JP2009218713A - Composite radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a radio tag perform a responding operation even when the residual capacity of a built-in battery of the radio tag runs short, in a composite radio communication system comprising the radio tag and a tag reader capable of radio communication using two different communication systems. <P>SOLUTION: The tag reader 2 of the composite radio communication system 1 includes a first reader communication part 21 for transmitting an interrogation signal by a first communication system and receiving a first response signal by the first communication system, and a second reader communication part 22 for receiving a second response signal by a second communication system. Meanwhile, the radio tag 5 includes a battery 52, a first tag communication part 53 for receiving the interrogation signal, and a second tag communication part 54. The first tag communication part 53 makes the second response signal be transmitted from the second tag communication part 54 using the supply voltage of the battery 52 when the second tag communication part 54 is capable of responding, and transmits the first response signal using a voltage generated from the interrogation signal when the second tag communication part 54 is incapable of responding. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composite wireless communication system, and more particularly, to a composite wireless communication system using a wireless tag and a tag reader capable of wireless communication using two different communication methods.

  In recent years, various services using a wireless automatic identification (hereinafter referred to as RFID) system have been provided. There are various types of wireless tags constituting the RFID system, which have different communication methods and different radio frequency bands, and those having characteristics suitable for the service to be provided are used. For example, the communication method adopted in wireless tags is a passive type that responds to a query signal from a tag reader without having a battery in the wireless tag, and a signal is spontaneously output using a battery built in the wireless tag. There is an active type that receives an interrogation signal from a tag reader and is driven by a semi-active type that responds using a built-in battery. Further, as the radio frequency band, a long wave band, a short wave band, a super short wave band, a microwave band, or the like is used.

  Recently, the application range of the RFID system is further diversified, and a system using a wireless communication function using a plurality of types of communication methods has also been proposed (see Patent Document 1). The wireless tag used in the system disclosed in Patent Document 1 receives an interrogation signal from a reader by an electromagnetic induction method, and sends a response signal by a specific low power radio using a built-in battery.

When the electromagnetic induction method is used, the reach range of the question signal transmitted from the reader can be defined with relatively high accuracy, and the wireless tag can receive the question signal with low power consumption. However, in order to output a response signal that can reach a range similar to the reach range of the interrogation signal from the wireless tag, a large amount of power is required, so that battery power consumption becomes significant. Also, the antenna installed on the reader side must be enlarged. On the other hand, when using wireless communication by specific low-power wireless, a battery is required as a driving power source for the wireless tag. However, the communication range can be extended by using a small antenna with low power consumption.
For this reason, the above system can detect the wireless tag with high accuracy while suppressing the power consumption of the built-in battery of the wireless tag by utilizing the advantages of both the electromagnetic induction method and the specific low power wireless. Yes.

JP 2006-350861 A

  However, in order for the wireless tag to respond to the interrogation of the reader by the specific low power wireless, a battery is required as described above. Therefore, in the conventional RFID system, when the remaining battery capacity is exhausted, the wireless tag cannot respond to the reader. Therefore, for example, when this RFID system is adopted for traffic control such as opening and closing of a door and the traffic restriction is canceled by the response of the radio tag (for example, the door is unlocked), the radio tag having no remaining capacity of the built-in battery The owner will no longer have a way to lift the traffic restrictions.

  In view of the above, an object of the present invention is to provide a composite wireless communication system capable of causing a wireless tag to perform a response operation even when the remaining capacity of a battery built in the wireless tag is insufficient.

  The present invention for solving such a problem is a composite wireless communication system that includes a wireless tag and a tag reader capable of wireless communication using two different communication methods, and detects a wireless tag existing in a predetermined area by the tag reader. I will provide a. In the composite wireless communication system, the tag reader transmits a question signal by the first communication method, and receives a first response signal by the first communication method transmitted from the wireless tag; And a second reader communication unit that receives a second response signal transmitted from the wireless tag according to the second communication method. On the other hand, the wireless tag receives the interrogation signal transmitted from the battery and the tag reader, and uses the voltage generated from the interrogation signal to transmit the first response signal according to the first communication method. And a second tag communication unit that transmits a second response signal according to the second communication method using the supply voltage of the battery. The first tag communication unit transmits a second response signal from the second tag communication unit when the second tag communication unit is ready to transmit a response signal when receiving the interrogation signal. If the second tag communication unit cannot transmit the response signal, the first tag communication unit transmits the first response signal.

