JPH10215210A - Data carrier system - Google Patents

Abstract

(57) Abstract: A data carrier system for transmitting a signal between a main unit having a power supply and a transmission / reception coil and a tag having a transmission / reception coil and operated by power supplied from the main unit, A means is provided for increasing the signal transmission distance between the main unit and the tag without increasing the power of the power supply of the main unit. SOLUTION: First control means for outputting a first signal,
Main unit 10 including first coil means including at least a transmission coil 21 for transmitting the first signal to the outside
A tuning circuit means including a tuning coil arranged opposite to the transmission coil of the first coil means and having a tuning circuit for tuning with the frequency of the first signal; and a second circuit including at least the reception coil 31a. A coil unit; and a second control unit that receives a first signal transmitted from the main body device via a receiving coil of the second coil unit and performs predetermined control based on the received first signal. Tag 30;

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data carrier system for transmitting a signal between a main unit and a tag, and more particularly to a power supply using electromagnetic coupling between a transmitting and receiving coil of the main unit and a transmitting and receiving coil of a tag. The present invention relates to a data carrier system for transmitting a signal between a main unit provided with a tag and a tag having no power supply.

[0002]

2. Description of the Related Art Conventionally, for example, a ski lift gate system uses a data carrier system for wirelessly transmitting and receiving signals between a main unit and a tag. The tag has a transmission / reception mechanism and a memory, and is attached to the skier's arm like a wristwatch. The memory stores various data, for example, the expiration date of the lift, the remaining number of times the ride can be performed, and the like. The main unit issues a question to the tag. When the skier passes near the main device, the tag receives a signal from the main device, obtains power from the received signal, and starts operation. Then, the tag reads data corresponding to the content of the question from the memory and transmits the data to the main device. The main device, based on the data transmitted from the tag,
It determines whether the lift can be used and controls the opening and closing of the gate.
Such data carrier systems include not only ski lift gate systems, but also railway automatic ticket gates,
It is used for various purposes, such as a system that attaches a tag to a product to prevent theft of the product.

[0003]

In such a data carrier system, the communication distance at which signals can be transmitted and received between the main unit and the tags is usually set so that various tags passing near the main unit can be individually recognized. , About 20 cm. By the way, depending on the use of the data carrier system, there is a case where it is desired to extend the communication distance. For this purpose, for example, a strong signal may be output from the main unit. However, since the tag operates by receiving power from the received signal, in this method, the main unit must considerably increase the output. In addition, since the main unit transmits a strong signal to a tag passing very close to the main unit, power in the main unit is wasted.

[0004] As this type of system, for example, USPat
ent No.5,500,651, entitled "System and Method for
Reading Multiple RF-ID Transponders "issued to JS
chuermann or corresponding Japanese Patent Kokai J
PA-8-180152 includes a transponder and a reader.
A system for transmitting and receiving signals between r) is disclosed. However, the invention of this patent aims at the reader to read each transponder without conflict between the transponders when there are a large number of transponders near one reader. No consideration is given to increasing the possible communication distance.

An object of the present invention is to provide a data carrier system for transmitting a signal between a main unit having a power supply and a transmission / reception coil and a tag having a transmission / reception coil and operated by electric power supplied from the main unit. An object of the present invention is to provide means for increasing the transmission distance of the signal between the main unit and the tag without increasing the power of the power supply of the main unit.

[0006]

According to the present invention, there is provided a data carrier system comprising: first control means for outputting a first signal; and first coil means including at least a transmission coil for transmitting the first signal to the outside. And a tuning circuit means including a tuning coil arranged opposite to the transmission coil of the first coil means, and a tuning circuit for tuning with the frequency of the first signal; and A second coil unit including a receiving coil, the first signal transmitted from the main body device being received via a receiving coil of the second coil unit, and a predetermined control based on the received first signal. And a tag having second control means for performing the following.

[0007] A tag monitoring device used in a data carrier system according to the present invention includes at least a first control means for outputting a first signal, and a transmitting coil for transmitting the first signal to a tag to be monitored. A main unit provided with a first coil unit, and a tuning circuit disposed as a tuning circuit unit separated from the main unit by a predetermined distance, and a tuning coil disposed opposite to a transmission coil of the first coil unit;
A tuning circuit having a capacitor connected in parallel to the tuning coil and tuning to the frequency of the first signal is provided, and a tag to be monitored by the monitor device is provided between the main device and the tuning circuit means. A passage for passing is provided.

In the present invention, the tuning coil of the tuning circuit is provided so as to face the transmission coil of the main unit, and the tag to be monitored is passed between the main unit and the tuning circuit. The electromagnetic coupling between the coil and the receiving coil of the tag is strengthened, and the signal transmission efficiency between the main device and the tag can be improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A data carrier system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

The data carrier system shown in FIG. 1A has an interrogator 10 as a main unit and a tag 30.
, A first tuning circuit 50, and a second tuning circuit 70. The tag 30 has a size of, for example, a business card, and is attached to a predetermined object. In this data carrier system, the interrogator 10 receives predetermined data stored in the tag 30 by transmitting and receiving signals between the interrogator 10 and the tag 30 passing near the interrogator 10.

