JP2009118074A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system which eliminates the necessity to mount a battery to the small apparatus such as a radio tag, easily selects one of the multiple apparatuses, and starts radio communication with the selected apparatus. <P>SOLUTION: A radio wave signal is transmitted from a question machine 1 so as to bring a plurality of radio tags 2 into operation states. In this state, the light emission part 21 of the question machine 1 is made to emit light. The light beam of the light emission part 21 is made incident to the light receiving part 37 of one radio tag 2, thereby allowing only the radio tag 2 to perform a response. Consequently, one of the plurality of radio tags 2 is easily selected and radio communication is started with the selected radio tag 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless communication system including an interrogator and a terminal that perform wireless communication with each other, and the terminal receives a radio signal from the interrogator and performs a response operation.

  As this type of system, there is a system that performs wireless communication between an interrogator (reader / writer) and a wireless tag. In this system, wireless communication can be performed between one interrogator and a plurality of wireless tags, and a radio signal is transmitted from the interrogator, and one of the wireless tags responds.

  However, when radio signals from the interrogator are received by a large number of wireless tags, it is possible to respond to these wireless tags, so it is necessary to identify one of the wireless tags and perform wireless communication. . For example, a large number of wireless tags once return their IDs to the interrogator, select one ID on the interrogator side, and start wireless communication with only one wireless tag using this ID. Follow the steps. Alternatively, the ID of all wireless tags may be stored in advance on the interrogator side, one ID may be selected, and wireless communication may be performed with only one wireless tag using this ID. .

  However, in the former case, it is necessary for the interrogator to receive the IDs of a large number of wireless tags, which complicates the communication procedure and increases the communication time. The scale increased and the cost increased.

  In the latter case, it is necessary to store IDs of a large number of wireless tags in advance, and when the number of wireless tags increases or decreases, it is necessary to redo ID registration each time. It took.

For this reason, in Patent Document 1, when an optical signal is received, transmission / reception of radio signals is started using this as a trigger signal, thereby reducing transmission / reception of unnecessary radio signals. By applying such a technique that uses such an optical signal as a trigger signal for starting wireless communication, it is possible to easily select one wireless tag and start wireless communication only with this wireless tag. It is done.
JP 2005-348057 A

  However, in Patent Document 1, it is necessary for an element or circuit for detecting an optical signal on the side that receives the optical signal to be always in an operating state, and power consumption for this is increased. For example, in order to always keep a small device such as a wireless tag in an operating state, it is necessary to mount a battery or the like, but it is necessary to downsize the battery, and a long-time operating state cannot be maintained at all. . Therefore, it is practically impossible to apply the technique of Patent Document 1 to a small wireless tag or the like.

  Therefore, the present invention has been made in view of the above-described conventional problems, and it is not necessary to mount a battery in a small device such as a wireless tag, and one of a number of devices can be easily selected. An object of the present invention is to provide a wireless communication system capable of starting wireless communication with a selected device.

  In order to solve the above problems, the present invention includes an interrogator and a terminal that perform wireless communication with each other, and the terminal receives a radio signal from the interrogator and performs a response operation. The terminal generates power from the radio signal received from the interrogator, supplies power for driving the terminal, light receiving means for receiving light from the outside, and the light receiving means Determining means for determining the presence or absence of light from the outside based on the received light output; and communication control means for starting a response operation to the interrogator when the determining means determines that there is external light. Yes.

  The determination means determines the presence or absence of light from the outside based on whether or not the light reception output level of the light reception means is equal to or higher than a specified value.

  Further, the determination means determines the presence or absence of light from the outside based on whether or not the pattern of light from the outside indicated by the light reception output of the light receiving means is a prescribed pattern.

  The power supply means generates power from the radio signal received from the interrogator, generates power from the light reception output of the light receiving means, and supplies the power for driving the terminal.

  Furthermore, it is provided on the interrogator side with a light emitting means for emitting external light received by the light receiving means.

  Further, the light emitted from the light emitting means is visible light.

  Furthermore, the light receiving part of the light receiving means is provided with a regulating member for regulating a light receiving range of the light from the outside.

  Meanwhile, another aspect of the invention includes an interrogator and a terminal that perform wireless communication with each other, and in the wireless communication system in which the terminal receives a radio signal from the interrogator and operates in response, the interrogator includes: A wide directivity radio signal and a narrow directivity radio signal are transmitted, and the terminal generates power from the wide directivity radio signal received from the interrogator, and uses this power for driving the terminal. Power supply means for supplying to the receiver, receiving means for receiving the narrow-directional radio signal from the interrogator, and presence / absence of the narrow-directional radio signal based on the narrow-directional radio signal received by the receiving means And a communication control means for starting a response operation to the interrogator when it is determined by the determination means that a narrow directivity radio signal is present.

