JP2007036439A - Signal processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to more improve communication efficiency using a human body as a communication medium. <P>SOLUTION: A portable terminal etc. for performing communication using a human body as a communication medium is configured in such a way that a signal electrode is arranged so as to contact the human body and electrostatic capacity Cte1201 of the signal electrode for the human body is connected to a signal transmission source 1251. In the portable terminal, a conductor plate constituting a reference electrode is constituted not by one large conductor plate but by a plurality of small conductor plates, and electrostatic capacities Ctg1202-1 through 1202-3 of these conductor plates with respect to a space are connected to the transmission source 1251 in parallel. This is applicable to a cellular phone. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a signal processing apparatus, and more particularly, to a signal processing apparatus that can further increase the efficiency of communication using a human body or the like as a communication medium.

  In recent years, wireless communication technology has also progressed. For example, it is expected to exchange data regardless of devices, such as personal computers, peripheral devices, home appliances, and mobile phones, using a 2.4 GHz band wireless transmission method (so-called Bluetooth). In addition, a technique for performing communication between a transmitter and a receiver using a conductor different from a normal communication medium such as a human body has been proposed (see, for example, Patent Document 1 or Patent Document 2).

Japanese National Patent Publication No. 11-509380 JP 10-229357 A

  However, in the technique of Patent Document 1, since a closed circuit coupled to a transmitter, a human body, a receiver, and an earth ground is configured and a signal is transmitted, the transmitter and the receiver that are far from the human body The connection between the electrode and the earth ground is very sparse and it is practically difficult to form a closed circuit. Further, in the technology of Patent Document 2, a transmitter, a human body, a receiver, and a closed circuit coupled to the atmosphere are configured to transmit a signal. The receiver must be located very close.

  The present invention has been made in view of such circumstances, and is intended to further improve the efficiency of communication using a human body or the like as a communication medium.

  One aspect of the present invention provides a reference electrode that provides a reference potential for signal transmission and reception, and a signal that is provided so that electrostatic coupling to the communication medium is stronger than the reference electrode and is transmitted through the communication medium. A signal processing apparatus comprising: a signal electrode for transmitting or receiving a signal; the reference electrode; and a communication control means for controlling transmission or reception of a signal based on a potential difference generated between the signal electrode, In the signal processing device, the reference electrode is composed of a plurality of electrodes, and is connected to the transmission / reception control means so that the capacitances between the electrodes and the space are parallel to each other.

  Each of the plurality of electrodes may be formed of a circular conductor plate.

  Each of the plurality of electrodes may be formed of a square conductor plate.

  The plurality of electrodes may be arranged at positions separated by a predetermined interval in the same plane.

  The plurality of electrodes may be stacked and arranged.

  In one aspect of the present invention, a reference electrode that provides a reference potential for signal transmission / reception, and an electrostatic coupling that is stronger than the reference electrode with respect to the communication medium are provided and transmitted via the communication medium. The reference of a signal processing apparatus including a signal electrode for transmitting or receiving a signal, the reference electrode, and a communication control means for controlling transmission or reception of a signal based on a potential difference generated between the signal electrode and the reference electrode The electrodes are composed of a plurality of electrodes, and are connected to the communication control means so that the capacitances between the electrodes and the spaces are parallel to each other.

  According to one aspect of the present invention, the efficiency of communication using a communication medium such as a human body can be further increased.

  Embodiments of the present invention will be described below. Correspondences between the configuration requirements of the present invention and the embodiments described in the detailed description of the present invention are exemplified as follows. This description is to confirm that the embodiments supporting the present invention are described in the detailed description of the invention. Accordingly, although there are embodiments that are described in the detailed description of the invention but are not described here as embodiments corresponding to the constituent elements of the present invention, It does not mean that the embodiment does not correspond to the configuration requirements. Conversely, even if an embodiment is described here as corresponding to a configuration requirement, that means that the embodiment does not correspond to a configuration requirement other than the configuration requirement. It's not something to do.

  One embodiment of the present invention is provided with a reference electrode (for example, the reference electrode 1102 in FIG. 15) that supplies a reference potential for signal transmission / reception, and so that electrostatic coupling is stronger with respect to a communication medium than the reference electrode. Of a signal based on a potential difference generated between a signal electrode (for example, signal electrode 1101 in FIG. 15) for transmitting or receiving a signal to be transmitted through a communication medium, the reference electrode, and the signal electrode. A signal processing device including communication control means for controlling transmission or reception (for example, the transmitter 1151 in FIG. 15), wherein the reference electrode is composed of a plurality of electrodes, and each of the electrodes and the space It is a signal processing device connected to the transmission / reception control means so that the capacitances are parallel to each other.

  Embodiments of the present invention will be described below with reference to the drawings. First, wireless communication used in the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a diagram illustrating a configuration example according to an embodiment of a communication system to which the present invention is applied.

