection system can be realized. It is more desirable to further reduce this size to a wavelength of 1Z10 or less and 1.2 cm or less.

The invention's effect

[0021] An effect obtained by a representative one of the inventions disclosed in the present application will be briefly described. The IC tag is downsized, and a small reader / writer antenna serving as a detection means for the IC tag is provided. An IC tag system can be realized. In addition, when an IC tag is used as a position sensor, it is possible to improve spatial resolution due to its miniaturization.

Brief Description of Drawings

FIG. 1 is a schematic diagram showing an example of the configuration of an IC tag system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of the outer shape of the IC tag in the IC tag system of FIG.

, (A), and (b) show different types of IC tags.

[Fig. 3] Reader / writer used in the experiment related to the present invention in the IC tag system of Fig. 1 FIG. 3 is a schematic diagram showing the outer shape of a general antenna, and (a) to (c) show three types of shapes each having a different size.

[FIG. 4] A table showing the results of estimating the electric field strength for each of the three types of antennas in FIG.

[FIG. 5] shows the result of measuring the communication distance using the antenna of FIG. 3 while changing the size of the IC tag of FIG. 2 (a). (A) is used for the experiment. An explanatory diagram of the IC tag, (b) is a table summarizing the experimental results.

FIG. 6 is a graph showing the experimental results of FIG. 5 (b).

[Fig. 7] shows an example of the configuration when the IC tag system of Fig. 1 is applied as a position detection system. (A) is a diagram showing an installation example of a reader / writer antenna, and (b) is ( FIG. 2 is a schematic diagram showing a configuration example of a reader / writer antenna in a).

FIG. 8 is a diagram showing an installation example of an IC tag when the IC tag system of FIG. 1 is applied as a position detection system.

FIG. 9 is a process flow diagram for explaining an example of a congestion control function provided in the IC tag and reader / writer in the IC tag system of FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

FIG. 1 is a schematic diagram showing an example of the configuration of an IC tag system according to an embodiment of the present invention. The IC tag system shown in FIG. 1 includes, for example, an IC tag 101, a reader / writer 103 and an antenna 102 provided therein, a control computer 104, and a database system 105. The IC tag 101 includes, for example, a power circuit, a storage medium, a communication circuit, an antenna, and the like (not shown) inside, and wireless communication with the reader / writer 103 is possible via this antenna. In addition, in FIG. 1, a force indicating one IC tag 101 In practice, there are a plurality of IC tags.

The reader / writer 103 receives control from the control computer 104 and performs wireless communication with the IC tag 101 via the antenna 102. That is, for example, from the control computer 104 The sent command (command) is received via the network, the signal corresponding to the command is sent from the antenna 102 to the IC tag 101, and the reply from the IC tag 101 is received by the antenna 103, and the received signal And the like, and the like. The communication range 106 between the antenna 102 of the reader / writer 103 and the IC tag 101 is almost determined by the relative positional relationship between them.

[0026] The control computer 104 executes, for example, an application program, and controls the command of the reader / writer 103 based on the application program, or performs information management for the purpose of the system using an internal database. Or In some cases, a database system 105 connected via a network may be constructed above the control computer 104.

[0027] In such an IC tag system, the feature of the present invention is that the size of the IC tag 101 (antenna included in the IC tag) and the size of the antenna 102 of the reader / writer 103 are intentionally reduced. The purpose is to increase the spatial resolution of the tag 101. In other words, it does not focus on extending the communication distance, but conversely increases the spatial resolution at the expense of the communication distance. In this way, for example, the IC tag 101 is used as a position sensor to construct a position detection system with high spatial resolution. However, if the size of the IC tag 101 is reduced in this way, it is expected that the communication performance will be greatly reduced and in some cases communication will be impossible. It is not easy. Therefore, the present inventors have determined the size through experiments and the like. In the following, we will explain the results of these experiments.

