JP3578013B2 - ID tag transceiver - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ID tag transmitting / receiving device for transmitting / receiving a radio signal to / from an ID tag.
[0002]
[Problems to be solved by the invention]
For example, as a moving object identification system, there is a remote ID system using high-frequency radio waves. In this method, communication between a controller and an ID tag is performed by radio waves, and data of an ID tag at a remote position is read or data is written to the ID tag.
[0003]
The remote ID system is considered to be applied to various systems such as a delivery system, an inventory management system, and a sales system. One example is a tallying system for rotating sushi restaurants. The outline of this system is to record data such as the type of sushi, the time it was made, and the selling price on an ID tag embedded in the plate on which the sushi is to be placed. It collects them in places, communicates with the ID tags on those dishes, and obtains data from the ID tags to calculate the amount to be paid by the customer.
[0004]
When applied to such an aggregation system, a handheld type reader / writer (transmitter / receiver) for communicating with the ID tag is employed. In a hand-held reader / writer, transmission / reception is usually performed by holding the reader / writer body above a plate stacked on a table. However, radio waves for transmission and reception are not so strong, and depending on the number of stacked dishes, there may be a problem that communication with the lower dish cannot be performed.
[0005]
In that case, it seems that it is sufficient to hold the reader / writer body in the middle of the stacked dishes for transmission and reception. However, the transmission antenna of the reader / writer is composed of one coil, and the transmission antenna coil Of the magnetic fluxes transmitted from the transmission antenna coil, the magnetic flux at the center of the transmission antenna coil goes substantially straight, and does not link with the antenna coil of the ID tag. For this reason, it is not possible to communicate with the ID tag of the plate immediately beside the reader / writer, and to communicate with all the plates, the reader / writer body must be moved up and down along the stacked plates, There is a problem that operation is troublesome.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ID tag transmission / reception device that can communicate with many ID tags without much movement.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention is to dispose a resonance antenna coil at a position deviated from a transmission antenna coil, open and close the resonance antenna coil by an opening / closing means during transmission, and provide a resonance antenna coil. The structure is such that the resonance frequency of the resonance antenna coil is controlled to be the same as the transmission frequency of the transmission antenna coil at the time of closing.
According to this configuration, when the resonance antenna coil is open, a radio signal is transmitted only from the transmission antenna coil, and when the resonance antenna coil is closed, an electromotive force is generated in the resonance antenna coil by the radio signal transmitted from the transmission antenna coil. As a result, the coil for the resonance antenna generates a magnetic flux. If the configuration is such that the radio wave signal is actively transmitted from the resonance antenna coil, the radio wave signal (magnetic flux) is also transmitted from the resonance antenna coil when the antenna is closed. For this reason, the direction and intensity of the magnetic flux change at the same location when the resonant antenna coil is opened and when it is closed. Can be communicated when the resonance antenna coil is closed. In addition, by setting the resonance frequency of the resonance antenna coil to be the same as the transmission frequency of the transmission antenna coil, required electric waves can be transmitted with a small amount of power.
[0008]
According to a second aspect of the present invention, when the modulation scheme of a signal for transmission is frequency shift keying, the resonance frequency of the resonance antenna coil is changed in synchronization with a change in the transmission frequency. By doing so, a radio signal can be transmitted more efficiently .
[0009]
According to a third aspect of the present invention, the resonance frequency of the transmission antenna coil is switched according to the opening and closing of the opening and closing means .
When the resonance antenna coil is closed, the transmission antenna coil is electromagnetically coupled to the resonance antenna coil and its reactance changes. Therefore, by switching the resonance frequency of the transmission antenna coil in accordance with the opening and closing of the opening and closing means, a radio signal can be transmitted with a small amount of power .
[0010]
According to a fourth aspect of the present invention, the transmitting and receiving apparatus is a hand-held type including a hand-held unit and a head provided at one end of the hand-held unit and provided with a transmission antenna coil and a resonance antenna coil. The antenna coil is formed in half the size of the transmission antenna coil, and is provided at a position facing the left half or the right half of the transmission antenna coil when the head is directed upward .
