JP2009290754A - Electric field communication system and electric field communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric field communication system and an electric field communication device that surely perform electric field communication even if environmental noise is generated. <P>SOLUTION: A first electric field communication device 200 transmits three communication state confirmation request signals corresponding to three different frequencies f1 to f3 to a second electric field communication device 200'. The second electric field communication device 200' determines a normal signal among all the transmitted communication state confirmation request signals to select the one frequency f3 out of the frequencies f1 to f3 of the plurality of decided communication state confirmation request signals, and transmits a communication state confirmation answer signal varied with the selected frequency f3 to the first electric field communication device 200. The first electric field communication device 200 varies the frequency of transmission data by using the same frequency as the frequency f3 of the transmitted communication state confirmation answer signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique of an electric field communication system and an electric field communication apparatus that perform communication by inducing an electric field in an electric field transmission medium.

  2. Description of the Related Art Conventionally, there has been proposed an electric field communication apparatus that induces an electric field based on data to be transmitted to an electric field transmission medium that transmits an electric field and performs data communication by detecting the electric field induced in the electric field transmission medium (patent) Reference 1). Hereinafter, each functional block included in the conventional electric field communication device and a processing flow of transmission data provided from the information terminal will be described.

  FIG. 2 is a functional block diagram showing functional blocks of a conventional electric field communication device. The electric field communication apparatus 200 shown in FIG. 2 receives the transmission data transmitted from the information terminal 100 connected via the interface 201, adjusts the signal amplitude of the transmission data by the level adjustment unit 203, and transmits the transmission unit 205. To the transmission electrode 301 via The transmission electrode 301 induces an electric field corresponding to the transmission data in the electric field transmission medium 400 after the transmission data is supplied from the transmission unit 205. Thereafter, the induced electric field is transmitted through the electric field transmission medium 400 and received by the receiving electrode 303 of another electric field communication device.

  On the other hand, when the electric field received by the receiving electrode 303 is supplied to the electric field detection unit 213, the electric field detection unit 213 changes the polarization of laser light separately generated in the electric field detection unit 213 using, for example, an electro-optic technique, The laser light whose polarization is changed is converted into an electric signal. The converted electric signal is supplied to the information terminal 100 via the interface 201 after unnecessary noise is removed in the signal processing unit 219 and the signal waveform is shaped.

Therefore, for example, as shown in FIG. 3A, the information terminal 100, the electric field communication device 200, and the electrode 300 are attached to a human arm, shoulder, trunk, etc. as the electric field transmission medium 400, and other information terminals 100 are also mounted. By arranging 'and another electric field communication device 200' and another electrode 300 'in contact with the floor as the electric field transmission medium 400, data can be transmitted and received between the electric field communication devices through the person and the floor. It is possible.
JP 2003-324395 A

  However, as shown in FIG. 3B, when an environmental noise having the same frequency component as the frequency f1 of transmission data transmitted from another electric field communication device 200 ′ is generated, this environmental noise becomes an interference wave for electric field communication. As a result, there is a problem that transmission data transmitted from another electric field communication device 200 ′ is damaged.

  The present invention has been made in view of the above, and an object of the present invention is to provide an electric field communication system and an electric field communication apparatus that reliably perform electric field communication even when environmental noise occurs.

  The present invention according to claim 1 is an electric field communication system including a first electric field communication device and a second electric field communication device capable of performing electric field communication by inducing an electric field from an electrode to an electric field transmission medium. The first electric field communication device includes an oscillation means for oscillating a communication state confirmation request signal for requesting confirmation of a communication state with the second electric field communication device connected via the electric field transmission medium, Frequency changing means for changing the frequency of the communication state confirmation request signal to a plurality of different frequencies and outputting a plurality of communication state confirmation request signals respectively corresponding to the plurality of frequencies, and the outputted plurality of communication state confirmation request signals Transmitting means from the transmission electrode to the second electric field communication device by an electric field, and the second electric field communication device responds with confirmation of the communication state with the first electric field communication device. Communication status check An oscillating means for oscillating an answer signal; a determination means for receiving the plurality of communication state confirmation request signals transmitted via the electric field transmission medium; and determining normality and abnormality of the plurality of communication state confirmation request signals; As a result of the determination, a frequency selection unit that selects one frequency from the frequencies of a plurality of normal communication state confirmation request signals, a frequency variable unit that varies the frequency of the communication state confirmation response signal to the selected frequency, Transmitting means for transmitting the changed communication state confirmation response signal from a transmission electrode to the first electric field communication device by an electric field, wherein the first electric field communication device is connected via the electric field transmission medium. The received communication status confirmation response signal is received, and the frequency of the transmission data transmitted to the second electric field communication device is varied to the same frequency as the communication status confirmation response signal. The the gist.