  Further, in the composite wireless communication system according to the present invention, the first tag communication unit receives the response signal when the supply voltage from the battery when the interrogation signal is received is less than a predetermined value. It is preferable to transmit the first response signal using the generated voltage generated by receiving the interrogation signal.

  Furthermore, in the composite wireless communication system according to the present invention, it is preferable that the second communication method is a communication method capable of obtaining a wide communication range with lower power consumption than the first communication method. As the first communication method, wireless communication using an electromagnetic induction method or a radio wave method can be used, and as the second communication method, specific low power wireless or weak wireless can be used.

  The composite wireless communication system according to the present invention has an effect that the wireless tag can perform a passive response operation without using the battery even when the remaining capacity of the battery built in the wireless tag is insufficient.

Hereinafter, an embodiment in which a composite wireless communication system according to the present invention is applied to an access control system will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of the access control system 1. As shown in FIG. 1, the entrance / exit management system 1 is managed by one or more tag readers 2 installed in the vicinity of an entrance / exit door (not shown) for restricting traffic and each tag reader 2, The electric lock 3, the management control device 4, and the wireless tag 5 are provided. In the access control system 1, the electric lock 3 is locked in a normal state. When the user who has the wireless tag 5 enters the reading range of the tag reader 2 (for example, within about 2 m around the tag reader 2), the wireless tag 5 responds to the inquiry signal from the tag reader 2 and transmits a response signal. To do. The response signal includes an identification code (hereinafter referred to as an ID code) for identifying the other wireless tag. When the tag reader 2 receives the response signal and confirms from the information of the wireless tag 5 that the user has a legitimate authority, the tag reader 2 temporarily unlocks the managed electric lock 3 to use it. Allow traffic. The tag reader 2 transmits the ID code of the responding wireless tag 5, the unlocking and locking times, the ID code of the tag reader 2 itself, and the like to the management control device 4 connected via the communication network 6 such as a LAN. The management control device 4 stores the information as a user's traffic history information in a built-in recording device (not shown).

Here, the wireless tag 5 requires a short-range wireless communication method capable of passively responding (passive response) without using the power of the built-in battery at a short distance, and a built-in battery for the response. It is possible to communicate with the tag reader 2 by two kinds of communication methods of the long distance wireless communication method capable of long-range response with low power consumption compared to the distance wireless communication method, and either one of them depending on the remaining capacity of the built-in battery. Select a communication method and send a response signal. As a result, even when the remaining capacity of the built-in battery of the wireless tag 5 is insufficient, communication between the tag reader 2 and the wireless tag 5 is possible at a short distance, and the situation where the electric lock 3 cannot be unlocked is prevented. The
Hereinafter, each part of the access control system 1 will be described in detail.

  FIG. 2 shows a functional block diagram of the tag reader 2. The tag reader 2 includes an LF transmission / reception unit 21, an RF reception unit 22, a power supply unit 23, an external interface unit 24, and a control unit 25.

The LF transmission / reception unit 21 is a communication unit using a short-range wireless communication method, and wirelessly communicates with the wireless tag 5 using an electromagnetic induction method. For this purpose, the LF transmitter / receiver 21 includes a modulator, a demodulator, and an antenna coil. In the present embodiment, the LF transmitter / receiver 21 uses the long wave (that is, the LF wave) of the 135 kHz band for the radio wave (that is, the interrogation signal) modulated by the modulator to the range of 2 m around the tag reader 2. Transmit from the antenna coil.
The LF transmitter / receiver 21 repeatedly transmits the question signal at a predetermined interval. For example, when transmitting an inquiry signal having a length of 0.2 sec, the LF transmitter / receiver 21 waits for 0.2 sec in order to prevent collision of response signals from the plurality of wireless tags 5 (anti-collision). The LF transmission / reception unit 21 repeats the operation and continuously transmits a question signal.
Further, when the LF transmission / reception unit 21 receives the LF response signal from the wireless tag 5, the LF response signal is demodulated by the demodulation unit and passed to the control unit 25.