  In FIG. 1, the communication system 100 includes a transmission device 110, a reception device 120, and a communication medium 130, and the transmission device 110 and the reception device 120 transmit and receive signals via the communication medium 130. That is, in the communication system 100, the signal transmitted from the transmission device 110 is transmitted via the communication medium 130 and received by the reception device 120.

  The transmission device 110 includes a transmission signal electrode 111, a transmission reference electrode 112, and a transmission unit 113. The transmission signal electrode 111 is an electrode for transmitting a signal to be transmitted via the communication medium 130, and is more communication medium than the transmission reference electrode 112 which is an electrode for obtaining a reference point for determining a difference in level of the signal. 130 is provided so that electrostatic coupling is strong. The transmission unit 113 is provided between the transmission signal electrode 111 and the transmission reference electrode 112, and gives an electric signal (potential difference) to be transmitted to the reception device 120 between these electrodes.

  The reception device 120 includes a reception signal electrode 121, a reception reference electrode 122, and a reception unit 123. The reception signal electrode 121 is an electrode for receiving a signal transmitted via the communication medium 130 and is more communicated than the reception reference electrode 122 which is an electrode for obtaining a reference point for determining a difference in level of the signal. It is provided so that electrostatic coupling is strong with respect to the medium 130. The reception unit 123 is provided between the reception signal electrode 121 and the reception reference electrode 122, converts an electric signal (potential difference) generated between these electrodes into a desired electric signal, and is transmitted by the transmission unit 113 of the transmission device 110. Restore the generated electrical signal.

  The communication medium 130 is made of a substance having physical characteristics capable of transmitting an electrical signal, such as a conductor or a dielectric. For example, the communication medium 130 is composed of a conductor represented by metal (for example, copper, iron, aluminum, or the like). Further, for example, the communication medium 130 is composed of an electrolytic solution such as pure water, rubber, glass, or saline, or a dielectric such as a living body that is a complex thereof. The communication medium 130 may have any shape, for example, an arbitrary shape such as a linear shape, a plate shape, a spherical shape, a prismatic shape, or a cylindrical shape.

  In such a communication system 100, first, the relationship between each electrode and the communication medium or the space around the apparatus will be described. In the following, for convenience of explanation, it is assumed that the communication medium 130 is a complete conductor. Further, it is assumed that there is a space between the transmission signal electrode 111 and the communication medium 130 and between the reception signal electrode 121 and the communication medium 130 and there is no electrical coupling. That is, a capacitance is formed between the transmission signal electrode 111 or the reception signal electrode 121 and the communication medium 130.

  The transmission reference electrode 112 is provided so as to face the space around the transmission device 110, and the reception reference electrode 122 is provided so as to face the space around the reception device 120. Generally, when a conductor exists in a space, a capacitance is formed in a space near the surface of the conductor. For example, when the shape of the conductor is a sphere having a radius of r [m], the capacitance C is obtained as in the following formula (1).

  In the formula (1), π represents a circumference ratio. Further, ε represents a dielectric constant of a medium surrounding the conductor, and is obtained as in the following formula (2).

  However, in Formula (2), ε0 indicates a dielectric constant in a vacuum and is 8.854 × 10 −12 [F / m]. Further, εr represents a relative dielectric constant, and represents a ratio to a vacuum dielectric constant ε0.

  As shown in the above formula (1), the larger the radius r, the larger the capacitance C. In addition, although the magnitude | size of the electrostatic capacitance C of a conductor of complicated shape other than a sphere cannot be expressed simply like Formula (1) mentioned above, it changes according to the magnitude | size of the surface area of the conductor. It is clear to do.

  As described above, the transmission reference electrode 112 forms a capacitance with respect to the space around the transmission device 110, and the reception reference electrode 122 forms a capacitance with respect to the space around the reception device 120. That is, when viewed from the virtual infinity point outside the transmission device 110 and the reception device 120, the potentials of the transmission reference electrode 112 and the reception reference electrode 122 are fixed and hardly change.

  Next, the principle of the communication mechanism in the communication system 100 will be described. In the following description, a capacitor may be simply expressed as a capacitance for convenience of explanation or from the context, etc., but these are consents.

  In the following description, it is assumed that the transmission device 110 and the reception device 120 in FIG. 1 are arranged so as to maintain a sufficient distance between the devices, and the mutual influence can be ignored. Further, in the transmission device 110, the transmission signal electrode 111 is electrostatically coupled only to the communication medium 130, and the transmission reference electrode 112 is placed at a sufficient distance from the transmission signal electrode 111, and the mutual influence can be ignored (electrostatic). Shall not be combined). Similarly, in the receiving device 120, the reception signal electrode 121 is electrostatically coupled only with the communication medium 130, and the reception reference electrode 122 is sufficiently spaced from the reception signal electrode 121, and the mutual influence can be ignored (static). Shall not be electrocoupled). Furthermore, in practice, the transmission signal electrode 111, the reception signal electrode 121, and the communication medium 130 also have capacitance to the space as long as they are arranged in the space, but here, for convenience of explanation. , They can be ignored.