  In the present invention, the first electric field communication device oscillates a communication state confirmation request signal for requesting confirmation of the communication state with the second electric field communication device, and the frequency of the oscillated communication state confirmation request signal is different. A plurality of communication state confirmation request signals which are variable to a plurality of frequencies and respectively correspond to the plurality of frequencies are transmitted to the second electric field communication apparatus by an electric field, and the second electric field communication apparatus transmits the electric field transmission medium via the electric field transmission medium. Normality / abnormality of the plurality of communication state confirmation request signals that have been determined, and as a result of the determination, one frequency is selected from the frequencies of the plurality of normal communication state confirmation request signals, and the communication state with the first electric field communication device The frequency of the communication state confirmation response signal that responds to the confirmation is changed to the selected frequency and transmitted to the first electric field communication device by the electric field, and the first electric field communication device transmits to the second electric field communication device. Transmission data frequency Is changed to the same frequency as the frequency of the communication state confirmation response signal, so that even if environmental noise occurs, transmission data modulated at a frequency with a good communication state is transmitted from the first electric field communication device to the second electric field. It becomes possible to transmit to a communication device, and an electric field communication system that reliably performs electric field communication can be provided.

  According to a second aspect of the present invention, the second electric field communication device oscillates a communication state confirmation request signal for requesting confirmation of a communication state with the first electric field communication device, and the communication state The frequency of the confirmation request signal is varied to a plurality of different frequencies, and the frequency variable means for outputting a plurality of communication state confirmation request signals respectively corresponding to the plurality of frequencies, and the plurality of communication state confirmation request signals output, Transmitting means for transmitting by an electric field from a transmission electrode to the first electric field communication device, wherein the first electric field communication device responds with confirmation of a communication state with the second electric field communication device. Oscillating means for oscillating a status confirmation response signal, and discrimination means for receiving the plurality of communication status confirmation request signals transmitted via the electric field transmission medium and discriminating normality and abnormality of the plurality of communication status confirmation request signals As a result of the determination, a frequency selection unit that selects one frequency from the frequencies of a plurality of normal communication state confirmation request signals, and a frequency variable unit that varies the frequency of the communication state confirmation response signal to the selected frequency. And transmitting means for transmitting the changed communication state confirmation response signal from the transmission electrode to the second electric field communication device by an electric field, wherein the second electric field communication device includes the electric field transmission medium. The gist is to change the frequency of transmission data to be transmitted to the first electric field communication device to the same frequency as the frequency of the communication state confirmation response signal.

  In the present invention, the second electric field communication device oscillates a communication state confirmation request signal for requesting confirmation of the communication state with the first electric field communication device, and the frequency of the oscillated communication state confirmation request signal is different. A plurality of communication state confirmation request signals that change to a plurality of frequencies and respectively correspond to the plurality of frequencies are transmitted to the first electric field communication apparatus by an electric field, and the second electric field communication apparatus transmits the electric field transmission medium via the electric field transmission medium. Normality / abnormality of the plurality of communication state confirmation request signals that have been received, and as a result of the determination, one frequency is selected from the frequencies of the plurality of normal communication state confirmation request signals, and the communication state with the second electric field communication device The frequency of the communication state confirmation response signal that responds to the confirmation is changed to the selected frequency and transmitted to the second electric field communication device by the electric field, and the second electric field communication device transmits to the first electric field communication device. Transmission data frequency Is changed to the same frequency as the frequency of the communication status confirmation response signal, so that even if environmental noise occurs, transmission data modulated at a frequency with a good communication status is transmitted from the second electric field communication device to the first electric field. It becomes possible to transmit to a communication device, and an electric field communication system that reliably performs electric field communication can be provided.

  According to a third aspect of the present invention, the frequency of the transmission data transmitted by the second electric field communication device to the first electric field communication device is selected by the frequency selection means of the second electric field communication device. The gist of this is to be variable.

  In the present invention, the second electric field communication device changes the frequency of the transmission data transmitted to the first electric field communication device to the frequency selected by the frequency selection means of the second electric field communication device. Even when noise occurs, transmission data modulated at a frequency with a good communication state can be transmitted from the second electric field communication device to the first electric field communication device, and the electric field for reliably performing electric field communication. A communication system can be provided.

  According to a fourth aspect of the present invention, the frequency of the transmission data transmitted by the first electric field communication device to the second electric field communication device is selected by the frequency selection means of the first electric field communication device. The gist of this is to be variable.