  According to the present invention, since the terminal generates power from the radio signal received from the interrogator and uses this power for driving the terminal, the terminal receives the radio signal from the interrogator. It becomes an operation state when And a terminal will start the response operation | movement with respect to an interrogator, if light from the outside is received by a light-receiving means and it determines light reception. Therefore, when a radio signal is transmitted from the interrogator and the terminal is in an operating state and then light is emitted toward the terminal, this light is received by the light receiving means of the terminal and the terminal responds. . Here, when radio signals from the interrogator are received by a large number of terminals, all of these terminals are in an operating state. However, when light is emitted toward one terminal, only this terminal responds. Operate. For this reason, it is possible to easily select one of a large number of terminals and start wireless communication with the selected terminal. Further, since the terminal generates electric power from the radio signal received from the interrogator and uses it for driving, it does not require a power source such as a battery.

  For example, the presence or absence of light from the outside may be determined based on whether or not the light reception output level of the light receiving means is greater than or equal to a specified value, or the pattern of light from the outside indicated by the light reception output of the light receiving means The presence or absence of light from the outside may be determined based on whether or not is a defined pattern.

  Further, not only power is generated from the radio wave signal received from the interrogator, but also power is generated based on the light reception output of the light receiving means, and these powers may be used for driving the terminal. In this case, more power can be obtained.

  Furthermore, a light emitting means is provided on the interrogator side and emits light from the outside. Such a light emitting means is used to emit light toward the terminal, but may be provided integrally with the interrogator or may be provided separately from the interrogator.

  Further, the light emitted from the light emitting means is visible light. In this case, the irradiation position of the light can be visually recognized, and the terminal receiving the light can be easily identified.

  Furthermore, a restricting member for restricting the light receiving range of light from the outside is provided at the light receiving portion of the light receiving means. In this case, since the light receiving range by the light receiving means becomes narrow, it is possible to reduce light detection errors by the light receiving means and to reduce the influence of disturbance light or the like.

  On the other hand, according to another aspect of the present invention, a terminal generates power from a wide-directional radio signal received from an interrogator, and uses the power for driving the terminal to be in an operating state. When a narrow directivity signal is received from the machine, a response operation to the interrogator is started. Therefore, when a radio wave signal having a wide directivity is transmitted from the interrogator and the terminal is in an operating state, and the radio signal having a narrow directivity is emitted toward the terminal, the radio signal with the narrow directivity is transmitted to the terminal. And the terminal responds. Again, when a wide directivity radio signal from the interrogator is received by a large number of terminals, all of these terminals are in an operating state, but the narrow directivity radio signal is directed to one terminal. When exiting, only this terminal responds. Therefore, it is possible to easily select one of many terminals and start wireless communication with the selected device. Further, since the terminal generates electric power from a wide-directional radio signal received from the interrogator and uses it for driving, it does not require a power source such as a battery.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a first embodiment of a wireless communication system of the present invention. The wireless communication system of the present embodiment includes an interrogator 1 and a wireless tag 2 that perform wireless communication with each other. Usually, a plurality of wireless tags 2 are provided, and between the interrogator 1 and one of the wireless tags 2. Wireless communication is performed.

  When the interrogator 1 starts wireless communication, it transmits a radio signal over a wide range and waits for a response from any one of the wireless tags 2. Each wireless tag 2 is a general battery-less passive type. When a radio signal from the interrogator 1 is received, the radio tag 2 is converted into electric power, and is activated by this electric power. Then, it is determined whether or not each wireless tag 2 performs a response operation, it is determined that only one wireless tag 2 performs a response operation, the impedance of the antenna is controlled, and the reflectance of the received radio wave by the antenna is determined. As a result, a transmission radio wave signal is generated and a response operation is performed.

  The interrogator 1 includes a control circuit 11, an oscillation unit 12, a modulation unit 13, a transmission power amplification unit 14, a circulator 15, an antenna 16, a demodulation unit 17, a nonvolatile memory 18, an output unit 19 including a display, an operation button, and the like. An input unit 20 and a light emitting unit 21 formed of a light emitting diode or the like.

  The control circuit 11 includes a CPU, a memory, an interface, and the like, and controls the interrogator 1 as a whole. For example, the control circuit 11 drives and controls the oscillating unit 12 to output a carrier wave signal from the oscillating unit 12 during wireless communication between the interrogator 1 and the wireless tag 2. This carrier wave signal is applied to the modulation unit 13 and the demodulation unit 17. In addition, the control circuit 11 outputs communication data to the wireless tag 2 to the modulation unit 13.

  When the communication unit 13 receives the communication data and the carrier signal, the modulation unit 13 modulates the carrier signal according to the communication data, and forms and outputs a transmission signal indicating the communication data. This transmission signal is amplified by the transmission power amplifying unit 14, then added to the antenna 16 through the circulator 15, and transmitted from the antenna 16 as a radio wave signal.

  A radio signal indicating response data from the wireless tag 2 is received by the antenna 16 of the interrogator 1 and becomes a received signal. This received signal is applied to the demodulator 17 through the circulator 15. The demodulator 17 receives the received signal from the antenna 16 and the carrier signal from the oscillator 12, demodulates the received signal using the carrier signal, forms response data from the wireless tag 2, and converts the response data into Output to the control circuit 11. The control circuit 11 stores the response data or the like in the nonvolatile memory 18 or outputs it to the output unit 19 for display.

