JP3402989B2 - Tag information reading device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tag information reading apparatus for externally reading and recognizing tag information as desired information stored in a tag IC carried by a person or attached to an object from outside. .

[0002]

19 is a diagram showing a tag information transmission / reception system. The tag information transmission / reception system shown in FIG. 19 includes a tag information reading device 20 and a wireless tag 21. That is, in the tag information reading device 20,
The wireless tag 21 is excited by electromagnetic induction, desired tag information transmitted from the excited wireless tag 21 is received, and the tag information is demodulated and converted into data.

Here, the tag information reading device 20 comprises an exciting coil 1, an exciting circuit section 2, a receiving coil 3 and a reading circuit section 4, and the wireless tag 21 has a memory 5, a tag coil 6 and an IC (Integrated Circuit). ) 7 is provided. That is, the exciting circuit unit 2 controls the exciting coil 1 by supplying an electric signal for exciting the exciting coil 1, and is configured by, for example, an AC power source.

The receiving coil 3 receives the magnetic flux containing the tag information generated by the wireless tag 21 as an electric signal, and the tag information received by the receiving coil 3 is amplified by the reading circuit section 4. , Demodulated and converted into data. Further, the memory 5 of the wireless tag 21 stores desired information as tag information (information for identifying an article to which the wireless tag 21 is attached), and the tag coil 6 is excited by the exciting coil 1. This is for obtaining energy for activating the wireless tag 21 by a signal by an electromagnetic induction technique and transmitting tag information stored in the memory 5.

Therefore, the tag coil 6 has a dual function as an energy receiving coil from the exciting coil 1 and a data transmitting coil for the receiving coil 3. The IC 7 controls to transmit the tag information stored in the memory 5 via the tag coil 6 when the wireless tag 21 is activated by the energy obtained by the tag coil 6.

In the tag information transmission / reception system shown in FIG. 19 described above, for example, as shown in FIG. 20 (a), the exciting coil 1 and the receiving coil 3 of the tag information reading device 20 and the tag coil 6 of the wireless tag 21 are arranged. The three coils are arranged substantially coaxially so that the coils are opposed to each other. In particular, the exciting coil 1 and the receiving coil 3 are arranged on substantially the same plane. The reading device 20 and the wireless tag 21
The energy and signal transmission efficiency between the two is improved.

That is, by arranging the tag information reading device 20 and the wireless tag 21 as described above, FIG.
As shown in (b), the excitation signal (magnetic flux for power supply to the wireless tag 21) 8 for the tag coil 6 generated in the excitation coil 1 can be efficiently passed through the tag coil 6, while the tag coil 6 is provided. The magnetic flux 9 (including the tag information to be transmitted to the tag information reading device 20) 9 generated in 1 can also be efficiently penetrated through the receiving coil 3.

[0008]

However, in the above-described tag information transmitting / receiving system shown in FIG. 19, the exciting coil 1 and the receiving coil 3 are arranged on substantially the same plane, and therefore, the structure shown in FIG. As described above, the unnecessary magnetic flux 8 from the exciting coil 1 also penetrates through the receiving coil 3,
There is a problem that the signal of the weak magnetic flux 9 cannot be demodulated and read.

In other words, in the tag information reading device 20, since the exciting coil 1 and the receiving coil 3 are formed on substantially the same plane, the receiving coil 3 has a magnetic flux 8 as an exciting signal from the exciting coil 1. Interlink according to the coil area ratio. Since this excitation signal 8 is usually stronger than the signal 9 from the tag coil 6 to be received, the receiving coil 3
The detection of the excitation signal 8 in (1) has been a factor of reducing the signal-to-noise ratio of the reception signal detected by the reception coil 3.

On the other hand, while the magnetic flux having a frequency of 125 kHz is used for energy transmission by the exciting coil 1, the magnetic flux having a frequency of 62.5 kHz is used for signal transmission from the tag coil 6 to the receiving coil 3. Set by changing the frequency to 125 kHz and 6
It is also conceivable to mount a filter circuit (for example, a low-pass filter or a band-pass filter) in the reading memory circuit unit 4 so as to remove the 125 kHz signal from the 2.5 kHz signal and extract the 62.5 kHz signal.

However, when a filter circuit is applied to remove the excitation signal 8 contained in the received signal of the receiving coil 3, there is a limit to the frequency transmission characteristic of this filter circuit. As described above, in the case of about 125 kHz: 62.5 kHz (= 2: 1), it becomes impossible to sufficiently remove the signal in the 125 kHz band.

In other words, in the reading circuit section 4,
When amplifying the received signal from the receiving coil 3, it is possible to remove the frequency component of the excitation signal 8 which is a disturbance by a filter circuit, but it is usually about twice as high as the frequency of the signal 9 from the wireless tag 21. There is a limit in the characteristics of the filter circuit to remove the excitation signal 8 by the filter circuit.

Further, as described above, in the tag information transmitting / receiving system shown in FIG. 19, in order to efficiently read the information from the wireless tag 21, the tag coil 6 of the wireless tag 21 is the receiving coil of the tag information reading device 20. The direction is almost the same as that of 3 and 2 on the tag information reading device 20 side
Since the condition is that they are on the extension lines of the central axes of the two coils 1 and 3, there are restrictions on the method of fixing the wireless tag 21 to the article, or when reading the article to which the wireless tag 21 is fixed, There is also a problem that it takes time and effort to rearrange the articles so that the tag 21 faces the tag information reading device 20 in an optimum direction.

In order to enable the tag information reading device 20 to read regardless of the orientation of the surface of the wireless tag 21, it is conceivable to dispose a plurality of exciting coils 1 in three dimensions. However, there is also a problem in that the individual receiving coils 3 receive the excitation signals from all the adjacent excitation coils 1, which may cause more and more disturbance.

The present invention was devised in view of such problems, and improves the signal-to-noise ratio when reading tag information to improve the accuracy of read data, and the direction in which the wireless tag is suitable. It is an object of the present invention to provide a tag information reading device capable of reading a signal from a wireless tag by eliminating such restrictions.