  In the present invention, the first electric field communication device changes the frequency of the transmission data transmitted to the second electric field communication device to the frequency selected by the frequency selection means of the first electric field communication device. Even when noise occurs, transmission data modulated at a frequency with a good communication state can be transmitted from the first electric field communication apparatus to the second electric field communication apparatus, and the electric field for reliably performing electric field communication. A communication system can be provided.

  According to the fifth aspect of the present invention, at least one of a plurality of frequencies used for varying the frequency of the communication state confirmation request signal by the frequency varying means of the first electric field communication device is 13.56 MHz ± 150 kHz. The gist is that the frequency is included in the range.

  According to a sixth aspect of the present invention, at least one of the plurality of frequencies used for varying the frequency of the communication state confirmation request signal by the frequency varying means of the second electric field communication device is 13.56 MHz ± 150 kHz. The gist is that the frequency is included in the range.

  The present invention according to claim 7 is an electric field communication apparatus capable of performing electric field communication by inducing an electric field from an electrode to the electric field transmission medium, and another electric field communication connected via the electric field transmission medium Oscillating means for oscillating a communication status confirmation request signal for requesting confirmation of a communication status with a device, and a plurality of communications corresponding to the plurality of frequencies by varying the frequency of the communication status confirmation request signal to a plurality of different frequencies. A frequency variable means for outputting a state confirmation request signal; and a transmission means for transmitting the output plurality of communication state confirmation request signals from a transmission electrode to the other electric field communication device by an electric field, and the electric field transmission A communication status confirmation response signal varied at one frequency selected from frequencies of a plurality of normal communication status confirmation request signals among the plurality of communication status confirmation request signals transmitted via the medium. Received from the electric field communication apparatus, and summarized in that the frequency of the transmission data to be transmitted to the other electric field communication apparatus variably to the same frequency as the frequency of the communication state confirmation response signal.

  In the present invention, a communication state confirmation request signal for requesting confirmation of a communication state with another electric field communication device is oscillated, and the frequency of the oscillated communication state confirmation request signal is changed to a plurality of different frequencies. A plurality of communication state confirmation request signals corresponding to the respective frequencies are transmitted to other electric field communication devices by electric fields, and a plurality of normal communication state confirmations among the plurality of communication state confirmation request signals transmitted via the electric field transmission medium A communication state confirmation response signal varied at one frequency selected from the frequency of the request signal is received from another electric field communication device, and the frequency of transmission data transmitted to the other electric field communication device is the frequency of the communication state confirmation response signal. Even if environmental noise occurs, transmission data modulated at a frequency with a good communication state is transmitted from the electric field communication device to another electric field communication device. Rukoto is possible, it is possible to provide a field communication device for performing electric field communication reliably.

  The present invention according to claim 8 is an oscillation means for oscillating a communication state confirmation response signal for responding to confirmation of a communication state with the other electric field communication device, and the other electric field communication device via the electric field transmission medium. Receiving a plurality of communication status confirmation request signals transmitted from the communication means, and determining means for determining normality and abnormality of the plurality of communication status confirmation request signals, and the frequency of the plurality of communication status confirmation request signals normal as a result of the determination Frequency selection means for selecting one frequency from the above, frequency variable means for changing the frequency of the communication state confirmation response signal to the selected frequency, and the communication state confirmation response signal changed from the transmission electrode to the other And transmitting means for transmitting to the electric field communication device by an electric field.

  According to a ninth aspect of the present invention, at least one of a plurality of frequencies used for varying the frequency of the communication state confirmation request signal by the frequency varying means is a frequency included in a range of 13.56 MHz ± 150 kHz. This is the gist.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where environmental noise generate | occur | produces, the electric field communication system and electric field communication apparatus which perform electric field communication reliably can be provided.

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

  FIG. 1 is a functional block diagram showing functional blocks of the electric field communication system according to the present embodiment. This electric field communication system includes an information terminal 100 functioning as a communication source (or communication destination), a first electric field communication device 200, an electrode 300, an information terminal 100 ′ functioning as a communication destination (or communication source), and a second terminal. The electric field communication device 200 ′ and the electrode 300 ′ are configured. The first electric field communication device 200 and the second electric field communication device 200 ′ are connected via the electric field transmission medium 400. Note that each functional block constituting the second electric field communication device 200 ′ and the electrode 300 ′ is the same as each functional block constituting the first electric field communication device 200 and the electrode 300, and therefore, here, the first electric field communication device Device 200 and electrode 300 will be described.

