JP4255931B2 - Non-contact IC medium and control device - Google Patents

Description

  The present invention relates to an IC tag used in an RFID (RADIO FREQUENCY IDENTIFICATION) system, and in particular, an active contactless IC tag or IC with a built-in battery that receives information from an external device in a non-contact manner and sends information to the external device. The present invention relates to non-contact IC media such as cards.

Since the conventional active non-contact IC medium has a battery mounted therein, it does not have a battery inside, and is a passive non-contact IC medium that operates only when power is supplied from the outside. Compared to the above, it is possible to transmit high-power radio waves and to transmit radio waves over a certain distance from the passive type. For this reason, this non-contact IC medium can be used even when the IC tag and the reader corresponding to this non-contact IC medium are separated.
However, the capacity of the electric energy stored in the battery is not infinite, and in order to use the non-contact IC medium for a long period of time, the transmission circuit is stopped and power consumption is suppressed during a period in which transmission / reception is unnecessary.
That is, in the conventional example, the current consumption is suppressed by transmitting at regular intervals or by transmitting based on sensor information such as vibration.

However, there is an application in which a non-contact IC medium receives a predetermined control signal and outputs a response signal to the control signal in accordance with the reception timing of the control signal.
For this reason, as described in Non-Patent Document 1, it is necessary to leave only a circuit that receives a control signal in a standby state and put another circuit in a sleep state.
http://savi.com/products/pr.rfid.echopoint.shtml (accessed July 12, 2004)

  However, in the IC tag shown in Non-Patent Document 1, it is necessary to always keep the circuit that receives the control signal in a standby state, and considering the longer life, the circuit that receives the radio wave of the control signal is configured. There is a problem that power consumption of a tuning circuit or the like cannot be ignored.

  The present invention has been made in view of such circumstances, and lowers the power consumption of the control signal receiving circuit compared to the conventional example, and can extend the life of the internal battery compared to the conventional example. An object of the present invention is to provide a non-contact IC medium (IC tag, IC card, etc.).

  The non-contact IC medium of the present invention includes a first antenna (for example, the coil 1 or the antenna 69 in the embodiment) that receives a signal in the first frequency band, and a second antenna that transmits a signal in the second frequency band. Antenna (for example, antenna 4 in the embodiment), a control circuit for detecting a control signal received by the first antenna and outputting control data (for example, the control circuit 65 or 70 in the embodiment), and the control data And a transmission circuit that outputs a response signal from the second antenna (for example, the uplink transmission circuit 62 in the embodiment), and the first frequency band is lower than the second frequency band. It is set to a belt.

In the non-contact IC medium of the present invention, the frequency of the alternating magnetic field is an LF (long wave) band (frequency 30 kHz to 300 kHz, wavelength 10 km to 1 km).
As a result, the non-contact IC medium of the present invention uses the above-described alternating magnetic field in the LF band, thereby reducing standby current and low power consumption compared to other communications (for example, ultrasonic waves and infrared rays). It is superior when used for a long time.

  The contactless IC medium of the present invention is characterized in that the control data is a busy tone.

  The non-contact IC medium of the present invention includes a signal strength measuring unit that detects the reception strength of the control signal, and a signal strength control circuit that controls the transmission strength of the response signal according to the detection result. .

  The non-contact IC medium of the present invention is a coil in which the first antenna is magnetically coupled to an external coil, detects a voltage induced by an alternating magnetic field generated by the external coil, and outputs it as a control signal to the control circuit. It is characterized by being.

  A non-contact IC medium control device according to the present invention is a control device that transmits control data to a non-contact IC medium, a control unit that generates control data in response to an input command, and a predetermined amount of the control data. A transmission circuit that outputs a control signal superimposed on the first frequency band signal, a first antenna that transmits the control signal in the first frequency band, and transmits and receives data in the second frequency band. And the second frequency band is set, and the first frequency band is set to a frequency band lower than the second frequency band.

  The contactless IC medium control device of the present invention is characterized in that the first frequency band is an LF band.

  The non-contact IC medium control device according to the present invention is characterized in that the control data is a busy tone.

  In the non-contact IC medium control device according to the present invention, the transmission unit measures the reception intensity of the response signal from the IC tag, and the signal intensity control controls the transmission intensity of the busy tone according to the measurement result. Part.

  In the non-contact IC medium control device according to the present invention, the first antenna generates an alternating magnetic field corresponding to the control signal, and performs magnetic coupling with another coil of the non-contact IC medium by the alternating magnetic field. It is a coil that transmits the control signal to the coil.

  As described above, according to the invention, the control signal transmitted in the first frequency band of the LF band is received, the busy tone that is the control data superimposed on the control signal is extracted, and this busy tone is supported. Since the non-contact IC medium performs efficient data transmission / reception control at the second frequency higher than the first frequency band, and does not use a high frequency band during standby, An operating tuning circuit or the like is not necessary, and power consumption can be greatly reduced in the control information input standby state as compared with a conventional non-contact IC medium.

  Further, according to the present invention, in the operation of the IC tag (non-contact IC medium), the receiving unit is synchronized except when it is necessary to transmit data to the interrogator (non-contact IC catalyst body control device). For this reason, that is, a busy tone input waiting instruction from the interrogator, and only the operation of the timer or CPU in the control circuit for that is operating, most of the time is in the standby state, In the case where there is no operation of a portion using power, such as a transmitter, the IC tag is in a low power consumption state, and a battery is mounted, the battery life can be extended as compared with the conventional example.

In addition, according to the present invention, when a plurality of IC tags (tags A and B) exist in the communicable area of the interrogator as shown in FIG. 11A, the interrogator controls the busy tone transmission output. Thus, transmission of tag B located closer to tag A can be selectively delayed.
Here, in the present invention, the busy tone transmission output is adjusted in response to the selection of the IC tag, and the remote tag (for example, IC tag A) is not reached, but the near tag (for example, IC tag B) is adjusted. To reach.

  As a result, the present invention detects that a nearby IC tag B detects a busy tone, thereby determining that the interrogator is transmitting with another IC tag and not performing transmission, and sequentially lowering the transmission output. Data is transmitted and received in order from the farthest IC tag, and the recognized IC tag is put in the sleep state (standby state) until the next transmission is required, so that reading is performed with priority from the farthest IC tag. Therefore, the IC tag does not perform communication more than necessary, and the battery life can be extended compared to the conventional example.