[0016]

Therefore, the tag information reading apparatus of the present invention provides an exciting coil for exciting a tag coil in a wireless tag and tag information transmitted from the wireless tag by exciting the tag coil with the exciting coil. In a tag information reading device having a receiving coil for receiving, the receiving coil has a pair of differentially connected coils in order to cancel the induced voltage due to the magnetic flux from the exciting coil.
And a pair of coils from the exciting coil.
It is constructed so that the absolute values of the magnetic flux entering each are equal.
In addition, the pair of coils is also in the plane of the exciting coil.
Or, place the surfaces of a pair of coils on top of each other
It is characterized in that it is placed so that the induced voltage due to the magnetic flux from the exciting coil is canceled out.
It is possible to eliminate the influence of the magnetic flux generated in the exciting coil when reading a weak signal including the tag information from the tag coil (claim 1).

Further , the tag information reading device of the present invention is
An exciting coil for exciting the tag coil in the wireless tag,
By exciting the tag coil with the excitation coil, the wireless tag
The receiver coil that receives the tag information sent from the
In the tag information reading device made up of
To cancel the induced voltage due to the magnetic flux from the exciting coil,
Formed by one figure-eight coil, and figure-eight coil
Of the two planes through which the magnetic flux from the exciting coil can pass
It is designed so that magnetic flux with the same absolute value enters each.
The figure 8 coil is formed by the exciting coil
Characterized by being placed in or near the plane
This causes the induced voltage due to the magnetic flux from the exciting coil.
Can be canceled out and the tag information from the tag coil is included.
It is generated by the exciting coil when reading a weak signal.
The influence of the magnetic flux generated is eliminated (claim 2).

[0018] In addition, the excitation coil and the receiving coil, no
-Out <br/> in that arranged at least two sets passage outer periphery of the line tags, thereby, without the influence of magnetic flux generated by the exciting coil in reading weak signal including the tag information from the tag coil However, the tag coil is excited to include the tag information.
Directional restrictions of tag ICs for reliable reading of signals
Can be reduced (claim 3).

Further , the pair of coils is a surface formed by the exciting coils.
The RFID tag is placed opposite to each other with the excitation coil above.
And so as to pass through the inside of the pair of coils
Also, even in this way, it is possible to eliminate the influence of magnetic flux generated by the exciting coil in reading weak signal including the tag information from the tag coil, further, the wireless tag
Ru can be enlarged communicable area with (Claim 4).

Further , the tag information reading device of the present invention is
Exciting the tag coil in the wireless tag,
In a tag information reading device that receives tag information,
Excitation coil for exciting the excitation coil, and the first excitation coil
From the RFID tag while canceling out the induced voltage due to the magnetic flux from
A pair of coils differentially connected to receive the tag information of
And a first receiving coil consisting of
The absolute values of the magnetic flux entering each of the pair of coils are equal.
And the pair of coils are not the first excitation coil.
The RFID tags are placed opposite to each other with the face of the first side being excited by the above-mentioned first excitation.
Configured to pass inside a coil and a pair of coils
And a tag coil.
A second exciting coil for exciting the
While canceling the voltage induced by the bundle, the tag information from the RFID tag is canceled.
Consists of a pair of coils that are differentially connected to receive information
A second receiving coil, and second receiving from the second exciting coil
The absolute value of the magnetic flux entering each of the pair of coils is
The pair of coils of the second receiving coil are configured to be equal.
In the plane formed by the second excitation coil or in the vicinity of the plane,
Arranged so that the surfaces formed by a pair of coils do not overlap each other
At least the second coil portion formed on the outer periphery of the first coil portion.
2 sets are also arranged facing each other, and the second exciting coil is connected to the first receiving coil.
Close to the boundary position of each of the pair of coils in the
It is characterized by being arranged like this.
Read a weak signal containing tag information from the tag coil.
Eliminates the influence of the magnetic flux generated by the excitation coil when taking
While energizing the tag coil, ensure a signal containing tag information
Eliminating the directional restriction of the tag IC for reading in parallel
(Claim 5).

Further, the tag information reading device of the present invention is
In a tag information reading device that excites a tag coil in a wireless tag to receive tag information from the wireless tag, a first exciting coil that excites the tag coil and an induced voltage due to a magnetic flux from the first exciting coil are canceled from the wireless tag. A first receiving coil composed of a pair of coils differentially connected to each other so as to receive the tag information, and the absolute values of the magnetic fluxes entering the pair of coils from the first exciting coil are equal to each other. A pair of coils are arranged so as to face each other with a surface formed by the first exciting coil interposed therebetween, and the wireless tag is provided with a first coil portion configured to pass through the inside of the first exciting coil and the pair of coils. a second excitation coil for exciting the tag coil, to receive tag information from the RFID tag while canceling the induced voltage by the magnetic flux from the second excitation coil, And a second receiver coil consisting of shaped coils of one 8, the second excitation coil of the second receiver coil
Absolute value of the magnetic flux magnetic flux figure of eight coil enters each of the two surfaces can pass is configured such that equal, shaped coil of the second receiver coil 8, eggplant plane or surface of the second excitation coil as the second coil portion which is placed in the vicinity, at least two pairs oppositely disposed on the outer periphery of the first coil portion and the second excitation coil, proximate to each of the boundary position of the pair of coils in the first receiver coil It is characterized by the fact that the tag coil is excited and the signal containing the tag information is generated while eliminating the influence of the magnetic flux generated by the exciting coil when reading the weak signal containing the tag information from the tag coil. It is possible to eliminate the directional restriction of the tag IC for sure reading (claim 6). Also, opposite
Connect the receiving coils of the placed second coil section in series.
It is also possible to use the first excitation coil and the second
The magnetic flux entering the receiving coil of the
The accuracy of the data can be improved (Claim 7).

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (A) Description of First Embodiment FIGS. 1 to 3 show a first embodiment of the present invention.
FIG. 2 is a schematic perspective view showing a tag information transmission / reception system to which the tag information reading device according to the first embodiment of the present invention is applied, and FIG. 2 is a tag information reading device and a wireless tag according to the first embodiment of the present invention. 3A and 3B are diagrams for explaining a communication mode between the tag information reading device and the tag information reading device according to the first embodiment of the present invention. 3A is a schematic diagram showing the main part thereof, and FIG. 3B is an equivalent circuit diagram of the main part.

Here, the tag information transmission / reception system according to the first embodiment shown in FIG. 1 or 2 is for reading the tag information stored in the wireless tag 21 attached to the article 30 moving on the conveyor 22. It has a tag information reading device 20A. That is, the tag information transmission / reception system as shown in FIG. 1 or FIG. 2 is applied to, for example, a physical distribution journal system that sorts a parcel that randomly flows on a conveyor. It is expected that the package can be identified by receiving the information wirelessly, which will simplify subsequent physical distribution journals and the like.