  The first electric field communication apparatus 200 includes an interface 201 that mediates various data, a level adjustment unit 203 that adjusts signal amplitude of various data, a transmission unit 205 that transmits various data and various signals, and a frequency of various data. A frequency setting unit 207 to set, a frequency variable unit 209 that varies the frequency of various signals, a signal oscillation unit 211 that oscillates various signals, and an electric field detection unit 213 that detects an electric field transmitted through the electric field transmission medium 400. A frequency filter 215 that allows various data and signals having a predetermined frequency to pass through, a determination unit 216 that determines normality / abnormality of various signals, a frequency selection unit 217 that selects a frequency, and various signals as predetermined procedures. And a signal processing unit 219 for processing.

  The interface 201 has a function of mediating various data between the information terminal 100 and other units in the first electric field communication device 200. Specifically, the transmission data to the information terminal 100 ′ transmitted from the information terminal 100 is once received, and the received transmission data is transmitted to the level adjustment unit 203. Further, the interface 201 receives transmission data to the information terminal 100 transmitted from the second electric field communication device 200 ′ based on the request of the information terminal 100 ′ from the signal processing unit 219, and receives the received transmission data from the information terminal To 100.

  The level adjustment unit 203 has a function of adjusting the signal amplitude and frequency of various data transmitted to the second electric field communication device 200 '. Specifically, when the signal amplitude of the transmission data to the information terminal 100 ′ transmitted from the information terminal 100 via the interface 201 is adjusted and the frequency is newly set by the frequency setting unit 207, The transmission data frequency is varied using the set frequency.

  The transmission unit 205 has a function of transmitting various data and various signals transmitted to the second electric field communication device 200 ′ to the transmission electrode 301. Specifically, transmission data whose signal amplitude has been adjusted by the level adjusting unit 203 and whose frequency has been changed, and a communication status confirmation request signal (which will be described later) whose frequency has been changed by the frequency variable unit 209 and / or A communication state confirmation response signal (described later) is transmitted from the transmission electrode 301 to the second electric field communication device 200 ′ by an electric field.

  The signal oscillating unit 211 has a function of oscillating various signals used when grasping the communication state with the second electric field communication device 200 ′ connected via the electric field transmission medium 400. Specifically, when the first electric field communication device 200 functions as a communication source, a communication state confirmation request signal used for requesting confirmation of the communication state with the second electric field communication device 200 'is oscillated. On the other hand, when the first electric field communication device 200 functions as a communication destination, the communication with the second electric field communication device 200 ′ is performed in response to the communication state confirmation request signal transmitted from the second electric field communication device 200 ′. A communication status confirmation response signal used for responding to the confirmation of the communication status is oscillated.

  The frequency variable unit 209 has a function of varying the frequency of various signals oscillated by the signal oscillating unit 211. Specifically, when the first electric field communication device 200 functions as a communication source, the frequency of the communication state confirmation request signal oscillated by the signal oscillating unit 211 is changed to a plurality of different frequencies, and each of these frequencies is supported. Output a plurality of communication status confirmation request signals. When the first electric field communication device 200 functions as a communication destination, the frequency of the communication status confirmation response signal is changed to the frequency selected by the frequency selection unit 217. As the frequency variable section 209, for example, a VCO (Voltage Controlled Oscillator) voltage control transmission circuit that changes the output frequency according to the voltage can be used. In order to output a plurality of communication state confirmation request signals substantially simultaneously, it is desirable to use a plurality of VCO voltage control transmission circuits corresponding to the respective frequencies. In addition, at least one of the plurality of frequencies is preferably a frequency included in the range of 13.56 MHz ± 7 kHz or a frequency included in the range of 13.56 MHz ± 150 kHz. In particular, as shown in FIG. 4, at least one of the plurality of frequencies described above was announced by the Ministry of Internal Affairs and Communications on March 13, 2002, “Towards Diversification of Wireless Card System Usage Forms—Information Communication It is desirable that the frequency is included in the frequency range described in the press report “Report from the Council”.

  The electric field detection unit 213 has a function of detecting an electric field transmitted through the electric field transmission medium 400 and converting various received data and various signals into electric signals. That is, when the electric field received by the receiving electrode 303 is supplied to the electric field detection unit 213, the electric field detection unit 213 changes the polarization of laser light separately generated in the electric field detection unit 213 using, for example, an electro-optic technique, The polarized laser beam is converted into an electrical signal.

  The frequency filter 215 has a function of passing various data and various signals having a predetermined frequency. Specifically, it is possible to use a plurality of band-pass filters respectively corresponding to a plurality of frequencies used to vary the frequency of the communication state confirmation request signal in the frequency variable unit 209, and a communication state having the plurality of frequencies. Only confirmation request signals and transmission data are allowed to pass.