[0011]
When articles with ID tags are stacked, when the resonance antenna coil is opened and closed in a state where the resonance antenna coil is vertically displaced with respect to the transmission antenna coil, the magnetic flux of almost going straight on Since the position changes up and down, it becomes possible to communicate with the ID tags of all the stacked articles. On the other hand, when holding the hand-held transmission / reception device beside the stacked articles, it is natural and easy to operate and operate when the hand-held part is in a horizontal state. For this reason, as in the second aspect of the present invention, when the head is turned upward and provided at a position opposite to the left half or the right half of the transmission antenna coil, the resonance antenna is used when the hand-held part is laid down. Since the coil is located above or below the coil for the transmitting antenna, it is possible to communicate with the ID tag in an easy-to-operate state .
[0012]
The invention according to claim 5 is characterized in that the resonance antenna coil is arranged on the ID tag side of the transmission antenna coil during transmission .
According to this configuration, by bringing the coil for the resonance antenna closer to the ID tag, the effect of the magnetic flux by the coil for the resonance antenna can be increased, and the shape of the magnetic field near the ID tag can be greatly changed. In particular, when the resonance antenna coil is configured to generate a magnetic flux by a radio signal transmitted from the transmission antenna coil, the amount of magnetic flux generated by the current induced in the resonance antenna coil depends on the transmission antenna coil. Since the amount is smaller than the amount of magnetic flux, the effect of the configuration of claim 5 is large .
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that this embodiment is applied to a tallying system of a revolving sushi shop. Here, the rotating sushi shop is a shop having the following system.
[0014]
Inside the store, a loop-shaped conveyor is provided, and seats are provided along the conveyor. Sushi is placed on a plate and transported to the audience by a conveyor. The customer takes the dish on which the favorite sushi is placed from among the dishes carried by the conveyor, and after eating, the dishes are sequentially stacked on the table. The shop places the sushi on a dish of a color or a pattern according to the selling price, so that the customer can know the approximate amount to be paid to the shop from the stacked dishes and the number of dishes. After the meal, the clerk counts the number of plates by color or pattern, and determines the amount to be paid to the store.
[0015]
As shown in FIG. 8, a dish 1 (read / write object) on which sushi is placed is made of plastic such as melanin resin, for example, and has an ID tag 2 embedded therein. As shown in FIG. 7, the electric circuit of the ID tag 2 includes an antenna coil 3 for transmitting and receiving a radio signal, a resonance capacitor 4, a control IC 5, and a smoothing unit 6. The control IC 5 and the smoothing unit 6 are mounted on a printed wiring board 7.
[0016]
The control IC 5 is a one-chip semiconductor element constituting a rectifier 9, a modulator / demodulator 10, a memory 11, etc., in addition to an MPU (microprocessor unit) 8 as a control unit. Here, the memory unit 11 has an EEPROM as an erasable nonvolatile memory for temporary storage. Although not shown, the smoothing unit 6 has a smoothing capacitor, a Zener diode, and the like.
[0017]
The antenna coil 3 is connected in parallel with the resonance capacitor 4 to form a resonance circuit. When a predetermined high-frequency power radio signal is transmitted from a reader / writer which is an external transmission / reception device, And supplies it to the rectifier 9. The rectifying unit 9 constitutes an operation power supply circuit together with the smoothing unit 6. The rectifying unit 9 rectifies an electric power radio signal transmitted from the resonance circuit, smoothes the electric power radio signal by the smoothing unit 6, and supplies a constant voltage DC power (operation electric power). ) And supply it to the MPU 8 and the like.
[0018]
A signal such as data transmitted from the reader / writer is transmitted while being superimposed on a power radio signal, and the signal is demodulated by the modem 10 and provided to the MPU 8. The MPU 8 operates according to an operation program stored in a ROM included in the memory unit 11, executes a process corresponding to a signal input from the modem unit 10, and writes received data to an EEPROM included in the memory unit 11. The data is read from the memory unit 11, modulated by the modem unit 10, and transmitted as a radio signal from the antenna coil 3.