Hereinafter, the configuration of the question signal will be described. The interrogation signal is composed of a preamble, modulated data, and an unmodulated carrier wave in order from the top.
The preamble is a synchronization bit string for clock synchronization. Further, the wireless tag 5 stores electric power necessary for driving a circuit built in the wireless tag 5 by using the radio wave of the preamble portion. Therefore, the preamble of the interrogation signal has a length that can store enough power for the wireless tag 5 to transmit the LF response signal without using the built-in battery. Therefore, by simply bringing the wireless tag 5 close to the tag reader 2, the wireless tag 5 can easily perform a passive response operation to the tag reader 2 without using a built-in battery.
The modulation data is obtained by modulating a command bit string for controlling the wireless tag 5 by the modulation unit. The command bit string includes an ID code for identifying the tag reader 2 from other tag readers.
The unmodulated carrier wave is an area for carrying data included in the response signal when the wireless tag 5 performs passive operation, that is, when responding with an LF wave.

  The RF receiving unit 22 is a communication unit based on a long-distance wireless communication method, and receives a response signal from the wireless tag 5 according to a communication method that can obtain a wide communicable range with lower power consumption than the LF transmitting / receiving unit 21. In the present embodiment, the RF receiving unit 22 receives a response signal (hereinafter referred to as an RF response signal) by an RF wave from the wireless tag 5 using a specific low power radio having a use frequency of 400 MHz. In this case, the RF receiver 22 can ensure a communication distance of several meters to several tens of meters using a small antenna. The RF reception unit 22 includes a demodulation unit and an antenna. When receiving the RF response signal from the wireless tag 5 via the antenna, the RF receiver 22 demodulates the response signal by the demodulator and passes it to the controller 25. The RF receiver 22 can operate independently of the LF transmitter / receiver 21.

  The power source unit 23 is a circuit that is connected to an external power source, converts an AC voltage supplied from the external power source into a DC voltage, and supplies power to each unit of the tag reader 2. Moreover, the power supply part 23 may have a battery so that the tag reader 2 can operate for a certain period even during a power failure.

  The external interface unit 24 includes an interface circuit connected to the electric lock 3 managed by the tag reader 2 and a communication interface circuit for communicating with other tag readers and the management control device 4 via the communication network 6. The external interface unit 24 transmits a control signal output from the control unit 25 to unlock or lock the electric lock 3 to the electric lock 3 under the management of the tag reader 2. Further, the external interface unit 24 sends the ID code of the wireless tag 5 responding to the tag reader 2, the ID code of the tag reader 2 itself, the unlocked or locked electric lock 3 to the management control device 4 via the communication network 6. Identification information, unlocking and locking times are transmitted.

The control unit 25 includes a microprocessor, a memory, and its peripheral circuits. The control unit 25 controls each unit of the tag reader 2. Then, the control unit 25 causes the LF transmission / reception unit 21 to repeatedly transmit the question signal continuously at regular intervals.
When the response signal from the wireless tag 5 is received and demodulated by the RF receiving unit 22 or the LF transmitting / receiving unit 21, the control unit 25 receives the ID code of the wireless tag 5. And the control part 25 collates the received ID code with the registration ID code of the registered wireless tag memorize | stored in memory, and determines whether there exists what corresponds. If the ID code received from the wireless tag 5 matches one of the registered ID codes, the control unit 25 authenticates the wireless tag 5 as having an authorized authority, and sends an external interface unit to the managed electric lock 3. An unlock signal for temporarily unlocking is output via 24. Further, the control unit 25 transmits the user's traffic history information such as the ID code of the wireless tag 5 to the management control device 4 via the external interface unit 24 and the communication network 6.