  When the first electric field communication apparatus 200 functions as a communication destination, the determination unit 216 determines whether the plurality of communication state confirmation request signals transmitted from the second electric field communication apparatus 200 ′ that is the communication source are normal or abnormal It has a function to determine whether each is. For example, a binary sequence (for example, 20 repetitions of 1 and 0) in which 1 data and 0 data are alternated a predetermined number of times is set as a communication status confirmation request signal, and the transmitted communication status confirmation request signal is If it is the same number of 1, 0 alternations, it is determined to be normal, and if it is different, it is determined to be abnormal. Further, the same communication state confirmation request signal as the communication state confirmation request signal transmitted from the second electric field communication apparatus 200 ′ is stored in advance in a storage means (not shown), and the second electric field communication apparatus 200 ′ When a communication status confirmation request signal is transmitted, it is compared with the communication status confirmation request signal read from the storage means, and if it matches, it is determined to be normal, and if it does not match, it is determined to be abnormal. May be. That is, any method can be used as long as the normality and abnormality of the communication status confirmation request signal can be discriminated.

  The frequency selection unit 217 has a function of selecting one frequency from the frequencies of a plurality of communication state confirmation request signals determined to be normal by the determination unit 216 when the first electric field communication device 200 functions as a communication destination. ing.

  The frequency setting unit 207 has a function of setting the frequency of various data variable by the level adjustment unit 203 so that various data is transmitted using the frequency selected by the frequency selection unit 217.

  The signal processing unit 219 has a function of performing signal processing such as low noise amplification, noise removal, and waveform shaping on the electric signal from the electric field detection unit 213 and supplying the processed signal to the information terminal 100 via the interface 201.

  The transmission electrode 301 and the reception electrode 303 may be configured by one integrated electrode 300 or may be integrated with the electric field communication device 200.

  The information terminal 100 is a computer that can communicate with the information terminal 100 ′ using the first electric field communication device 200, and uses, for example, a personal computer equipped with a CPU, MPU, etc., a wearable computer that can be carried by a human being, and the like. be able to.

  The electric field transmission medium 400 may be any medium as long as it can transmit the electric field from the first electric field communication device 200 and / or the second electric field communication device 200 ′. A desk can be used.

  Subsequently, a first processing flow of the electric field communication system according to the present embodiment will be described. In the first processing flow, the first electric field communication device 200 functioning as a communication source transmits a communication state confirmation request signal, and the communication state confirmation request signal is transmitted from the second electric field communication device 200 ′ functioning as a communication destination. A processing flow in a case where transmission of transmission data from the first electric field communication apparatus 200 is started after receiving a communication state confirmation response signal for the above will be described.

  First, the frequency variable unit 209 of the first electric field communication device 200 oscillates in the signal oscillation unit 211 before transmitting the transmission data transmitted from the information terminal 100 to the second electric field communication device 200 ′. The frequency of the confirmation request signal is changed to three different frequencies f1 to f3, and three communication state confirmation request signals corresponding to the respective frequencies are output (step S101).

  Next, the transmission unit 205 transmits the three communication state confirmation request signals whose frequencies are changed by the frequency variable unit 209 from the transmission electrode 301 to the second electric field communication device 200 ′ via the electric field transmission medium 400 by an electric field. (Step S102). Note that the transmission unit 205 desirably transmits all the communication state confirmation request signals simultaneously or within a time when a human is in contact with the floor (for example, a short time of 10 ms or less).

  Here, it is assumed that environmental noise including a component of frequency f1 is generated while these three communication state confirmation request signals are transmitted through the electric field transmission medium 400, and the description will be continued. Further, it is assumed that the frequency filter 215 ′ of the second electric field communication device 200 ′ is formed in advance so as to pass communication state confirmation request signals having the frequencies f1 to f3.

  Thereafter, the frequency filter 215 ′ of the second electric field communication device 200 ′ transmits the communication state confirmation request signal of the frequency f1 to the frequency f3 transmitted through the electric field transmission medium 400 and detected by the electric field detection unit 213 ( Step S103).

  The determination unit 216 'receives all the communication state confirmation request signals that have passed through the frequency filter 215' and determines whether these three communication state confirmation request signals are normal or abnormal (step S104). As described above, since the environmental noise including the component of the frequency f1 is generated, the communication state confirmation request signal of the frequency f1 is damaged (abnormal), and the communication state confirmation request signals of the frequencies f2 and f3 are not damaged ( Normal).

  The frequency selection unit 217 'selects one frequency f3 from the frequencies f2 and f3 of the normal communication state confirmation request signal (step S105).