  FIG. 2 is a diagram illustrating the communication system 100 of FIG. 1 with an equivalent circuit. The communication system 200 is an equivalent circuit of the communication system 100 and is substantially equivalent to the communication system 100.

  That is, the communication system 200 includes a transmission device 210, a reception device 220, and a connection line 2230. The transmission device 210 corresponds to the transmission device 110 of the communication system 100 shown in FIG. Corresponds to the receiving device 120 of the communication system 100 shown in FIG. 1, and the connection line 230 corresponds to the communication medium 130 of the communication system 100 shown in FIG.

  In the transmission device 210 of FIG. 2, the signal source 213-1 and the ground point 213-2 correspond to the transmission unit 113 of FIG. The signal source 213-1 generates a sine wave having a specific period ω × t [rad] as a transmission signal. Here, t [s] indicates time. Further, ω [rad / s] represents an angular frequency and can be expressed as the following equation (3).

  In Expression (3), π represents a circular ratio, and f [Hz] represents a frequency of a signal generated by the signal source 213-1. The ground point 213-2 is a point connected to the circuit ground in the transmission device 210. That is, one of the terminals of the signal source 213 is set to a predetermined reference potential of a circuit in the transmission device 210.

  Cte 214 is a capacitor and represents the capacitance between the transmission signal electrode 111 and the communication medium 130 of FIG. That is, the Cte 214 is provided between the terminal on the opposite side of the ground point 213-2 of the signal source 213-1 and the connection line 230. Further, Ctg 215 is a capacitor and represents the capacitance with respect to the space of the transmission reference electrode 112 in FIG. The Ctg 215 is provided between a terminal on the installation point 213-2 side of the signal source 213-1 and a grounding point 216 indicating a point at infinity (virtual point) with respect to the transmitter 110 in space. .

  In the receiving device 220 of FIG. 2, Rr 223-1, detector 223-2, and ground point 223-3 correspond to the receiving unit 123 of FIG. Rr 223-1 is a load resistor (reception load) for extracting a received signal, and a detector 223-2 configured by an amplifier detects and amplifies the potential difference between the terminals on both sides of the Rr 223-1. The ground point 223-3 is a point connected to the circuit ground in the receiving device 220. That is, one of the terminals of Rr 223-1 (one of the input terminals of the detector 223-2) is set to a predetermined reference potential of the circuit in the receiving device 220.

  The detector 223-2 may further have other functions such as demodulating the detected modulated signal and decoding encoded information included in the detected signal. Good.

  Cre 224 is a capacitor and represents the capacitance between the reception signal electrode 121 and the communication medium 130 of FIG. That is, Cre 224 is provided between the terminal of Rr 223-1 opposite to the ground point 223-3 and the connection line 230. Crg 225 is a capacitor and represents the capacitance with respect to the space of the reception reference electrode 122 in FIG. Crg 225 is provided between a terminal on the installation point 223-3 side of Rr 223-1 and a ground point 226 indicating a point at infinity (virtual point) on the basis of the receiving device 120 in space.

  The connection line 230 represents the communication medium 130 that is a perfect conductor. In the communication system 200 of FIG. 2, Ctg 215 and Crg 225 are expressed as being electrically connected to each other via a ground point 216 and a ground point 226 on an equivalent circuit. These do not need to be electrically connected to each other, and each of them only needs to form a capacitance with respect to the space around the transmitter 210 or the receiver 220. That is, the ground point 216 and the ground point 226 do not need to be electrically connected, and may be independent from each other.

  If there is a conductor, a capacitance proportional to the size of the surface area is always formed in the surrounding space. That is, for example, the transmission device 210 and the reception device 220 may be any distance from each other. For example, when the communication medium 130 of FIG. 1 is a perfect conductor, the conductivity of the connection line 230 can be regarded as infinite, so the length of the connection line 230 does not affect communication. If the communication medium 130 is a conductor having sufficient conductivity, the distance between the transmission device and the reception device does not affect the stability of communication in practice.

  In the communication system 200, a circuit including a signal source 213-1, Rr 223-1, Cte 214, Ctg 215, a Cre capacitor 224, and Crg 225 is formed. The combined capacitance Cx of the four capacitors (Cte 214, Ctg 215, Cre capacitor 224, and Crg 225) connected in series can be expressed by the following equation (4).

  Further, the sine wave vt (t) generated by the signal source 213-1 is expressed as the following equation (5).

  Here, Vm [V] represents the maximum amplitude voltage of the signal source voltage, and θ [rad] represents the initial phase angle. That is, the effective value Vtrms [V] of the voltage from the signal source 213-1 can be obtained as in the following equation (6).