  On the other hand, if the ID code received from the wireless tag 5 does not match any registered ID code, the control unit 25 keeps the electric lock 3 under management in a locked state, and sends the unauthorized tag to the management control device 4. As information, the ID code of the wireless tag 5 is transmitted. In addition, when the tag reader 2 has a notification unit composed of a liquid crystal display, an LED, a speaker, and the like, the control unit 25 uses the notification unit to indicate that the wireless tag 5 is illegal for the user. You may make it alert | report.

  FIG. 3 shows a functional block diagram of the wireless tag 5. The wireless tag 5 includes a memory 51, a battery 52, an LF transmission / reception unit 53, an RF transmission unit 54, and a control unit 55.

The memory 51 is configured by a non-volatile memory such as a flash memory, EEPROM, or FRAM (registered trademark). The memory 51 holds an ID code for identifying the wireless tag 5 from other wireless tags.
The battery 52 is composed of a small battery built in the wireless tag 5, and supplies power for driving each part of the wireless tag 5 via the control unit 55. The small battery used for the battery 52 is preferably a replaceable or rechargeable type.

The LF transmission / reception unit 53 is a communication unit using a short-range wireless communication method, and wirelessly communicates with the tag reader 2 using an electromagnetic induction method. In the present embodiment, the LF transmission / reception unit 53 performs wireless communication with the LF transmission / reception unit 21 of the tag reader 2 using an LF wave in the 135 kHz band. For this purpose, the LF transmitter / receiver 53 includes an antenna coil 531, a voltage generating means 532 having a capacitor and a rectifier circuit, a signal processing means 533 having an embedded processor circuit, and a power monitoring means for monitoring the remaining capacity of the battery 52. 534. The LF transmission / reception unit 53 operates in a low power consumption mode in which only the power necessary for standby for signal reception is consumed using the power supplied from the battery 52 while the question signal is not received from the tag reader 2.
On the other hand, when the LF transmitter / receiver 53 receives an interrogation signal from the tag reader 2 by electromagnetic induction with the antenna coil of the LF transmitter / receiver 21 of the tag reader 2 via the antenna coil 531, the voltage generator 532 is obtained by electromagnetic induction. The AC voltage is rectified to a DC voltage and stored as a generated voltage used for driving the LF transceiver 53. The signal processing means 533 operates according to the generated voltage or the supply voltage from the battery 52, and demodulates the received interrogation signal.

  The power monitoring unit 534 determines whether or not the remaining capacity of the battery 52 is sufficient for the wireless tag 5 to transmit the RF response signal. For this purpose, the power monitoring unit 534 detects whether or not the supply voltage from the battery 52 supplied via the control unit 55 is equal to or higher than a predetermined value, and outputs the detection result to the signal processing unit 533. The predetermined value is, for example, a voltage value necessary for driving the RF transmission unit 54 and the control unit 55 so that the RF transmission unit 54 transmits an RF response signal.

  The signal processing unit 533 executes different processing according to the remaining capacity of the battery 52 when the question signal is received from the tag reader 2. When the detection result indicating that the supply voltage from the battery 52 is equal to or higher than a predetermined value is received from the power supply monitoring unit 534, the signal processing unit 533 demodulates the RF transmission unit 54 so that a predetermined response signal can be transmitted. The signal is passed to the control unit 55.

  On the other hand, when the detection result indicating that the supply voltage from the battery 52 is less than the predetermined value is received from the power supply monitoring unit 534, the signal processing unit 533 does not use the supply voltage from the battery 52, and the voltage generation unit. An LF response signal to be transmitted from the LF transmitter / receiver 53 itself is generated using the voltage generated by 532. For this purpose, the signal processing means 533 reads the ID code of the wireless tag 5 from the memory 51, and modulates the unmodulated carrier wave included in the interrogation signal with the ID code. Then, the signal processing unit 533 outputs the LF response signal from the antenna coil 531 using the generated voltage generated by the voltage generating unit 532 using the preample part of the question signal. In this way, the LF transceiver 53 can make a passive response using the induced electromotive force accompanying reception of the interrogation signal.