  Then, the frequency varying unit 209 'varies the frequency of the communication state confirmation response signal oscillated by the signal oscillating unit 211' to the frequency f3 selected by the frequency selecting unit 217 '(step S106).

  The transmission unit 205 ′ transmits the communication state confirmation response signal having the frequency f <b> 3 changed by the frequency variable unit 209 ′ from the transmission electrode 301 ′ to the first electric field communication device 200 by an electric field (step S <b> 107).

  Thereafter, the frequency filter 215 of the first electric field communication device 200, which is three bandpass filters respectively corresponding to the three frequencies f1 to f3 used to vary the frequency of the communication state confirmation request signal in the frequency variable unit 209, The communication state confirmation request signal having the frequency f3 transmitted from the second electric field communication device 200 ′ is passed (step S108).

  Since the frequency selection unit 217 has only one communication state confirmation request signal of the frequency f3 that has passed through the frequency filter 215, the frequency selection unit 217 inevitably selects the frequency f3 (step S109).

  The frequency setting unit 207 sets the frequency of transmission data variable by the level adjustment unit 203 so that transmission data is transmitted at the frequency f3 selected by the frequency selection unit 217 (step S110).

  The level adjustment unit 203 varies the frequency of the transmission data using the frequency f3 set by the frequency setting unit 207 (step S111).

  Finally, the transmission unit 205 transmits the transmission data changed to the frequency f3 by the level adjustment unit 203 from the transmission electrode 301 to the second electric field communication device 200 'via the electric field transmission medium 400 (step S112).

  According to the present embodiment, the first electric field communication device 200 oscillates the communication state confirmation request signal for requesting confirmation of the communication state with the second electric field communication device 200 ′, and the oscillated communication state confirmation request signal Are changed to a plurality of different frequencies, and a plurality of communication state confirmation request signals respectively corresponding to the plurality of frequencies are transmitted to the second electric field communication device 200 ′ by an electric field, and the second electric field communication device 200 ′ The normality and abnormality of the plurality of communication state confirmation request signals transmitted via the electric field transmission medium 400 are determined, and as a result of the determination, one frequency is selected from the frequencies of the plurality of normal communication state confirmation request signals. The frequency of the communication state confirmation response signal that responds to the confirmation of the communication state with the first electric field communication device 200 is changed to the selected frequency and transmitted to the first electric field communication device 200 by the electric field, and the first electric field communication Since the device 200 changes the frequency of the transmission data transmitted to the second electric field communication device 200 ′ to the same frequency as the frequency of the communication state confirmation response signal, the communication state is good even when environmental noise occurs. Transmission data modulated by frequency can be transmitted from the first electric field communication apparatus 200 to the second electric field communication apparatus 200 ′, and an electric field communication system that reliably performs electric field communication can be provided.

  In steps S101 to S112, the processing flow in the case where transmission data is transmitted from the first electric field communication apparatus 200 to the second electric field communication apparatus 200 ′ has been described. As described above, the second electric field communication apparatus Since the functions included in 200 ′ are the same as the functions included in first electric field communication apparatus 200, the same electric field communication apparatus 200 ′ as the first electric field communication apparatus is performed by performing the same processing flow as in steps S101 to S112. It goes without saying that the same effect can be obtained even when transmission data is transmitted to 200.

  Next, the second processing flow will be described. In this second processing flow, the first electric field communication apparatus 200 transmits a communication state confirmation request signal, and the transmission of transmission data from the second electric field communication apparatus 200 ′ is performed based on the frequency of the transmitted communication state confirmation request signal. The process flow when starting transmission will be described.

  First, the frequency variable unit 209 of the first electric field communication device 200 oscillates in the signal oscillation unit 211 before transmitting the transmission data transmitted from the information terminal 100 to the second electric field communication device 200 ′. The frequency of the confirmation request signal is changed to three different frequencies f1 to f3, and three communication state confirmation request signals respectively corresponding to the respective frequencies are output (step S201).

  Next, the transmission unit 205 transmits the three communication state confirmation request signals whose frequencies are changed by the frequency variable unit 209 from the transmission electrode 301 to the second electric field communication device 200 ′ via the electric field transmission medium 400 by an electric field. (Step S202). Note that the transmission unit 205 desirably transmits all the communication state confirmation request signals simultaneously or within a time when a human is in contact with the floor (for example, a short time of 10 ms or less).

  Here, it is assumed that environmental noise including a component of frequency f1 is generated while these three communication state confirmation request signals are transmitted through the electric field transmission medium 400, and the description will be continued. Further, it is assumed that the frequency filter 215 ′ of the second electric field communication device 200 ′ is formed in advance so as to pass communication state confirmation request signals having the frequencies f1 to f3.

