Communication device and communication method

The present invention relates to a communication device provided with an RFID tag that performs radio wave communication with a predetermined device, and more particularly to a communication device and a communication method capable of easily and efficiently controlling the distance and directivity of radio wave communication. ..

In recent years, RFID (Radio Frequency Identification) tags have been commercialized, and RFID tags are gradually becoming widespread in the field of logistics and the like. Then, a system for managing goods stored in a warehouse or the like has been devised using this RFID tag (see, for example, Patent Document 1).

RFID tags, also called IC tags, store various data and perform radio wave communication with readers and writers that read and write data on RFID tags.

The range of distance that the RFID tag can communicate with the reader / writer and the directivity of the communication radio wave differ depending on changes in conditions such as the output of the RFID tag's radio wave, the size of the antenna, the winding method, and the shape.

That is, when it is desired to communicate with a reader / writer farther away, or when it is desired to adjust the directivity of the communication radio wave, the RFID tag may be replaced with an RFID tag suitable for each condition.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2000-113077</text></patcit>

<p> However, the above-mentioned conventional technology has a problem that it is difficult to promptly respond to the request when it is desired to control the distance and directivity of radio wave communication at the introduction site where the RFID tag is introduced.</p><p> Specifically, at the site where RFID tags are introduced, there are factors that disturb radio wave communication such as metal and moisture, so in order to stabilize radio wave communication, the distance and directivity of radio wave communication should be adjusted to the situation at the site. It needs to be adjusted accordingly.</p><p> However, when trying to change the distance or directivity of radio wave communication, it is necessary to replace it with an RFID tag that meets the desired conditions, and several types of RFID tags must be prepared in advance.</p><p> Therefore, it is important how easy and efficient it is to control the distance and directivity of radio communication without performing complicated work such as exchanging RFID tags at the installation site where RFID tags are installed. It has become a problem.</p><p> The present invention has been made to solve the above-mentioned problems caused by the prior art and to solve the above-mentioned problems, and is a communication device capable of easily and efficiently controlling the distance and directivity of radio wave communication. The purpose is to provide a communication method.</p>

<p> In order to solve the above-mentioned problems and achieve the object, the present invention is a communication device provided with an RFID tag that performs radio communication with a predetermined device, and is a metal body, and the RFID tag and the metal body. The metal body is interchangeable with another metal body, and the distance adjusting means is such that the metal body is exchanged with another metal body. In this case, the distance between the exchanged metal body and the RFID tag can be adjusted.</p><p> Further, the present invention is a communication device provided with an RFID tag that performs radio wave communication with a predetermined device, and is a distance adjustment capable of adjusting the distance between the metal body and the RFID tag and the metal body. The distance adjusting means is a screw, and the distance between the RFID tag and the metal body can be adjusted by tightening or adjusting the screw.</p><p> Further, the present invention is characterized in that, in the above invention, the distance adjusting means invalidates the communication function of the RFID tag by bringing the RFID tag into contact with a metal body.</p><p> Further, in the present invention, in the above invention, the distance adjusting means is a non-metal body, and the distance between the RFID tag and the metal body is fixed by fixing the RFID tag and the metal body at a certain distance. Is characterized by being adjustable.</p><p> Further, the present invention is a communication method in which an RFID tag performs radio wave communication with a predetermined device, and the distance between the RFID tag and the metal body is adjusted by using an adjusting unit for adjusting the distance. After the adjustment is performed, the RFID tag executes radio wave communication with a predetermined device.</p>