FIG. 2 is a schematic diagram showing an example of the external shape of the IC tag system in the IC tag system of FIG. 1, and (a) and (b) show different types of IC tags, respectively. . The IC tags 201a and 201b shown in FIGS. 2 (a) and 2 (b) are so-called inlets, and such an inlet force is packaged in a shape such as a stick type or a card type as described above. In the present invention, the shape of the IC tag is not particularly limited, and may be in a knocked state or an inlet state. In this section, we will describe an example of a passive IC tag that operates in the 2.45 GHz band and can be made smaller than the active type.

[0029] The IC tag 201a shown in FIG. 2 (a) has an IC chip 202a and an antenna on an antenna material 204a, for example. The tena part 203a is mounted, and the IC chip 202a and the antenna part 203a are both connected by the connection part 205a. The IC chip 202a is a chip in which various circuits for realizing wireless communication are integrated on a single semiconductor substrate having, for example, silicon. Specifically, for example, a power supply circuit that rectifies a carrier such as a reader / writer and generates a power supply voltage, a communication circuit including a modulation circuit and a demodulation circuit, a ROM or a non-volatile RAM, an IC, It is also composed of a storage medium that stores unique IDs that are different for each tag. The IC chip 202a includes two terminals connected to the antenna unit 203a. In recent years, the size of the IC chip 202a can be realized, for example, with a size of lmm square or less.

[0030] The antenna material 204a can be formed from a wide range of resins, for example, from high-performance resins represented by polyimide to general-purpose resins such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate). It is. Actually, it is preferable that the production as a film material is industrially stable. Here, Upilex (R) which is a polyimide-based resin film is used.

[0031] The antenna unit 203a is generally made of a metal material such as copper or aluminum. However, methods such as conductive paint and conductive ink printing are also applicable. Here, copper oil is used, and this is bonded to the antenna material 204a via an adhesive layer. In addition, the surface of the antenna portion 203a after the bonding is subjected to Su plating, thereby forming a base for making an alloy connection with the IC chip 202a and an antenna exposed to the air. Two functions of surface protection of metal parts are realized at the same time.

Note that various methods can be used for electrical connection between the IC chip 202a and the antenna portion 203a. For example, metal alloy methods such as solder bonding and An—Sn alloy bonding, wire bonding methods that use ultrasonic energy and metal wires, and direct US that directly bumps the bumps on the chip to the antenna part 203a using ultrasonic waves. Examples include a bonding method and a thermocompression bonding method using an anisotropic conductive material composed of a mixture of a conductive material and an insulating material. Here, heating is performed in a state where the gold bumps formed on the IC chip 202a and the Su plating on the surface of the copper wiring as the antenna 203a electrode are mechanically pressed to form an Au—Sn alloy and bonded. The method to obtain

[0033] The antenna unit 203a in Fig. 2 (a) is a 1Z2 wavelength dipole antenna. Among them, a so-called folded type or a held type is adopted. That is, the two terminals of the IC chip 202a are connected via the antenna 203a. The size of the IC tag 201a in the long side direction depends on the size of the antenna 203a suitable for the 2.45 GHz band (usually about 5 cm to 6 cm) and is about 6 cm to 7 cm. Further, the size of the IC tag 201a in the short side direction is about 5 mm. The details will be described later. In the present invention, the size of the IC tag 201a in the long side direction is reduced to a minimum of about 5 mm.

[0034] Similarly to FIG. 2 (a), the IC tag 20 lb shown in FIG. 2 (b) has the IC chip 202b and the antenna portion 203b mounted on the antenna material 204b, and the IC chip 202b and the antenna portion 203b are Both are connected by the connecting part 2 05b. In this IC tag 201b, unlike FIG. 2 (a), the antenna section 203b is a normal 1Z2 wavelength dipole type. That is, the antenna portion 203b is separated into two antennas extending in opposite directions, and the other Z is connected to one end Z the other end of the IC chip 202b.

Next, the contents of an experiment in which the IC tag size and the reader / writer antenna size are determined using such an IC tag system will be described. In this experiment, for example, it is assumed to realize a system in which a plurality of IC tags are arranged at different specific positions, and the IC tags are detected and specified by the reader / writer antenna. Therefore, it is desirable to make the size of the IC tag as small as possible in order to perform position detection with high resolution. Therefore, we conducted an experiment to reduce the size of the IC tag and measure the readable communication distance using three types of reader / writer antennas.

