JP4191727B2

JP4191727B2 - Electric field communication system

Info

Publication number: JP4191727B2
Application number: JP2005359266A
Authority: JP
Inventors: 直志美濃谷; 満品川
Original assignee: Nippon Telegraph and Telephone Corp; NTT Inc USA
Current assignee: NTT Inc; NTT Inc USA
Priority date: 2005-12-13
Filing date: 2005-12-13
Publication date: 2008-12-03
Anticipated expiration: 2025-12-13
Also published as: JP2007166185A

Description

本発明は、電界を電界伝達媒体に誘起し、この誘起した電界を検出して情報の送受信を行う通信に適用する電界通信システムに関する。 The present invention relates to an electric field communication system applied to communication in which an electric field is induced in an electric field transmission medium, and the induced electric field is detected to transmit / receive information.

携帯端末の小型化および高性能化により、生体に装着可能なウェアラブルコンピュータが注目されてきている。従来、このようなウェアラブルコンピュータ間の情報通信として、コンピュータに電界通信トランシーバを接続して装着し、この電界通信トランシーバが誘起する電界を、電界伝達媒体である生体を介して伝達させることによって、情報の送受信を行う方法が提案されている（特許文献１、２参照）。 Due to the miniaturization and high performance of portable terminals, wearable computers that can be attached to living bodies have been attracting attention. Conventionally, as information communication between such wearable computers, an electric field communication transceiver is connected and attached to a computer, and an electric field induced by the electric field communication transceiver is transmitted through a living body which is an electric field transmission medium, thereby Have been proposed (see Patent Documents 1 and 2).

この方法を適用して、通信媒体である人体に電界を誘起し、誘起された電界を検出して通信を行う電界通信を利用すると、情報源に触れた人体に情報を送ることができる。
特開２００４−１５３７０８号公報ＵｎｉｔｅｄＳｔａｔｅｓＰａｔｅｎｔＡｐｐｌｉｃａｔｉｏｎＰｕｂｌｉｃａｔｉｏｎ，Ｐｕｂ．Ｎｏ．：ＵＳ２００４／００９２２９６Ａ１Ｐｕｂ．Ｄａｔｅ：Ｍａｙ１３，２００４ By applying this method and using electric field communication in which an electric field is induced in a human body as a communication medium and communication is performed by detecting the induced electric field, information can be sent to the human body touching the information source.
JP 2004-153708 A United States Patent Application Publication, Pub. No. : US2004 / 0092296A1 Pub. Date: May 13, 2004

しかしながら上述のような従来の技術においては、人体が情報源に触れているのと同じタイミングで、その人体にのみ触れていた他の人体にも情報源から情報が送られてしまうため、たとえばＩＤ認証等に電界通信を適用する場合には情報源に触れた人体を特定できない可能性があった。 However, in the conventional technology as described above, information is sent from the information source to other human bodies that have only touched the human body at the same timing as the human body touches the information source. When electric field communication is applied to authentication or the like, there is a possibility that the human body touching the information source cannot be specified.

また、ポーリング（ｐｏｌｌｉｎｇ）動作等を行っているＩＤ認証システムのリーダーから常時大きな信号を出力していると、周囲の電子機器に意図しない影響を与える可能性もあった。 In addition, if a large signal is always output from a reader of an ID authentication system that performs a polling operation or the like, there is a possibility of unintentional influence on surrounding electronic devices.

本発明は上記を鑑みてなされたものであり、その目的は、人体が触れた時や、触れた人体が一人の場合にのみ信号を大きくして通信して、誤認識の防止や周囲の電子機器等への影響を低減することにある。 The present invention has been made in view of the above. The purpose of the present invention is to prevent misrecognition and to prevent surrounding electronic communication by increasing the signal only when a human body touches or when the touched human body is alone. The purpose is to reduce the impact on equipment.

上記の目的を達成するために、請求項１に記載の本発明は、送信すべき情報に基づく電界を電界伝達媒体に誘起し、この誘起した電界を用いて情報の送信を行う電界通信システムであって、所定の周波数を有する交流信号で前記送信すべき情報を変調し送信信号を生成して出力する送信手段と、前記送信信号を前記電界伝達媒体に送信するための電極と、前記送信手段と前記電極との間に配置され、前記電極と大地グランド間の容量Ｃ_ｓｇと、前記電界伝達媒体と前記大地グランド間の浮遊容量Ｃ_ｂと、を合成した合成容量Ｃ_ｓｇ＋Ｃ_ｂとの間で前記送信信号を共振させるためのリアクタンス手段と、を備える。 In order to achieve the above object, the present invention according to claim 1 is an electric field communication system in which an electric field based on information to be transmitted is induced in an electric field transmission medium and information is transmitted using the induced electric field. A transmitter that modulates the information to be transmitted with an AC signal having a predetermined frequency to generate and output a transmission signal; an electrode for transmitting the transmission signal to the electric field transmission medium; and the transmitter between the disposed between the electrodes, and the capacitance C _sg between the electrodes and the earth ground, and the stray capacitance C _b between the earth ground and the electric field transmission medium, and the synthesized composite capacitance C _{sg +} C _b And reactance means for resonating the transmission signal.