<First Embodiment>
Hereinafter, a non-contact IC medium and a non-contact IC medium controller according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a non-contact IC medium (IC tag 12) and a non-contact IC medium control device (interrogator 50) according to the first embodiment. In the first embodiment, the exciting device and the receiving device are configured as an interrogator (non-contact IC medium control device), and transmission from the non-contact IC medium control device to the non-contact IC medium, that is, the frequency is low in the downlink. The region of the LF band (for example, 125 kHz, 4 kbps, ASK Manchester code system) is a busy tone (busy tone preamble) channel, while the transmission from the non-contact IC medium to the non-contact IC medium controller, that is, the high frequency region in the uplink (For example, as a UHF band of 400 MHz band, 20 k to 30 kbps, GFSK / OOK / DSSS) is used as a data channel (data transmission). Hereinafter, as in the first and second embodiments, an IC tag will be described as an example of a non-contact IC medium. Although not shown, a battery is mounted on the IC tag 12 to supply driving power to each internal circuit.

In FIG. 1, an interrogator 50 receives an uplink reception circuit 51 for receiving data from the IC tag 12 on the uplink and a control signal such as a busy tone signal on the downlink to the IC tag 12 by an alternating magnetic field of the LF signal. A downlink excitation circuit 52 for transmission and a control circuit 54 for converting user input or a preset command or the like into control data and processing data input from the IC tag 12 are provided.
Here, the uplink receiving circuit 51 has a receiver 53 that receives a transmission signal of data transmitted from the IC tag 12.
Further, the downlink excitation circuit 52 converts a command input by a user into control data, superimposes the control data (including busy tone) on a predetermined LF band frequency, for example, 125 kHz AC current, 10 includes an exciter 55 for supplying an alternating current with control data superimposed thereon and generating an alternating magnetic field with control data superimposed thereon. Here, in the first embodiment, an alternating magnetic field is used as a carrier that propagates a space by superimposing control data.

In the downlink from the interrogator 50, the IC tag 12 includes a downlink receiver circuit 61 that receives a busy tone signal by the alternating magnetic field of the LF signal, an uplink transmitter circuit 62 that transmits data to the interrogator 50, and The control circuit 65 extracts data from the DC voltage of the alternating magnetic field to be described and outputs a corresponding control signal.
Here, the downlink reception circuit 61, generated in the coil 1 that coil 10 and the electromagnetic coupling rectifies the predetermined ac voltage alternating magnetic field (alternating magnetic field) is induced as the induced voltage by interlinking The receiver 63 has a DC voltage.
Here, the coil 1 is linked with an alternating magnetic field (alternating magnetic field) generated by another coil that is electromagnetically coupled (for example, the coil 10 of the excitation device 55 described later), thereby generating a predetermined alternating voltage as an induced voltage. Induce. Here, control data is superimposed on the alternating magnetic field depending on whether or not a magnetic field is generated.

That is, the receiver 63 is connected to the coil 1 and has a rectifier inside, and rectifies the alternating voltage to obtain a DC voltage.
Therefore, the receiver 63 extracts control data by using the rectifying unit to set the alternating magnetic field as a DC voltage, and outputs a corresponding control signal to the control circuit 65.
Further, an amplifier for amplifying the LF signal is provided in either or both of the non-contact IC medium (IC tag 12) and the interrogator 50 which is a non-contact IC medium control device, or the size of the coil 10 is increased. Or you may.

For example, when an amplifier is provided in the IC tag 12, the amplifier is inserted between the coil 1 and the receiver 63. This improves the signal sensitivity of the alternating magnetic field that is the reception level at the receiver 63 of the IC tag 12.
On the other hand, when an amplifier is provided in the interrogator 50, the amplifier is inserted between the excitation device 55 and the coil 10.

As a result, the current (several hundred mA) supplied to the coil 10 can be increased to a value of several tens of A to generate a stronger magnetic field.
As described above, by inserting an amplifier in one of the IC tag 12 and the interrogator 50, or by inserting both, it is possible to extend the reachable transmission distance of the control signal by the alternating magnetic field.
Furthermore, the size of the coil 10 may be a few centimeters in radius, but by increasing the radius to several tens of centimeters, the transmission distance of the control signal can be similarly increased.

Further, the uplink transmission circuit 62 has a transmitter 64 that transmits predetermined information to the interrogator 50 via the antenna 4 in accordance with a control signal from the control circuit 65.
Here, the transmission circuit 64 transmits the predetermined information using, for example, a radio wave having a frequency band of UHF (Ultra High Frequency; frequency 300 MHz to 3 GHz, wavelength 10 to 100 cm).

Here, the busy tone signal will be described. A dedicated communication line (for example, an uplink) for transmitting and receiving data between the IC tag 12 and the interrogator 50 and a busy tone line (for example, a downlink) for notifying the use status of this dedicated communication line are provided. It is assumed that a wireless system is used.
This busy tone signal is transmitted from the interrogator 50 when the interrogator 50 and any one of the IC tags 12 are transmitting data, and prohibits transmission of data from other IC tags 12, It is used to avoid data collision caused by transmission from the IC tag 12.

For example, as shown in FIG. 2, in the present invention, in the environment where the interrogator 50 and the tags A and B (IC tag 12) communicate, when the tag A performs transmission processing, the tag A When detection is performed and it is detected that the busy tone signal is not transmitted from the interrogator 50, the ID (identification information) is transmitted to the interrogator 50 through the uplink.
When the interrogator 50 starts data transmission with the tag A, the interrogator 50 transmits a busy tone signal on the downlink.
While the busy tone signal is being transmitted, the other tag B detects the busy tone signal when transmitting the ID to the interrogator 50, and the busy tone signal is detected. The busy tone signal is detected again after a lapse of a predetermined time, and if no busy tone signal is detected, its own ID is transmitted to the interrogator 50 via the uplink.