  Here, if the wireless tag 5 is out of battery and the distance from the tag reader 2 is too far, the power generated by receiving the question signal is small, and the power necessary to drive the LF transceiver 53 is obtained. I can't. Even if the LF transmitter / receiver 53 can transmit the LF response signal, the tag reader 2 cannot receive the LF response signal unless the generated voltage necessary to increase the distance to the tag reader 2 is obtained. Therefore, in order to generate and transmit the LF response signal and cause the tag reader 2 to receive the LF response signal, the wireless tag 5 is closer to the tag reader 2 than the distance (for example, 2 m) where the interrogation signal can be received. Need to be. That is, when the wireless tag 5 is at a close distance (for example, within several centimeters to several tens of centimeters) of the tag reader 2, it uses the induced electromotive force due to reception of the interrogation signal without using the battery 52, and LF A response signal can be transmitted to the tag reader 2 (passive response).

  The RF transmission unit 54 is a communication unit based on a long-distance wireless communication system, and transmits a response signal to the tag reader 2 according to a communication system that can obtain a wide communicable range with lower power consumption than the LF transmission / reception unit 53. In the present embodiment, the RF transmission unit 54 uses a specific low-power radio having a use frequency of 400 MHz. For this reason, the RF transmission unit 54 can cause the RF response signal to reach a range of several meters to several tens of meters using a small antenna. Further, by using the specific low power radio, the power consumption for the radio tag 5 to transmit the RF response signal can be very small as compared with the case where the LF response signal is skipped by the same distance. The RF transmission unit 54 includes modulation means 541 and an antenna 542. Then, the modulation unit 541 generates an RF response signal in accordance with a response signal transmission instruction from the control unit 55. The RF response signal includes the ID code of the tag reader 2 included in the interrogation signal received by the wireless tag 5 and the ID code of the wireless tag 5 read from the memory 5. The generated RF response signal is transmitted from antenna 542.

The control unit 55 includes a built-in CPU and its peripheral circuits. The control unit 55 operates using the supply voltage from the battery 52 to control each unit of the wireless tag 5. The control unit 55 operates the LF transmission / reception unit 53 in the above-described low power consumption mode in order to suppress the power consumption of the battery 52 while the question signal is not received. The clock is stopped and the device operates in a sleep mode in which only peripheral circuits are operated. Further, the power supply to the RF transmitter 54 that is not necessary for receiving the interrogation signal is stopped and the operation is turned off.
When the demodulated signal of the interrogation signal received by the LF transmitter / receiver 53 is input, the controller 55 controls the RF transmitter 54 to output an RF response signal. At this time, the control unit 55 transfers the ID code of the tag reader 2 included in the demodulated signal and the ID code of the wireless tag 5 read from the memory 5 to the RF transmission unit 54.

  FIG. 4 shows a flowchart of the response operation of the wireless tag 5 when the interrogation signal is received. First, when the LF transmission / reception unit 53 of the wireless tag 5 receives the question signal, the wireless tag 5 shifts from the standby state and starts a response operation. Then, the LF transmitter / receiver 53 performs a question signal reception process (step S401). Specifically, the voltage generation means 532 of the LF transmission / reception unit 53 generates and accumulates an induced electromotive force by electromagnetic induction using a preamble part included in the question signal. Further, the signal processing means 533 of the LF transceiver 53 demodulates the question signal.

  Thereafter, the signal processing unit 533 determines whether or not the remaining capacity of the battery 52 detected by the power supply monitoring unit 534 of the LF transmission / reception unit 53 is greater than or equal to a predetermined value (step S402). When it is determined that the remaining capacity of the battery 52 is less than the predetermined value (that is, when the remaining capacity of the battery 52 is insufficient to transmit the RF response signal), the signal processing unit 533 The LF response signal is generated using only the generated voltage generated by the voltage generating unit 532 without using the supply voltage, and the LF response signal is transmitted from the antenna coil 531 of the LF transceiver 53 (step S403).