また、請求項２に記載の本発明は、請求項１において、前記送信手段は常態において搬送波のみを出力し、前記電極に印加されている前記搬送波をモニタするための検波部を有し、前記検波部から出力される検波出力が前記リアクタンス手段における前記合成容量Ｃ_ｓｇ＋Ｃ_ｂとの共振により増大した場合において、前記送信信号を前記搬送波で変調し出力する。 Further, the present invention according to claim 2 provides the detector according to claim 1, wherein the transmitting means outputs a carrier wave in a normal state and has a detector for monitoring the carrier wave applied to the electrode, When the detection output output from the detection unit increases due to resonance with the combined capacitance C _sg + C _b in the reactance means , the transmission signal is modulated with the carrier wave and output.

また、請求項３に記載の本発明は、送信すべき情報に基づく電界を電界伝達媒体に誘起し、この誘起した電界を用いて情報の送信を行う電界通信システムであって、所定の周波数を有する交流信号で送信すべき情報を変調し送信信号を生成して出力する送信手段と、前記送信信号を前記電界伝達媒体に送信するための電極と、前記送信手段の回路グランドと前記電界伝達媒体との間の浮遊容量Ｃ_ｂｇと、回路グランドと前記電極との間の浮遊容量Ｃ_ｓｇと、を合成した合成容量Ｃ_ｂｇ＋Ｃ_ｓｇとの間で前記送信信号を共振させるために前記送信手段と前記電極との間に配置されたリアクタンス手段と、を備える。 According to a third aspect of the present invention, there is provided an electric field communication system in which an electric field based on information to be transmitted is induced in an electric field transmission medium and information is transmitted using the induced electric field, and a predetermined frequency is set. Transmitting means that modulates information to be transmitted with an AC signal and generates and outputs a transmission signal, an electrode for transmitting the transmission signal to the electric field transmission medium, a circuit ground of the transmission means, and the electric field transmission medium said transmitting means and the stray capacitance C _bg, in order to resonate the transmission signals between the combined capacitance C _{bg +} C _sg of the stray capacitance C _sg, was synthesized between the the circuit ground electrode between the Reactance means disposed between the electrodes.

また、請求項４に記載の本発明は、請求項３において、前記電極と大地グランドとの間に配置され、前記リアクタンス手段と前記合成容量Ｃ_ｂｇ＋Ｃ_ｓｇとの間で前記送信信号を共振させるための第２のリアクタンス手段を備える。 According to a fourth aspect of the present invention, in the third aspect, the transmission signal is disposed between the electrode and the ground and resonates the transmission signal between the reactance means and the combined capacitance C _bg + C _sg . Second reactance means is provided.

また、請求項５に記載の本発明は、請求項１〜４のいずれかにおいて、前記リアクタンス手段は、リアクタンス制御手段によりリアクタンス値が可変制御される可変リアクタンス手段である。 According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the reactance means is variable reactance means in which a reactance value is variably controlled by the reactance control means .

また、請求項６に記載の本発明は、請求項１〜５のいずれかにおいて、前記電界伝達媒体に誘起された受信すべき情報に基づく電界を前記電極を介して受信するための受信手段を備える。 According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the reception means for receiving an electric field based on information to be received induced in the electric field transmission medium via the electrode. Prepare.

また、請求項７に記載の本発明は、請求項６において、前記受信手段が受信した受信信号に対して影響を与えないために前記電極から前記リアクタンス手段を切り離すためのスイッチを備える。 According to a seventh aspect of the present invention, there is provided the switch according to the sixth aspect, further comprising a switch for separating the reactance means from the electrode so as not to affect the reception signal received by the reception means.