The interrogator 10 has a transmitting coil 21 for transmitting a signal from the controller 11 to the tag 30 and a receiving coil 22 for receiving a signal from the tag. On the other hand, the tag 30 has a receiving coil 31a for receiving a signal from the interrogator 10. The first tuning circuit 50 includes a tuning coil 51. The first tuning circuit 50 includes the interrogator 1
The first tuning circuit 50 is provided to increase the distance for stably transmitting and receiving a signal between the tag 0 and the tag 30, and is characterized by the present invention.

Now, here, the interrogator 10, the first tuning circuit 5
FIG. 1 shows the positional relationship when the tag 30 is used.
This will be described with reference to FIG. Transmission coil 2 of interrogator 10
1 is planar and made circular or rectangular, preferably square. On the other hand, the tuning coil 51 of the first tuning circuit 50 is also formed in a planar shape, preferably in the same shape as the transmitting coil 21. If the transmitting coil 21 is circular with a radius r, preferably the tuning coil 51 is circular with a radius R, preferably R ≒
r. When the transmitting coil 21 is square, the tuning coil 21 is also square, and preferably one side has the same length. Further, as shown in FIG. 1B, the transmission coil 21 and the tuning coil 50 are substantially parallel and coaxial with each other, that is, such that the center axis of the transmission coil 21 coincides with the center axis of the tuning coil 50. Deploy. The tag 30 is
As described later, the transmission / reception common coil 31a is formed by arranging it on one plane, or the transmission coil 31a
And the receiving coil 32a are separately formed, and they are arranged and formed on one plane.

When used as a data carrier system, the tag has its coil 31 as shown in FIG.
In a posture such that the plane of “a” is substantially parallel to the plane of the coil 21 of the interrogator 10, it moves so as to pass through the passage 100 between the coil 21 of the interrogator 10 and the coil 51 of the first tuning circuit. . For the movement of the tag, the user may hold the tag in his / her hand and pass it through a predetermined passage, or a transfer machine having a mechanism for automatically feeding the tag through the passage 100 may be provided. Interrogator 10 and first tuning circuit 5
“0” functions as a tag monitor that monitors the contents of the tag.

As shown in FIG. 2, the interrogator 10 has a controller 11, an FSK modulation circuit 12, a power amplifier 13, a filter 14, a reception amplifier 15, a detection circuit 16, a transmission coil 21, and a reception coil 22. Here, a circuit portion including the controller 11, the FSK modulation circuit 12, and the power amplifier 13 is referred to as first control means. Normally, the tag randomly passes through the passage 100, so that the interrogator 10 repeatedly transmits a specific call signal at a predetermined cycle, for example, at a rate of 1 to 10 times / sec. Occurs. When the interrogator 10 receives the specific confirmation signal, the interrogator 10 determines that the tag is currently passing through the passage 100 and transmits a signal regarding a legitimate question. The controller 11 controls the transmission of a signal such as a call signal to a tag and a signal related to a legitimate question, and determines contents such as a confirmation signal received from the tag and an answer to the question signal.

The FSK modulation circuit 12 includes a controller 11
The FSK (Frequency Shift) expressed by the combination of the signals of two different frequencies
t Keying) It modulates to a modulation signal. This FSK
Specifically, the modulation circuit 12 includes an oscillator 121, a first frequency divider 122, and a second frequency divider 123, as shown in FIG.
, A third frequency divider 124, a data register 125, and a band-pass filter 126.

The data register 125 stores the binary signal S ₁ sent from the controller 11. The data register 125 supplies the binary signal S ₁ to the first frequency divider 122 as a control signal S ₂ . The reference clock C output from the oscillator 121 is sent to the first frequency divider 122. Here, the frequency of the reference clock C is 16.0 MHz.
It is. The first frequency divider 122 divides the reference clock C by switching the frequency division ratio to 16 or 17 according to the control signal S ₂ from the data register 125. For example, when the control signal S ₂ is “1”, the first frequency divider 122 performs the frequency-dividing operation by 16, and the control signal S ₂ becomes “0”.
, The first frequency divider 122 performs a 17-frequency division operation.
The second frequency divider 123 divided by 8 the output signal S ₃ of the first frequency divider 122. Output signal S ₄ of second frequency divider 123
Is output to the band-pass filter 126 and sent to the third frequency divider 124.

The third frequency divider 124 divides the output signal of the second frequency divider 123 by 16. The output signal S ₅ of the third divider 124 is supplied as a data clock to the clock terminal of the data register 125 (not shown). First frequency divider 1
The control signal S ₂ for switching the frequency division ratio of the _second frequency divider 22 is the output signal S _{5 of} the third frequency divider 124 (that is, the first frequency divider 1
The data register 125 supplies the output signal to the first frequency divider 122 in synchronism with the output signal of the P.22 signal divided by 128. Therefore, when the control signal S ₂ is “0”, the frequency of the output signal S ₄ of the second frequency divider 123 is (16 MHz / 17) × (１ ／) = 1117.647 k
Hz, and when the control signal S ₂ is “1”, the second frequency divider 1
The frequency of the 23 output signal S ₄ is (16 MHz / 16) × (１ ／) = 125 kHz. The third frequency divider 124, for each 16 cycles of the above-mentioned signal S _4, and generates a signal S _5, in response to the signal S _5,
Data register 125 provides the following binary signal S ₂ to the first frequency divider 122.