  The synthetic impedance Z in the entire circuit can be obtained as in the following equation (7).

  That is, the effective value Vrrms of the voltage generated at both ends of Rr 223-1 can be obtained as shown in Expression (8).

  Therefore, as shown in the equation (8), as the resistance value of Rr 223-1 is larger, the capacitance Cx is larger, and the frequency f [Hz] of the signal source 213-1 is higher, 1 / (( 2 × π × f × Cx) 2) is reduced, and a larger signal can be generated at both ends of Rr 223-1.

  For example, the effective value Vtrms of the voltage by the signal source 213-1 of the transmission apparatus 210 is fixed to 2 [V], and the frequency f of the signal generated by the signal source 213-1 is 1 [MHz], 10 [MHz], or 100 [MHz], the resistance value of Rr 223-1 is 10 K [Ω], 100 K [Ω], or 1 M [Ω], and the capacitance Cx of the entire circuit is 0.1 [pF], 1 [pF], Alternatively, the calculation result of the effective value Vrrms of the voltage generated at both ends of Rr 223-1 when 10 [pF] is obtained is as shown in Table 250 shown in FIG.

  As shown in Table 250, when the other conditions are the same, the calculation result of the effective value Vrrms is larger when the frequency f is 10 [MHz] than when the frequency f is 1 [MHz], and is a reception load. The resistance value of Rr223-1 is larger when it is 1M [Ω] than when it is 10K [Ω], and is larger when the capacitance Cx is 10 [pF] than when it is 0.1 [pF]. Takes a value. That is, the larger the value of the frequency f, the resistance value of Rr 223-1, and the capacitance Cx, the larger effective value Vrrms can be obtained.

  Further, it can be seen from Table 250 that an electrical signal is generated in Rr 223-1 even with a capacitance of picofarad or less. That is, when the signal level of the transmitted signal is very small, communication can be performed by amplifying the signal detected by the detector 223-2 of the receiving device 220.

  From the above results, as a basic principle, it is possible to transfer a signal from the transmission device to the reception device by using the capacitance formed with the space.

  The capacitance with respect to the space of the transmission reference electrode and the reception reference electrode described above can be formed if there is a space at the position of each electrode. Therefore, if the transmission signal electrode and the reception signal electrode described above are coupled by a communication medium, the transmission device and the reception device described above can obtain communication stability without depending on the distance between each other.

  Next, the influence on communication due to the distance between the transmission device and the reception device will be described. As described above, according to the principle of the present invention, if a sufficient capacitance can be formed in the space between the transmission reference electrode and the reception reference electrode, a path by the ground in the vicinity between the transmission / reception device and other electrical It does not require a path and does not depend on the distance between the transmission signal electrode and the reception signal electrode. Therefore, for example, as in the communication system 700 shown in FIG. 4, the transmission device 710 and the reception device 720 are placed at a long distance, and the transmission signal electrode 711 and the reception signal are transmitted by the communication medium 730 having sufficient conductivity or dielectric property. Communication is possible by electrostatically coupling the electrode 721. At this time, the transmission reference electrode 712 is electrostatically coupled to a space outside the transmission device 710, and the reception reference electrode 722 is electrostatically coupled to a space outside the reception device 720. Therefore, the transmission reference electrode 712 and the reception reference electrode 722 do not need to be electrostatically coupled to each other. However, as the communication medium 730 becomes longer and larger, the capacitance with respect to the space also increases. Therefore, it is necessary to consider these when determining each parameter.

  4 is a system corresponding to the communication system 100 in FIG. 1. The transmission device 710 corresponds to the transmission device 110, the reception device 720 corresponds to the reception device 120, and the communication medium 730 is a communication device. This corresponds to the medium 130.

  In the transmission device 710, the transmission signal electrode 711, the transmission reference electrode 712, and the signal source 713-1 correspond to the transmission signal electrode 111, the transmission reference electrode 112, and the transmission unit 113 (or a part thereof), respectively. Similarly, in the reception device 720, the reception signal electrode 721, the reception reference electrode 722, and Rr723-1 correspond to the reception signal electrode 121, the reception reference electrode 122, and the reception unit 123 (or a part thereof), respectively.

  Therefore, the description about each of these parts is omitted.

  As described above, the communication system 700 does not require a physical reference point path, and can realize communication using only the communication signal transmission path.

  In the above description, the transmission signal electrode and the reception signal electrode are described as being in non-contact with the communication medium. However, the present invention is not limited thereto, and the transmission reference electrode and the reception reference electrode are sufficient between the surrounding spaces of the respective devices. If a sufficient electrostatic capacity can be obtained, the transmission signal electrode and the reception signal electrode may be connected by a conductive communication medium.