また、請求項８に記載の本発明は、送信すべき情報に基づく電界を電界伝達媒体に誘起し、この誘起した電界を用いて情報の送信を行う送信装置と、電界伝達媒体に誘起された受信すべき情報に基づく電界を受信する受信装置と、の間で通信を行う電界通信システムであって、前記送信装置は、所定の周波数を有する交流信号で送信すべき情報を変調し送信信号を生成して出力する送信手段と、前記送信信号を電界伝達媒体に送信するための送信電極と、前記送信電極と大地グランド間の容量との間で前記送信信号を共振させるために前記送信手段と前記送信電極との間に配置されたリアクタンス手段と、を備え、前記受信装置は、前記電界伝達媒体に送信された前記送信信号を受信するための受信電極と、受信すべき情報を電気信号に変換して復調し受信信号を生成して出力する受信手段と、を備え、前記受信装置の回路グランドと前記送信装置の前記送信電極との間の浮遊容量Ｃ_ｒと、前記受信装置の回路グランドと大地グランドとの間の浮遊容量Ｃ_ｇｒｃｖと、前記電界伝達媒体と大地グランドとの間の浮遊容量Ｃ_ｂと、前記送信電極に印加される送信信号Ｖ_ｓｇと、前記受信装置の受信部の入力インピーダンスＺ_ｒｃｖと、前記受信装置の受信部で受信する受信限界強度信号Ｖ _{ｒｃｖ，ｔｈ}と、人体に印加される信号Ｖ _ｂ，ｍと、虚数ｊと角周波数ωと、の関係が、１＜（１＋１／ｊωＣ_ｒＺ_ｒｃｖ＋１／ｊωＣ_ｂＺ_ｒｃｖ）（Ｖ_{ｒｃｖ，ｔｈ}／Ｖ_ｓｇ）＜（Ｃ_ｇｒｃｖ／Ｃ_ｒ）（Ｖ_ｂ，ｍ／Ｖ_ｓｇ）であることを特徴とする電界通信システム。 The present invention according to claim 8 induces an electric field based on information to be transmitted in the electric field transmission medium, and transmits the information using the induced electric field, and is induced in the electric field transmission medium. An electric field communication system that communicates with a receiving device that receives an electric field based on information to be received, wherein the transmitting device modulates information to be transmitted with an AC signal having a predetermined frequency, Transmission means for generating and outputting; a transmission electrode for transmitting the transmission signal to an electric field transmission medium; and the transmission means for causing the transmission signal to resonate between a capacitance between the transmission electrode and a ground. Reactance means disposed between the transmitting electrode and the receiving device, wherein the receiving device receives the transmitting signal transmitted to the electric field transmission medium, and converts the information to be received into an electric signal. conversion And a receiving means for generating and outputting a received signal demodulating Te, stray capacitance and C _r, circuit ground and ground of the receiving device between the transmitting electrodes of the transmitter and the circuit ground of the receiving device The stray capacitance C _grcv between the ground, the stray capacitance C _b between the electric field transmission medium and the ground, the transmission signal V _sg applied to the transmission electrode, and the input impedance of the receiving unit of the receiving device The _relationship between Z _rcv , the reception limit strength signal V _{rcv, th} received by the receiving unit of the receiving device, the signal V _{b, m} applied to the human body , the imaginary number j, and the angular frequency ω is 1 <( _{_{1 + 1 / jωC r Z rcv}} + 1 / j ω C b Z rcv) (V rcv, th / V sg) <(C grcv / C r) (V b, the electric field communication, which is a m _{/ V sg)} system.

本発明によれば、人体が触れた時や、触れた人体が一人の場合にのみ信号を大きくして通信することができ、誤認識の防止や周囲の電子機器等への影響を低減することができる。 According to the present invention, communication can be performed with a large signal only when a human body touches or when only one human body touches, thereby preventing erroneous recognition and reducing the influence on surrounding electronic devices. Can do.

＜第１の実施の形態＞
図１には、電界通信システムに係る第１の実施の形態を説明するためのブロック図を示す。 <First Embodiment>
FIG. 1 shows a block diagram for explaining a first embodiment of the electric field communication system.

この図１には、電界伝達媒体となる人体５と、この人体５に装着された携帯端末側通信装置４と、携帯端末側処理装置３と、が示されており、さらにこの人体５が接する対象として固定設置された設置側通信装置１と、設置側処理装置２とが示されている。 FIG. 1 shows a human body 5 serving as an electric field transmission medium, a mobile terminal side communication device 4 attached to the human body 5, and a mobile terminal side processing device 3, and this human body 5 is in contact with the human body 5. An installation-side communication device 1 and an installation-side processing device 2 that are fixedly installed as targets are shown.