The band pass filter 126 is a second frequency divider.
123 output signal S_FourThe signal band to a sine wave
It is to suppress. Output from band pass filter 126
The signal to be transmitted is an FSK modulated signal S₆Power amplifier 1
3, after being amplified by the transmission coil 21
You. This FSK modulated signal S₆Of the signal S_FourFrequency
Control signal S_Two125kHz when is "1"
z and the control signal S _TwoIs about 117 kHz when is "0"
z. Thus, in the interrogator 10, these two
By switching frequency signals, you can send questions
Emission from the tag 21 to the tag 30. In addition, it was sent from the interrogator.
One question is formed by, for example, 12 bits.

The filter 14 extracts a signal having a predetermined frequency from signals received by the receiving coil 22. The signal extracted by the filter 16 is received by the receiving amplifier 1
After being amplified at 5, the signal is sent to the detection circuit 16. The detection circuit 16 demodulates the signal amplified by the reception amplifier 15 into a binary signal. This binary signal is sent to the controller 1
1 is output.

The present inventors conducted the following studies when determining the size of the transmitting coil 21. When current flows I in a circular coil having a radius r, the magnetic field strength H at the position where the distance d on the central axis from the center of the ^{coil, H = nIr 2/2 (} r 2 + d 2) 3/2 ··· (1) Here, n is the number of turns of the coil. The power P dissipated in the coil is proportional to the maximum energy stored in the coil given by LI ^2/2. Here, L is the self-inductance of the coil. In the case of a circular coil, the self-inductance L is the radius r of the coil.
And therefore proportional to the area of the coil. By the way, as the current I and the radius r of the coil are increased, the power consumption P of the coil increases, but as a practical problem, the power consumption P of the coil has a limit. Therefore, equation (1) will be considered under the condition that power P is constant.

Now, the radius r of the coil is 1 cm and the distance d is
The intensity of the magnetic field given by the equation (1) when it is 0.1 cm is defined as H ₀ . At this time, if the relationship between the distance d and the magnetic field strength ratio H / H ₀ is drawn for a certain radius r under the condition that the power P is constant, a graph shown in FIG. 7 is obtained. Here, series 1 has a coil radius r of 1 cm, series 2 has a coil radius r of 2 cm, series 3 has a coil radius r of 5 cm, and series 4 has a coil radius r of 5 cm. When 10 cm is set, series 5 is set when the coil radius r is set to 20 cm, and series 6 is set when the coil radius r is set to 20 cm.
Is 30 cm, series 7 has a coil radius r of 50
cm.

As can be seen from this graph, when the distance d is very short, for example, when d = 0.1 cm, the radius r
Is smaller, the strength H of the magnetic field is larger. Conversely, when the distance d is larger, for example, when d = 100 cm, the larger the radius r, the larger the strength H of the magnetic field.
If the distance d is constant in the middle, for example, d = 10
cm, a coil with a radius r = 10 cm approximately equal to the distance d creates the maximum magnetic field strength H. Therefore, the radius r
Is substantially equal to the distance d. On the other hand, it is not desirable to use large coils, as it is economically desirable to make the device as compact as possible. Therefore, in this embodiment, in order to use as little power as possible and to make the device compact, a planar loop-shaped coil having a radius r of about 20 cm is used as the transmission coil 21. The shape of the transmission coil is not necessarily circular, but may be, for example, square. When a rectangular coil is used, the radius is converted into the radius of a circular coil having the same area as that of the coil, and the converted radius is set to 20 cm.

As the receiving coil 22, a planar loop having a radius of about 15 cm, which is slightly smaller than the transmitting coil 21, is used. The transmitting coil 21 and the receiving coil 22 are arranged on the same plane with their centers aligned. As shown in FIG. 1, the first tuning circuit 50 has a planar loop-shaped coil 51 and a capacitor 52 connected in parallel to the coil 51. The tuning frequency determined by the coil 51 and the capacitor 52 of the first tuning circuit 50 is set to be substantially the same as the frequency of the signal sent from the interrogator 10 to the tag 30. As mentioned above,
In this embodiment, since two signals of 125 kHz and 117 kHz are transmitted, the tuning frequency is an average value of the frequencies of the two signals, that is, 121 kHz. Further, the radius R of the coil 51 is about 20 cm, like the radius r of the transmission coil 21 of the interrogator 10 as described above.

As shown in FIG. 1B, the first tuning circuit 5
0 planar coil 51 and the planar coil 21 of the interrogator 10
Are arranged parallel to each other and preferably such that their central axes coincide. Also, when the tag 30 moves through the passage 100 between the coil 51 and the transmitting coil 21, it receives a signal from the interrogator 10. The interrogator 10 and the first tuning circuit 50 function as a tag monitor for monitoring the contents of the tag passing therebetween.