The tag information transmission / reception system can also be applied to a system in which a person carries the wireless tag 21 and identifies each person. Here, the tag information reading device 20A of the first embodiment includes the exciting coil 1 and
The receiver coil 3 is provided with a pair of coils 3A and 3B, and the exciting circuit unit 2 and the reading circuit unit 4 having substantially the same functions as those shown in FIG. In the above, the exciting circuit section 2 and the reading circuit section 4 are not shown). A coil set 23 is formed by the above-described exciting coil 1 and the pair of coils 3A and 3B.

Here, the exciting coil 1 of the first embodiment is
The tag coil in the wireless tag 21 is excited, and it is arranged so as to generate an exciting magnetic flux in a direction substantially orthogonal to the traveling direction of the wireless tag 21. As the wireless tag 21, the same one as shown in FIG. 19 can be used, and the detailed description thereof will be omitted.

Further, the receiving coil 3 composed of the pair of coils 3A and 3B receives the tag information transmitted from the wireless tag 21 by exciting the tag coil 6 (see FIG. 19) of the wireless tag 21 by the exciting coil 1. The signal is received, and the induced voltage due to the exciting magnetic flux from the exciting coil 1 is offset. Specifically, the coils 3A,
3B has a size sufficiently larger than that of the wireless tag 21, and is sequentially arranged in the traveling direction of the wireless tag 21 so that the surfaces of the coils 3A and 3B do not overlap each other.

Further, the coils 3A and 3B are arranged in the plane formed by the exciting coil 1 and each of the coils 3A and 3B.
The area of the surface formed by B is ½ of that of the exciting coil 1, and the surfaces of the coils 3A and 3B are arranged so as not to overlap each other. As a result, the magnetic fluxes 8 from the exciting coil 1 [see FIG. 3 (a)] entering the coils 3A and 3B are made equal in absolute value.

In other words, the coils 3A and 3B are in the plane formed by the exciting coil 1 so that the absolute values of the magnetic fluxes 8 entering the respective coils 3A and 3B from the exciting coil 1 are equal to each other. The surfaces formed by 3B are arranged so as not to overlap each other. Also these 2
The magnetic fields from the exciting coil 1 are arranged at the same positions in the three coils 3A and 3B and are differentially connected.

Here, the coil has a polarity depending on the direction (or winding direction) of the magnetic poles when a current is applied, but the differential connection of the coils means that the two coils have the same polarity. It connects one another. Therefore, since the pair of coils 3A and 3B as the receiving coils are differentially connected, the output signal (the induced voltage across the coils 3A and 3B) is the induced voltage generated in the two coils 3A and 3B. The difference is output.

As a mode of the above-mentioned differential connection, it suffices that at least two coils 3A and 3B having the same polarity are connected to each other, as shown in FIG. 1 or FIG.
As shown in (b), the pair of coils 3A and 3B may be arranged such that the winding directions thereof are opposite to each other, or the winding directions thereof may be arranged to face the same direction. Also, coil 3
When canceling the induced voltage by A and 3B, based on Lenz's law that a current flows in a direction that prevents the magnetic flux from changing, even if the pair of coils 3A and 3B have the same position, the polarities are opposite (for example, winding (Rotate from right to left)
When it is set, the fact that the direction of the induced current changes is used.

For example, of the magnetic flux 8 generated by the exciting coil 1, if the magnetic flux penetrating the coil 3A or the coil 3B is φ, the exciting signal e received by the coil 3A or the coil 3B.
Is represented by Faraday's law as shown in equation (1). e = -N (dφ / dt) (1) Here, N is the number of turns of the coils 3A and 3B, and e is a signal having the same frequency as the excitation signal from the excitation coil 1 but a phase change. Further, when the pair of coils 3A and 3B are differentially connected, even if the same magnetic flux φ penetrates from the same direction, the voltages induced in the individual coils 3A and 3B have opposite phases. Theoretically zero.

That is, if the absolute values of the magnetic fluxes from the exciting coil 1 entering the coils 3A and 3B are made equal to each other, the exciting coil 1 will be used in the output signals of the differentially connected coils 3A and 3B.
The induced voltage due to will be canceled out. With the above configuration, in the tag information reading device 20A according to the first embodiment of the present invention, as shown in FIGS. 1 and 2, the article 30 to which the wireless tag 21 is attached advances on the conveyor 22 and this wireless communication is performed. When the tag 21 approaches any one of the pair of coils 3A and 3B, the wireless tag 21 is activated by receiving the excitation signal from the excitation coil 1 and being excited. In the activated wireless tag 21, the IC 7 (see FIG.
9), the tag information stored in the memory 5 is transmitted via the tag coil 6.

At this time, the magnetic flux 9 emitted from the wireless tag 21
Can be received by the coil 3A, 3B, which is closer to the wireless tag 21, of the pair of coils 3A, 3B. That is, the magnetic flux 9 emitted from the wireless tag 21 can be read when it is close to any one of the pair of coils 3A and 3B. For example, as shown in FIG. 2, when the wireless tag 21 passes through the position P on the conveyor 22, the tag information transmitted from the wireless tag 21 is stored in the pair of coils 3
When the wireless tag 21 is passed through the position R by being received by one coil 3A of the coils A and 3B, the tag information transmitted from the wireless tag 21 is the information of the other of the pair of coils 3A and 3B. It is received by the coil 3B.

When the wireless tag 21 passes through either the position P or R on the conveyor 22, the pair of coils 3A and 3B receives the same amount of magnetic flux φ from the exciting coil 1, but is differentially connected. In the output signals from the coils 3A and 3B, the induced voltage due to the magnetic flux from the exciting coil 1 is canceled. That is, the pair of coils 3
A and 3B receive the same exciting magnetic flux from the exciting coil 1, but since the pair of coils 3A and 3B are differentially connected, the coil 3A,
In the reception signals output from the output terminals A and B of 3B [see FIG. 3 (b)], the exciting magnetic flux from the exciting coil 1 is canceled. Therefore, the receiving coil 3 can output the tag information read signal while improving the signal noise ratio.