[0036] Fig. 3 is a schematic diagram showing the outer shape of the reader / writer antenna used in the experiment related to the present invention in the IC tag system of Fig. 1. Each of (a) to (c) shows the size of each antenna. Three different shapes are shown. The reader / writer antenna 302a shown in Fig. 3 (a) uses a circularly polarized wave system and is a noch type antenna composed of four patches, with a gain of 14.0 dBi, VSWR power of 5, and size of It is 200mm square. The reader / writer antenna 302b shown in Fig. 3 (b) is a circular antenna that uses a circularly polarized wave system and consists of one patch, and has a gain of 5.5 dBi, a VSWR force of 5, and a size of 72 mm. It is a horn. Figure 3 (b) The antenna 302b shown is one of the four patches in the antenna 302a shown in FIG. 3 (a).

[0037] The antenna 302c shown in Fig. 3 (c) is a 1Z2 wavelength operation type, patch-type antenna using ceramic as a dielectric, gain of 2. OdBi, VSWR of 3.0, and size of 12mm. It is a horn. Hereinafter, the antenna 302a shown in FIG. 3 (a) is classified as type [1], the antenna 302b shown in FIG. 3 (b) is classified as type [2], and the antenna 302c shown in FIG. 3 (c) is classified as type [3]. . The size of the antenna is type [1]> type [2]> type [3], and the relationship of gain characteristics is also type [1]> type [2]> type [3].

[0038] It should be noted that the patch antenna generally refers to a planar antenna in which a conductor plate is placed on a dielectric substrate and the other surface is a ground plate (conductor plate). In general, the main radiation surface has directivity, so that it is easy to obtain high gain. On the other hand, the dipole antenna described above refers to an antenna having a configuration in which two conductor elements are arranged in a straight line. In addition, the case where a half wavelength is used as the length of the two conductor elements arranged in a straight line is widely known. However, there are several other configurations for dipole antennas, and the folded configuration shown in Fig. 2 (a) is a type of dipole antenna. VSWR (Voltage Standing Wave Ratio) is the voltage standing wave ratio, and is an index that indicates how much power supplied to the antenna is radiated without being reflected. When VSWR is 1.5, 96% of the power supplied to the antenna is radiated, and when 3.0, 75% is radiated.

FIG. 4 is a table showing the results of estimating the electric field strengths for the three types of antennas in FIG. As shown in Fig. 4, the antenna 302a of type [1] includes four circular radiating parts, and the area of the radiating part is 5024 mm ² (the radiating part is circular). Further, when the supply lOOmW to § antenna 302a, the 96% is radiated, by dividing this by radiating section side product, the effective electric field strength near the antenna becomes 0. 019mWZmm ^2. Similarly, the antenna 302b of type [2] has a radiation area of 1256 mm ² and an effective electric field strength of 0.076 mWZmm ² . In addition, the antenna 302c of type [3] has a radiation area of 144 mm ² , and when lOOmW is supplied to the antenna 302 c, 75% of it is radiated, so the effective electric field strength is 0.521 mWZmm ² . Become. Therefore, each antenna Comparing the radiant energy density of each species, it is as follows: Type [1]: Type [2]: Type [3] = 1. 0: 4. 0: 27.3.

[0040] Fig. 5 shows the result of measurement of the communication distance using the antenna of Fig. 3 while changing the size of the IC tag of Fig. 2 (a). (A) An explanatory diagram of the IC tag used, (b) is a table summarizing the experimental results. FIG. 6 is a graph showing the experimental results of FIG. 5 (b). As shown in Fig. 5 (a), in this experiment, the IC tag 201a provided with the folded dipole antenna shown in Fig. 2 (a) was left by cutting both ends in the long side direction. Create IC tags 201a with different levels in the middle (length) L. Note that the size L of the IC tag 201a is approximately equal to the size (length) of the antenna 203a. In this experiment, an IC tag 20 la having seven types of length L (54 mm, 42 mm, 35 mm, 27 mm, 19 mm, 14 mm, 5 mm) is created.