  On the other hand, the wireless tag 2 includes a control circuit 31, a rectifier circuit 32, an antenna 33, a nonvolatile memory 34, a data modulation / demodulation circuit 35, a clock extraction circuit 36, and a light receiving unit 37.

  The wireless tag 2 is not provided with a power source such as a battery. Instead, when the wireless communication between the interrogator 1 and the wireless tag 2 is performed, a radio signal from the interrogator 1 is received by the antenna 33 and received. The signal is added to the rectifier circuit 32 to be rectified, and driving power is output from the rectifier circuit 32. This electric power is applied to the control circuit 31, the non-volatile memory 34, the data modulation / demodulation circuit 35, the clock extraction circuit 36, and the light receiving unit 37, and these are put into operation.

  The control circuit 31 includes a CPU, a memory, an interface, and the like, and controls the entire wireless tag 2.

  The clock extraction circuit 36 receives a reception signal from the antenna 33, extracts and generates a synchronization clock signal from the reception signal, and outputs the clock signal to the control circuit 31, the data modulation / demodulation circuit 35, and the like.

  At this time, the control circuit 31 determines whether or not a response operation is performed, and activates the data modulation / demodulation circuit 35 if the response operation is performed. The data modulation / demodulation circuit 35 receives a reception signal from the antenna 33, demodulates the reception signal, forms communication data from the interrogator 1, and outputs the communication data to the control circuit 31. The control circuit 31 forms response data for the communication data and adds the response data to the data modulation / demodulation circuit 35. The data modulation / demodulation circuit 35 controls the impedance of the antenna 33 according to the response data, changes the reflectance of the received radio wave by the antenna 33, generates a radio signal indicating the response data, and transmits it.

  Here, since the plurality of wireless tags 2 are provided as described above, the antenna 16 of the interrogator 1 has a wide directivity, and the radio signal from the interrogator 1 is transmitted over a wide range. The radio signal from 1 can be received by any wireless tag 2. For this reason, the plurality of wireless tags 2 simultaneously receive radio signals from the interrogator 1 and are ready for response operation. At this time, one wireless tag 2 that communicates with the interrogator 1 is connected. Need to be identified. However, it is not desirable that the communication procedure becomes complicated or the communication time becomes long for this specification.

  Therefore, in the system of the present embodiment, a radio signal is transmitted from the interrogator 1, the plurality of wireless tags 2 are set in an operating state, and the light emitting unit 21 of the interrogator 1 is caused to emit light in this state. 21 light beams are incident on the light receiving portion 37 of one wireless tag 2, and only the wireless tag 2 is caused to respond. Thereby, one of the plurality of wireless tags 2 can be easily selected, and wireless communication with the selected wireless tag 2 can be started.

  Next, a processing procedure until the start of wireless communication between the interrogator 1 and the wireless tag 2 will be described.

  First, in the interrogator 1, when the communication start is instructed by the operation of the input unit 20, the control circuit 11 controls the oscillation unit 12, the modulation unit 13, the transmission power amplification unit 14 and the like in response to this. A transmission signal indicating communication data is transmitted from the antenna 16 as a radio wave signal.

  Further, the control circuit 11 causes the light emitting unit 21 to emit light. If the interrogator 1 is of the installation type, the light-emitting unit 21 is separated from the interrogator 1, and the light-emitting unit 21 is directed toward one wireless tag 2 by holding the light-emitting unit 21 in hand. An operation for entering the light receiving portion 37 of the wireless tag 2 is made possible. Further, if the interrogator 1 is a portable type that can be freely operated by being held in the hand, the light emitting unit 21 is provided integrally with the interrogator 1, the interrogator 1 is held in the hand, and the light of the light emitting unit 21 is provided. You may make it adjust the direction of a beam.

  Each wireless tag 2 receives a radio wave signal from the interrogator 1 by the antenna 33 and is activated by the driving power from the rectifier circuit 32.

  At this time, in one wireless tag 2, as shown in FIG. 2, the light beam LB from the light emitting unit 21 of the interrogator 1 is received by the light receiving unit 37, so that the output level of the light receiving unit 37 is high. . For this reason, the control circuit 31 determines that the light reception output level of the light receiving unit 37 is equal to or higher than the threshold value, determines that the wireless tag 2 is selected, and determines execution of the response operation. Then, the control circuit 31 activates the data modulation / demodulation circuit 35, inputs communication data from the interrogator 1 from the data modulation / demodulation circuit 35, forms response data for the communication data, and sends the response data to the data modulation / demodulation circuit 35. Output. The data modulation / demodulation circuit 35 controls the impedance of the antenna 33 according to the response data, and transmits a radio signal indicating the response data from the antenna 33.