<p> According to the present invention, since the distance between the RFID tag and the metal body can be adjusted, it is possible to easily and efficiently control the distance and directivity of radio wave communication.</p><p> Further, according to the present invention, the metal body can be exchanged with another metal body, and when the metal body is exchanged with another metal body, the distance between the exchanged metal body and the RFID tag can be determined. Since it is made adjustable, by replacing the attached metal body with a metal body with a different shape, it is possible to easily and efficiently control the distance and directionality of radio communication. ..</p><p> Further, according to the present invention, since the distance between the RFID tag and the metal body is adjusted by tightening the screw, the distance and directivity of radio wave communication can be easily and efficiently controlled on the spot. It has the effect of being able to.</p><p> Further, according to the present invention, the communication function of the RFID tag is invalidated by bringing the RFID tag into contact with the metal body. Therefore, when it is desired to invalidate the function of the RFID tag, it can be done on the spot. It has the effect of being easy to carry out.</p><p> Further, according to the present invention, the non-metal body makes it possible to adjust the distance between the RFID tag and the metal body by fixing the RFID tag and the metal body at a certain distance. It has the effect of being able to easily and efficiently control the distance and directivity of radio communication.</p><p> Further, according to the present invention, after adjusting the distance using an adjusting unit that can adjust the distance between the RFID tag and the metal body, the RFID tag executes radio wave communication with a predetermined device. Therefore, it is possible to easily and efficiently control the distance and directivity of radio wave communication to perform radio wave communication.</p>

Hereinafter, examples of the communication device according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

First, the communication device according to the first embodiment will be described. FIG. 1 is a diagram illustrating a communication device 10 according to a first embodiment. As shown in FIG. 1, the communication device 10 includes an RFID tag 11, an insulator 12, a metal plate 13, a distance adjusting screw 14, and a spring 15.

The RFID tag 11 is a tag that stores various data in a built-in memory and performs radio wave communication with a reader / writer that reads or writes data to the RFID tag.

The insulator 12 is an insulator such as plastic that holds the RFID tag 11. The metal plate 13 is a conductive metal plate, for example, a metal plate formed of a material such as aluminum, copper, iron, or stainless steel.

The distance adjusting screw 14 is a screw that enables the distance between the RFID tag 11 and the metal plate 13 to be adjusted by tightening or adjusting. The spring 15 is a spring that widens the distance between the insulator 12 and the metal plate 13 until it is fixed by the distance adjusting screw 14.

The metal plate 13 can be easily removed by loosening the distance adjusting screw 14, and the metal plate 13 can be replaced with a metal plate having a different shape or material. FIG. 1 shows replacement metal plates 16a to 16c having a width different from that of the metal plate 13.

FIG. 2 is a diagram showing the effect of the distance between the RFID tag 11 and the metal plate 13 on the maximum communication distance between the RFID tag 11 and the reader / writer. Here, the case where the material of the metal plate 13 is aluminum and the frequency band of the communication radio wave is the UHF (Ultra-High Frequency) band is shown.

The vertical axis of FIG. 2 is the maximum communication distance of the RFID tag 11, and the horizontal axis is the distance between the RFID tag 11 and the metal plate 13. And FIG. 2 shows the case of two metal plates 13 of different widths (3 cm, 5 cm) made of aluminum.

As shown in FIG. 2, it can be seen that the maximum communication distance increases as the distance between the RFID tag 11 and the metal plate 13 increases in the metal plate 13 of any width. Further, when the distance between the RFID tag 11 and the metal plate 13 is the same, the maximum communication distance of the metal plate 13 having a width of 3 cm is larger.

Further, when the distance between the RFID tag 11 and the metal plate 13 is 0, that is, when the RFID tag 11 and the metal plate 13 are in contact with each other, the maximum communication distance is 0, and the communication of the RFID tag 11 The function is disabled.

The maximum communication distance of the RFID tag 11 without the metal plate 13 was 250 cm. Therefore, it can be seen that the maximum communication distance can be increased or decreased by adjusting the distance between the RFID tag 11 and the metal plate 13.

FIG. 3 is a diagram showing the effect of the width of the metal plates 20a and 20b on the directivity of radio wave communication between the RFID tag 21 and the reader / writer 22a to 22e and 23a to 23e.

FIG. 3 shows metal plates 20a and 20b having different widths, which are installed at a predetermined distance from the RFID tag 21 by using the distance adjusting screw 14. Here, the reader / writer 22a to 22e and 23a to 23e are devices having a built-in antenna and performing radio wave communication with the RFID tag 21.