[0041] When the communication distance (reading distance) is measured for the plurality of IC tags 201a having different sizes using the reader / writer antenna of types [1] to [3] described above, The result is shown in Fig. 5 (b). FIG. 6 is a graph of the results of FIG. 5 (b), with the horizontal axis representing the length (mm) of the IC tag 201a and the vertical axis representing the communication distance (mm). In FIG. 6, the vertical axis is the log scale, and the result 601 of type [1], the result 602 of type [2], and the result 6003 of type [3] are plotted.

[0042] From these experimental results, it can be seen that as the IC tag 201a is shortened, only a combination with a small reader / writer antenna is a necessary condition for establishing communication. In other words, in the type [1] with the largest antenna size, communication is impossible when the length L of the IC tag 201a (antenna 203a) is 27 mm or less, while the antenna size is the smallest! / And type [3] If used, communication is possible even if the length L of the IC tag 201a is 5 mm. However, in this case, the communication distance is 7 mm, but depending on the use of the position detection system, this communication distance may be sufficient. Although not shown in the figure, when the length L of the IC tag 201a is set to 4 mm or the like, it has been observed that communication is impossible. The above phenomenon can be explained, for example, as follows.

[0043] First, since the power supplied from the reader / writer 103 to the antenna 102 is constant, if the area of the radio wave radiation surface of the antenna 102 is reduced, as shown in FIG. Electric field strength (energy density) can be increased. On the other hand, as the IC tag 201a is reduced in length, communication sensitivity is reduced due to differences in tuning frequency, reception area, etc. It becomes like. Therefore, it is considered that the sensitivity reduction phenomenon of the IC tag 201a caused by the reduction of the length of the IC tag 201a is complemented by the device 102 of the reader / writer side (the improvement of the radio wave intensity by the miniaturization of the radio wave radiation part). It is done.

From another point of view, the combination of a small IC tag antenna and a small reader / writer antenna has a limited range of communication compared to the ideal case. It is considered that the communication range is narrowed together with this. However, when such a phenomenon is actively used, the spatial resolution can be improved.

[0045] As described above, since it has been found that it is effective to combine a small and small reader / writer antenna with respect to an IC tag, a position detection system desirable in practical use can be constructed. In other words, for example, an IC tag can be installed on an object with a certain degree of unevenness, and a reader / writer antenna can be installed on a finger or the like, for example, and a position can be detected with a sense of palpation. An example of such a position detection system will be described below.

FIG. 7 shows an example of a configuration when the IC tag system of FIG. 1 is applied as a position detection system. (A) is a diagram showing an installation example of a reader / writer antenna. ) Is a schematic diagram showing a configuration example of the reader / writer antenna in (a). FIG. 8 is a diagram showing an installation example of an IC tag when the IC tag system of FIG. 1 is applied as a position detection system.

[0047] As shown in FIG. 7 (a), for example, the small antenna unit 702 using the 12 mm square reader / writer antenna of the above-mentioned type [3] is mounted on the tip of the index finger in the glove 701. The An antenna cable 703 is drawn out from the small antenna unit 702 using the antenna of type [3], and this antenna cable 703 passes through the glove 703 and is connected to the reader / writer 103 and the like. In addition, in the small antenna unit 702 using the antenna of type [3], as shown in FIG. 7 (b), the ceramic antenna element 704 is mounted on the ground plane 705, and the ceramic antenna element 704 is connected to the antenna cable 703. Against The electrical connection is made. The ground plane 705 is formed of, for example, a thin metal plate or a metal mesh, and enhances wearability to human fingers. Here, a copper plate is used as the ground plane 705. As described above, by using the ceramic antenna element 704 having a size of about 12 mm square, it is possible to substantially match the sense of the size of a human finger, and the usability as a position detection system is improved.