  Thereafter, the frequency filter 215 ′ of the second electric field communication device 200 ′ transmits the communication state confirmation request signal of the frequency f1 to the frequency f3 transmitted through the electric field transmission medium 400 and detected by the electric field detection unit 213 ( Step S203).

  The determination unit 216 'receives all the communication state confirmation request signals that have passed through the frequency filter 215', and determines whether these three communication state confirmation request signals are normal or abnormal (step S204). As described above, since the environmental noise including the component of the frequency f1 is generated, the communication state confirmation request signal of the frequency f1 is damaged (abnormal), and the communication state confirmation request signals of the frequencies f2 and f3 are not damaged ( Normal).

  The frequency selection unit 217 'selects one frequency f3 from the frequencies f2 and f3 of the normal communication state confirmation request signal (step S205).

  Then, the frequency setting unit 207 ′ sets the frequency of the transmission data variable by the level adjustment unit 203 ′ so as to transmit the transmission data transmitted from the information terminal 100 ′ at the frequency f3 selected by the frequency selection unit 217 ′. (Step S206).

  The level adjustment unit 203 'varies the frequency of the transmission data using the frequency f3 set by the frequency setting unit 207' (step S207).

  Finally, the transmission unit 205 ′ transmits the transmission data changed to the frequency f3 by the level adjustment unit 203 ′ from the transmission electrode 301 ′ to the first electric field communication device 200 via the electric field transmission medium 400 (step S208). .

  According to the present embodiment, the second electric field communication device 200 ′ selects the frequency of transmission data to be transmitted to the first electric field communication device 200 by the frequency selection unit 217 ′ of the second electric field communication device 200 ′. The transmission data modulated at a frequency with a good communication state is transmitted from the second electric field communication device 200 ′ to the first electric field communication device 200 even when environmental noise occurs. Therefore, it is possible to provide an electric field communication system that reliably performs electric field communication.

  In steps S201 to S208, the processing flow in the case where transmission data is transmitted from the second electric field communication apparatus 200 ′ to the first electric field communication apparatus 200 has been described. As described above, the first electric field communication apparatus 200 has the same function as that of the second electric field communication device 200 ′. Therefore, the same electric flow from the first electric field communication device 200 to the second electric field communication device 200 is performed by performing the same processing flow as in steps S201 to S208. It goes without saying that the same effect can be obtained even when transmission data is transmitted to '.

It is a functional block diagram which shows the functional block of the electric field communication system which concerns on this Embodiment. It is a functional block diagram which shows the functional block of the conventional electric field communication apparatus. It is explanatory drawing explaining the state of a communication status confirmation request signal when environmental noise acts on an electric field transmission medium. It is a figure which shows a part of news report about the diversification of the use form of the wireless card system announced by the Ministry of Internal Affairs and Communications.

Explanation of symbols

100, 100 '... information terminal 200, 200' ... first electric field communication device 201, 201 '... interface 203, 203' ... level adjustment unit 205, 205 '... transmission unit 207, 207' ... frequency setting unit 209, 209 '... frequency variable unit 211,211' ... signal generation unit 213,213 '... electric field detection unit 215,215' ... frequency filter 216,216 '... discrimination unit 217,217' ... frequency selection unit 219,219 '... signal processing Unit 300, 300 '... electrode 301, 301' ... transmission electrode 303, 303 '... reception electrode 400 ... electric field transmission medium f1-f3 ... frequency S101-S112, S201-S208 ... step

Claims (9)