The tag 30 has a distance between the passage 100 and the interrogator 10 such that the coil 31a passes through a position within the maximum possible communication distance between the coil 31a and the transmitting coil 21 of the interrogator 10. Is set. On the other hand, the first tuning circuit 50 is provided to increase the communicable distance between the interrogator 10 and the tag 30 as will be described later.
0 is set so as to be located between the transmission coil 21 of the interrogator 10 and the coil 51 of the first tuning circuit 50. In the present invention, the distance D between the coil 51 and the transmission coil 21 is set to about 50 cm. The setting of this interval will be described later in detail.

As shown in FIG. 1A, the second tuning circuit 70 has a planar loop-shaped coil 71 and a capacitor 72 connected in parallel to the coil 71. The tuning frequency determined by the coil 71 and the capacitor 72 of the second tuning circuit 70 is set to be substantially the same as the frequency of the signal transmitted from the tag 30 to the interrogator 10, for example, about 60 kHz. The coil 71 has a smaller radius than the coil 21, for example, about 7.5 cm.
Are concentrically arranged on the same plane.

The reason why the transmitting coil 21, the receiving coil 22, and the coil 71 are arranged on the same plane so that the centers thereof coincide with each other is to make the interrogator 10 compact. Next, the tag 30 used in the data carrier system of the present embodiment will be described. As shown in FIG. 4A, the tag 30 includes a resonance circuit 31, a rectification circuit 35, a smoothing circuit 36, an FSK detection circuit 41, and a controller 42.
, A ROM 43, a RAM 44, and a transmission circuit 45. Here, the FSK detection circuit 41 and the controller 4
2. The ROM 43, the RAM 44, and the transmission circuit 45 correspond to the second control unit of the present invention. This tag 30 usually contains
From the viewpoint of maintenance and the like, batteries and the like are not used.
The tag 30 operates by obtaining power from a signal received by the resonance circuit 31. Therefore, the tag 30 is provided with a rectifying circuit 35 and a smoothing circuit 36.

The resonance circuit 31 has a transmission / reception coil 31a electromagnetically coupled to the transmission coil 21, and a capacitor 31b. The transmission / reception coil 31 a electromagnetically couples with the transmission coil 21 of the interrogator 10 to receive a signal from the transmission coil 21 and generate a magnetic field for transmitting a signal to the interrogator 10. The resonance frequency of the resonance circuit 31 is determined by the transmission coil 2 from the FSK modulation circuit 12 of the interrogator 10.
The frequency is set so as to be substantially the same as the frequency of the AC signal sent to 1. The FSK modulation circuit 12
Since two AC signals of 5 kHz and 117 kHz are transmitted, the resonance frequency of the resonance circuit 31 is an average value of the frequencies of the two AC signals, that is, 121 kHz.

In FIG. 4A, a coil 31 for both transmission and reception is used.
Although a is used, the coil 31a may be used only for reception and the transmission-only coil 32a may be separately provided. In that case,
The transmitting coil 32a is connected to a transmitting circuit 45 as shown in FIG. 4B, and a capacitor 32b is connected in parallel with the transmitting circuit 45. The transmitting / receiving coil 31a is formed by connecting two coil portions formed by printing a spiral pattern having a predetermined shape of a conductive material on both surfaces of a flat resin film, respectively, in series. Similarly, when the transmission coil and the reception coil are separately formed, each coil is divided into two coil portions, and each coil portion is concentrically printed on both surfaces of the resin film. The various ICs that make up the tag
It is appropriately formed on a portion of the resin film where the transmission / reception coil is not formed.

The size of the transmitting and receiving coil 31a is smaller than the receiving coil of the interrogator 10 and is approximately 3 to 4 cm in the case of a circular coil. The length is about 3 to 4 cm, and the number of turns is about 50. An electromotive force induced by a magnetic field generated in the transmission coil 21 is generated in the transmission / reception coil 31a of the resonance circuit 31. The induced current due to the electromotive force is rectified by the rectifier circuit 35, and then the smoothed circuit 36
Is smoothed. The smoothing circuit 36 has a resistor 36a, a zener diode 36b, and a capacitor 36c. The electric charge is stored in the capacitor 36c, and the voltage determined by the capacitance becomes the power supply voltage. This power supply voltage is
FSK detection circuit 41, controller 42, ROM 43,
The signals are supplied to the RAM 44 and the transmission circuit 45, whereby each unit starts operating. In the present embodiment, the tag 30 is 1
It is designed to operate normally with an induced electromotive force of 3 Vpp (the induced electromotive force whose maximum value is 6.5 V). The reason why the zener diode 36b is provided in the smoothing circuit 36 is to prevent the voltage from rising to a certain value or more and each part from being destroyed.