As shown in FIG. 3, when a narrow metal plate 20a is installed, the range in which communication radio waves are shielded by the metal plate 20a is narrowed, so that communication is performed between the RFID tag 21 and the reader / writer 22a to 22e. The possible angles are greater.

On the other hand, when a wide metal plate 20b is installed, the range in which communication radio waves are blocked by the metal plate 20b is widened, so the angle at which communication is possible between the RFID tag 21 and the reader / writer 22a to 22e is It becomes smaller.

In this way, by installing the metal plates 20a and 20b having different widths with respect to the RFID tag 21 by a predetermined distance, the radio wave communication between the RFID tag 21 and the reader / writer 22a to 22e, 23a to 23e The directivity of can be adjusted.

As described above, in the first embodiment, since the distance between the RFID tag 11 and the metal plate 13 can be adjusted, the distance and directivity of radio wave communication can be easily and efficiently controlled. Can be done.

Further, in the first embodiment, the metal plate 13 can be replaced with another metal body, and when the metal plate 13 is replaced with the replacement metal plates 16a to 16c, the replaced metal body and the RFID tag Since it was decided that the distance between the metal plate 13 and the metal plate 13 could be adjusted, the distance and directionality of radio communication could be facilitated by replacing the attached metal plate 13 with replacement metal plates 16a to 16c having different shapes. And it can be controlled efficiently.

Further, in the first embodiment, since the distance between the RFID tag 11 and the metal plate 13 is adjusted by tightening or adjusting the distance adjusting screw 14, the distance and directivity of radio wave communication can be easily adjusted on the spot. It can be controlled efficiently.

Further, in the first embodiment, the communication function of the RFID tag 11 is invalidated by bringing the RFID tag 11 into contact with the metal plate 13. Therefore, when it is desired to invalidate the function of the RFID tag 11, it is determined. Can be easily executed on the spot.

Further, in the first embodiment, after the distance is adjusted by the distance adjusting screw 14 for adjusting the distance between the RFID tag 11 and the metal plate 13, radio communication is performed with the reader / writer. Therefore, it is possible to easily and efficiently control the distance and directivity of radio wave communication to perform radio wave communication.

By the way, in the first embodiment, the distance between the RFID tag 11 and the metal plate 13 is adjusted by tightening the distance adjusting screw 14, but the RFID tag and the metal plate have a predetermined thickness. The distance between the RFID tag and the metal plate may be adjusted by attaching the RFID tag via a spacer.

Therefore, in the second embodiment, a case where the RFID tag and the metal plate are attached via a spacer having a predetermined thickness will be described.

First, the communication device according to the second embodiment will be described. FIG. 4 is a diagram illustrating the communication device 30 according to the second embodiment. FIG. 4 shows a plan view and a side view of the communication device 30.

As shown in FIG. 4, the communication device 30 includes an RFID tag 31, a metal plate 32, and a spacer 33.

The RFID tag 31 is a tag that stores various data in the built-in memory and performs radio wave communication with a reader / writer that reads or writes data to the RFID tag.

The metal plate 32 is a conductive metal plate, for example, a metal plate formed of a material such as aluminum, copper, iron, or stainless steel.

The spacer 33 is a non-conductive non-metal body made of a material such as balcer material or styrofoam, and is a component that holds the distance between the RFID tag 31 and the metal plate 32 at a predetermined distance. By replacing the spacer 33 with a spacer having a different thickness, it is possible to control the communication distance of the radio wave communication performed by the RFID tag 31.

FIG. 5 is a diagram showing the effect of the thickness of the spacer 33 on the maximum communication distance between the RFID tag 31 and the reader / writer. The vertical axis of FIG. 5 is the maximum communication distance of the RFID tag 31, and the horizontal axis is the thickness of the spacer 33.

Here, the thickness of the spacer 33 corresponds to the distance between the RFID tag 31 and the metal plate 32. Further, in the example of FIG. 5, the case where the frequency band of the communication radio wave is the 2.45 GHz band is shown. In this case, one wavelength of radio waves corresponds to a length of 12 cm.