[0019]
As an ID tag transmitting / receiving device that communicates with the ID tag 2, there is a hand-held reader / writer 12 shown in FIG. As shown in FIGS. 3 and 4, the hand-held reader / writer 12 includes an operation unit 13 also serving as a hand-held unit, and a head 14 provided at one end of the operation unit 13. The unit 14 is provided with a display unit 15 made of, for example, liquid crystal. The operation unit 13 is provided with a plurality of key switches, and the operation of the keys is instructed by the key switches, and various data such as a unit price of the plate 1 is input.
[0020]
As shown in FIG. 1 showing the electrical configuration of the hand-held reader / writer 12, the control unit 19 mainly includes an MPU 16, a ROM 17 storing operation programs and the like, and a RAM 18 temporarily storing data and the like. A transmission unit 20 and a reception unit 21 are connected to 19. The transmitting unit 20 is connected to the transmitting antenna coil 22, and the receiving unit 21 is connected to the receiving antenna coil 23. The transmitting antenna coil 22 and the receiving antenna coil 23 are arranged side by side inside the front part (the side where the display unit 15 is arranged) of the head 14 of the hand-held reader / writer 12 (see FIG. 4). In FIG. 1, the key switch of the operation unit 13 and the display unit 15 are omitted.
[0021]
The MPU 16 controls the whole of the handheld reader / writer 12. When communicating with the ID tag 2, first, the MPU 16 modulates the carrier signal by the transmission unit 20 and converts the carrier signal from the transmission antenna coil 22 into a power radio signal. Transmit and operate the ID tag 2. Thereafter, the data to be transmitted is superimposed on the electric wave signal for electric power, modulated by the transmission unit 20 and transmitted from the coil 22 for the transmission antenna. When the radio signal transmitted from the ID tag 2 is received, the radio signal transmitted from the ID tag 2 is received by the receiving antenna coil 23, demodulated by the receiving unit 21, and discriminated as data.
[0022]
In the transmission and reception between the hand-held reader / writer 12 and the ID tag 2, as a modulation method, frequency shift keying (FSK) in which “0” and “1” of data to be transmitted correspond to two frequencies. In this embodiment, "1" corresponds to 125 KHz and "0" corresponds to 100 KHz.
[0023]
Now, the handheld reader / writer 12 is provided with the resonance antenna coil 24 in order to be able to communicate with the ID tags 2 of all the dishes 1 stacked without moving too much. The resonance antenna coil 24 is formed in half the size of the transmission antenna coil 22 and is disposed inside the front part of the head 14. Specifically, as shown in FIGS. 3 and 4, when the hand-held reader / writer 12 is held in a posture in which the head 14 is directed upward, the resonance antenna coil 24 is provided in front of the transmission antenna coil 22. It is arranged at a position facing the right half or the left half of the transmission antenna coil 22.
[0024]
The resonance antenna coil 24 is connected to a resonance frequency switching circuit 25 as resonance control means connected to the MPU 16. In this case, one end of the resonance antenna coil 24 is directly connected to the resonance frequency switching circuit 25, and the other end is connected to the resonance frequency switching circuit 25 via a relay 26 as opening / closing means. . The relay 26 is constituted by a switch using a semiconductor, and is controlled to be opened and closed by a drive circuit 27 operated by a drive signal from the MPU 16.
[0025]
By the way, the function of the coil of the resonance antenna coil 24 as a coil is invalidated or activated by opening and closing the relay 26. The mutual induction between the transmission antenna coil 22 and the resonance antenna coil 24 occurs or does not occur depending on whether the resonance antenna coil 24 is enabled or disabled, so that the inductance of the transmission antenna coil 22 changes. Then, since the resonance frequency of the transmission antenna coil 22 changes, the output of the radio signal is reduced.
[0026]
In order to solve this problem, the transmission unit 20 is provided with an automatic tuning circuit 28 as automatic tuning means. The automatic tuning circuit 28 includes a transmission antenna coil 24 and a plurality of capacitors (not shown) forming a resonance circuit. The capacitance of the capacitor connected to the transmission antenna coil 24 is determined when the relay 26 is opened and closed. It is different from the above. Then, in order to cope with the fact that the transmission frequency differs according to “0” and “1” of the data to be transmitted, the automatic tuning circuit 28 determines whether to transmit “0” or “1”. The capacitance of the capacitor connected to the transmission antenna coil 24 is also made different.