The FSK detection circuit 41 includes the transmitting and receiving coil 3
1a detects the FSK modulation signal received.
Specifically, the FSK detection circuit 41 includes an oscillator 411, a gate signal detection circuit 412, a gate circuit 413, a counter circuit 414, and a memory 41, as shown in FIG.
5 and a determination circuit 416. FSK modulated signal (input signal) S ₁₁ the resonance circuit 31 has received is input to the gate signal detection circuit 412. Gate signal detection circuit 412
Gate signal S ₁₂ output from is supplied to the control terminal of the gate circuit 413. Output S ₁₃ of the oscillator 411 via the gate circuit 413 is sent to the counter circuit 414. The output of the counter circuit 414 is supplied to a first input terminal of the memory 415 and the determination circuit 416, and the output of the memory 415 is supplied to a second input terminal of the determination circuit 416. Input signal S ₁₁ is FSK modulated, the modulation cycle has a 16 cycles of the carrier signal. Therefore, the cycle per bit of digital data transmitted from the interrogator and received by the coil 31a is:
This corresponds to 16 cycles of the carrier signal. The oscillator 41
1 is set to 3 MHz.

[0032] The waveform of the input signal S ₁₁ in FIG. 6 (a), 6
The gate signals S ₁₂ detected by the gate signal detecting circuit 412 (b), the output S ₁₃ of the oscillator 411 in FIG. 6 (c),
Figure 6 (d) shows the output S ₁₄ of the gate circuit 413. Gate signal detection circuit 412, as shown in FIG. 6 (b), the gate signal S ₁₂ of 4 cycles of time of the input signal S ₁₁ width, 1
They are taken out at intervals of two or two cycles. This, FSK modulation cycle of the input signal S ₁₁ corresponds to it is in the 16 cycles of the carrier signal.
That is, the interval t ₁ for one cycle of the input signal S ₁₁ is twice,
2 cycles interval t ₂ to one of the input signals S _11, further duration t ₃ of the gate signals S ₁₂ 3 times, which together repeatedly operates at 16 cycles of the gate signal detection circuit 412 is the input signal S ₁₁ as to, it is set the interval between the gate signals S _12. This is referred to as one modulation cycle (period of an H ₁ in FIG. 6).

The gate circuit 413 outputs the output S of the oscillator 411 only during the period t ₃ of the gate signal S ₁₂ shown in FIG.
₁₃ is sent to the counter circuit 414. Counter circuit 414
Counts the output S ₁₃ of the oscillator 411 sent through the gate circuit 413,
To supply. The memory 415 stores the count value C ′ for each of the three gate signal periods t ₃ over one modulation cycle.
_1, C stores _'2, C' _3. In the judgment circuit 416,
In the next modulation cycle period, the count value supplied from the counter circuit 414 is changed to the corresponding gate signal period t.
Compare every _three . That is, the count values C ′ ₁ , C ′ ₂ and C ′ ₃ shown in FIG. 6D are compared with the count values C ₁ , C ₂ and C ₃ one modulation cycle period earlier. Frequency f of the high input signal S ₁₁ is the carrier frequency which has received the FSK modulation side
Since the count value differs by 4 or more between the case of _HIGH (= 125 kHz) and the case of the frequency f _LOW (= 117 kHz) on the lower side of the carrier frequency, the input signal is subjected to FSK modulation by comparing the difference between the count values. It is possible to determine whether the frequency f _HIGH on the higher carrier frequency or the frequency f _LOW on the lower carrier frequency. In addition, the signal sent from the interrogator to the tag includes a known binary signal of "1" or "0" at the beginning, and based on its carrier frequency, whether the subsequent binary signal is "0" or not. It is determined whether it is "1". The result of the determination circuit 416 is output to the controller 42.

The ROM 43 stores a predetermined program, and the RAM 44 stores predetermined data. The controller 42 determines the content of the question from the interrogator 10 based on the signal output from the FSK detection circuit 41,
A signal corresponding to the inquiry is sent to the transmission circuit 45. Specifically, a signal for recognizing that the tag 30 exists near the interrogator 10,
A signal related to information, a signal related to data stored in the RAM 44, and the like are output to the transmission circuit 44.

The transmission circuit 45 modulates the power supply current received by the transmission / reception coil 31a based on the signal from the controller 42, and AM-modulates the received signal to transmit. . Such a transmission circuit 4
Reference numeral 5 has a resistor and a switch. When the switch is closed, the power supply current flows through the resistor, and power is consumed by the resistance. On the other hand, when the switch is opened, the power supply current flows without passing through the resistance. When the transmission circuit 45 controls the opening and closing of the switch according to the binary signal from the controller 42, the load of the power supply changes, and the magnetic field generated in the coil 31a of the resonance circuit 31 also changes. Thus, the signal received by the resonance circuit 31 is subjected to AM modulation at the same time as the reception, and a magnetic field is generated.
For example, when a signal having a frequency of 125 kHz is received, a signal having a modulation frequency of 62.5 kHz is sent back. Therefore, in the present embodiment, the tag 30
It is not necessary to provide a transmitting coil and a receiving coil separately,
One coil can be used for both transmission and reception.
Note that the resistor 36a serves to balance the current supplied from the transmission circuit 45 to the rectifier circuit 35 so that the current does not flow too much toward the smoothing circuit 36.

The signal transmitted from the transmitting / receiving coil 31a of the tag 30 in this manner is received by the receiving coil 22 of the interrogator 10. The filter 14 of the interrogator 10 extracts only the side band of the received signal. The extracted sideband is amplified by the receiving amplifier 15 and then demodulated by the detection circuit 16.