On the other hand, the IC tag is mounted at a specific position on the rock surface as shown in FIG. 8, for example. In FIG. 8, for example, an IC tag 802 having a length Ll = 8 mm, an IC tag 803 having a length L2 = 12 mm, and an IC tag 804 having a length L3 = 14 mm are arranged on a rock 801. . The width of the IC tags 802 to 804 is about 5 mm, for example, and the arrangement interval between the IC tags is 4 mm, for example. Since there is unevenness on the surface of the rock 801, communication between the small antenna portion 702 and the IC tags 802 to 804 needs to be able to be performed without being completely adhered. For example, in the case of rock 801 or the like, if the communication distance is about 1 cm, it is sufficient to satisfy this condition by using an IC tag of 8 mm or more based on the experimental results in FIG.

[0049] Using the position detection system as described above, when the finger on which the small antenna 702 for reader / writer is installed is moved on the surface of the rock 801, the rock 801 and the finger are detected depending on whether or not each IC tag is detected. It becomes possible to recognize the positional relationship. It should be noted that the position detection system as shown in FIGS. 7 and 8 has been confirmed to operate normally by experiments of the present inventors. Therefore, in contrast to the conventional technique that only a spatial resolution exceeding 5 cm can be obtained, by using the present invention, for example, when 8 mm IC tags are spread at small intervals, practically, lcm to 2 cm The position can be detected with a spatial resolution of.

[0050] It should be noted that here, the power shown in the example of mounting an IC tag on a rock, and other various objects that are prone to communication obstruction, such as plastic bottles with water, milk cartons, etc. Even when mounted, normal operation has been confirmed. In other words, because the spatial resolution is intentionally narrowed, conversely, communication obstruction occurs. Thus, according to the present invention, a position detection system with high spatial resolution can be realized while targeting various materials.

[0051] Furthermore, the present invention is not limited to the position detection system, and can be applied as a management system for small parts such as 1 cm to 2 cm, for example. In other words, IC This system implements component management by mounting a tag, storing the management information of the component in this IC tag, and reading it with a small reader / writer antenna. Of course, in this case, it is also possible to deal with various objects that are prone to communication obstruction. However, such an IC tag system has a short communication distance.

"Or, it becomes a system close to palpation-type movements such as" reading information from a wireless tag at a location touched by a fingertip ".

[0052] By the way, in the IC tag system as shown in FIG. 7 and FIG. 8, for example, when the reader / writer antenna is positioned between the IC tags where the distance between the IC tags is narrow, a plurality of IC tag forces are also present. A reply may be made toward the reader / writer antenna. In such a case, for example, the IC tags may be distinguished using congestion control as shown in FIG.

FIG. 9 is a process flow diagram for explaining an example of the congestion control function provided in the IC tag and reader / writer in the IC tag system of FIG. Here, a general processing flow of congestion control taking the international standard IS018 000-4 as an example will be described. Congestion control is a method that recognizes each IC tag by preventing interference of radio waves reflected by multiple IC tag forces when the reader / writer force recognizes multiple IC tags. For this recognition method, several methods are generally known. Here, a method using random numbers is used. In this case, each IC tag is equipped with a 1-bit random number generator for congestion and a counter for congestion. The following description is based on FIG. 9 assuming that there is a reader / writer 103 and two IC tags 101 (tag A and tag B) arranged in close proximity.

First, the reader / writer 103 issues a congestion command for inquiring about a unique ID that differs for each IC tag to the IC tag 101 (tag A, tag B) (S903). In this example, the tag A responds to the unique ID [A] and the tag B responds to the congestion command with the unique ID [B] (S904, S905). Then, since tag A and tag B respond at the same timing, a collision of reply data occurs. Therefore, the reader / writer 103 issues an indistinguishable command to notify each tag that the unique ID cannot be recognized because a plurality of tags have responded all at once (S906).

[0055] Tag A and tag B that have received the indistinguishable command internally generate a 1-bit random number for congestion, and decide whether to retransmit the unique ID or no response depending on the value. For example, tag A The unique ID [A] is retransmitted because the 1-bit random number for congestion is “0”, and tag B becomes no response because the 1-bit random number for congestion is “1” (S907). At this time, if both the 1-bit random numbers for congestion of tag A and tag B become '0', a reply data collision will occur again, so an indistinguishable command should be issued again. become. That is, the reader / writer 103 repeatedly issues an indistinguishable command until there is one response tag.