However, the frequency band of the communication radio wave of the RFID tag 31 to which the present invention is applicable is not limited to the 2.45 GHz band, and the same applies to the RFID tag 31 that uses radio waves of other frequency bands such as the UHF band. Can be applied.

Further, FIG. 5 shows the maximum communication distance when the RFID tag 31 alone is used for communication without the metal plate 32 and the spacer 33. In this case, the maximum communication distance is about 100 cm.

As shown in FIG. 5, when the thickness of the spacer 33 is an integral multiple of 1/2 of the radio wave wavelength, that is, n / 2 times (n = 0,1,2, ...), The metal Since the plate 32 acts as a reflecting plate that reflects radio waves, the radio waves that directly reach the RFID tag 31 and the radio waves reflected by the metal plate 32 cancel each other out, and the maximum communication distance becomes almost zero (for example, the area). A).

That is, if the distance between the reader / writer and the RFID tag 31 is within 1 m, communication is usually sufficient, but the spacer 33, whose thickness is n / 2 times the radio wave wavelength, is referred to as the RFID tag 31. If it is sandwiched between the metal plate 32, communication will not be possible.

When it is desired to disable the communication function of the RFID tag 31 by utilizing this feature, the RFID tag 31 is introduced by bonding the RFID tag 31 and the metal plate 32 via the spacer 33. You will be able to do it easily and efficiently at the installation site.

When the RFID tag 31 is a multi-frequency compatible RFID tag that communicates using radio waves in a plurality of frequency bands, the thickness of the spacer 33 is n / 2 times the wavelength of the radio wave corresponding to a certain frequency. By setting to, the communication function of the RFID tag 31 using the radio wave of another frequency can be disabled while the communication function of the RFID tag 31 using the radio wave of the other frequency is enabled.

Further, if the reader / writer communicating with the RFID tag 31 can change the frequency of the radio wave used for communication, the metal plate 32 and the spacer 33 having a predetermined thickness are attached by changing the frequency. The communication function of a specific RFID tag 31 can be enabled or disabled.

When the thickness of the spacer 33 is 1/4 times (3 cm) or 3/4 times (9 cm) of the radio wave wavelength, the radio wave that directly reaches the RFID tag 31 and the radio wave that is reflected by the metal plate 32. Can strengthen each other and increase the maximum communication distance (area B).

Specifically, when the thickness of the spacer 33 is 1/4 times and 3/4 times the radio wave wavelength, as shown in FIG. 5, the maximum communication distance is that the RFID tag 31 alone communicates. It will be about 2 times and about 1.5 times, respectively.

By utilizing this characteristic, stable communication with high communication density and almost no influence of external multipath reflection can be easily and efficiently realized at the installation site where RFID tag 31 is installed, and the RFID tag can be used. Can read and write data to 31.

In FIG. 5, when the thickness of the spacer 33 is 1/4 times or 3/4 times the radio wave wavelength, the maximum communication distance is significantly longer than that of the RFID tag 31 alone, but other Under the experimental conditions, the thickness of the spacer 23 is maximum even when it is an odd multiple of 1/4 of the radio wave wavelength, that is, (2n + 1) / 4 times (n = 0,1,2, ...). Since the communication distance may increase, in such a case, the thickness of the spacer 33 should be (2n + 1) / 4 times the radio wave wavelength (n = 0,1,2, ...). May be good.

When the thickness of the spacer 33 is 1/4 times or less of the radio wave wavelength, the maximum communication distance increases almost linearly as the thickness of the spacer 33 increases, as shown in FIG. It turns out (area C).

By utilizing this characteristic and using a spacer 33 having an appropriate thickness, the maximum communication distance of the RFID tag 31 can be controlled without changing the output strength of the radio wave. Therefore, when it is desired to communicate only with the RFID tag 31 at a predetermined distance from the reader / writer and read / write data to the RFID tag 31, the communication range can be easily and efficiently performed at the site where the RFID tag 31 is introduced. Can be set.