The wireless tag 21 has two coils 3A,
When passing through an intermediate position (position Q in FIG. 2) of 3B, the magnetic flux 9 generated from the wireless tag 21 is also canceled, but at least the front position of either of the coils 3A and 3B (FIG. 2).
Can be read reliably at the positions P and R). As described above, according to the tag information reading device 20A of the first embodiment of the present invention, the coils 3A and 3B can cancel the induced voltage due to the magnetic flux from the exciting coil 1, so that the RFID tag 21 outputs It is possible to improve the signal-to-noise ratio when receiving and reading a signal including tag information, improve the accuracy of read data, and expand the communicable area with the wireless tag 21. .

In the first embodiment described above, the exciting signal from the exciting coil 1 is canceled by differentially connecting the pair of coils 3A and 3B. However, the present invention is not limited to this. For example, even if an eight-shaped coil configured such that magnetic fluxes having the same absolute value enter each of the two surfaces through which the magnetic flux from the exciting coil 1 can pass, the two coils are differentially connected. Since a coil equivalent to that in the case described above can be configured, the same advantages as in the case of the above-described first embodiment can be obtained even in this case.

Further, in the above-described first embodiment, at least two sets of the exciting coil 1 and the pair of coils 3A and 3B forming the coil set 23 can be arranged on the outer circumference of the passage of the wireless tag 21. That is, for example, as shown in FIG. 4, two sets of left and right coil sets 23-1 and 23-2 can be provided so as to face each other along the conveyor 22. Here, as shown in FIG. 5, the coil set 23-
1, the coil set 23-2, the excitation coil 1-
1, 1-2 and receiving coils 3-1 and 3-2. Each receiving coil 3-1 and 3-2 is composed of a pair of differentially connected coils 3A and 3B.

Further, the exciting coils 1-1 and 1-2 are connected in series to the same AC power source (exciting circuit section) 2, so that the exciting coils 1-1 and 1-2 are connected to each other. Magnetic flux of the same phase that is substantially orthogonal to the traveling direction of the wireless tag 21 is generated. Furthermore, each receiving coil 3-
Both 1 and 3-2 are two exciting coils 1-1 and 1-2.
However, the output signals from the two receiving coils 3-1 and 3-2 are used as a reading circuit section (see reference numeral 4 in FIG. 19) as a signal combiner. At 10, the signals from the wireless tag 21 are added.

Therefore, by providing the two coil sets 23-1 and 23-2 so as to face each other along the conveyor 22, the induced voltage due to the magnetic flux from the exciting coils 1-1 and 1-2 is offset. Therefore, it is possible to obtain the same advantages as in the case of the above-described first embodiment, and it is possible to
Has the advantage that it can receive the tag information regardless of whether it is facing left or right with respect to the traveling direction, and the restrictions on the direction of the wireless tag 21 attached to the article 30 can be reduced.

Further, as shown in FIG. 6, for example, coil sets 23-1 to 23-4 are provided on four surfaces (not only on the left and right sides of the conveyor 22 but also on the upper and lower surfaces) of the outer periphery of the passage of the wireless tag 21.
Can be provided. That is, the coil set 23-1 to
Each of 23-4 is provided with an exciting coil and a receiving coil (not shown) having the same function as that shown in FIG. 1 described above (in FIGS. 7 to 10 described later,
Only the receiving coil 3-2 of the coil set 23-2 and the exciting coils 1-1 to 1-4 of the coil sets 23-1 to 23-4 are shown).

Here, in the case where the coil sets 23-1 to 23-4 are arranged on the four surfaces on the outer circumference of the passage of the wireless tag 21, the influence of the two exciting coils facing each other on the receiving coil facing the same direction will be described. 7 and 8
Will be described below. In this case,
As shown in FIG. 7, in particular, the figure-eight coil 3-2 as the receiving coil of the coil set 23-2 has exciting coils 1-1, 1- that are oriented in the same direction with respect to the figure-8 coil 3-2.
Focusing on the influence from 2, the other receiving coil 3
The same applies to -1, 3-3 and 3-4.

Here, in FIG. 7 and FIG. 8, assuming that two kinds of magnetic fluxes penetrating the figure-eight coil 3-2 are φa and φb, the relationship between these φa and φb is as shown in equation (2). Will be equal. Therefore, the output of the figure-eight coil 3-2, which is equivalent to two differentially connected coils, is as shown in Expression (3), and the magnetic fluxes from the exciting coils 1-1 and 1-2 are canceled. . As a result, the 8-shaped coil 3-2 becomes the exciting coil 1.
It can be said that there is no influence from the magnetic flux generated at -1, 1-2.

Φa = φb (2) φa−φb = 0 (3) Further, regarding the influence of the receiving coil on the receiving coil due to the magnetic flux from the exciting coil which is adjacent (or close to) the receiving coil in a direction different by 90 °. This will be described below with reference to FIGS. 9 and 10.

Also in this case, as shown in FIG. 9, the 8-shaped coil 3-2 as the receiving coil of the coil set 23-2 is oriented 90 degrees with respect to the 8-shaped coil 3-2. ° Exciting coils 1-3, 1 that are adjacent to each other differently
We are paying attention to the influence from -4. Here, the values of the two types of magnetic fluxes φa and φb generated in the exciting coils 1-3 and 1-4 and intersecting with the receiving coil 3-2 are small, and are approximated as shown in Expression (4). can do. Therefore, the output of the figure-eight coil 3-2, which is equivalent to two differentially connected coils, is as shown in equation (5), and the magnetic fluxes from the exciting coils 1-3 and 1-4 are canceled out. You can
As a result, the 8-shaped coil 3-2 becomes the exciting coil 1-3,
It can be said that there is no influence of the magnetic flux generated in 1-4.

.Phi.a = .phi.b.apprxeq.0 (4) .phi.a-.phi.b = 0 (5) That is, when the four opposed coil sets 23-1 to 23-4 are arranged on the upper, lower, left and right sides of the conveyor 22, respectively. It is possible to cancel the penetration of the magnetic flux from the exciting coil into the receiving coil.

Therefore, by providing the coil sets 23-1 to 23-4 on the four outer peripheral surfaces of the wireless tag 21,
In addition to the advantages similar to those of the first embodiment described above, the tag information can be received regardless of whether the wireless tag 21 faces up, down, left, or right with respect to the traveling direction, and is attached to the article 30. The tag information can be reliably received without the restriction on the direction of the wireless tag 21.