  Next, a specific application example of the communication system as described above will be described. For example, the communication system as described above can use a living body as a communication medium. FIG. 5 is a schematic diagram illustrating an example of a communication system when communication is performed via a human body. In FIG. 5, a communication system 750 transmits music data from a transmission device 760 attached to the arm of the human body, receives the music data by a reception device 770 attached to the head of the human body, and converts the music data into speech. This is a system for outputting and allowing the user to view. The communication system 750 is a system corresponding to the above-described communication system (for example, the communication system 100), and the transmission device 760 and the reception device 770 correspond to the transmission device 110 and the reception device 120, respectively. In the communication system 750, the human body 780 is a communication medium and corresponds to the communication medium 130 in FIG.

  That is, the transmission device 760 includes the transmission signal electrode 761, the transmission reference electrode 762, and the transmission unit 763, and corresponds to the transmission signal electrode 111, the transmission reference electrode 112, and the transmission unit 113 in FIG. The reception device 770 includes a reception signal electrode 771, a reception reference electrode 772, and a reception unit 773, and corresponds to the reception signal electrode 121, the reception reference electrode 122, and the reception unit 123 of FIG.

  Therefore, the transmission device 760 and the reception device 770 are installed so that the transmission signal electrode 761 and the reception signal electrode 771 are in contact with or close to the human body 780 that is a communication medium. Since the transmission reference electrode 762 and the reception reference electrode 772 only need to have a capacitance with respect to the space, it is not necessary to couple with the ground in the periphery or between the transmission / reception devices (or electrodes).

  FIG. 6 is a diagram for explaining another example for realizing the communication system 750. In FIG. 6, the receiving device 770 contacts (or approaches) the human body 780 at the sole portion, and performs communication with the transmitting device 760 attached to the arm portion of the human body 780. Also in this case, the transmission signal electrode 761 and the reception signal electrode 771 are provided so as to be in contact with (or close to) the human body 780 that is a communication medium, and the transmission reference electrode 762 and the reception reference electrode 772 are provided toward the space. ing. In particular, this is an application example that cannot be realized by the conventional technology in which the earth is one of the communication paths.

  As described above, according to the present invention, it is possible to perform wireless communication using a human body or the like as a communication medium without providing a wired facility such as a cable.

  In the communication system as described above, there is no particular limitation on the modulation method of the signal flowing in the communication medium as long as it can be handled by both the transmission device and the reception device. Based on the characteristics of the entire communication system, , The most suitable method can be selected. Specifically, the modulation method includes any one of a baseband, amplitude-modulated, or frequency-modulated analog signal, a baseband, amplitude-modulated, frequency-modulated, or phase-modulated digital signal, Alternatively, a plurality of mixtures may be used.

  Further, in the communication system as described above, a plurality of communications can be established by using one communication medium, and full-duplex communication or communication between a plurality of devices using a single communication medium can be executed. You may be able to do it.

  An example of a method for realizing such multiplex communication will be described. The first is a method of applying a spread spectrum method. In this case, a frequency bandwidth and a specific time series code are negotiated between the transmission device and the reception device. Then, the transmission apparatus changes the frequency of the original signal in accordance with the time-series code within this frequency bandwidth, spreads it over the entire frequency band, and transmits it. After receiving the spread component, the receiving device decodes the received signal by integrating the received signal.

  The effect obtained by frequency spreading will be described. According to the channel capacity theorem of Shannon and Hartley, the following equation holds.

  Here, C [bps] indicates the channel capacity, and indicates the theoretical maximum data rate that can be sent to the communication path. B [Hz] indicates the channel bandwidth. S / N indicates a signal-to-noise power ratio (SN ratio). Further, if the above equation is expanded by Macrolin and the S / N is low, the above equation (9) can be approximated as the following equation (10).

  Thus, for example, if S / N is a level below the noise floor, S / N << 1, but by increasing the channel bandwidth B, the channel capacity C can be raised to a desired level.

  If the time-series code is different for each communication channel and the frequency spread behavior is different, the frequency spreads without interfering with each other and mutual interference is eliminated, so that multiple communications can be performed simultaneously. it can.

  The second is a method of applying a frequency division method in which a frequency bandwidth is determined between a transmission device and a reception device and is further divided into a plurality of regions. In this case, the transmission device (or the reception device) follows a specific frequency band allocation rule or detects a free frequency band at the start of communication, and performs frequency band allocation based on the detection result.

  In other words, by using different frequency bands for each communication path, mutual interference can be suppressed and a plurality of communications can be performed simultaneously on one communication medium. Further, by using the frequency division method, many-to-one communication or many-to-many communication can be performed.

  The third is a method of applying a time division method in which the communication time is divided into a plurality of times between the transmission device and the reception device. In this case, the transmission device (or the reception device) follows a specific time division rule or detects a free time region at the start of communication, and divides the communication time based on the detection result.