  Further, in the other wireless tag 2, as shown in FIG. 2, the light beam from the light emitting unit 21 of the interrogator 1 is not received by the light receiving unit 37, and the output level of the light receiving unit 37 remains low. For this reason, the control circuit 31 determines that the light reception output level of the light receiving unit 37 is less than the threshold value, and does not perform operations such as demodulation of communication data and transmission of response data.

  The control operation of the wireless tag 2 will be described with reference to the flowchart shown in FIG.

  When the radio tag 2 receives the radio signal from the interrogator 1 by the antenna 33 (step S201), the wireless tag 2 is activated by the driving power from the rectifier circuit 32 (step S202).

  At this time, there is incident light on the light receiving unit 37 (“light present” in step S203), and this incident light is a light beam from the light emitting unit 21 of the interrogator 1, and its intensity is strong. If it is determined that the received light output level 37 is equal to or higher than the threshold value ("strong" in step S204), this wireless tag 2 is selected, so that the communication data is demodulated and a response operation is performed (step S205). ).

  If there is no incident light on the light receiving unit 37 (“No light” in step S203), the light beam from the light emitting unit 21 of the interrogator 1 is not incident and the wireless tag 2 is not selected. The process waits for incident light to the light receiving unit 37 and repeats step S203.

  Further, even if there is incident light on the light receiving unit 37 (“light present” in step S203), since the incident light is weak disturbance light or the like, the light reception output level of the light receiving unit 37 is less than the threshold value. When the determination is made ("weak" in step S204), this wireless tag 2 is not selected, and waiting for the incident light to the light receiving unit 37, steps S203 and S204 are repeated.

  As described above, in the present embodiment, radio signals are transmitted from the interrogator 1, the plurality of wireless tags 2 are set in an operating state, the light emitting unit 21 of the interrogator 1 is caused to emit light in this state, and the light emitting unit 21 Is incident on the light receiving unit 37 of one wireless tag 2 and only this wireless tag 2 is responding, so that the communication procedure becomes complicated to identify one wireless tag 2 or the communication time It won't be long. Further, since the wireless tag 2 generates and uses electric power from the received radio wave signal from the interrogator 1, it does not require a power source such as a battery, and can maintain a standby state indefinitely.

  The light beam emitted from the light emitting unit 21 of the interrogator 1 may be visible light, infrared light, or ultraviolet light. When a plurality of wireless tags 2 are arranged close to each other, if one can visually recognize an irradiation spot of a light beam by using a light beam of visible light, one wireless tag 2 can be reliably secured by the light beam. It becomes possible to select. Also, in an environment with a lot of disturbance light, if the light receiving unit 37 of the wireless tag 2 selectively detects only infrared or ultraviolet light using an infrared or ultraviolet light beam, the influence of the disturbance light is reduced. Can be avoided.

  Further, the light beam emitted from the light emitting unit 21 of the interrogator 1 is irradiated with a specified periodic pattern, and it is determined whether or not the light reception output of the light receiving unit 37 of the wireless tag 2 indicates the specified periodic pattern. However, the presence or absence of the light beam may be determined based on this determination. In this case, a demodulation circuit for extracting the periodic pattern of the light beam from the light reception output of the light receiving unit 37 is inserted between the light receiving unit 37 and the control circuit 31, and the demodulation output of this demodulation circuit is added to the control circuit 31, The presence or absence of a periodic pattern of the light beam is detected by the control circuit 31.

  Further, the light reception output of the light receiving unit 37 may be rectified and used as driving power together with the output of the rectification circuit 32.

  Further, a cylindrical regulating member 38 as shown in FIG. 4 may be provided at the site of the light receiving portion 37 of the wireless tag 2. The light receiving unit 37 is disposed at the center of the cylindrical regulating member 38 and receives only light incident from the opening of the cylindrical regulating member 38. In this case, since the light receiving range by the light receiving unit 37 is narrowed, the light beam is received by the wireless tag 2 unless the light beam emitted from the light emitting unit 21 of the interrogator 1 is directed to the vicinity of the center of the cylindrical regulating member 38. It is possible to reduce the detection error of the light beam by the light receiving unit 37 without being incident on the unit 37, and to reduce the influence of disturbance light or the like.

  FIG. 5 is a block diagram showing a second embodiment of the wireless communication system of the present invention. The wireless communication system of the present embodiment includes an interrogator 1A and a wireless tag 2A that perform wireless communication with each other. Usually, a plurality of wireless tags 2A are provided, and between the interrogator 1A and one of the wireless tags 2A. Wireless communication is performed.

  Also in the system of the present embodiment, a radio signal is transmitted from the interrogator 1A and any one of the wireless tags 2A performs a response operation, as in the system of FIG. Since the radio wave signal at this time has a wide directivity transmitted from a wide directivity antenna, the communication area is wide and can be received by a plurality of wireless tags 2A.

  Each wireless tag 2A is a general battery-less passive type. When a radio wave signal having a wide directivity from the interrogator 1A is received, the radio wave tag 2A converts the received radio wave signal into electric power. Become.