An electric field communication system including a first electric field communication device and a second electric field communication device capable of performing electric field communication by inducing an electric field from an electrode into an electric field transmission medium,
The first electric field communication device is:
Oscillating means for oscillating a communication state confirmation request signal for requesting confirmation of a communication state with the second electric field communication device connected via the electric field transmission medium;
A variable frequency means for varying the frequency of the communication state confirmation request signal to a plurality of different frequencies, and outputting a plurality of communication state confirmation request signals respectively corresponding to the plurality of frequencies;
Transmitting means for transmitting the plurality of output communication state confirmation request signals from the transmission electrode to the second electric field communication device by an electric field,
The second electric field communication device is:
Oscillating means for oscillating a communication state confirmation response signal for responding to confirmation of a communication state with the first electric field communication device;
Determining means for receiving the plurality of communication state confirmation request signals transmitted via the electric field transmission medium, and determining normality and abnormality of the plurality of communication state confirmation request signals;
As a result of the determination, frequency selection means for selecting one frequency from the frequencies of a plurality of normal communication state confirmation request signals;
Frequency variable means for changing the frequency of the communication status confirmation response signal to the selected frequency,
Transmission means for transmitting the communication state confirmation response signal that has been changed from the transmission electrode to the first electric field communication device by an electric field,
The first electric field communication device receives the communication state confirmation response signal transmitted via the electric field transmission medium, and sets the frequency of transmission data to be transmitted to the second electric field communication device to the communication state confirmation response signal. An electric field communication system characterized in that it is variable to the same frequency as the frequency of The second electric field communication device is:
Oscillating means for oscillating a communication state confirmation request signal for requesting confirmation of a communication state with the first electric field communication device;
A variable frequency means for varying the frequency of the communication state confirmation request signal to a plurality of different frequencies, and outputting a plurality of communication state confirmation request signals respectively corresponding to the plurality of frequencies;
A transmission means for transmitting the plurality of output communication state confirmation request signals from the transmission electrode to the first electric field communication device by an electric field;
The first electric field communication device is:
Oscillating means for oscillating a communication status confirmation response signal for responding to confirmation of the communication status with the second electric field communication device;
Determining means for receiving the plurality of communication state confirmation request signals transmitted via the electric field transmission medium, and determining normality and abnormality of the plurality of communication state confirmation request signals;
As a result of the determination, frequency selection means for selecting one frequency from the frequencies of a plurality of normal communication state confirmation request signals;
Frequency variable means for changing the frequency of the communication status confirmation response signal to the selected frequency,
Transmitting means for transmitting the changed communication state confirmation response signal from the transmission electrode to the second electric field communication device by an electric field;
The second electric field communication device receives the communication state confirmation response signal transmitted via the electric field transmission medium, and sets the frequency of transmission data to be transmitted to the first electric field communication device to the communication state confirmation response signal. The electric field communication system according to claim 1, wherein the electric field communication system is variable to the same frequency as the first frequency. The second electric field communication device is:
3. The electric field communication system according to claim 1, wherein a frequency of transmission data transmitted to the first electric field communication device is varied to a frequency selected by a frequency selection unit of the second electric field communication device. . The first electric field communication device is:
4. The electric field communication system according to claim 2, wherein a frequency of transmission data to be transmitted to the second electric field communication device is varied to a frequency selected by a frequency selection unit of the first electric field communication device. 5. .   At least one of a plurality of frequencies used for varying the frequency of the communication state confirmation request signal by the frequency varying means of the first electric field communication device is a frequency included in a range of 13.56 MHz ± 150 kHz. The electric field communication system according to any one of claims 1 to 4.   At least one of the plurality of frequencies used for changing the frequency of the communication state confirmation request signal by the frequency variable means of the second electric field communication device is a frequency included in a range of 13.56 MHz ± 150 kHz. The electric field communication system according to any one of claims 2 to 5. An electric field communication apparatus capable of performing electric field communication by inducing an electric field from an electrode into an electric field transmission medium,
Oscillating means for oscillating a communication state confirmation request signal for requesting confirmation of a communication state with another electric field communication device connected via the electric field transmission medium;
A variable frequency means for varying the frequency of the communication state confirmation request signal to a plurality of different frequencies, and outputting a plurality of communication state confirmation request signals respectively corresponding to the plurality of frequencies;
Transmitting means for transmitting the plurality of communication state confirmation request signals output from the transmission electrode to the other electric field communication device by an electric field,
A communication state confirmation response signal varied at one frequency selected from frequencies of a plurality of normal communication state confirmation request signals out of the plurality of communication state confirmation request signals transmitted via the electric field transmission medium. An electric field communication apparatus characterized in that the frequency of transmission data received from the electric field communication apparatus and transmitted to the other electric field communication apparatus is changed to the same frequency as the frequency of the communication state confirmation response signal. Oscillating means for oscillating a communication status confirmation response signal for responding to confirmation of a communication status with the other electric field communication device;
Determining means for receiving a plurality of communication state confirmation request signals transmitted from the other electric field communication devices via the electric field transmission medium, and determining normality and abnormality of the plurality of communication state confirmation request signals;
As a result of the determination, frequency selection means for selecting one frequency from the frequencies of a plurality of normal communication state confirmation request signals;
Frequency variable means for changing the frequency of the communication status confirmation response signal to the selected frequency,
Transmitting means for transmitting the communication state confirmation response signal that has been changed from the transmission electrode to the other electric field communication device by an electric field;
The electric field communication apparatus according to claim 7, further comprising:   9. The frequency included in a range of 13.56 MHz ± 150 kHz, at least one of the plurality of frequencies used for changing the frequency of the communication status confirmation request signal by the frequency changing unit. The electric field communication apparatus according to 1.

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