Next, with reference to FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5, the operation of the wireless communication system comprising the non-contact IC catalyst body and the non-contact IC medium control device according to the third embodiment will be described. To do. FIG. 3 is a flowchart showing an operation example on the IC tag 12 side of the wireless communication system. 4 and 5 are flowcharts showing an operation example on the interrogator 50 side of the wireless communication system (when the position of the IC tag and the number of IC tags are unknown, or when the IC tag moves).
4 and 5 show the operation when the signal strength measuring circuit 60 and the signal strength control circuit 56 as shown in FIG. 6 described later are not provided, and the interrogator 50 is a downlink transmission circuit. 59 shows a case where the downlink circuit transmission signal intensity cannot be controlled.

However, FIG. 5 shows the confirmation operation in the state where there is no movement of the IC tag 12 from the second time after obtaining the identification signals of all the IC tags 12 in the communicable range of the downlink presentation circuit 52 for the first time. Yes.
In step S1, the IC tag 12 is in a sleep state (standby state), and only the downlink reception circuit 61 is in operation.

Next, in step S2, since the control circuit 54 collects data for each IC tag 12, a predetermined pattern preamble for shifting the state of the IC tag 12 during downlink operation is set in advance. Is transmitted on the downlink as a radio wave of a certain intensity level.
As a result, in the IC tag 12, the receiver 63 receives the preamble via the coil 1, that is, detects the preamble due to the LF signal which is a low frequency signal, rectifies this, and sends it to the control circuit 65 as a digital signal. Output.

Next, in step S3, the control circuit 65 detects whether or not a preamble that shifts the state of the IC tag 12 from the interrogator 50 during downlink operation is received.
At this time, if the control circuit 65 detects that a preamble for instructing a shift to downlink operation has been received, the control circuit 65 proceeds to step S4, while receiving a preamble for instructing a shift to a downlink operation. If not detected, the process proceeds to step S7.

Next, in step S4, the control circuit 65 transitions to a state in which a downlink operation is performed when detecting reception of a preamble indicating activation.
Then, the control circuit 65 detects the carrier whether or not another IC tag 12 has already performed communication using the uplink in a state in which the downlink is in operation (a state in which reception of the busy tone is confirmed). judge.
For this reason, the control circuit 54 makes a transition from the standby state to a state in which the IC tag 12 can receive the busy tone more clearly than the reception of the preamble, that is, a downlink operating state, that is, a downlink operating state. Let
Next, in step S5, the control circuit 65 detects whether or not an instruction indicating the start of data collection from the interrogator 50 is input within a predetermined period.
At this time, if the control circuit 65 detects that a command indicating the start of data collection is input within the predetermined period, the control circuit 65 advances the process to step S6. If the input cannot be detected, the process returns to step S1.

  Next, in step S6, when the busy tone signal is not detected, the control circuit 65 transmits the data including the ID to the interrogator 50. When the busy tone signal is detected, the control circuit 65 waits for a predetermined time, and then again. If a busy tone signal is detected and not detected, a unique data including its own ID (sensor data acquired by an internal sensor stored in the memory of the IC tag 12 is used as a one-to-one transmission / reception state. Including).

Next, in step S7, the control circuit 65 determines whether a timer (or counter) provided in the internal circuit overflows (in the counter, a carry of calculation) or a predetermined calculation is performed in an internal CPU (central processing unit) part. It is detected whether or not the IC tag 12 itself receives an internal event as an instruction to change the state of the IC tag 12 by measuring the elapsed time based on the above.
At this time, if the reception of the internal event is detected, the control circuit 65 advances the process to step S8. If the reception of the internal event is not detected, the control circuit 65 returns the process to step S2.

Next, in step S8, when receiving the internal event, the control circuit 65 immediately shifts to processing during uplink operation, performs transmission detention and delays, and advances the processing to step S9.
In step S9, the control circuit 65 detects whether or not the busy tone signal is detected, that is, whether or not the uplink (channel) is usable, and can use the uplink without detecting the busy tone. If this is detected, the process returns to step S1. If a busy tone is detected and it is detected that the uplink cannot be used, the process returns to step S7.
As described above, the IC tag 12 responds to the interrogator 50 by receiving the alternating magnetic field LF signal from the interrogator 50.

Next, the first (first) identification operation of the IC tag 12 on the interrogator 50 side will be described using the flowchart of FIG.
In step S21, the control circuit 54 causes the IC tag 12 to change the state of the IC tag 12 during the downlink operation, that is, to shift the IC tag 12 from the sleep state to the wake-up state via the downlink excitation circuit 52. For this reason, a preamble having a predetermined pattern (instructing the transition to the wake-up state) is transmitted to the downlink using a radio wave having a predetermined intensity level, for example, the maximum intensity level that can be output by itself.

Next, in step S <b> 22, the control circuit 54 transmits a frame of control data that instructs transmission of information data including the identification number to the IC tag 12.
Here, the downlink excitation circuit 52 includes a preamble of a pattern for synchronizing communication, a frame of control data, and an FCS (Frame Check Sequence) for determining whether or not the frame is normally received at the reception destination. A frame is generated and transmitted by being superimposed on an alternating magnetic field.

Next, in step S23, the control circuit 54 uses the information corresponding to the transmission instruction in the frame from each IC tag 12, that is, whether or not information data is received as response data, for uplink communication. This is performed by carrier detection in the frequency band.
Here, in the IC tag 12, the control circuit 65 causes the transmitter 64 of the information line transmission circuit 62 to superimpose information data on a carrier of a predetermined frequency in response to the control data from the interrogator 50. A frame of information data is transmitted via the antenna 4.
At this time, if the control circuit 54 detects reception of information data by the receiver 53, the process proceeds to step S24.

Next, in step S24, the control circuit 54 transmits the busy tone superimposed on the alternating magnetic field by the downlink excitation circuit 52.
As a result, in the plurality of IC tags 12, the frame transmission processing is suppressed by the busy tone for the IC 12 tags other than the information data frame output.
In step S25, the control circuit 54 detects the carrier in the receiver 53, thereby detecting whether or not frames of information data from the plurality of IC tags 12 exist (that is, a plurality of alternating magnetic fields). By detecting whether or not there is a plurality of IC tag 12 frames, it is determined whether or not the frames of the plurality of IC tags 12 are competing.

Here, the control circuit 54 advances a process to step S26, when the competition of the response from the some IC tag 12 is not detected.
In step S26, the control circuit 54 adds a time stamp (current time) to the information data transmitted from the IC tag 12 in correspondence with the received identification number of the IC tag 12, and stores the internal storage unit. To remember.
On the other hand, when the competition of the plurality of IC tags 12 is detected, the control circuit 54 advances the process to step S27 and returns the process to step S21.