  Further, in the interrogator 1A, instead of emitting a light beam from the light emitting unit 21 as in the interrogator 1 of FIG. 1, a narrow directivity radio signal is transmitted, and this narrow directivity radio signal is transmitted to one wireless tag. The wireless tag 2A is selected by receiving only by 2A. This wireless tag 2A receives a narrow directivity radio signal from the interrogator 1A, responds, controls the impedance of the antenna, changes the reflectance of the radio wave received by this antenna, and generates a transmission radio signal Let

  At this time, the other wireless tag 2A does not receive the narrow directivity radio signal from the interrogator 1A and does not perform a response operation.

  The interrogator 1A includes a control circuit 41, a nonvolatile memory 42, an output unit 43 including a display, and an input unit 44 including operation buttons. Further, it includes a wide directional antenna 45 for transmitting and receiving a wide directional radio signal, an oscillation unit 46, a modulation unit 47, a transmission power amplification unit 48, a circulator 49, and a demodulation unit 50, and further a narrow directional radio signal. Includes a narrow directional antenna 51, an oscillating unit 52, a modulating unit 53, a transmission power amplifying unit 54, a circulator 55, and a demodulating unit 56.

  The wide directional antenna 45 is, for example, a dipole antenna, and the narrow directional antenna 51 is, for example, a parabolic antenna.

  In the wireless communication between the interrogator 1A and the wireless tag 2A, the control circuit 41 drives and controls the oscillating unit 46 to output the first carrier signal from the oscillating unit 12. The first carrier signal is modulated by the modulating unit 47 and the demodulating unit. Add to part 50. Further, the control circuit 41 outputs communication data for the wireless tag 2 </ b> A to the modulation unit 47.

  The modulation unit 47 modulates the first carrier wave signal according to the communication data, and forms and outputs a transmission signal indicating the communication data. This transmission signal is amplified by the transmission power amplifying unit 48, then added to the wide directional antenna 45 through the circulator 49, and transmitted as a wide directional radio signal.

  At the same time, the control circuit 41 drives and controls the oscillating unit 52 to output a second carrier signal (a frequency different from the first carrier signal) from the oscillating unit 52, and the second carrier signal is modulated by the modulating unit 53 and the demodulating unit. Add to 56. In addition, the control circuit 41 creates specified data for selecting a wireless tag and outputs the specified data to the modulation unit 53.

  The modulation unit 53 modulates the second carrier signal according to the specified data for selecting the wireless tag, and forms and outputs a transmission signal indicating the specified data. This transmission signal is amplified by the transmission power amplifying unit 54, then added to the narrow directional antenna 51 through the circulator 55, and transmitted as a narrow directional radio signal.

  As shown in FIG. 6, this narrow directivity radio signal is emitted in a narrow range like a light beam, so that it can be received by only one wireless tag 2A and this wireless tag 2A can be selected. is there. If the interrogator 1A is of the installation type, the narrow directional antenna 51 is separated from the interrogator 1A so that the operation of the narrow directional antenna 51 is facilitated. The narrow directional antenna 51 may be integrally provided in the interrogator 1A as long as it is portable and can be freely operated.

  Next, when a radio signal indicating the response data from the wireless tag 2A (frequency of the first carrier signal) is transmitted, this radio signal is received by the wide directional antenna 45 of the interrogator 1A, and the received signal Is added to the demodulator 50 through the circulator 49. The demodulator 50 demodulates the received signal into response data and outputs this response data to the control circuit 41. The control circuit 41 stores this response data in the nonvolatile memory 42 or outputs it to the output unit 43 for display.

  Alternatively, if the radio signal from the wireless tag 2A has the frequency of the second carrier signal, this radio signal is received by the narrow directivity antenna 51 of the interrogator 1A, and the received signal is sent to the demodulator 56 through the circulator 55. In addition, it is demodulated into response data, and this response data is output to the control circuit 41.

  On the other hand, the wireless tag 2 </ b> A includes a control circuit 61, a rectifier circuit 62, and a nonvolatile memory 63. Also, a wide directional antenna 64 for transmitting and receiving a wide directional radio signal, a data modulation / demodulation circuit 65, and a clock extraction circuit 66, and a narrow directional antenna 67 for transmitting and receiving a narrow directional radio signal, A data modulation / demodulation circuit 68 and a clock extraction circuit 69 are provided.

  The wide directional antenna 64 is, for example, a dipole antenna, and the narrow directional antenna 67 is, for example, a Yagi antenna.

  In the wireless tag 2A, when a wide directional radio signal from the interrogator 1 is received by the wide directional antenna 64, the received signal is added to the rectifier circuit 62 and rectified. Is output. This electric power is applied to the control circuit 61, the non-volatile memory 63, the data modulation / demodulation circuits 65 and 68, and the clock extraction circuits 66 and 69, and these are put into operation.

  Further, the received signal from the wide directional antenna 64 is applied to the data modulation / demodulation circuit 65 and the clock extraction circuit 66.