  That is, by performing communication in a different time band for each communication path, mutual interference can be suppressed and a plurality of communications can be performed simultaneously on one communication medium. Further, by using the time division method, many-to-one communication and many-to-many communication can be performed.

  Furthermore, as a method other than those described above, two or more of the first to third communication methods may be combined.

  The ability of a transmitting device and a receiving device to communicate with multiple other devices at the same time is particularly important in certain applications. For example, assuming application to a ticket for transportation facilities, when a user who possesses both a device A having commuter pass information and a device B having an electronic money function uses an automatic ticket gate, By using the method, communication is performed simultaneously with the devices A and B. For example, when the use section includes a section other than the commuter pass, the shortage amount is deducted from the electronic money of the apparatus B. It can be used for various purposes.

  The flow of communication processing executed in the communication between the transmission apparatus and the reception apparatus as described above will be described with reference to an example of communication between the transmission apparatus 110 and the reception apparatus 120 of the communication system 100 in FIG. This will be described with reference to a flowchart.

  The transmitter 113 of the transmitter 110 generates a signal to be transmitted in step S11, and transmits the generated signal onto the communication medium 130 via the transmission signal electrode 111 in step S12. When the signal is transmitted, the transmission unit 113 of the transmission device ends the communication process. A signal transmitted from the transmission device 110 is supplied to the reception device 120 via the communication medium 130. The reception unit 123 of the reception device 120 receives the signal via the reception signal electrode 121 in step S21, and outputs the received signal in step S22. The receiving unit 123 that has output the received signal ends the communication process.

  As described above, the transmission device 110 and the reception device 120 can perform basic communication through a simple process without requiring complicated processing via the communication medium 130. In other words, the transmitting device 110 and the receiving device 120 do not need to construct a closed circuit using the reference electrode, and therefore perform transmission / reception via the signal electrode, and easily perform stable communication processing without being affected by the environment. be able to. Thereby, the transmission apparatus 110 and the reception apparatus 120 (communication system 100) can reduce the load of communication processing for performing stable communication without being influenced by the environment, and can also reduce the manufacturing cost. Further, by simplifying the structure of communication processing, the communication system 100 can easily use various communication methods such as modulation, encoding, encryption, or multiplexing.

  In the above communication system, the transmission device and the reception device are described as separate units. However, the present invention is not limited to this, and communication is performed using the transmission / reception device having the functions of both the transmission device and the reception device described above. A system may be constructed.

  FIG. 8 is a diagram showing another configuration example of the communication system to which the present invention is applied.

  In FIG. 8, the communication system 950 includes a transmission / reception device 961, a transmission / reception device 962, and a communication medium 130. The communication system 950 is a system in which the transmission / reception device 961 and the transmission / reception device 962 transmit and receive signals bidirectionally via the communication medium 130.

  The transmission / reception device 961 has both the configuration of the transmission unit 110 similar to the transmission device 110 in FIG. 1 and the reception unit 120 similar to the reception device 120. That is, the transmission / reception device 961 includes a transmission signal electrode 111, a transmission reference electrode 112, a transmission unit 113, a reception signal electrode 121, a reception reference electrode 122, and a reception unit 123.

  That is, the transmission / reception device 961 transmits a signal via the communication medium 130 using the transmission unit 110 and receives a signal supplied via the communication medium 130 using the reception unit 120. At this time, the transmission / reception device 961 is configured such that communication by the transmission unit 110 and communication by the reception unit 120 do not interfere with each other.

  The transmission / reception device 962 has the same configuration as that of the transmission / reception device 961 and operates in the same manner, and thus the description thereof is omitted. That is, the transmission / reception device 961 and the transmission / reception device 962 perform bidirectional communication via the communication medium 130 in the same manner.

  Thus, the communication system 950 (the transmission / reception device 961 and the transmission / reception device 962) can easily realize bidirectional wireless communication without providing a wired facility such as a cable.

  In the example of FIG. 8, different electrodes are used for transmission and reception, but only one set of signal electrode and reference electrode may be provided to switch transmission and reception.

  By the way, in the wireless communication described above with reference to FIGS. 1 to 8, as described with reference to FIGS. 2 and 3, if the value of the frequency f and the resistance value of Rr 223-1 are the same, It is known that a larger effective value Vrrms can be obtained as the capacitance Cx is larger.

  Here, the effective value Vrrms is the effective value of the voltage generated at both ends of the Rr 223-1 of the receiving device 220 in FIG. , And Crg225).

  Therefore, by increasing the value of the overall capacitance Cx of the communication system 200 composed of the transmission device 210 and the reception device 220, the amplitude of the signal detected by the reception device 220 can be increased and more accurately. A signal can be received. In other words, it can be said that the larger the value of the entire capacitance Cx, the higher the communication capability (ability to transmit signals reliably) of the communication system 200.