In step S27, the control circuit 54 associates the detected identification number of one of the IC tags 12 received in competition with the identification number of the IC tag 12 as received information data. A time stamp (current time) is added to the information data and stored in the internal storage unit, and the process proceeds to step S28.
Next, in step S28, the control circuit 54 stops the busy tone output from the downlink excitation circuit 52 and advances the process to step S29.

In step S29, the control circuit 54 detects that no information data has been received with respect to the IC tag 12, that is, no data has been received, while the control circuit 54 sleeps with respect to the IC tag 12 in which the identification signal is stored. Control data indicating the transition to the state is transmitted by the downlink excitation circuit 52, and the process returns to step S21.
Thereby, in the IC tag 12, the IC tag 12 in which the identification signal is recognized shifts to the sleep state, and only the IC tag 12 in which the identification information is not recognized is in the wake-up state.

In step S23, when the receiver 55 detects that no information data is received from any IC tag 12, the control circuit 54 advances the process to step S30.
Next, in step S30, the control circuit 54 detects whether or not it is within a predetermined number of times (for example, 5 times) after stopping the busy tone, that is, whether or not it has exceeded, ie, steps S31, S21, S22, It is detected whether or not the value obtained by counting the number of passes through S23 and S30 by the internal counter is within a predetermined number of times (whether or not exceeded).

Here, the control circuit 54 advances the process to step S31 when it is detected that the stop of the busy tone is within a predetermined number of times (not exceeding the predetermined number).
Then, in step S31, the control circuit 54 stops the busy tone transmission to the downlink excitation circuit 52, waits for the transmission timing for a preset period, and advances the process to step S21.
On the other hand, if the control circuit 54 detects that the stop of the busy tone is not within the predetermined number of times (exceeds the predetermined number of times), the process proceeds to step S32.
In step S32, the control circuit 54 determines that there is no IC tag 12 that has not yet received the identification signal in the communicable range of its own downlink excitation circuit 52, completes the first process, and performs the second process. In order to start the process, the process proceeds to step S41 (see FIG. 5).

Next, the second and subsequent identification operations of the IC tag 12 on the interrogator 50 side will be described using the flowchart of FIG.
In step S41, when the control circuit 54 detects the elapse of a predetermined time (for example, several minutes) after the processing of the flowchart of FIG. 4 is completed, the control circuit 54 performs the downlink operation as the identification operation of the IC tag 12 stored in the storage unit. For each IC tag 12 via the excitation circuit 52, a predetermined pattern (wake-up state) is used to change the state of the IC tag 12 during downlink operation, that is, to shift the IC tag 12 from the sleep state to the wake-up state. Is transmitted to the downlink using a radio wave having a predetermined intensity level, for example, a maximum intensity level that can be output by itself. The control circuit 54 stores the time when the preamble is transmitted in the storage unit as the transmission time.

Next, in step S <b> 42, the control circuit 54 transmits a frame of control data instructing the IC tag 12 to transmit information data including the identification number.
Here, the downlink excitation circuit 52 generates the frame including the preamble of the pattern for synchronizing the communication, the frame of the control data, and the FCS that determines whether or not the frame is normally received at the reception destination. , And superimpose it on an alternating magnetic field.

Next, in step S43, the control circuit 54 determines whether or not information data corresponding to the transmission instruction in the frame from each IC tag 12 has been received by carrier detection in the frequency band used for communication.
Here, in the IC tag 12, the control circuit 65 causes the transmitter 64 of the uplink transmission circuit 62 to superimpose information data on a carrier of a predetermined frequency in response to the control data from the interrogator 50. A frame of information data is transmitted via the antenna 4.
At this time, if the control circuit 54 detects reception of information data by the receiver 53, the process proceeds to step S44.

Next, in step S44, the control circuit 54 transmits the busy tone superimposed on the alternating magnetic field by the downlink excitation circuit 52.
As a result, in the plurality of IC tags 12, the frame transmission processing is suppressed by the busy tone for the IC 12 tags other than the information data frame output.
In step S45, the control circuit 54 detects a carrier in the receiver 53, thereby detecting whether or not there is a frame of information data from the plurality of IC tags 12. It is determined whether or not the frames of the IC tag 12 are competing.

Here, the control circuit 54 advances a process to step S46, when the competition of the some IC tag 12 is not detected.
In step S46, the control circuit 54 searches the internal storage unit for the received identification number of the IC tag 12, and if the identification number is detected in the storage unit, the control circuit 54 uses the IC tag corresponding to this identification number. The transmitted information data is overwritten (the time stamp is also changed to the current time). On the other hand, if the input identification number is not detected, the time stamp (current time) is added to the information data of the IC tag corresponding to the identification number. Is added to the storage unit and the process proceeds to step S47.
Next, in step S47, the control circuit 54 stops the busy tone output from the downlink excitation circuit 52 and advances the process to step S41.
On the other hand, in step S45, when the competition of the plurality of IC tags 12 is detected, the control circuit 54 advances the process to step S48.

In step S48, the control circuit 54 stores the identification number of the IC tag 12 received as the received information data of any one of the detected identification numbers of the IC tag 12 in competition. If the identification number is detected in the storage unit and the identification number is detected in the storage unit, the information data transmitted from the IC tag is overwritten corresponding to the identification number (the time stamp is also changed to the current time), while the input identification If the number is not detected, a time stamp (current time) is added to the information data of the IC tag corresponding to the identification number and written to the storage unit, and the process proceeds to step S47.
On the other hand, if the reception of information data by the receiver 53 is not detected in step S43, the control circuit 54 advances the process to step S49.

In step S49, the control circuit 54 searches for the identification number to which the time stamp of the previous time is added from the transmission time at which the preamble was transmitted in step S41.
At this time, if the identification number of the time stamp before the transmission time is detected, the control circuit 54 advances the process to step S50.
Next, in step S50, the control circuit 54 detects that the IC tag 12 has moved outside the communicable range because there is no response from the IC tag 12 that performed the previous identification process, and the identification target to which the IC tag 12 is added. 4 is detected, and the process returns to step S21 in the flowchart of FIG.
On the other hand, in step S49, if the identification number of the time stamp prior to the transmission time is not detected, the control circuit 54 identifies the identification number stored in the storage unit, and thus the IC moved out of communicable state. It is detected that there is no tag 12, and the process proceeds to step S41.