  When the received signal from the wide directional antenna 64 is input, the clock extraction circuit 66 extracts and generates a synchronization clock signal from the received signal, and outputs this clock signal to the control circuit 61, the data modulation / demodulation circuit 65, and the like.

  At this time, the control circuit 61 determines whether or not a response operation is performed, and activates the data modulation / demodulation circuit 65 if the response operation is performed. The data modulation / demodulation circuit 65 receives a reception signal from the antenna 64, demodulates the reception signal, forms communication data from the interrogator 1A, and outputs the communication data to the control circuit 61. The control circuit 61 forms response data for the communication data and adds the response data to the data modulation / demodulation circuit 65. The data modulation / demodulation circuit 65 controls the impedance of the antenna 64 according to the response data, changes the reflectance of the received radio wave by the antenna 64, generates a radio signal indicating the response data, and transmits it.

  Here, since the radio wave of the first carrier signal is transmitted from the wide directivity antenna 45 of the interrogator 1A, this radio wave signal is received by any of the wireless tags 2A. For this reason, each wireless tag 2A simultaneously receives the radio wave signal of the first carrier signal from the interrogator 1A, and becomes ready for a response operation.

  Further, the narrow directivity antenna 51 of the interrogator 1A transmits a radio wave of a second carrier signal indicating prescribed data for selecting a radio tag, and this radio wave signal of narrow directivity is one radio tag as shown in FIG. Received only at 2A.

  In this one wireless tag 2A, the radio wave of the second carrier signal from the narrow directional antenna 51 of the interrogator 1A is received by the narrow directional antenna 67, and the received signal is added to the data modulation / demodulation circuit 68 and the clock extraction circuit 69. It is done.

  The clock extraction circuit 69 extracts and generates a clock signal for synchronization from the received signal, and outputs this clock signal to the control circuit 61, the data modulation / demodulation circuit 68, and the like. The data modulation / demodulation circuit 68 demodulates the received signal to form the specified data for selecting the RFID tag from the interrogator 1A, and outputs the specified data for selecting the RFID tag to the control circuit 61.

  The control circuit 61 identifies the specified data for selecting the wireless tag, determines that the wireless tag 2A is selected, and determines execution of the response operation. Then, the control unit 61 activates the data modulation / demodulation circuit 65, inputs the communication data from the interrogator 1A from the data modulation / demodulation circuit 65, forms response data for the communication data, and uses the response data as the data modulation / demodulation circuit. In addition to 65, this response data is transmitted from the wide directional antenna 64.

  Alternatively, the control unit 61 adds response data to the data modulation / demodulation circuit 68. The data modulation / demodulation circuit 68 controls the impedance of the narrow directional antenna 67 according to the response data, changes the reflectance of the received radio wave by the narrow directional antenna 67, and generates and transmits a radio signal indicating the response data. .

  Further, the other wireless tag 2A does not receive the second carrier wave from the narrow directional antenna 51 of the interrogator 1A as shown in FIG.

  The control operation of the wireless tag 2A will be described as follows with reference to the flowchart shown in FIG.

  In the wireless tag 2A, when a wide directional radio signal from the interrogator 1A is received by the wide directional antenna 64 (step S301), the wireless tag 2A is activated by the driving power from the rectifier circuit 62 (step S302).

  At this time, when a narrow directivity radio signal is received by the narrow directivity antenna 67 (“radio wave present” in step S303), this wireless tag 2A is selected, so the communication data is demodulated, A response operation is performed (step S304).

  If the narrow directivity signal 67 is not received by the narrow directivity antenna 67 (“no radio wave” in step S303), the wireless tag 2A is not selected, so that the narrow directivity of the narrow directivity antenna 67 is reduced. Step S303 is repeated after waiting for reception of the radio signal.

  As described above, in the present embodiment, a wide directivity radio wave signal is transmitted from the wide directivity antenna 45 of the interrogator 1A, and the plurality of wireless tags 2A are set in an operating state. In this state, the narrow directivity of the interrogator 1A is set. Since the narrow-directional radio signal is transmitted from the directional antenna 51, the narrow-directional radio signal is received by the narrow-directional antenna 67 of one radio tag 2A, and only the radio tag 2A is responded. The communication procedure for identifying one wireless tag 2A is not complicated, and the communication time is not prolonged. Further, since the wireless tag 2A generates and uses electric power from the received radio wave signal from the interrogator 1A, it does not require a power source such as a battery and can maintain a standby state for almost indefinite period.

  In the wireless tag 2A, the received signal from the wide directional antenna 64 is rectified by the rectifier circuit 62, and the output of the rectifier circuit 62 is used as driving power. However, as shown in FIG. A rectifier circuit 70 for rectifying the received signal from the conductive antenna 67 may be provided, and the output of the rectifier circuit 70 may also be used as driving power.