[0056] Tag B that has made no response in S907 updates the value of the congestion counter that counts the number of times of no response to an indistinguishable command provided in the tag by one. On the other hand, the reader / writer 103 can recognize the unique ID [A] when only the tag A responds. Therefore, the reader / writer 103 accesses the identified tag A and performs processing for removing the tag A from congestion control (S908). As a result, tag A stops responding in subsequent congestion control.

Subsequently, the reader / writer 103 issues an identification success command to an unidentified tag (S910). Then, the IC tag that has received the identification success command updates the congestion counter by 11, and as a result, the tag having the counter value power replies to the reader / writer 103. Here, the unidentified tag is tag B, and tag B that has received the identification success command has a value of 0 when the congestion counter is updated by 11. Therefore, a unique ID [B ] Is returned (S911). In this way, the reader / writer 103 can recognize the unique IDs of a plurality of IC tags one by one by repeating the indistinguishable command and the successful identification command.

[0058] By providing the congestion control function as described above, for example, it is possible to identify that the position of the finger is between a specific IC tag, and not only the position above the IC tag but also the IC tag's position. Since the sky position in between can be identified, the spatial resolution can be further enhanced. Note that the congestion control method is not limited to the method using random numbers as described in FIG. 9, and it is of course possible to use the generally known method V.

[0059] As described above, the IC tag system according to the present invention can be summarized as follows.

It can be said that it has the features (1) and (2).

(1) First, the IC tag system according to the present invention uses a frequency band of UHF (usually 300 MHz to 3 GHz) or more, and preferably uses a frequency band of 2.45 GHz or more. In such an IC tag system, the length of the antenna of the IC tag is 1Z6 or less, preferably 1Z10 or less, of the wavelength of the frequency band to be used. Also, the reader / writer The antenna has a size less than or equal to the size of this IC tag. Specifically, the maximum size of the outer shape is 1Z6 or less of the wavelength of the frequency band to be used, preferably lZio or less. The maximum dimension referred to here means, for example, the long side dimension when the outer shape of the antenna is square, and the diameter dimension when the shape is circular. Further, the antenna of the IC tag is a dipole antenna, and preferably a folded dipole antenna. On the other hand, the antenna of the reader / writer is preferably a patch type antenna.

[0061] For example, in the case of the 2.45 GHz band, such a feature is that the antenna length of the IC tag is 2 cm or less (preferably 1.2 cm or less), and the maximum dimensional force of the reader / writer antenna is equal to this. The size is below the level (at least 2 cm). In other words, when verified and inferred from the experimental results in Fig. 5, the antenna of type [2] (maximum dimension: 7.2 cm) is too large to communicate with an IC tag with such a size, A small level antenna is required. The antenna of type [2] can communicate up to a 2.7 cm IC tag, and the antenna of type [3] (maximum size 1.2 cm) can communicate with a 5 mm IC tag. The reader / writer antenna is considered to be able to sufficiently communicate with an IC tag of 2 cm or less.

[0062] Furthermore, since the same communication method is used in an IC tag system using the UHF band (microwave band) or higher, it is considered that the same characteristics can be applied. The higher the frequency band, the shorter the antenna length. In the existing case, the 2.45 GHz band is preferable to the 900 MHz band. The IC tag is desirably a passive type that can be reduced in size.

[0063] (2) Next, as an example of a practical form of an IC tag system having the characteristics as described in (1), for example, as described in FIG. One example is a position detection system that detects IC tags by spatial scanning of a reader / writer antenna. In such a position detection system, the arrangement relationship between the reader / writer antenna and the IC tag may be exchanged. As an example of another practical form, an IC tag storing management information corresponding to a minute detection target is installed, and this management information is read by a small reader / writer antenna. Management of minute detection objects Management system that performs

[0064] While the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. There's nothing wrong!