<Second Embodiment>
Hereinafter, a non-contact IC medium and a non-contact IC medium controller according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram showing a configuration example of a non-contact IC medium (IC tag 12) and a non-contact IC medium control device (interrogator 50) according to the second embodiment. The second embodiment is different from the third embodiment in that the low-frequency LF band (for example, 125 kHz, for example) is used via an antenna using radio waves instead of using a communication system using an alternating magnetic field for the downlink. The region of 4 kbps, ASK Manchester code system) is used as a busy tone (and preamble) channel. Similar to the first embodiment, the second embodiment will be described using an IC tag as an example of a non-contact IC medium.

In FIG. 6, an interrogator 50 transmits an uplink receiving circuit 51 that receives data from the IC tag 12 on the uplink, and a busy tone signal from the LF signal (LF band signal) on the downlink to the IC tag 12. And a control circuit 54 for converting user input or a preset command or the like into control data and processing data input from the IC tag 12.
Here, the uplink receiving circuit 51 includes a receiver 53 that receives a transmission signal of data transmitted from the IC tag 12, and a signal strength measurement circuit 60 that detects the reception intensity (that is, the received radio wave intensity) of the transmission signal. have.
Further, the downlink transmission circuit 59 superimposes the control data obtained by converting the command input by the user on the control circuit 54 on a carrier having a predetermined LF band frequency, for example, a frequency of 125 kHz. And a signal intensity control circuit 56 for controlling the radio wave intensity (signal intensity) when transmitting the control data.
In addition, the uplink receiving circuit 51 measures the radio field intensity of the received radio wave with the receiver 53 that receives data from the IC tag 12 via the antenna 8 (second antenna of the interrogator) with predetermined information. And a signal strength measuring circuit 60 for outputting to the control circuit 54.

In the downlink from the interrogator 50, the IC tag 12 receives the busy tone signal via the antenna 69 (first antenna of the IC tag) via the LF band radio wave and the interrogator 50. An uplink transmission circuit 62 that transmits data, and a control circuit 70 that analyzes a signal received by the downlink reception circuit 61 and transmits a corresponding response from the uplink transmission circuit 62.
Here, the downlink receiving circuit 61 includes a receiver 66 that receives radio waves in the LF band, and a signal strength measuring circuit 67 that measures the radio wave intensity of the received radio waves.
Further, the uplink transmission circuit 62 adjusts the transmitter 64 for transmitting predetermined information to the interrogator 50 via the antenna 4 (second antenna of the IC tag) and the radio wave intensity of the transmitted radio wave. And a signal strength control circuit 68.
Here, the transmission circuit 64 transmits the predetermined information using, for example, a radio wave having a frequency band of UHF (Ultra High Frequency; frequency 300 MHz to 3 GHz, wavelength 10 to 100 cm).

Next, with reference to FIG. 6, FIG. 7, FIG. 8, FIG. 9 and FIG. 10, the operation of the wireless communication system comprising the non-contact IC catalyst body and the non-contact IC medium control device according to the second embodiment will be described. To do. FIG. 7 is a flowchart showing an operation example on the tag IC 12 side of the wireless communication system.
The flowchart of FIG. 7 is substantially the same as the flowchart of FIG. 3 in the first embodiment, and only step S12 is different.
In step S2 of the first embodiment, only detection of the LF signal, that is, determination of whether or not the preamble can be detected as a signal is performed. However, in step S12, the signal strength measurement circuit 67 in the IC tag 12 measures the reception strength of the LF signal transmitted by the interrogator 50 received by the receiver 61.

Then, the signal strength control circuit 68 obtains the radio wave intensity transmitted from the response signal to the interrogator 50 based on the measured received intensity, and transmits the response to the interrogator 50 at this radio wave intensity. The device 64 is controlled.
Unlike the first embodiment, the IC tag 12 includes a signal strength measurement circuit 67 and a signal strength control circuit 68. As described above, the transmitter 64 receives the signal strength (RSSI :) received by the receiver 66. In response to the received signal strength indicator (received signal strength indicator signal), the transmission intensity is adjusted and the response signal is transmitted, so that the power consumption of the IC tag 12 can be suppressed.

Of course, as shown in FIG. 11 (a), when the interrogator 50 can confirm the response of the IC tag 12 that is located farthest in the communication area, the interrogator 50 gradually decreases the transmission intensity of the radio wave, By sequentially setting a certain tag A (IC tag 12) in a standby state and making the standby state of these IC tags 12 relatively long, power consumption can be suppressed and power can be reduced. Can extend the lifespan.
The ISMA (Idle Signal Multiple Access) shown in FIG. 11 (b) is one of collision avoidance mechanisms and transmits a busy tone at a high frequency similar to the channel through which the interrogator transmits data. Therefore, since it is necessary to operate at a high frequency in the IC tag to receive, it is not possible to save power and extend the battery life. Since a busy tone and a data frame are transmitted and received on one channel, there is a period during which an idle signal (busy tone) occupies the channel, so that transfer efficiency decreases.

Next, the first (first) identification operation of the IC tag 12 on the interrogator 50 side will be described using the flowchart of FIG.
In step S51, the control circuit 54 causes the IC tag 12 to change the state of the IC tag 12 during the downlink operation, that is, to shift the IC tag 12 from the sleep state to the wake-up state via the downlink transmission circuit 59. Therefore, a preamble of a predetermined pattern (instructing the transition to the wake-up state) is transmitted to the downlink (IC tag 12) by a radio wave having a predetermined intensity level, for example, the lowest intensity level that can be output by itself. To send.

Next, in step S <b> 52, the control circuit 54 transmits a frame of control data instructing the IC tag 12 to transmit information data including the identification number.
Here, the downlink transmission circuit 59 is composed of a preamble of a pattern for synchronizing communication, a frame of control data, and an FCS (Frame Check Sequence) for determining whether or not the frame is normally received at the reception destination. A frame is generated and transmitted by being superimposed on a carrier in the LF band.