Next, an experiment performed by the present inventors on the data carrier system of the present embodiment will be described.
First, the present inventors will explain how the communication distance in which a signal can be transmitted from the interrogator 10 to the tag 30 changes when the first tuning circuit 50 is provided and not provided in such a data carrier system. Was examined.

First, the first tuning circuit 50 was removed from the data carrier system. Then, the distance between the tag 30 and the interrogator 10 is sufficiently small so that the transmission / reception coil 31a of the tag 30 faces the transmission coil 21 of the interrogator 10,
For example, it was 0.1 cm (state). In this state,
An induced electromotive force of about 30 Vpp is generated in the tag 30, and the tag 3
0 was working well. Next, the tag 30 is attached to the interrogator 10.
, The transmission coil 31a and the transmission coil 21 gradually separated from each other along the direction in which they face each other. Then tag 3
The induced electromotive force generated at 0 gradually decreased. When the distance became about 30 cm, the induced electromotive force became lower than about 13 Vpp, and the tag 30 could not operate completely. further,
Move the tag 30 away from the interrogator 10 and the distance
At 0 cm, the tag 30 has an induced electromotive force of about 9 Vpp.
And stopped working completely. And the tag 30
Was fixed at the position having an induced electromotive force of about 9 Vpp (state). In this state, the present inventors set the first tuning circuit 50 to the tag 30 so that the coil 51 of the first tuning circuit 50 faces the transmission coil 21 of the interrogator 10.
Was installed at a position opposite to the interrogator 10. Then, an induced electromotive force of about 13 Vpp is generated in the tag 30,
The tag 30 has resumed operation. in this way,
The present inventors provide the first tuning circuit 50,
It has been found that the signal from the interrogator 10 becomes stronger and the communication distance over which the signal can be transmitted from the interrogator 10 to the tag 30 increases.

Further, the present inventors conducted an experiment in further detail. The communication distance was determined by the distance D between the transmission coil 21 of the interrogator 10 and the coil 51 of the first tuning circuit 50 and the coil 5.
1 was obtained, depending on the inner area (or radius).
That is, when the distance D is larger than the radius of the transmitting coil 21, the inner area of the coil 51 needs to be equal to or larger than the inner area of the transmitting coil 21.
This is because the magnetic field generated by a circular coil is almost uniform at a distance sufficiently close to the radius of the circular coil, but at a distance sufficiently far from the radius of the circular coil, the magnetic field is a cube of the distance. Weakens in inverse proportion to Therefore, when the coil 51 is placed at a distance farther than the radius of the transmission coil 21, the size of the coil 51 is
Must be greater than or equal to the size of As a practical matter, it is difficult to make the tuning coil much larger than the transmitting coil, so a tuning coil having the same size as the transmitting coil is used. That is,
Assuming that the size of the transmitting coil and the tuning coil is expressed in terms of the radius of a circular coil of the same size, and the size of the transmitting coil is R and the size of the tuning coil is r, then R = r. In this case, the distance D is a value that satisfies the expression 2R ≦ D ≦ 3R.

The present inventors assume that when the radius of the transmitting coil 21 is about 20 cm, the distance D between the transmitting coil 21 and the coil 51 is about 50 cm, and the radius of the coil 51 is about 20 cm,
By providing the first tuning circuit 50, a communication distance of about 5
We confirmed that we increased. In this case, the experiment was conducted by arranging the transmitting coil 21, the transmitting / receiving coil 31 a of the tag 30, and the coil 51 on a straight line, and making the planes formed by the coils parallel. In addition, when experiments were conducted under various conditions, the communication distance was increased by at least 10% to 20%. Even if the communication distance is increased by only 10%, it is very effective in terms of electric power.

According to the investigation by the present inventors, there was no effect even if the number of turns of the coil 51 was changed or a core was inserted in the coil 51. Next, the present inventors, in such a data carrier system, when the second tuning circuit 70 is provided and when the second tuning circuit is not provided, from the tag 30 the interrogator 10.
We investigated how the communication distance at which signals can be transmitted changes. As a result of this experiment, by providing the second tuning circuit 70, similarly to the above, the signal from the tag 30 becomes strong,
It turned out that the communication distance increased. In this case, tag 3
Considering that the transmission / reception coil 31a of 0 is small,
As the coil 71 of the second tuning circuit 70, the receiving coil 2
2/4 or less of the inner area of the transmission / reception coil 31
It is desirable to use one having an inner area larger than the inner area of a.