  On the other hand, when it is determined in step S402 that the remaining capacity of the battery 52 is greater than or equal to a predetermined value (that is, when the remaining capacity of the battery 52 is sufficient to transmit the RF response signal), the signal processing means. 533 outputs the demodulated signal to the control unit 55 of the wireless tag 5. And the control part 55 drives the RF transmission part 54 using the supply voltage from the battery 52, and produces | generates an RF response signal (step S404). Then, an RF response signal is transmitted from the antenna 542 of the RF transmitter 54 (step S405). After step S403 or S405, the wireless tag 5 finishes the response operation and enters the standby state again.

  As described above, in the composite wireless communication system to which the present invention is applied, when the remaining capacity of the battery built in the wireless tag is sufficient, the monitoring range can be set with high accuracy and the wireless tag standby An inquiry is made by an electromagnetic induction method using an LF wave with a small electric power, and the tag reader is responded by using a specific low power radio having a small antenna and low power consumption and a wide communicable range as compared with the case of using the LF wave. Therefore, such a system enables reliable and low power consumption communication between the tag reader and the wireless tag without requiring the user to hold the wireless tag over the tag reader. Furthermore, when the remaining capacity of the battery built in the wireless tag is insufficient, the wireless tag transmits a response signal using power generated based on the inquiry signal received from the tag reader. Therefore, the system can communicate between the tag reader and the wireless tag even when the remaining capacity of the built-in battery of the wireless tag is exhausted.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. For example, each of the tag reader 2 and the wireless tag 5 may include a short-distance transmission / reception unit that performs electromagnetic induction-type wireless communication using short-wave radio waves, instead of the LF transmission / reception unit. Similarly, each of the tag reader 2 and the wireless tag 5 has a short-range transmission / reception unit that performs radio communication using a radio wave system using UHF / ultra-short wave or microwave band, instead of the LF transmission / reception unit. Also good. In the case of using the radio communication of the radio wave system, the short-range transmission / reception unit of the radio tag 5 makes a passive response using radio wave reflection when transmitting the LF response signal.

Further, the RF receiving unit of the tag reader 2 and the RF transmitting unit of the wireless tag 5 may use weak radio. Alternatively, the RF reception unit and the RF transmission unit may operate according to wireless LAN standards such as infrared communication, Bluetooth (registered trademark), IEEE802.11a, b, g, and n. However, the communicable range of the response signal transmitted from the RF transmission unit is preferably equal to or wider than the communicable range of each LF transceiver unit. By selecting the communication method used in the RF transmitter in this way, it is possible to secure a wide communication range with low power consumption compared to the electromagnetic induction method, so that the remaining capacity of the built-in battery of the wireless tag is sufficient at normal times. The response can be performed reliably and with low power consumption.
In the above embodiment, the LF transmitter / receiver of the wireless tag 5 determines whether or not the RF transmitter can respond by monitoring the supply voltage from the battery. It may be configured to hold the determination result that the response is impossible in response to the capacity reduction signal. Moreover, you may comprise so that the operation state (ON / OFF of a power supply) of RF transmission part may be monitored.

  Further, as in the above embodiment, when the reach range of the response signal transmitted from the RF transmission unit ranges from several meters to several tens of meters, the response that controls the RF reception function by making the RF reception unit independent from the tag reader You may comprise as a receiver. In this case, particularly when a plurality of tag readers are connected to a response receiver via a communication network, the RF response signal from the wireless tag to each of the plurality of tag readers is received by one response receiver, and the RF response is received. Since the response signal can be transmitted to the tag reader corresponding to the ID code of the tag reader included in the signal, the cost of the entire system can be suppressed.