Next, in step S53, the control circuit 54 uses whether or not information data corresponding to the transmission instruction in the frame from each IC tag 12 is received, that is, whether or not information data is received as response data, for uplink communication. This is performed by carrier detection in the frequency band.
Here, in the IC tag 12, the control circuit 70 causes the transmitter 64 of the information line transmission circuit 62 to superimpose information data on a carrier having a predetermined frequency in response to the control data from the interrogator 50. A frame of information data is transmitted via the antenna 4.
At this time, if the control circuit 54 detects reception of information data by the receiver 53, the process proceeds to step S54.

Next, in step S54, the control circuit 54 transmits the busy tone superimposed on the carrier in the LF band by the downlink transmission circuit 59.
As a result, in the plurality of IC tags 12, the frame transmission processing is suppressed by the busy tone for the IC 12 tags other than the information data frame output.
In step S55, the control circuit 54 detects the carrier in the receiver 53, thereby detecting whether or not there is a frame of information data from the plurality of IC tags 12 (that is, the plurality of carriers). By detecting the presence / absence of presence, it is determined whether or not the frames of the plurality of IC tags 12 are competing.

Here, the control circuit 54 advances a process to step S56, when the competition of the carrier from the some IC tag 12 is not detected.
At this time, the signal strength measurement circuit 60 obtains the radio wave strength of the carrier received from the IC tag 12 and outputs it to the control circuit 54.
In step S56, the control circuit 54 adds a time stamp (current time) and the radio wave intensity to the information data transmitted from the IC tag 12 in association with the received identification number of the IC tag 12. And stored in the internal storage unit.

Further, the control circuit 54 transmits the control signal for entering the sleep state from the downlink transmission circuit 59 to the IC tag 12 with the identified identification number superimposed on the carrier in the LF band, and the process proceeds to step S57. .
Thereby, in the IC tag 12, the IC tag 12 in which the identification signal is recognized shifts to the sleep state, and only the IC tag 12 in which the identification information is not recognized is in the wake-up state.

Next, in step S57, the control circuit 54 stops the output of the busy tone and returns the process to step S51.
On the other hand, the control circuit 54 advances a process to step S61, when the competition in the response from the some IC tag 12 is detected.
At this time, the signal strength measurement circuit 60 obtains the radio field strength of the carrier received from the IC tag 12 having a high radio field strength, and outputs it to the control circuit.

In step S61, the control circuit 54 stores the lower radio field intensity of the IC tag 12 received in competition in the internal storage unit in association with the time stamp (current time), and the process is performed in step S62. Proceed to
Next, in step S62, the control circuit 54 stops the busy tone output from the downlink transmission circuit 59, and advances the process to step S63.

In step S63, the control circuit 54 detects that no information data has been received with respect to the IC tag 12, that is, no data has been received, and the process proceeds to step S64.
Next, in step S64, the control circuit 54 reads out the radio field intensity stored at the time of competition, and adjusts the signal intensity circuit 56 so as to transmit a busy tone with a radio field intensity higher than the radio field intensity.

On the other hand, in step S53, if the receiver 53 detects that no information data is received from any IC tag 12, the control circuit 54 advances the process to step S58.
Next, in step S58, the control circuit 54 counts the number of times this branch has been repeated after transmission of the busy tone is stopped, and determines whether or not the counted number is within a predetermined number (for example, 5 times). Detection of whether or not (exceeded), that is, whether or not the value obtained by counting the number of passes through steps S59, S51, S52, S53, and S58 by the internal counter is within a predetermined number of times (whether or not exceeded) To do.

Here, when the control circuit 54 detects that the number of passes through steps S59, S51, S52, S53, and S58 after the busy tone is stopped is within a predetermined number of times (not exceeding the predetermined number), the processing is performed. Advances to step S59.
In step S59, if the busy tone is not stopped, the control circuit 54 performs a busy tone stop process. If the busy tone is already stopped, the control circuit 54 sets the radio wave intensity transmitted by the signal strength control circuit 56 to a predetermined value. Control to decrease the width is performed, and the process proceeds to step S51.
On the other hand, if it is detected in step S58 that the stop of the busy tone is not within the predetermined number of times (exceeds the predetermined number), the process proceeds to step S60.
In step S60, the control circuit 54 determines that there is no IC tag 12 that has not yet received the identification signal in the communicable range of its own downlink transmission circuit 59, completes the first process, and performs the second and subsequent processes. In order to perform the process, the process proceeds to step S71 (see FIG. 9).

Next, the second and subsequent identification operations of the IC tag 12 on the interrogator 50 side will be described using the flowcharts of FIGS.
In step S71, when the control circuit 54 detects the elapse of a predetermined time (for example, several minutes) after the processing of the flowchart of FIG. The intensity control circuit 56 is controlled to transmit a busy tone to each IC tag 12 via the transmission circuit 59 at a higher radio field intensity than the highest radio field intensity stored in the storage unit. Originating from the downlink transmission circuit 59, the process proceeds to step S72.

  Next, in step S72, the control circuit 54 changes the state of the IC tag 12 during downlink operation, that is, in order to shift the IC tag 12 from the sleep state to the wake-up state, a predetermined pattern (transition to the wake-up state). Is transmitted to the downlink by a radio wave having a predetermined intensity level, for example, an intensity level of the maximum intensity that can be output by itself. Further, the control circuit 54 stores the time when the preamble is transmitted in the storage unit as the transmission time, and proceeds to step S73.

  In step S73, the control circuit 54 controls the signal intensity control circuit 56 to transmit a radio wave having a higher radio field intensity than the highest radio field intensity stored in the storage unit, and has the longest distance (the farthest). The identification number of the IC tag 12 is added to the IC tag 12 and a frame including control data for transmitting information data is superimposed on the carrier in the LF band and transmitted from the downlink transmission circuit 59.

Next, in step S74, the control circuit 54 determines whether or not information data corresponding to the transmission instruction in the frame from each IC tag 12 has been received by carrier detection in the frequency band used for communication.
When the control circuit 54 detects reception of information data by the receiver 53, the control circuit 54 advances the process to step S75.