(B) Description of Second Embodiment FIG. 11 is a schematic perspective view showing a tag information transmitting / receiving system to which the tag information reading device according to the second embodiment of the present invention is applied, and is shown in FIG. The tag information transmission / reception system is for reading the tag information stored in the wireless tag 21 attached to the article 30 traveling on the conveyor 22 as in the case of the first embodiment described above, and The tag information reading device 20B different from that of the first embodiment is provided.

In FIG. 11, the same symbols as those in FIG. 1 indicate the same parts. Here, the tag information reading device 20B shown in FIG. 11 also includes the exciting coil 11 and the pair of coils 13A and 13B as the receiving coil 13, and has the same exciting circuit unit as that in the first embodiment. 2 and the reading circuit unit 4 (in FIG. 11, the reading circuit unit 4 is included).
Is not shown).

Further, in the tag information transmitting / receiving system according to the second embodiment, the exciting coil 11 and the pair of coils 13A, 13 constituting the tag information reading device 20B.
The conveyor 22 as a passage for the article 30 penetrates through the opening B. That is, the pair of coils 13A, 1 of the tag information reading device 20B according to the second embodiment.
3B are opposed to each other with the surface formed by the exciting coil 11 interposed therebetween, and the wireless tag 21 passes through the inside (opening) of the exciting coil 11 and the pair of coils 13A and 13B.

Specifically, three coils (excitation coil 1
1 and the pair of coils 13A and 13B) have substantially the same size so that the areas of the surfaces formed by the three coils 11, 13A and 13B have substantially the same size.
A pair of coils 3A and 3B are arranged at the point where the magnetic flux from the exciting coil 11 is the same in the front and rear along the traveling direction of the conveyor 22 while the exciting coil 11 is at the center. The exciting coil 11 and the pair of coils 13A and 13B arranged as described above constitute a coil set 24.

Here, the exciting coil 11 is the wireless tag 21.
For exciting the tag coil, and is arranged so as to generate an exciting magnetic flux in a direction substantially parallel to the traveling direction of the wireless tag 21. Further, the pair of coils 13A and 13B as the receiving coil 13 receives the tag information transmitted from the wireless tag 21 by exciting the tag coil 6 (see FIG. 19) of the wireless tag 21 by the exciting coil 1. Then, as in the first embodiment described above,
The differential connection is made to cancel the induced voltage due to the exciting magnetic flux from the exciting coil 1.

That is, in the pair of coils 13A and 13B,
Although the same exciting magnetic fluxes are received from the exciting coil 11, as shown in FIG. 12, since the pair of coils 13A and 13B are differentially connected, the output of the coils 13A and 13B is the output of the receiving coil 13. In the reception signals output from the output terminals A and B, the exciting magnetic flux from the exciting coil 11 is canceled.

The pair of coils 13A and 13B according to the second embodiment are connected in series while the winding directions are opposite to each other as shown in FIGS. 11 and 12, but according to the present invention. For example, the winding directions may be the same as long as they are differentially connected. With the configuration described above, in the tag information reading device 20B according to the second embodiment of the present invention, as shown in FIGS. 11 and 12, the article 30 with the RFID tag 21 advances on the conveyor 22, and The wireless tag 21 passes through the inside of each of the exciting coil 11 and the pair of coils 13A and 13B.

Here, the wireless tag 21 includes the pair of coils 13
The surface of the wireless tag 21 that is closer to either A or 13B is the exciting coil 11 and the pair of coils 13.
At the same time as the surface formed by A and 13B, the RFID tag 21 is excited by receiving the excitation signal from the excitation coil 11.
Is started. Furthermore, in the activated wireless tag 21, the tag information stored in the memory 5 is transmitted to the receiving coil 13 via the tag coil 6 under the control of the IC 7 (see FIG. 19).

At this time, the magnetic flux 9 emitted from the wireless tag 21
Is the wireless tag 21 of the pair of coils 13A and 13B.
Can be received by the coils 13A and 13B that are closer to. That is, the magnetic flux 9 emitted from the wireless tag 21 can be read when it is close to any one of the pair of coils 13A and 13B. Here, a pair of coils 1
3A and 13B receive the same exciting magnetic fluxes from the exciting coil 11, but the pair of coils 13A and 13B
Are differentially connected, the excitation signals from the excitation coil 11 cancel out the reception signals output from the output terminals A and B of the coils 13A and 13B as outputs of the reception coil 13. Therefore, the receiving coil 13 can output the tag information read signal while improving the signal noise ratio.

When the wireless tag 21 passes through the exciting coil 11, the magnetic flux emitted from the wireless tag 21 is canceled, but the tag information is surely provided at least at a position close to one of the coils 13A and 13B. Can be read. Thus, according to the tag information reading device 20B according to the second embodiment of the present invention, the pair of coils 13A,
13B are arranged to face each other with the surface formed by the exciting coil 11 interposed therebetween, and the wireless tag 21 is configured to pass inside the exciting coil 11 and the pair of coils 13A and 13B. The induced voltage due to the magnetic flux from 11 can be canceled, the signal-to-noise ratio at the time of receiving and reading the signal including the tag information from the wireless tag 21 can be improved, and the accuracy of the read data can be improved. There is also an advantage that the communicable area with the tag 21 can be expanded.

(C) Description of Third Embodiment FIG. 13 is a schematic perspective view showing a tag information transmitting / receiving system to which the tag information reading device according to the third embodiment of the present invention is applied, and is shown in FIG. The tag information transmission / reception system includes a tag information reading device 20C different from that in each of the above-described embodiments, and a conveyor 22 having substantially the same functions as those in each of the embodiments.

Here, the tag information reading device 20C according to the third embodiment is for exciting the tag coil 6 (see FIG. 19) in the wireless tag 21 to receive the tag information from the wireless tag 21. The coil set 23-1 to 23-4 similar to that shown in FIG. 6 and the coil set 24 similar to that shown in FIG. 11 are provided. That is, the tag information reading device 20C includes a coil set (second coil portion) 2 which is arranged on the outer circumference of the conveyor 22 in four sets of upper, lower, left and right.
3-1 to 23-4 are provided, and the coil set (first coil unit) 24 in the tag information reading device 20B according to the second embodiment is arranged, whereby the wireless tag 21 is oriented in all directions. However, the tag information can be surely received.