  Further, when the remaining capacity of the battery 52 of the wireless tag 5 decreases, a warning may be given to the user. For example, the wireless tag 5 further includes an LED, and when it is estimated that the remaining capacity of the battery 52 is such that the remaining capacity disappears when an RF response signal is transmitted several times, the user runs out of battery by causing the LED to emit light. May be warned. The power supply monitoring unit 534 compares the supply voltage from the battery 52 with a second predetermined value that is higher than the predetermined value used for determining whether the battery is dead, and the supply voltage is less than the second predetermined value. , It is estimated that the remaining capacity of the battery 52 is such that the RF response signal can be transmitted several times. Alternatively, when the power monitoring unit 534 estimates that the remaining capacity of the battery 52 is such that the remaining capacity disappears when the RF response signal is transmitted several times, the RF transmission unit 54 of the wireless tag 5 uses the RF response signal as the RF response signal. A warning signal indicating that the remaining capacity of the battery 52 is small may be included. In this case, when the warning signal is included in the received RF response signal, the tag reader 2 notifies the user of the battery of the wireless tag 5 possessed via the notification unit provided in the tag reader 2. You may make it warn of a piece.

  Further, the tag reader 2 may include an operation unit for instructing the wireless tag 5 to forcibly transmit a response signal using an LF wave. In this case, the operation unit includes, for example, one or a plurality of operation button switches arranged on the surface of the tag reader 2. When the operation unit is operated (for example, when an operation button of the operation unit is pressed), the tag reader 2 communicates between the wireless tag 5 and the tag reader 2 even when there is no remaining capacity of the built-in battery of the wireless tag 5. A relief operation is performed so that it is possible. Specifically, when the relief operation is executed by operating the operation unit, the tag reader 2 includes a command for transmitting a response signal by an LF wave in the question signal transmitted from the LF transceiver unit 21. On the other hand, when the wireless tag 5 checks the command included in the interrogation signal and detects a command indicating that the response signal is transmitted by the LF wave, the LF transceiver 53 transmits the LF response signal.

Furthermore, the use of the composite radio system according to the present invention is not limited to the above-described access control system. For example, the present invention can be applied to a security system that performs control in accordance with the moving direction of a user, as disclosed in JP-A-2006-350861.
As described above, various modifications can be made within the scope of the present invention according to the embodiment to be implemented.

1 is a schematic configuration diagram of an access management system to which a composite wireless communication system according to the present invention is applied. It is a functional block diagram of the tag reader used by embodiment of this invention. It is a functional block diagram of the wireless tag used by embodiment of this invention. It is a flowchart which shows the response operation | movement of the wireless tag at the time of question signal reception.

Explanation of symbols

1 Access control system (composite radio communication system)
2 Tag Reader 3 Electric Lock 4 Management Control Device 5 Wireless Tag 6 Communication Network 21 LF Transmission / Reception Unit 22 RF Reception Unit 23 Power Supply Unit 24 External Interface Unit 25 Control Unit 51 Memory 52 Battery 53 LF Transmission / Reception Unit 54 RF Transmission Unit 55 Control Unit

Claims (3)

In a composite wireless communication system that is configured with a wireless tag and a tag reader capable of wireless communication using two different communication methods, and that detects the wireless tag present in a predetermined area by the tag reader,
The tag reader is
A first reader communication unit that transmits a question signal in a first communication method and receives a first response signal transmitted from the wireless tag in accordance with the first communication method;
A second reader communication unit that receives a second response signal transmitted from the wireless tag according to a second communication method;
The wireless tag is
Battery,
A first tag communication unit that receives the interrogation signal transmitted from the tag reader and transmits the first response signal according to the first communication method using a voltage generated from the interrogation signal;
A second tag communication unit that transmits the second response signal according to the second communication method using a supply voltage of the battery;
The first tag communication unit receives the second response signal from the second tag communication unit when the second tag communication unit is capable of transmitting a response signal when the interrogation signal is received. Transmitting the first response signal from the first tag communication unit when the second tag communication unit is in a state where the response signal cannot be transmitted.
A composite wireless communication system.   When the supply voltage from the battery when the first tag communication unit receives the interrogation signal is less than a predetermined value, the second tag communication unit is in a state where the response signal cannot be transmitted. The composite wireless communication system according to claim 1, wherein the first response signal is transmitted using the generated voltage generated by receiving the inquiry signal.   The composite wireless communication system according to claim 1 or 2, wherein the second communication method is a communication method capable of obtaining a wide communication range with lower power consumption than the first communication method.

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