Here, in the IC tag 12, the control circuit 70 measures the radio field intensity received by the receiver 66 by the signal intensity measurement circuit 67, and corresponds to the control data from the interrogator 50 in the information line transmission circuit 62. The transmitter 64 controls the signal intensity control circuit 68 to transmit radio waves so that the radio wave intensity is the same as the received radio wave intensity, superimposes information data on a carrier of a predetermined frequency, and sets the antenna 4 A frame of information data is transmitted via
That is, the control circuit 70 of the IC tag 12 stores in advance as a table the radio field intensity transmitted by the transmitter 64 that reaches the distance range of this radio field intensity corresponding to the radio field intensity of the carrier in the LF band to be received and received. The radio wave intensity transmitted from the transmitter 64 is adjusted in a timely manner from the radio wave intensity of the carrier in the LF band.

Next, in step S75, the control circuit 54 detects whether or not there is a frame of information data from the plurality of IC tags 12 by detecting the carrier in the receiver 53 (that is, a plurality of carriers). It is determined whether or not the frames of the plurality of IC tags 12 are competing.
Here, the control circuit 54 advances a process to step S76, when the competition of the carrier from the some IC tag 12 is not detected.
At this time, the signal strength measurement circuit 60 obtains the radio wave strength of the carrier received from the IC tag 12 and outputs it to the control circuit 54.

In step S76, the control circuit 54 adds a time stamp (current time) and the radio wave intensity to the information data transmitted from the IC tag 12 in association with the received identification number of the IC tag 12. And stored in the internal storage unit.
Further, the control circuit 54 transmits a control signal for entering the sleep state from the downlink transmission circuit 59 to the IC tag 12 with the identified identification number superimposed on the carrier in the LF band, and the process proceeds to step S77. .
Thereby, in the IC tag 12, the IC tag 12 in which the identification signal is recognized shifts to the sleep state, and only the IC tag 12 in which the identification information is not recognized is in the wake-up state.

Next, in step S77, the control circuit 54 extracts the IC tag 12 of the identification number having the next highest radio field intensity stored in the storage unit, and is similar to the radio field intensity of the UHF band received by the receiver 53. The signal strength control circuit 56 is controlled so as to transmit the radio wave so that the radio wave intensity becomes the same, and the information data is superimposed on the carrier in the LF band of the predetermined frequency, and the frame of the information data is transmitted via the antenna 58. To do.
That is, the control circuit 54 stores in advance as a table the radio field intensity transmitted from the transmitter 57 that reaches the distance range of this radio field intensity corresponding to the radio field intensity of the received UHF band carrier, and receives the received UHF band carrier. The radio wave intensity transmitted from the transmitter 57 is adjusted in a timely manner in accordance with the radio wave intensity.

In step S78, the control circuit 54 transmits a preamble with the above-mentioned radio wave intensity.
Next, in step S79, the control circuit 54 causes the signal strength so that the control circuit 54 transmits a radio wave having a radio wave intensity higher than the next highest radio wave intensity stored in the storage unit and lower than the radio wave intensity transmitted immediately before. The control circuit 56 is controlled to add the identification number of the IC tag 12 to the IC tag 12 having the next distance (the next most distant), and the frame including the control data for transmitting the information data is sent to the LF band. Is transmitted from the downlink transmission circuit 59 while being superimposed on the other carrier.

Next, in step S80, the control circuit 54 determines whether or not information data corresponding to the transmission instruction in the frame from each IC tag 12 has been received by carrier detection in the frequency band used for communication.
When the control circuit 54 detects reception of information data by the receiver 53, the control circuit 54 advances the process to step S81.

Here, in the IC tag 12, the control circuit 70 measures the radio field intensity received by the receiver 66 by the signal intensity measurement circuit 67 and corresponds to the control data from the interrogator 50 in the uplink transmission circuit 62. The transmitter 64 superimposes information data on a carrier having a predetermined frequency so as to obtain the same radio wave intensity as the received radio wave intensity, and transmits a frame of information data via the antenna 4.
That is, the control circuit 70 of the IC tag 12 stores in advance as a table the radio field intensity transmitted by the transmitter 64 that reaches the distance range of this radio field intensity corresponding to the radio field intensity of the carrier in the LF band to be received and received. The radio wave intensity transmitted from the transmitter 64 is adjusted in a timely manner from the radio wave intensity of the carrier in the LF band.

Next, in step S81, the control circuit 54 detects the carrier in the receiver 53, thereby detecting whether or not there is a frame of information data from the plurality of IC tags 12 (that is, a plurality of carriers). It is determined whether or not the frames of the plurality of IC tags 12 are competing.
Here, the control circuit 54 advances a process to step S82, when the competition of the carrier from the some IC tag 12 is not detected.
At this time, the signal strength measurement circuit 60 obtains the radio wave strength of the carrier received from the IC tag 12 and outputs it to the control circuit 54.

In step S82, the control circuit 54 adds a time stamp (current time) and the radio wave intensity to the information data transmitted from the IC tag 12 in association with the received identification number of the IC tag 12. And stored in the internal storage unit.
Further, the control circuit 54 transmits a control signal for entering the sleep state from the downlink transmission circuit 59 to the IC tag 12 identified with the identification number by superimposing it on the carrier in the LF band, and the process proceeds to step S83. .
Thereby, in the IC tag 12, the IC tag 12 in which the identification signal is recognized shifts to the sleep state, and only the IC tag 12 in which the identification information is not recognized is in the wake-up state.

In step S83, the control circuit 54 searches for the identification number to which the time stamp of the previous time is added from the transmission time at which the preamble is transmitted in step S41, that is, from the transmission time at which the preamble is transmitted. By detecting the presence / absence of a time stamp at the previous time, the presence / absence of an untransmitted IC tag 12 is detected.
At this time, if an identification number of a time stamp before the transmission time is detected, the control circuit 54 advances the process to step S77.
On the other hand, if the identification number of the time stamp before the transmission time is not detected, the control circuit 54 determines that there is no untransmitted IC tag 12 and advances the process to step S71.

Further, the control circuit 54 performs the processing in step S84 or S80 when it is detected that no data is received from any of the IC tags 12 and when it is detected that there is a conflict in step S75 or S81. Proceed to
In step S84, the control circuit 54 detects that the state of the IC tag 12 has changed (for example, a state in which position movement has occurred), and returns the process to step S51.