  For example, in the communication system 200 of FIG. 2, the transmission device 210 is configured by a small portable terminal or the like, the reception device 220 is configured by a dedicated reader / writer or the like, and is carried instead of the connection line 230 as in FIG. Considering a case where a human body of a user who owns (carries) a terminal serves as a communication medium and signals are transmitted, Ctg 215 in FIG. 2 is a capacitance between a reference electrode of the portable terminal and a point at infinity in space. Crg 225 corresponds to the capacitance between the reference electrode of the reader / writer and the point at infinity in space. Cte 214 or Cre 224 corresponds to a capacitance formed between the signal electrode of the portable terminal or the signal electrode of the reader / writer and the human body, respectively.

  Here, in order to increase the communication capability of the communication system 200, it is necessary to increase the overall capacitance as described above. Since the capacitance formed between the conductor and the space changes according to the size of the surface area of the conductor as described above, it is a conductor in order to increase the overall capacitance of the communication system 200. It is effective to increase the surface area of the signal electrode or the reference electrode.

  However, in this case, since the surface area of the signal electrode provided so as to contact the human body is limited to the contact area with the human body, the size of the signal electrode is naturally limited in consideration of the shape and function of the human body. Therefore, there is a limit to increasing the capacitances of Cte 214 and Cre 224.

  On the other hand, since the reference electrode is provided so as to face the space, there is much room for improvement in increasing the surface area of the reference electrode and increasing the capacitance of Ctg 215 and Crg 225. However, although it is easy to increase the surface area of the reference electrode of the reader / writer that can take up a sufficient installation space and increase the capacitance of Crg225, for example, in a small portable terminal configured so that the user can freely carry it In view of the size of the portable terminal, it is not easy to increase the Ctg 215 capacitance by increasing the surface area of the reference electrode.

  Therefore, a method for increasing the capacitance of Ctg 215 without changing the surface area of the reference electrode will be considered.

  For example, when the reference electrode is configured as a circular conductor plate, it is known that the capacitance with respect to the space of the circular conductor plate is obtained by 8εr (r is the radius of the circle). On the other hand, it is known that when a charge is injected into a circular conductor plate, the charge is biased toward the outer periphery of the conductor plate (circle). In other words, the charges gather around the circumference, and the larger the circumference, the wider the region where the charges can exist. For this reason, it is considered that the capacitance is proportional to the radius r.

  Therefore, there is a possibility that the capacitance is larger even when the surface area is the same, using a plurality of small circular conductor plates than using a single large circular conductor plate as a reference electrode.

  Now, as shown in FIG. 9, considering that one circular conductor plate having a radius of 2r is used as a reference electrode, its capacitance (corresponding to the capacitance of Ctg 215) is 16εr (= 8ε × 2r). Is calculated.

  On the other hand, as shown in FIG. 10, when four circular conductor plates having a radius r are connected in parallel and used as a reference electrode, the total surface area (total surface area of the four circular conductor plates) is the same as in FIG. Although not replaced, the total capacitance is 32εr (= 8εr × 4), and the capacitance is larger than in the case of FIG.

  That is, by using a plurality of small circular conductor plates as reference electrodes instead of using one large circular conductor plate as a reference electrode, the communication capability of the communication system can be increased more efficiently. Furthermore, although a large conductor plate is difficult to handle, for example, a small conductor plate having a size of a fraction of a size can be stored more compactly in a device (for example, a portable terminal), and as a result, the configuration of the device Can be made easier.

  In the case where four conductor plates are connected in parallel as in the example of FIG. 10 and used as a reference electrode, the conductor plates have the same polarity and repel each other. is there.

  The same applies to the case where the reference electrode is a non-circular conductor plate. For example, when a square conductor plate is used as the reference electrode, the places where charges are collected on the conductor plate are the four corners and the outer periphery of the square.

  For example, as shown in FIG. 11, rather than using a single square conductor plate with a side length of 2L to form the reference electrode, as shown in FIG. Even if the total surface area is the same, the reference electrode is composed of a square conductor plate, and the number of corners is quadrupled and the outer periphery is increased. growing.

  Alternatively, as shown in FIG. 13, the number of conductor plates used as reference electrodes may be further increased (in this case, eight square conductor plates each having a length of L / 2).

  Thus, instead of using one large square conductor plate as a reference electrode, the communication capability of the communication system can be increased more efficiently by using a plurality of small square conductor plates as reference electrodes. (However, as in the case of circular conductor plates, it is necessary to separate the conductor plates from each other to some extent.)

  In the above, the example in which the reference electrode is configured by a plurality of small circular or square conductor plates has been described. For example, as shown in FIG. 14, one large square (a square having a side length of 2L) is formed. Instead of the conductor plate, four rectangular conductor plates having a horizontal length of 2L and a vertical length of L / 2 may be used as the reference electrode. Alternatively, the shape of the conductor plate such as an ellipse or a triangle may be changed as necessary.