The coil set 24 has a first exciting coil 11 and a first receiving coil 13 which are substantially the same as those in the above-described second embodiment (see FIG. 11), while
The coil sets 23-1 to 23-4 respectively include the second exciting coils 1-1 to 1-4 and the second receiving coils 3-1 to 3-4 having substantially the same functions as those shown in FIG. Therefore, detailed description thereof will be omitted.

That is, the first receiving coil 13 of the coil set 24 also has a pair of coils 13A and 13B similar to those in the above-described second embodiment, and the first receiving coil 13 of the coil sets 23-1 to 23-4. 2 receiver coils 3-1 to 3-4
Also has a pair of coils 13A and 13B similar to those shown in FIG. Here, the second exciting coils 1-1 to 1-4 are arranged so as to be close (adjacent) to the respective boundary positions of the pair of coils 13A and 13B in the first receiving coil 13, and the first exciting coil 11
Are arranged along the boundary between the pair of coils 3A and 3B in the coil sets 23-1 to 23-4.

In the tag information reading device 20C according to the third embodiment, the coil sets 23-1 and 23-2 are also included.
As the receiving coil 3-4, it is possible to use, for example, an 8-shaped coil configured so that magnetic fluxes whose absolute values are equal to each other enter into each of two surfaces through which the magnetic flux from the exciting coil 1 can pass. By the way, the second receiving coil 3-1
To 3-4 are the second exciting coils 1-1 to 1-4 by differentially connecting the pair of coils 3A and 3B.
However, as shown in FIGS. 14 to 16, these second receiving coils 3-1 to 3-4 include the first exciting coil 11 of the coil set 24. It is also possible to cancel the induced voltage due to the magnetic flux from.

14 to 16, the coil set 23 is generated by the magnetic flux from the first exciting coil 11.
The explanation is given focusing on the influence of the second receiving coils 3-1 and 3-2 of -1,23-2. Further, FIG. 14 is a schematic perspective view showing a positional relationship between the first exciting coil 11 and the second receiving coils 3-1 and 3-2 of the tag information reading device 20C, and FIG. 15 is generated in the first exciting coil 11. FIG. 16 is a diagram showing that the magnetic fluxes entering the second receiving coils 3-1 and 3-2 are shown, and FIG. 16 is a diagram showing that the receiving coils 3-1 and 3-2 are connected in series (equivalent circuit diagram). Is.

Since the second receiving coils 3-1 and 3-2 facing each other (opposing) with the conveyor 22 interposed therebetween are arranged symmetrically with respect to the exciting coil 11, the second receiving coil 3 is provided. -1, 3-2 pair of coils 3A, 3
The relationship of the magnetic flux received from the exciting coil 11 in each of B is
The expressions (6) to (10) are as follows. In equations (6) to (10), among the magnetic fluxes generated in the exciting coil 11, the magnetic fluxes that enter the pair of coils 3A and 3B in the second receiving coil 3-1 are defined as φd and φc, respectively. 2 a pair of coils 3 in the receiving coil 3-2
The magnetic fluxes entering A and 3B are φb and φa, respectively.

| Φa | = | φb | = | φc | = | φd | (6) φa = -φb (7) φc = -φd (8) φa = -φc (9) φb = -φd (10) A pair of coils 3 in the second receiving coils 3-1 and 3-2
Since A and 3B are differentially connected, each of the above equations (6)
~ Based on (10), each second receiving coil 3-1 and 3-2
From, the magnetic flux components due to the exciting coil 11 are respectively detected by the following equations (11) and (12).

Φa−φb = 2φa> 0 (11) φc−φd = 2φc> 0 (12) By the way, as described above, the second receiving coils 3 facing each other.
Since the outputs of -1, 3-2 are added, the addition result (outputs of terminals A and B in FIG. 16) is expressed by the following equation (13).

2φa + 2φc = 2φa-2φa = 0 (13) That is, in the respective outputs of the second receiving coils 3-1 and 3-2 (outputs by the differential connection of the pair of coils 3A and 3B), the first excitation is performed. The magnetic flux from the coil 11 cannot be offset, but when the opposing second receiving coils 3-1 and 3-2 are connected in series, the magnetic flux from the first exciting coil 11 is offset to read the tag information. It is possible to output a signal.

As shown in FIG. 15, this means that a clockwise magnetic flux enters the second receiving coil 3-2 of the opposing coil set 23-2 while the second receiving coil 3-2 of the opposing coil set 23-1 receives the second magnetic flux.
It can also be understood from the fact that counterclockwise magnetic flux enters the receiving coil 3-1 and the output voltages induced in the second receiving coils 3-1 and 3-2 have opposite phases. In addition, in FIG.
As in the case of FIG. 16, the tag information read signal offset by the induced voltage due to the magnetic flux generated in the first exciting coil 11 is output from the second receiving coils 3-3 and 3-4 connected in series. can do.

Therefore, at least the opposing second receiving coils 3-1 and 3-2 (or the second receiving coils 3-3 and 3-).
4) are connected in series, the second receiving coil 3-
1 to 3-4 can also cancel the induced voltage due to the magnetic flux from the first exciting coil 11. Further, as in the case of the above-described second embodiment, the pair of coils 13A and 13B of the first receiving coil 13 are differentially connected to cancel the induced voltage due to the magnetic flux from the first exciting coil 11. However, as shown in FIGS. 17 and 18, the first receiving coil 13 includes the second exciting coils 1-1 to 1-
The induced voltage due to the magnetic flux from 4 can also be canceled.

Note that, in FIGS. 17 and 18, the description is given focusing on the influence of the magnetic flux from the second exciting coils 1-1 and 1-2 on the first receiving coil 13 of the coil set 24. Here, FIG. 17 is a schematic perspective view showing the positional relationship between the second exciting coils 1-1 and 1-2 and the first receiving coil 13 of the tag information reading device 20C, and FIG. 18 is the second exciting coil 1-1. , 1-2 is the first magnetic flux generated
It is a figure which shows a mode that a pair of coils 13A and 13B in the receiving coil 13 is entered.

By the way, the second exciting coils 1-1 and 1-2
The magnetic flux generated at is different from the second exciting coils 1-1 and 1-2 in the direction by 90 ° and is adjacent to (adjacent to) the pair of coils 1.
The components φa and φb intersecting with 3A and 13B are small. As shown in FIG. 18, this is a pair of coils 13
Each of the second exciting coils 1-1,
This is because magnetic fluxes of opposite directions and of the same magnitude intersect from 1-2, and both φa and φb can be approximated to 0, as shown in equation (14).