In the data carrier system according to the present embodiment, the first tuning circuit that has a loop-shaped coil disposed opposite to the transmission coil and tunes to the frequency of the signal transmitted from the transmission coil is provided. The signal transmitted from the transmission coil can be strengthened. Also, by providing a loop-shaped coil arranged concentrically with the transmission coil on the plane created by the transmission coil and providing a second tuning circuit for tuning to the frequency of the signal transmitted from the transmission / reception coil of the tag Thus, the signal from the transmitting / receiving coil can be strengthened. Therefore, it is possible to extend the communication distance in which signals can be transmitted and received between the interrogator and the tag without increasing the output of the interrogator. In addition, if the effect of the expansion of the communication distance is used in reverse, the communication distance can be maintained when the transmission / reception coil is not reduced even if the transmission / reception coil of the tag is small. There is also an effect that can be achieved.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the invention. For example, in the above embodiment, the case where the coil of the second tuning circuit is arranged concentrically on the plane formed by the transmission coil of the interrogator, but the coil of the second tuning circuit is not necessarily the transmission coil of the interrogator. It is not necessary to arrange them on the same plane as the above, for example, they may be arranged behind the interrogator.

In the above embodiment, the case where the interrogator receives predetermined data stored in the tag by transmitting and receiving signals between the interrogator and the tag passing near the interrogator is described. However, the tag may only receive a signal from the interrogator and not transmit a signal. For example, the data carrier system of the present invention can be applied to a tag that emits light when a signal is received as a tag.

[0045]

As described above, according to the present invention, there is provided a loop-shaped first tuning coil disposed opposite to a main body transmission coil of a main body apparatus, and a signal transmitted from the main body transmission coil. By providing the first tuning circuit that tunes to the frequency, the signal transmitted from the main body transmission coil can be strengthened, so that the signal can be transmitted from the main body device to the tag without increasing the output of the main body device. A data carrier system capable of extending a communication distance can be provided.

[Brief description of the drawings]

FIG. 1A is a diagram schematically showing a configuration of a data carrier system according to an embodiment of the present invention, and FIG.
(A) The transmitting coil of the data carrier system, the first
It is a figure which shows the positional relationship of a tuning circuit and a tag.

FIG. 2 is a block diagram showing a configuration of an interrogator of the data carrier system of FIG.

FIG. 3 is a block diagram showing a configuration of an FSK detection circuit of the interrogator of FIG. 2;

FIG. 4A is a diagram illustrating a data carrier system.
FIG. 3B is a block diagram illustrating a schematic configuration when a tag transmission coil and a reception coil are shared, and FIG. 2B is a diagram illustrating a configuration of a transmission coil portion when a tag transmission coil and a reception coil are separately provided; is there.

FIG. 5 is a block diagram showing a configuration of an FSK detection circuit of the tag of FIG.

FIG. 6 is a diagram illustrating signal waveforms at various parts for explaining the operation of the FSK detection circuit in FIG. 5;

FIG. 7 is a graph showing the relationship between the magnetic field strength on the central axis of the circular coil and the distance from the center of the circular coil using the radius of the circular coil as a parameter under a constant power condition.

[Explanation of symbols]

 Reference Signs List 10 interrogator 11 controller 12 FSK modulation circuit 13 power amplifier 14 filter 15 reception amplifier 16 detection circuit 21 transmission coil 22 reception coil 30 tag 31 resonance circuit 31a transmission / reception coil 31b capacitor 35 rectification circuit 36 smoothing circuit 36a resistance 36b zener diode 36c capacitor 41 FSK detection circuit 42 Controller 43 ROM 44 RAM 45 Transmission circuit 50 First tuning circuit 51 Coil 52 Capacitor 70 Second tuning circuit 71 Coil 72 Capacitor 121 Oscillator 122 First frequency divider 123 Second frequency divider 124 Third frequency dividing Instrument 125 Data register 126 Band pass filter 411 Oscillator 412 Gate signal detection circuit 413 Gate circuit 414 Counter circuit 415 Memory 416 Judgment circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 1/59 H04B 1/59

Claims (22)