  FIG. 15 is a block diagram illustrating a configuration example of a transmission device (for example, a portable terminal) when a reference electrode is configured by a plurality of small conductor plates. In this example, a signal electrode 1101 and four small reference electrodes 1102-1 to 1102-4 are connected to the transmitter 1151, and for example, the signal electrode 1101 is provided in contact with the user's human body, and the reference electrode 1102 is provided. -1 to 1102-4 are provided to face the space. Signals are transmitted / received to / from a receiving device (not shown) using the user's human body as a communication medium as described above with reference to FIGS.

  Here, the reference electrodes 1102-1 to 1102-4 may be provided so as to be arranged in a plane in the apparatus, or may be provided so as to be stacked (stacked) at different height positions. May be. Usually, the reference electrodes 1102-1 to 1102-4 are configured as sufficiently thin conductor plates, and thus the apparatus can be further miniaturized by being provided so as to be laminated.

  FIG. 16 is a diagram illustrating FIG. 15 as an equivalent circuit. In the figure, the transmitter 1151 of FIG. 15 is replaced with a signal source 1251, and the signal source 1251 generates a signal of a predetermined frequency, for example. Cte 1201 is a capacitor and represents the capacitance between the signal electrode 1101 in FIG. 15 and the communication medium (in this case, the human body). Ctg 1202-1 to 1202-4 are capacitors connected in parallel, respectively, and represent the capacitance with respect to the space of the reference electrodes 1102-1 to 1102-4 in FIG.

  The combined capacitance of the capacitors Ctg 1201-1 to 1201-4 is 4 Ctg. For example, as described in FIGS. 9 and 10, if Ctg = 8εr (capacitance of the small conductor plate in FIG. 10), the combined capacitance is only 16εr with one large conductor plate (FIG. 9). However, the combined capacity of the four small conductive plates connected in parallel is 4Ctg = 32εr, which clearly increases the capacitance. Thereby, the communication capability can be enhanced as described above.

  The steps of executing the series of processes described above in this specification are performed in parallel or individually even if they are not necessarily processed in time series, as well as processes performed in time series in the order described. It also includes processing.

It is a figure which shows the structural example which concerns on one Embodiment of the communication system to which this invention is applied. It is a figure which shows the example of the equivalent circuit of the communication system of FIG. 1 in an ideal state. FIG. 3 is a diagram illustrating an example of a calculation result of an effective value of a voltage generated at both ends of a reception load resistor in the model of FIG. It is a figure which shows the example of arrangement | positioning of the communication system of FIG. It is a figure which shows the actual usage example which concerns on one Embodiment of the communication system to which this invention is applied. It is a figure which shows the other usage example which concerns on one Embodiment of the communication system to which this invention is applied. It is a flowchart which shows the example of the flow of a communication process. It is a figure which shows the further another structural example of the communication system to which this invention is applied. It is a figure which shows the example in case a reference electrode is comprised with a circular conductor board. It is a figure which shows the example in case a reference electrode is comprised with a some circular conductor board. It is a figure which shows the example in case a reference electrode is comprised with a square conductor board. It is a figure which shows the example in case a reference electrode is comprised with a several square conductor board. It is a figure which shows another example in case a reference electrode is comprised with a several square conductor board. It is a figure which shows the example in case a reference electrode is comprised with a some rectangular conductor board. It is a block diagram which shows the structural example of the transmitter in case a reference | standard electrode is comprised with a several conductor board. It is a figure which shows the example of the equivalent circuit of the transmitter of FIG.

Explanation of symbols

  100 communication system 110 transmission device 111 transmission signal electrode 112 transmission reference electrode 113 transmission unit 120 reception device 121 reception signal electrode 122 reception reference electrode 123 reception unit 130 communication medium 961 and 962 transmission / reception device 1101 Signal electrode, 1102-1 to 1102-4 Reference electrode, 1151 Transmitter

Claims (5)

A reference electrode for providing a reference potential for signal transmission and reception;
A signal electrode for transmitting or receiving a signal to be transmitted via the communication medium, the electrostatic coupling being provided to the communication medium stronger than the reference electrode;
A signal processing device including a communication control means for controlling transmission or reception of a signal based on a potential difference generated between the reference electrode and the signal electrode,
The signal processing device, wherein the reference electrode is composed of a plurality of electrodes, and is connected to the communication control means so that electrostatic capacitances between the electrodes and the spaces are parallel to each other. The signal processing device according to claim 1, wherein each of the plurality of electrodes is formed of a circular conductor plate. The signal processing device according to claim 1, wherein each of the plurality of electrodes is configured by a square conductor plate. The signal processing device according to claim 1, wherein the plurality of electrodes are arranged at positions separated from each other by a predetermined interval in the same plane. The signal processing apparatus according to claim 1, wherein the plurality of electrodes are stacked and arranged.

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