  FIG. 9 is a block diagram showing a third embodiment of the wireless communication system of the present invention. The wireless communication system of the present embodiment includes an interrogator 1B and a wireless tag 2B that perform wireless communication with each other. Usually, a plurality of wireless tags 2B are provided, and between the interrogator 1B and one of the wireless tags 2B. Wireless communication is performed.

  In the system according to the present embodiment, a radio wave signal having a wide directivity is transmitted from the interrogator 1B. Therefore, the radio wave signal can be received by a plurality of radio tags 2B.

  In the interrogator 1B, as in the interrogator 1 of FIG. 1, a light beam is emitted from the light emitting unit 21, and this light beam is received by only one wireless tag 2B, and this wireless tag 2B is selected. The wireless tag 2B receives the light beam from the interrogator 1B, photoelectrically converts the light beam into driving power, and enters an operating state with this power. The wireless tag 2B receives and responds to the wide directivity radio signal from the interrogator 1B, controls the impedance of the antenna, changes the reflectance of the radio wave received by the antenna, and transmits the transmission radio signal. Is generated.

  At this time, the other wireless tag 2B does not receive the light beam from the interrogator 1B, does not enter an operating state, and does not perform a response operation.

  The interrogator 1B includes a control circuit 81, an oscillation unit 82, a modulation unit 83, a transmission power amplification unit 84, a circulator 85, an antenna 86, a demodulation unit 87, a nonvolatile memory 88, an output unit 89 including a display, an operation button, and the like. The light emitting part 91 which consists of the input part 90 which consists of, and a light emitting diode etc. is provided.

  In the wireless communication between the interrogator 1B and the wireless tag 2B, the control circuit 81 drives and controls the oscillation unit 82 to output a carrier wave signal from the oscillation unit 82, and adds the carrier wave signal to the modulation unit 83 and the demodulation unit 87. . In addition, the control circuit 81 outputs communication data to the wireless tag 2B to the modulation unit 83.

  The modulation unit 83 modulates the carrier wave signal according to the communication data, forms a transmission signal indicating the communication data, and outputs it. This transmission signal is amplified by the transmission power amplifying unit 84, then added to the antenna 86 through the circulator 85, and transmitted as a wide directivity radio signal.

  At the same time, the control circuit 81 drives the light emitting unit 91 to emit light. Thereby, a light beam is emitted from the light emitting unit 91.

  Since the light beam LB is emitted in a narrow range as shown in FIG. 10, it is possible to receive the light with only one wireless tag 2B and select the wireless tag 2B. If the interrogator 1B is of a stationary type, the light emitting unit 91 is separate from the interrogator 1B so that the operation of the light emitting unit 91 is easy, and the interrogator 1B is of a portable type. For example, the light emitting unit 91 may be provided integrally with the interrogator 1B.

  Next, when a radio signal indicating response data from the wireless tag 2B is transmitted, this radio signal is received by the antenna 86 of the interrogator 1B and becomes a received signal. This received signal is applied to the demodulator 87 through the circulator 85, where it is demodulated into response data, and this response data is output to the control circuit 81. The control circuit 81 stores this response data in the nonvolatile memory 88 or outputs it to the output unit 89 for display.

  On the other hand, the wireless tag 2B includes a control circuit 101, an antenna 103, a nonvolatile memory 104, a data modulation / demodulation circuit 105, a clock extraction circuit 106, and a solar battery 107.

  In one wireless tag 2B, the light beam LB from the light emitting unit 91 of the interrogator 1B is received by the solar cell 107 as shown in FIG. For this reason, the light beam is converted into driving power by the solar battery 107, and the control circuit 101, the nonvolatile memory 104, the data modulation / demodulation circuit 105, and the clock extraction circuit 106 are activated by this power.

  At this time, when a wide directivity radio signal is received from the interrogator 1B by the antenna 103, the received signal is applied to the data modulation / demodulation circuit 105 and the clock extraction circuit 106.

  The clock extraction circuit 106 extracts and generates a clock signal for synchronization from the received signal, and outputs this clock signal to the control circuit 101, the data modulation / demodulation circuit 105, and the like.

  The data modulation / demodulation circuit 105 demodulates the received signal to form communication data from the interrogator 1B, and outputs this communication data to the control circuit 101. The control circuit 101 stores this communication data in the nonvolatile memory 104 as necessary.

  Then, the control unit 101 forms response data and adds the response data to the data modulation / demodulation circuit 105. The data modulation / demodulation circuit 105 controls the impedance of the antenna 103 according to the response data, changes the reflectance of the radio wave received by the antenna 103, generates a radio signal indicating the response data, and transmits it.

  Further, in the other wireless tag 2B, the light beam from the light emitting unit 91 of the interrogator 1B is not received by the solar cell 107 as shown in FIG. No response action is performed.

  The control operation of the wireless tag 2B will be described with reference to the flowchart shown in FIG.