[0065] For example, FIG. 7 shows an example in which an antenna is mounted on a glove. Of course, any function that can hold an antenna, such as a band-fixing bisack or a ring type, can be substituted. Furthermore, although the antenna is attached to the index finger part of the glove, it is natural that other fingertips may not be used. Further, although an example in which one reader / writer antenna is used has been described, position detection may be performed using a plurality of antennas. In this case, it becomes possible to detect a relative moving complex vector that is more precise and highly utilized. Moreover, it can be used as a means for grasping position information with respect to a target object or a target object without using a person, for example, as a palpation sensor of a robot.

[0066] Further, for example, by mounting IC tags at a plurality of specific positions on the surface of an object and arranging a plurality of reader / writer antennas at a plurality of specific positions around the object, the orientation Z of the object A position detection system that detects a state such as an angle can also be realized.

Industrial applicability

[0067] The IC tag system of the present invention is a technology that is particularly useful when applied as a position detection system that combines a small IC tag using a 45 GHz band and a small reader / writer antenna. It can be widely applied to parts management systems for small parts and systems that require a small IC tag using the UHF band or higher.

Claims

The scope of the claims

[1] An IC tag system including an IC tag having an antenna and a reader / writer antenna for performing wireless communication with the IC tag, and using a frequency band higher than the UHF band for the wireless communication. And

The antenna of the IC tag is

A dipole antenna,

It has a length of 1Z6 or less of the wavelength corresponding to the frequency band to be used,

The IC tag system according to claim 1, wherein the maximum size of the outer shape of the reader / writer antenna is 1Z6 or less of a wavelength corresponding to the frequency band to be used.

[2] In the IC tag system according to claim 1,

The antenna of the IC tag is a folded dipole antenna,

The reader / writer antenna is a patch antenna, and is an IC tada system.

[3] In the IC tag system according to claim 1,

The IC tag system, wherein the antenna of the IC tag has a length of 1Z10 or less of a wavelength corresponding to the frequency band to be used.

[4] In the IC tag system according to claim 1,

The IC tag system according to claim 1, wherein the maximum size of the outer shape of the reader / writer antenna is 1Z10 or less of a wavelength corresponding to the frequency band to be used.

[5] The IC tag system according to claim 1,

The frequency band to be used is an IC tag system characterized by 2.45 GHz band.

[6] including a plurality of IC tags each having an antenna and a reader / writer antenna for performing wireless communication with the plurality of IC tags, and using a frequency band equal to or higher than the UHF band for the wireless communication IC tag system,

Each of the plurality of IC tags is mounted at a specific position of one detection object, and the antennas of the plurality of IC tags are

A dipole antenna,

It has a length of 1Z6 or less of the wavelength corresponding to the frequency band to be used, The maximum dimension of the outer shape of the reader / writer antenna is 1Z6 or less of the wavelength corresponding to the frequency band to be used.

When the reader / writer antenna is arranged in the space near the detection object, the positional relationship between the detection object and the reader / writer antenna is specified by detecting the presence / absence of responses from the plurality of IC tags. IC tag system characterized by

[7] In the IC tag system according to claim 6,

The antenna of the plurality of IC tags is a folded dipole antenna, and the reader / writer antenna is a patch antenna.

[8] In the IC tag system according to claim 6,

The IC tag system has a congestion control function.

[9] In the IC tag system according to claim 7,

The antennas of the plurality of IC tags have a length of 1Z10 or less of a wavelength corresponding to the frequency band to be used,

[10] In the IC tag system according to claim 7,

The frequency band used is 2.45 GHz band,

The IC tag system, wherein the reader / writer antenna is installed on a human finger.

[11] An IC tag system including an IC tag having an antenna and a reader / writer antenna for performing wireless communication with the IC tag, and using a frequency band higher than the UHF band for the wireless communication. And

An IC tag system characterized in that both the IC tag and the reader / writer antenna are miniaturized, and wireless communication between the IC tag and the reader / writer antenna is always performed with a short communication distance.