[Claims] A first control means for outputting a first signal;
A main unit comprising: a first coil unit including at least a transmission coil for transmitting the first signal to the outside; and a tuning coil disposed opposite to a transmission coil of the first coil unit; Tuning circuit means having a tuning circuit for tuning with the frequency of the first signal; second coil means including at least a receiving coil; and reception of the first signal transmitted from the main unit by the second coil means. A tag provided with a second control unit that receives the signal via a coil and performs predetermined control based on the received first signal. 2. The tuning coil according to claim 1, wherein
2. The data carrier system according to claim 1, wherein the size of the coil surface is substantially the same as that of the transmission coil of the coil means. 3. The second control means of the tag includes a means for generating a second signal based on the received first signal, and the second coil means of the tag includes: A transmitting coil for transmitting a signal, wherein the first coil means of the main body device transmits the second coil transmitted by the transmitting coil of the tag.
2. The data carrier system according to claim 1, further comprising a receiving coil for receiving the signal of (1). 4. The data carrier system according to claim 3, wherein the receiving coil and the transmitting coil of the second coil means of the tag are formed in one common transmitting and receiving coil. 5. The transmitting coil and the receiving coil of the first coil means of the main body device are formed as concentrically arranged loop-shaped circular coils, and the radius of the receiving coil is smaller than the radius of the transmitting coil. The data carrier system according to claim 4, wherein: 6. A loop-shaped circular second tuning coil arranged concentrically with the receiving coil of the first coil means of the main unit, and a second capacitor connected in parallel to the second tuning coil. 6. A data carrier system according to claim 5, further comprising a second tuning circuit means including a second tuning circuit for tuning to a frequency of said second signal transmitted from said tag. 7. The transmitting and receiving coil of the second coil means of the tag, wherein the second tuning coil is one-fourth or smaller than the inner area of the receiving coil of the first coil means of the main unit. 7. The data carrier system according to claim 6, wherein the data carrier system has an inner area larger than the inner area. 8. The transmitting coil of the first coil means of the main body device is a circular coil, and the tuning coil of the tuning circuit means is a circular coil having substantially the same radius as the circular coil of the transmitting coil. The data carrier system according to claim 1, wherein 9. When the size of each of the transmitting coil and the tuning coil is represented by the radius of a circular coil having the same inner area, the size of the transmitting coil of the first coil means is R, When the size of the tuning coil of the tuning circuit can be represented by r, R is substantially equal to r, and the value of the distance D between the first coil means and the tuning circuit means is 2R ≦ D ≦ 3R
2. The data carrier system according to claim 1, wherein the following condition is satisfied. 10. A first coil means including a transmission coil and a reception coil, receiving a first signal from the outside via the reception coil, performing various controls based on the received first signal, Control means for generating at least a second signal; a tag including means for transmitting the second signal to the outside via the transmission coil; and electromagnetic coupling with the reception coil of the first coil means of the tag A magnetic transmission coil for transmitting a signal to the tag, and a transmission coil of the first coil means of the tag which is electromagnetically coupled to receive a signal transmitted from the tag and transmit the signal in a circular loop. A second coil means including a coil and a circular loop-shaped receiving coil arranged concentrically; and a circular loop-shaped tuning coil arranged concentrically with the receiving coil of the second coil means. , Data carrier system characterized by comprising: a tuning circuit means comprising a tuning circuit including the connected tuning capacitor in parallel with the tuning coil. 11. The data carrier system according to claim 10, wherein the tuning coil has a larger size than a receiving coil of the second coil means of the main unit. 12. The data carrier system according to claim 10, wherein the transmitting coil and the receiving coil of the tag are formed in one common transmitting and receiving coil. 13. A tag including: a loop-shaped receiving coil for receiving a signal sent from the outside; a control unit for performing various controls based on the received signal; and a electromagnetic coupling with the receiving coil of the tag. A main unit having a loop-shaped transmitting coil for transmitting a signal to the receiving coil of the tag; and a main unit disposed near the receiving coil of the tag, between the receiving coil of the tag and the transmitting coil of the main unit. Means for enhancing the electromagnetic coupling of the data carrier system. 14. The means for enhancing electromagnetic coupling includes a tuning circuit having a tuning coil and a capacitor connected in parallel to the tuning coil, wherein the tuning circuit tunes to a frequency of a signal transmitted from the main unit to the tag. 14. The data carrier system according to claim 13, including circuit means for configuring. 15. A tag including a control unit for generating a first signal, a tag including a loop-shaped transmission coil for transmitting the first signal to the outside, and electromagnetically coupling with the transmission coil of the tag, and A main unit having a loop-shaped receiving coil for receiving the first signal to be transmitted; and a main unit disposed near the receiving coil of the main unit, between the receiving coil of the main unit and the transmitting coil of the tag. Means for enhancing the electromagnetic coupling of the data carrier system. 16. The means for enhancing electromagnetic coupling includes circuit means having a tuning coil and a capacitor connected in parallel with the tuning coil, forming a tuning circuit for tuning to the frequency of the first signal. The data carrier system according to claim 15, wherein: 17. A main body device comprising: first control means for outputting a first signal; and first coil means including at least a transmission coil for transmitting the first signal toward a tag to be monitored. A tuning circuit arranged at a predetermined distance from the main unit, and a tuning coil arranged opposite to a transmission coil of the first coil means, and a capacitor connected in parallel to the tuning coil. A tag monitor device for use in a data carrier system, comprising: a tuning circuit means having a tuning circuit for tuning to a frequency of the first signal. 18. The tag monitoring device according to claim 17, further comprising a passage provided between said main device and said tuning circuit means, for passing a tag to be monitored by said monitoring device. 19. The tag monitor device according to claim 17, wherein the size of the coil surface of the transmitting coil of the first coil means is the same as the size of the coil surface of the tuning coil. 20. The first coil means of the main body device,
A receiving coil for receiving a second signal transmitted from the tag to be monitored, wherein the transmitting coil and the receiving coil of the first coil means are both formed in a circular loop shape and arranged concentrically; 18. The tag monitor according to claim 17, wherein: 21. The tag monitor device according to claim 20, wherein a radius of said reception coil of said first coil means is smaller than a radius of said transmission coil. 22. When the size of each of the transmitting coil of the first coil means and the tuning coil of the tuning circuit means is represented by a radius of a circular coil having a coil surface of the same size as each coil surface, When the size of the transmitting coil of the first coil means is R and the size of the tuning coil is r, the value of the distance D between the main unit and the tuning circuit means is 2R
The condition of ≦ D ≦ 3R is satisfied.
The tag monitor device according to the above.