In particular, in the case of RFID tag 31 that communicates using radio waves whose frequency is in the UHF band, the communication range may be too wide, or the influence of radio waves reflected by the surrounding metal surface may be large, but spacers By using 33, the communication range can be easily and efficiently adjusted according to the situation at the site where the RFID tag 31 is installed, and the effect of multipath reflection is greater than when communication is performed with the RFID tag 31 alone. It is possible to obtain stable communication characteristics that are almost nonexistent.

Furthermore, when the object to which the RFID tag 31 is attached is a metal such as a can or a metal container, stable communication can be realized by attaching the RFID tag 31 to the object via the spacer 33. it can.

Here, the linear relationship between the thickness of the spacer 33 and the maximum communication distance when the thickness of the spacer 33 is 1/4 times or less of the radio wave wavelength is used, but the thickness of the spacer 33 is used. Use the linear relationship between the thickness of the spacer 33 and the maximum communication distance when is n / 4 times or more and (n + 1) / 4 times (n = 2,3,4, ...) or less. May be.

In this way, when introducing the RFID tag 31 to the site, the relationship between the maximum communication distance and the thickness of the spacer 33 as shown in FIG. 5 is investigated in advance, and the communication environment at the site is evaluated. , Stabilization of communication of RFID tag 31 and adjustment of communication distance can be easily and efficiently realized.

Further, as in the case described with reference to FIG. 3, when the spacer 33 is used, the directivity of radio wave communication can be controlled by replacing the metal plate 32 with a metal plate having a different width.

As described above, in the second embodiment, the spacer 33, which is a non-metal body, fixes the RFID tag 31 and the metal plate 32 at a certain distance from each other so that the RFID tag 31 and the metal plate 32 are connected to each other. Since the distance between them can be adjusted, the distance and directivity of radio wave communication can be easily and efficiently controlled.

Although the embodiments of the present invention have been described so far, the present invention may be implemented in various different embodiments within the scope of the technical idea described in the claims, in addition to the above-described embodiments. It's a good one.

For example, although the experimental results are not shown in Example 1, the relationship between the maximum communication distance and the thickness of the spacer 33 shown in FIG. 5, that is, between the maximum communication distance and the RFID tag 31 and the metal plate 32. The same relationship as the relationship with the distance of is also established in the communication device 10 shown in FIG.

Therefore, using the distance adjusting screw 14, the distance between the RFID tag 11 and the metal plate 13 can be set to n / 2 times the wavelength of the communication radio wave (n = 0,1,2, ...) Or (2n). +1) / 4 times (n = 0,1,2, ...), or n / 4 times or more, (n + 1) / 4 times (n = 0,1,2, ...) or less By setting the distance to, the communication range can be controlled as described in the second embodiment.

As described above, the communication device and the communication method according to the present invention are useful for a communication system in which it is necessary to easily and efficiently control the distance and directivity of radio wave communication.

<figref num="1">FIG. 1 is a diagram illustrating a communication device 10 according to a first embodiment.</figref><figref num="2">FIG. 2 is a diagram showing the effect of the distance between the RFID tag 11 and the metal plate 13 on the maximum communication distance between the RFID tag 11 and the reader / writer.</figref><figref num="3">FIG. 3 is a diagram showing the effect of the width of the metal plates 20a and 20b on the directivity of radio wave communication between the RFID tag 21 and the reader / writer 22a to 22e and 23a to 23e.</figref><figref num="4">FIG. 4 is a diagram illustrating the communication device 30 according to the second embodiment.</figref><figref num="5">FIG. 5 is a diagram showing the effect of the thickness of the spacer 33 on the maximum communication distance between the RFID tag 31 and the reader / writer.</figref>

Code description

10,30 Communication equipment 11,21,31 RFID tags 12 insulator 13,20a, 20b, 32 metal plate 14 Distance adjustment screw 15 spring 16a ~ 16c Replacement metal plate 22a ~ 22e, 23a ~ 23e Reader / Writer 33 spacer