.Phi.a = .phi.b.apprxeq.0 (14) Since the pair of coils 13A and 13B are differentially connected, the output of the first receiving coil 13 (A in FIG. 12) is expressed by the equation (15). -Refer to B terminal output)
It becomes like Formula (15). φa−φb = 0 (15) Therefore, the first receiving coil 13 is the second exciting coil 1−
The induced voltage due to the magnetic flux from 1, 1-2 can also be canceled.

Regarding the influence of the first receiving coil 13 by the magnetic fluxes from the second exciting coils 1-3 and 1-4,
This is similar to the case of FIGS. 17 and 18 described above. Therefore, the first receiving coil 13 can cancel the induced voltage due to the magnetic flux from the second exciting coils 1-1 to 1-4. That is, the first receiving coil 13 and the second receiving coil 3-
In the tag information read signals output from 1 to 3-4, the induced voltage due to the magnetic flux from all the exciting coils 1-1 to 1-4 and 11 can be canceled.

With the above-mentioned configuration, the tag information reading device 20C according to the third embodiment of the present invention is shown in FIG.
As shown in FIG. 3, the article 30 with the RFID tag 21 advances on the conveyor 22, and the RFID tag 21 passes inside the exciting coil 11 and the pair of coils 13A and 13B. Here, even if the tag coil 6 (see FIG. 19) of the wireless tag 21 faces in any direction on the conveyor 22, the first exciting coil 11 and the second exciting coil 1-1.
Are excited by at least one of the magnetic fluxes from 1-4.

When excited, the wireless tag 21 transmits the tag information stored in the memory 5 through the tag coil 6 under the control of the IC 7. At this time, the magnetic flux 9 emitted from the wireless tag 21 intersects with at least one of the first receiving coils 3-1 to 3-4 and the second receiving coil 13. In other words, the tag information transmitted from the wireless tag 21 can be received by at least one of the first receiving coils 3-1 to 3-4 and the second receiving coil 13.

In the tag information read signals output from the first receiving coil 13 and the second receiving coils 3-1 to 3-4, all the exciting coils 1-1 to 1-4 and 1 are included.
The induced voltage due to the magnetic flux from 1 is canceled. Therefore, the first receiving coil 13 or the second receiving coils 3-1 to 3-1
The tag information read signal from -4 can be output while improving the signal-noise ratio.

As described above, according to the tag information reading device 20C of the third embodiment of the present invention, the second exciting coils 1-1 to 1-4 are the pair of coils 13A and 13B in the first receiving coil 13. Are arranged so as to be close to their respective boundary positions, all of the exciting coils 1 are included in the tag information read signals output from the first receiving coil 13 and the second receiving coils 3-1 to 3-4. -1-
The induced voltage due to the magnetic flux from 1-4 and 11 can be canceled, the signal noise ratio at the time of receiving and reading the signal including the tag information from the wireless tag 21 can be improved, and the accuracy of the read data can be improved. Wireless tag 2
1 has an advantage of being able to expand the communicable area with 1, and reliably receives tag information with the receiving coils 3-1 to 3-4, 13 regardless of the direction of the wireless tag 21. There is also an advantage that can be done.

[0077]

As described in detail above, according to the tag information reading apparatus of the present invention as defined in claim 1 or 2 , the receiving coil cancels the induced voltage due to the magnetic flux from the exciting coil. Since it is configured as described above, it is possible to improve the signal-to-noise ratio when receiving and reading the signal including the tag information from the wireless tag, improve the accuracy of the read data, and communicate with the wireless tag. There is also an advantage that the possible area can be expanded.

According to the tag information reading apparatus of the present invention as defined in claim 3 , the exciting coil and the pair of coils are:
Since at least two sets are arranged on the outer periphery of the passage of the wireless tag, there is also an advantage that it is possible to reduce restrictions on the installation direction of the wireless tag. Further, according to the tag information reading apparatus of the present invention as set forth in claim 4 , the pair of coils are arranged opposite to each other with the surface formed by the exciting coil interposed therebetween, and the wireless tag passes through the inside of the exciting coil and the pair of coils. Since the receiving coil cancels the induced voltage due to the magnetic flux from the exciting coil, it can improve the signal-to-noise ratio when receiving and reading the signal containing the tag information from the wireless tag. In addition to being able to improve the accuracy of, there is an advantage that the communication area with the wireless tag can be expanded.

Further, according to the tag information reading apparatus of the present invention as set forth in claim 5 or 6 , the second exciting coil is arranged so as to be close to the respective boundary positions of the pair of coils in the first receiving coil. Therefore, in the tag information read signal output from the first receiving coil and the second receiving coil, the induced voltage due to the magnetic flux from all the exciting coils can be canceled and the tag information from the wireless tag is included. The signal-to-noise ratio when receiving and reading signals can be improved, the accuracy of read data can be improved, and the communication area with the RFID tag can be expanded. Even when facing the direction, there is an advantage that the tag information can be reliably received by the first receiving coil or the second receiving coil. Well
According to the tag information reading device of the present invention according to claim 7,
If this is done, the receiving coil of the second coil section, which is arranged opposite to
The first excitation coil to the second coil are connected in series.
The magnetic flux entering the receiver coil of the
The accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a tag information transmission / reception system to which a tag information reading device according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram for explaining a communication mode between a tag information reading device and a wireless tag according to the first embodiment of the present invention.

3A and 3B show a main part of the tag information reading device according to the first embodiment of the present invention, FIG. 3A is a schematic diagram showing the main part, and FIG. 3B is an equivalent circuit diagram of the main part. .

FIG. 4 is a schematic perspective view showing a tag information transmitting / receiving system to which a tag information reading device according to a modification of the first embodiment of the present invention is applied.

FIG. 5 is a diagram (equivalent circuit diagram) showing a main part of a tag information reading device according to a modification of the first embodiment of the present invention.

FIG. 6 is a schematic perspective view showing a tag information transmitting / receiving system to which a tag information reading device according to a modified example of the first embodiment of the present invention is applied.

FIG. 7 is a diagram for explaining the operation of the modified example of the first embodiment of the present invention.

FIG. 8 is a diagram for explaining the operation of the modified example of the first embodiment of the present invention.

FIG. 9 is a diagram for explaining the operation of the modified example of the first embodiment of the present invention.