[0027]
On the other hand, the resonance antenna coil 24 generates an induced electromotive force by a radio signal transmitted by the transmission antenna coil 22 when the relay 26 is closed. In this case, the frequency of the radio signal differs between the case where the data transmitted from the transmission antenna coil 22 is “0” and the case where the data is “1”. The resonance frequency switching circuit 25 has a function of making the resonance frequency of the resonance antenna coil 24 different between a case where the radio signal from the transmission antenna coil 22 is “0” and a case where the radio signal is “1”.
[0028]
The resonance frequency switching circuit 25 includes a resonance antenna coil 24 and a plurality of capacitors (not shown) forming a resonance circuit. Based on a control signal from the MPU 16, the capacitance of the capacitor connected to the resonance antenna coil 24 is controlled. The capacity is made different according to “0” and “1” of the data signal transmitted by the transmission antenna coil 22.
[0029]
Here, when the relay 26 is in the open state during the transmission of the hand-held reader / writer 12 and a current flows through the transmission antenna coil 22, as shown in FIG. It is near the line A passing through the center of the coil 22. When the relay 26 is closed, a current flows through both the transmission antenna coil 22 and the resonance antenna coil 24, so that the direction and strength of the magnetic flux generated by the transmission antenna coil 22 and the resonance antenna coil 24 change. I do. As a result, as shown in FIG. 5 (b), the magnetic flux that travels substantially straight is present near the line B that is shifted from the line A passing through the center of the transmission antenna coil 22 to the opposite side of the resonance antenna coil 24. become.
[0030]
Next, the operation of the above configuration will be described with reference to the flowchart of FIG.
As shown in FIG. 6, when totaling the payment amounts of customers who have completed a meal, the operation unit 13 of the handheld reader / writer 12 is held in hand, and the head 14 of the group of dishes 1 stacked on the table is provided. Hold it at the center in the horizontal direction. At this time, as the hand-held reader / writer 12, the posture when the operation unit 13 is laid down is a comfortable posture for holding the operation unit 13, and in this state, the transmission antenna coil 22 and the resonance antenna coil 24 Is in the form of being located vertically.
[0031]
In this state, an operation for starting communication is performed by the operation unit 13. Then, the MPU 16 opens the relay 26 (step S1), and in this state, sets the automatic tuning circuit 28 of the transmission unit 20 to the capacitance when the resonance antenna coil 24 is disabled, and sets the transmission antenna. The resonance frequency of the power coil 22 is made to match the frequency of the power radio signal to be transmitted (step S2).
[0032]
In this state, the MPU 16 modulates the carrier signal in the transmission unit 20 and transmits it as a power radio signal from the transmission antenna coil 22, and then transmits the power radio signal according to “0” and “1” of the data to be transmitted The signal is transmitted from the transmission antenna coil 22 while changing the frequency of the signal. At the time of transmitting this data, the MPU 16 automatically tunes so that the resonance frequency of the transmission antenna coil 22 becomes a frequency corresponding to “0” or “1” every time the transmission data changes to “0” or “1”. The circuit 28 is controlled.
[0033]
On the other hand, on the ID tag 2 side of the plate 1, the transmitted radio signal is received by the antenna coil 3, and the radio signal is rectified and smoothed by the rectifying unit 9 and the smoothing unit 6 to be converted into DC power of a constant voltage. Power supply for operation.
[0034]
By supplying the power for operation, the MPU 8 of the ID tag 2 of each plate 1 starts to operate and performs processing according to the content of the transmitted radio signal, in this case, the ID number of the plate 1 from the memory unit 11, An operation of reading data such as the type of the plate 1 and the selling price, modulating the data with the modem 10 and transmitting the data from the antenna coil 3 is performed. The radio signal transmitted from the ID tag 2 of each plate 1 is received by the receiving antenna coil 23, and the received signal is demodulated by the receiving unit 21 and stored in the RAM 18 as data (step S3).
[0035]
Here, in the handheld reader / writer 12, since the radio wave signal is transmitted only from the transmission antenna coil 22, the magnetic flux near the line indicated by A in FIG. The magnetic flux does not interlink with the use coil 3. Therefore, communication with the ID tag 2 is not possible.