On the other hand, in the first and second embodiments of the present invention, BTMA (Busy-Tone Multiple Access) is used to notify the IC tag of the channel availability at a frequency where the busy tone is low. In addition, the power consumption during standby of the IC tag can be suppressed, the battery life can be extended, and the data frame and the busy tone are transmitted / received through different channels, so that the transfer efficiency is improved as compared with the ISMA.
In the second embodiment, the interrogator 50 receives the response signal (information on whether or not the IC tag 12 has received the alternating magnetic field signal), so that the signal strength measurement circuit 54 receives the response signal. If the radio wave has a weak signal strength (RSSI: Received Signal Strength Indicator), for example, as shown in FIG. 11A, tag A located far from the interrogator 50 in the communicable area. It can be detected that the response is from the (IC tag 12).

Then, the interrogator 50 reduces the transmission intensity of the alternating magnetic field by the signal intensity control circuit 56, assuming that the remaining other tag B (IC tag 12) is present nearby.
As a result, compared with the case where the interrogator 50 changes the alternating magnetic field to a strong state, the transmission / reception area is limited, and the period during which the tag A (IC tag 12) located far away is kept in the standby state. Can be long.
In addition, the power used for reception processing and transmission processing in the IC tag 12 can be reduced, and the lifetime of the IC tag 12 can be extended as a whole.

  Note that the control circuit 54 in FIG. 1 (configuration of the interrogator 50) and FIG. 5 (operation of the interrogator 50), the signal in FIG. 6 (configuration of the interrogator 50), FIG. 9, and FIG. By recording a program for realizing the functions of the intensity control circuits 56 and 68 and the control circuit 70 on a computer-readable recording medium, and causing the computer system to read and execute the program recorded on the recording medium, You may control each process of the IC tag 12 mentioned above. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer system” includes a WWW system having a homepage providing environment (or display environment). The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

1 is a block diagram illustrating a configuration example of an IC tag 12 and an IC tag control system according to a first embodiment of the present invention. It is a conceptual diagram which shows the correspondence of transmission / reception of the data of the IC tag 12 and the interrogator 50 in the IC tag control system by 1st Embodiment. It is a flowchart which shows the operation example by the side of the IC tag 12 of the IC tag control system by 1st Embodiment. It is a flowchart which shows the operation example (the identification process of the 1st IC tag 12) by the interrogator 50 side of the IC tag control system by 1st Embodiment. It is a flowchart which shows the operation example (identification process of IC tag 12 after the 2nd time) of the interrogator 50 side of the IC tag control system by 1st Embodiment. It is a conceptual diagram which shows the correspondence of transmission / reception of the data of the IC tag 12 and the interrogator 50 in the IC tag control system by 2nd Embodiment. It is a flowchart which shows the operation example by the side of IC12 of the IC tag control system by 2nd Embodiment. It is a flowchart which shows the operation example (the identification process of the 1st IC tag 12) by the interrogator 50 side of the IC tag control system by 2nd Embodiment. It is a flowchart which shows the operation example (identification process of IC tag 12 after the 2nd time) of the interrogator 50 side of the IC tag control system by 2nd Embodiment. It is a flowchart which shows the operation example (identification process of IC tag 12 after the 2nd time) of the interrogator 50 side of the IC tag control system by 2nd Embodiment. It is a conceptual diagram explaining the point which is superior to the description of the power-saving process of communication with the interrogator 50 and the some IC tag 12 in the IC tag control system of FIG. 6, and ISMA.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 ... Coil 3 ... Transmission circuit 4, 8, 58, 69 ... Antenna 12 ... IC tag 50 ... Interrogator 51 ... Uplink receiving circuit 52 ... Downlink excitation circuit 53, 63, 66 ... Receiver 54, 65, DESCRIPTION OF SYMBOLS 70 ... Control circuit 55 ... Exciter 56, 68 ... Signal strength control circuit 57, 64 ... Transmitter 59 ... Downlink transmission circuit 60, 67 ... Signal strength measurement circuit 61 ... Downlink reception circuit 62 ... Uplink transmission circuit

Claims (8)

It communicates with the control device using the busy tone return method, and the transmission intensity of the busy tone signal from the control device decreases sequentially, and while the busy tone signal is detected, the control device Non-contact IC medium that does not communicate with
A first antenna for receiving the busyton signal in a first frequency band;
A second antenna for transmitting a response signal in the second frequency band;
A control circuit for detecting a busy tone signal received by the first antenna and outputting it as control data;
A transmission circuit that outputs a response signal from the second antenna according to the control data,
When the first frequency band is set to a frequency band lower than the second frequency band and the control circuit does not detect a busy tone signal, the transmission circuit transmits the response signal, while the busy tone signal is detected. The non-contact IC medium is characterized in that the busy tone signal is detected again after a predetermined time has elapsed . The contactless IC medium according to claim 1, wherein the first frequency band is an LF band. A signal strength measuring unit for detecting the reception strength of the busy tone signal, according to claim 1 or claim 2 and having a signal intensity control circuit for controlling the outgoing intensity of the response signal according to the detection result Non-contact IC medium. The first antenna is a coil that is magnetically coupled to an external coil, detects a voltage induced by an alternating magnetic field generated by the external coil, and outputs the detected voltage to the control circuit as the busy tone signal. The non-contact IC medium according to claim 1 or 2 . When a non-contact IC medium is already in communication with one non-contact IC medium, the control device transmits a busy tone signal and controls communication from a plurality of non-contact IC media .
A control unit that generates the preamble signal in response to an input command;
A transmission circuit that superimposes the preamble signal on a signal of a predetermined first frequency band and outputs it as a control signal;
A first antenna for transmitting the control signal in a first frequency band;
A second antenna for transmitting and receiving data in the second frequency band,
The first frequency band is set to a frequency band lower than the second frequency band, and the transmission intensity of the control signal is sequentially reduced, so that data is transmitted and received sequentially from a distant non-contact IC medium. A non-contact IC medium control device. 6. The non-contact IC medium control device according to claim 5, wherein the first frequency band is an LF band. The transmission unit includes a signal strength measurement unit that measures the reception strength of the response signal from the IC tag, and a signal strength control unit that controls the transmission strength of the control signal according to the measurement result. The non-contact IC medium control device according to claim 5 or 6 . The first antenna generates an alternating magnetic field corresponding to the control signal, performs magnetic coupling with another coil of the non-contact IC medium by the alternating magnetic field, and transmits the control signal to the other coil. The non-contact IC medium control device according to claim 5 , wherein the non-contact IC medium control device is a non-contact IC medium control device.

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