FIG. 10 is a diagram for explaining the operation of the modified example of the first embodiment of the present invention.

FIG. 11 is a schematic perspective view showing a tag information transmitting / receiving system to which the tag information reading device according to the second embodiment of the present invention is applied.

FIG. 12 is a diagram (equivalent circuit diagram) showing a main part of the tag information reading device according to the first embodiment of the present invention.

FIG. 13 is a schematic perspective view showing a tag information transmitting / receiving system to which a tag information reading device according to a third embodiment of the present invention is applied.

FIG. 14 is a diagram for explaining the operation of the third embodiment of the present invention.

FIG. 15 is a diagram for explaining the operation of the third embodiment of the present invention.

FIG. 16 is a diagram for explaining the operation of the third embodiment of the present invention.

FIG. 17 is a diagram for explaining the operation of the third embodiment of the present invention.

FIG. 18 is a diagram for explaining the operation of the third embodiment of the present invention.

FIG. 19 is a diagram showing a tag information transmitting / receiving system.

20 (a) and 20 (b) are diagrams showing coil arrangement examples in the tag information transmitting / receiving system shown in FIG.

[Explanation of symbols]

1,1-1 to 1-4 Excitation coil 2 Excitation circuit section 3, 3-1 to 3-4 receiver coil 3A, 3B coil 4 Reading circuit section 5 memory 6 tag coils 7 IC 8, 9 magnetic flux 11 Excitation coil 13 receiver coil 13A, 13B coil 20, 20A to 20C Tag information reading device 21 wireless tag 22 conveyor 23-1 to 23-4 Coil set (second coil part) 24 coil set (first coil part) 30 articles

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-50621 (JP, A) JP-A-56-83000 (JP, A) Jikkoku-Sho 50-27880 (JP, Y1) Special table Sho-63- 502394 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B 5/00-5/02 G06K 17/00 H01F 17/02 H01Q 7/00 H04B 1/59

Claims (7)

(57) [Claims] 1. A tag information reading device comprising: an exciting coil for exciting a tag coil in a wireless tag; and a receiving coil for receiving tag information transmitted from the wireless tag by exciting the tag coil with the exciting coil. In the above, the receiving coil is configured by a pair of differentially connected coils to cancel the induced voltage due to the magnetic flux from the exciting coil.
Made from the excitation coil to that of the pair of coils
Configured so that the absolute values of the magnetic flux entering each are equal
Together with the pair of coils within the plane formed by the exciting coil
Or, put the faces of the pair of coils on top of each other in the vicinity of the faces.
A tag information reading device, which is arranged so as not to be folded. 2. A tag coil in a wireless tag is excited.
Exciting coil and the tag coil is excited by the exciting coil.
Receives tag information transmitted from the wireless tag by magnetizing
Tag information reading device with a receiving coil
At the receiver coil, the induced coil is induced by the magnetic flux from the exciting coil.
Formed by a single figure-8 coil to offset the pressure,
And the magnetic flux from the exciting coil in the figure 8 coil
On each of the two planes through which the
It is constructed so that a new magnetic flux enters, and
Yl, characterized in that arranged <br/> near or within the plane surface formed of the exciting coils, tag information reading device. 3. The exciting coil and the receiving coil are
3. The tag information reading device according to claim 1 , wherein at least two sets are arranged on the outer circumference of the passage of the line tag . 4. A surface formed by the pair of coils and the exciting coil.
Are placed opposite to each other with the above-mentioned excitation coil
The tag information reading device according to claim 1 , wherein the tag information reading device is configured to pass through the inner side of the coil and the pair of coils . 5. Exciting a tag coil in a wireless tag
Read tag information to receive tag information from the wireless tag
In a device, a first exciting coil for exciting the tag coil, and the first exciting coil
While canceling the induced voltage due to the magnetic flux from the coil, the radio
A pair that is differentially connected to receive tag information from the tag.
A first receiving coil composed of
Absolute of magnetic flux entering each of the pair of coils from the coil
The pair of coils are configured to be equal in value and
One of the exciting coils is disposed so as to face each other with the surface formed by the exciting coil interposed therebetween.
The inside of the first excitation coil and the pair of coils described above.
When a first coil portion configured to pass is provided
A second excitation coil that excites the tag coil, and a second excitation coil
While canceling the induced voltage due to the magnetic flux from the coil, the radio
A pair that is differentially connected to receive tag information from the tag.
Second receiving coil composed of
From the coil to each of the pair of coils of the second receiving coil
The absolute values of the magnetic flux entering the
The pair of coils of the second receiving coil is the second exciting coil.
The surface formed by the pair of coils in or near the surface
Coil part arranged so that the two do not overlap each other
However, at least two sets are arranged so as to face each other on the outer circumference of the first coil portion.
The second exciting coil is replaced by the second exciting coil in the first receiving coil.
Arrange them so that they are close to the boundary positions of the pair of coils.
Characterized in that the location, the tag information reading device. 6. Exciting a tag coil in a wireless tag
Read tag information to receive tag information from the wireless tag
In a device, a first exciting coil for exciting the tag coil, and the first exciting coil
While canceling the induced voltage due to the magnetic flux from the coil, the radio
A pair that is differentially connected to receive tag information from the tag.
A first receiving coil composed of
Absolute of magnetic flux entering each of the pair of coils from the coil
The pair of coils are configured to be equal in value and
One of the exciting coils is disposed so as to face each other with the surface formed by the exciting coil interposed therebetween.
The inside of the first excitation coil and the pair of coils described above.
When a first coil portion configured to pass is provided
A second excitation coil that excites the tag coil, and a second excitation coil
While canceling the induced voltage due to the magnetic flux from the coil, the radio
A single figure eight coil to receive tag information from the tag
And a second receiving coil formed by
The magnetic flux of the figure-8 coil of the second receiving coil from the coil
The absolute value of the magnetic flux entering each of the two surfaces that can pass is equal
The figure-8 of the second receiving coil is configured to be
The coil is in or near the surface formed by the second excitation coil
The second coil portion arranged on the, on the outer periphery of the first coil portion
At least two pairs are arranged so as to face each other, and the second exciting coil is
Boundary of each of the pair of coils in the first receiving coil
Characterized by being placed close to the field position ,
Tag information reading device. 7. A reception coil of the second coil section arranged to face each other.
Claim, characterized in that the files are connected in series
Item 5. A tag information reading device according to item 5 or 6 .