[0036]
After a lapse of a predetermined time, the MPU 16 closes the relay 26 and activates the resonance antenna coil 24 (step S4). Next, the MPU 16 controls the automatic tuning circuit 28 of the transmission unit 20 so that the resonance frequency of the transmission antenna coil 22 is changed to the power radio wave in a state where the resonance antenna coil 24 and the transmission antenna coil 22 cause mutual induction. The transmission frequency of the signal is made to match (step S5).
[0037]
Thereafter, the MPU 16 changes the frequency of the radio signal in accordance with “0” and “1” of the data transmitted from the transmission antenna coil 22. At this time, the MPU 16 sets the resonance frequency of the transmission antenna coil 22 and the resonance antenna coil 24 to a frequency corresponding to “0” and “1” each time the transmission data changes to “0” or “1”. The automatic tuning circuit 28 and the resonance frequency switching circuit 25 are controlled.
[0038]
Now, when the resonance antenna coil 24 is activated, the direction and strength of the magnetic flux change, and the position of the magnetic flux traveling straight changes as shown in FIG. For this reason, a magnetic flux interlinking with the antenna coil 3 of the ID tag 2 which has not been able to communicate until now is generated, and communication with the ID tag 2 becomes possible, and when communication with the ID tag 2 is completed. (The above is the step S6), and ends.
[0039]
The present invention is not limited to the embodiment described above and shown in the drawings, but can be extended or modified as follows.
The size of the resonance antenna coil 24 is not necessarily half that of the transmission antenna coil 22. For example, the configuration is such that the resonance antenna coil 24 has the same size as the transmission antenna coil 22 and the resonance antenna coil 24 is arranged next to the transmission antenna coil 22 (in the left-right direction when the head 14 is directed upward). There may be.
The read / write object is not limited to the dish 1 of the rotating sushi shop.
The modulation method is not limited to frequency shift keying.
It may be also output the same radio signal transmitting antenna coil 22 from the resonance antenna coil 24.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an electric configuration of a hand-held reader / writer according to an embodiment of the present invention; FIG. 2 is a flowchart showing control contents during communication; FIG. 3 is a front view of the hand-held reader / writer; FIG. 5 is a view showing a magnetic flux when the resonance antenna coil is opened and closed. FIG. 6 is a perspective view showing a state of communication with the ID tag. FIG. 7 is a view showing an electric configuration of the ID tag. Block diagram shown [Figure 8] Perspective view of plate [Explanation of reference numerals]
In the figure, 1 is a plate, 2 is an ID tag, 3 is an antenna coil, 12 is a hand-held reader / writer (ID tag transceiver), 13 is an operation unit (hand-held unit), 14 is a head, 16 is an MPU, 19 is a control unit, 22 is a transmission antenna coil, 23 is a reception antenna coil, and 24 is a resonance antenna coil.

Claims (5)

In an ID tag transmitting / receiving device that transmits / receives a radio signal to / from an ID tag,
A coil for a transmitting antenna,
A resonance antenna coil that is arranged off-center from the transmission antenna coil;
Opening and closing means for opening and closing the resonance antenna coil ;
An ID comprising resonance control means for controlling the resonance frequency of the resonance antenna coil to be the same as the transmission frequency of the transmission antenna coil when the resonance antenna coil is closed by the opening / closing means. Tag transceiver. 2. A modulation method of a signal for transmission is frequency shift keying, and said resonance control means changes a resonance frequency of said resonance antenna coil in synchronization with a change of a transmission frequency. ID tag transmitting / receiving device. The transmitting / receiving device for an ID tag according to claim 1 or 2 , wherein a resonance frequency of the coil for the transmitting antenna is switched according to opening / closing of the opening / closing means . A hand-held part, comprising a head provided with the transmitting antenna coil and the resonance antenna coil provided on one end side of the hand-held part,
The resonance antenna coil is formed to be half the size of the transmission antenna coil, and is provided at a position facing the left half or the right half of the transmission antenna coil when the head is directed upward. The transmitting / receiving device for an ID tag according to any one of claims 1 to 3, wherein: The ID tag according to any one of claims 1 to 4, wherein the resonance antenna coil is arranged so as to be closer to the ID tag than the transmission antenna coil in a communication state . Transmitter / receiver.

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