  In the wireless tag 2B, there is incident light on the solar cell 107 (“light present” in step S401), and this incident light is a light beam from the light emitting unit 91 of the interrogator 1B, and its intensity is strong. When the received light output level of the solar cell 107 is sufficiently high (“strong” in step S402), this wireless tag 2B is selected, and the solar cell 107 converts the light beam into driving power, An operating state is established by this power (step S403). Then, the communication data is demodulated, response data for the communication data is formed, and a radio signal indicating the response data is transmitted from the antenna 103 (step S404).

  If there is no incident light on the solar cell 107 (“No light” in step S401), the light beam from the light emitting unit 91 of the interrogator 1B is not incident, and the wireless tag 2B is not selected. The process waits for incident light to the solar cell 107 and repeats step S401.

  Further, even if there is incident light on the solar cell 107 (“light present” in step S401), since the incident light is weak disturbance light or the like, the received light output level of the solar cell 107 is low ( In step S402, “Weak”), since this wireless tag 2B is not selected, the process waits for incident light to the solar cell 107 and repeats steps S401 and S402.

  As described above, in the present embodiment, the light beam of the light emitting unit 91 of the interrogator 1B is received by only one wireless tag 2B, and only the wireless tag 2B is in an operating state, and a radio wave signal is transmitted from the interrogator 1B. Since the response operation by only the wireless tag 2A in this operating state is enabled, the communication procedure for identifying one wireless tag 2B is not complicated, and the communication time is not prolonged. Further, since the wireless tag 2B generates and uses electric power from the light beam from the interrogator 1B, it does not require a power source such as a battery, and can maintain a standby state almost indefinitely.

  In addition, this invention is not limited to the said embodiment, It can deform | transform variously. For example, the configuration of the interrogator or the wireless tag may be changed as appropriate. The present invention can be applied not only to communication between an interrogator and a wireless tag but also to other systems.

1 is a block diagram showing a first embodiment of a wireless communication system of the present invention. It is a figure which shows the communication state between the interrogator and one wireless tag in the system of FIG. 2 is a flowchart showing a control operation of a wireless tag in the system of FIG. It is a perspective view which shows the modification of the wireless tag in the system of FIG. It is a block diagram which shows 2nd Embodiment of the radio | wireless communications system of this invention. It is a figure which shows the communication state between the interrogator and one wireless tag in the system of FIG. 6 is a flowchart showing a control operation of the wireless tag in the system of FIG. It is a block diagram which shows the modification of the wireless tag in the system of FIG. It is a block diagram which shows 3rd Embodiment of the radio | wireless communications system of this invention. It is a figure which shows the communication state between the interrogator and one radio | wireless tag in the system of FIG. 10 is a flowchart showing a control operation of the wireless tag in the system of FIG.

Explanation of symbols

1, 1A, 1B Interrogator 2, 2A, 2B Radio tag 11 Control circuit 12 Oscillator 13 Modulator 14 Transmit power amplifier 15 Circulator 16 Antenna 17 Demodulator 18 Non-volatile memory 19 Output unit 20 Input unit 21 Light emitting unit

Claims (8)

In a wireless communication system comprising an interrogator and a terminal for performing wireless communication with each other, wherein the terminal receives a radio signal from the interrogator and operates in response.
The terminal is
Power supply means for generating electric power from a radio signal received from the interrogator and supplying the electric power for driving the terminal;
A light receiving means for receiving light from outside;
Determining means for determining the presence or absence of light from the outside based on the light reception output of the light receiving means;
A wireless communication system comprising: a communication control unit that starts a response operation to the interrogator when the determination unit determines that there is external light.   The wireless communication system according to claim 1, wherein the determination unit determines the presence or absence of light from the outside based on whether a light reception output level of the light reception unit is equal to or higher than a specified value.   The determination unit is configured to determine the presence or absence of light from the outside based on whether or not the pattern of light from the outside indicated by the light reception output of the light receiving unit is a specified pattern. The wireless communication system according to 1.   The power supply unit generates power from a radio wave signal received from the interrogator, generates power from a light reception output of the light receiving unit, and supplies the power for driving the terminal. The wireless communication system according to claim 1.   The wireless communication system according to claim 1, further comprising a light emitting unit that is provided on the interrogator side and emits external light received by the light receiving unit.   6. The wireless communication system according to claim 5, wherein the light emitted from the light emitting means is visible light.   2. The wireless communication system according to claim 1, wherein a restriction member for restricting a light receiving range of the light from the outside is provided at a light receiving portion of the light receiving means. In a wireless communication system comprising an interrogator and a terminal for performing wireless communication with each other, wherein the terminal receives a radio signal from the interrogator and operates in response.
The interrogator transmits a wide directivity radio signal and a narrow directivity radio signal,
The terminal is
Power supply means for generating power from a wide directivity radio signal received from the interrogator and supplying the power for driving the terminal;
Receiving means for receiving a narrow-directional radio signal from the interrogator;
Determination means for determining the presence or absence of the narrow directivity radio signal based on the narrow directivity radio signal received by the receiving means;
A wireless communication system comprising: a communication control unit that starts a response operation to the interrogator when the determination unit determines that a narrow directivity radio signal is present.

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