設置側通信装置１は、人体５が接触する絶縁体１１と、送受信電極１０と、この送受信電極１０に接続された送受切替ＳＷ（スイッチ）８と、受信部１５と、受信部１５に受信信号を入力する入力部９と、送信部６と、送信部６の出力に接続されたリアクタンス部Ｘｓ７と、を備えている。 The installation-side communication device 1 includes an insulator 11 with which the human body 5 contacts, a transmission / reception electrode 10, a transmission / reception switching SW (switch) 8 connected to the transmission / reception electrode 10, a reception unit 15, and a reception signal to the reception unit 15. Are input unit 9, transmitting unit 6, and reactance unit Xs 7 connected to the output of transmitting unit 6.

そして、設置側通信装置１は大地グランド１４に接地しており、送受信電極１０と大地グランド１４との間には浮遊容量Ｃ_ｓｇ１２が存在し、送受信電極１０と大地グランド１４との電位差はＶ_ｓｇ２２である。人体５と大地グランド１４との間にも浮遊容量Ｃ_ｂ１３が存在している。 The installation-side communication device 1 is grounded to the ground ground 14, and a stray capacitance C _sg 12 exists between the transmission / reception electrode 10 and the ground ground 14. The potential difference between the transmission / reception electrode 10 and the ground ground 14 is V _sg 22. A stray capacitance C _b 13 also exists between the human body 5 and the ground 14.

このような構成において、第１の実施の形態では、大地グランド１４に接地された設置側通信装置１と、大地グランド１４から浮遊した携帯端末側通信装置４との間で通信を行う。設置側では設置側処理装置２から一定間隔ごとに出力された送信要求信号等のデータを送信部６で所定の周波数を持つ搬送波で変調し、リアクタンス部Ｘ_ｓ７を介して送受信電極１０にこの搬送波を常態で出力しておく。 In such a configuration, in the first embodiment, communication is performed between the installation-side communication device 1 grounded to the earth ground 14 and the mobile terminal-side communication device 4 floating from the earth ground 14. On the installation side, data such as a transmission request signal output from the installation side processing device 2 at regular intervals is modulated with a carrier wave having a predetermined frequency by the transmission unit 6, and this is transmitted to the transmission / reception electrode 10 via the reactance unit X _s 7. The carrier wave is output normally.

携帯端末側通信装置４を持った人体５が設置側通信装置１の送受信電極１０に絶縁体１１を介して触れると、信号を携帯端末側通信装置４の図示しない受信部で復調して搬送波に重畳されたデータを携帯端末側処理装置３に送る。携帯端末側処理装置３では搬送波で変調されたデータを受信すると、折り返しに自身の識別のためのＩＤ等のデータを設置側通信装置１に送信する。 When the human body 5 having the mobile terminal side communication device 4 touches the transmission / reception electrode 10 of the installation side communication device 1 via the insulator 11, the signal is demodulated by a receiving unit (not shown) of the mobile terminal side communication device 4 to be a carrier wave. The superimposed data is sent to the mobile terminal side processing device 3. When the mobile terminal side processing device 3 receives the data modulated by the carrier wave, the mobile terminal side processing device 3 transmits data such as an ID for identifying itself to the installation side communication device 1 in return.

なお、このような構成の電界通信システムの適用例としては、たとえばＩＤ等のデータを設置側通信装置１へ送信することをトリガにして携帯端末側通信装置４との間で通信を継続する。この通信によりたとえば個人認証や、あるいは任意のサービス提供に関する課金等の処理を行うことが可能である。また、このとき使用する変復調方式は振幅変調や周波数変調あるいは位相変調のいずれでもよい。また、設置側通信装置１から携帯端末側通信装置４への通信と、携帯端末側通信装置４から設置側通信装置１への通信と、のそれぞれの変調方式を変えてもよい。 As an application example of the electric field communication system having such a configuration, for example, transmission of data such as ID to the installation side communication device 1 is a trigger to continue communication with the mobile terminal side communication device 4. With this communication, it is possible to perform processing such as personal authentication or billing for providing arbitrary services. The modulation / demodulation method used at this time may be any of amplitude modulation, frequency modulation, and phase modulation. Moreover, you may change each modulation system of the communication from the installation side communication apparatus 1 to the portable terminal side communication apparatus 4, and the communication from the portable terminal side communication apparatus 4 to the installation side communication apparatus 1. FIG.

また、設置側通信装置１において、送信と受信の切替は送受切替ＳＷ８で行い、図１では送受切替ＳＷ８の接点が送信の状態を示している。この送信において、たとえば送信部６からの送信がパケット方式による通信の場合には、送信部６からパケット出力を実行するときにのみ通信のための搬送波を出力してもよい。たとえば設置側処理装置２からパケット出力を行う前に送信開始を知らせる信号を送信部６に送り、パケット出力後において送信終了を知らせるための信号を送る方法により、搬送波を通信時にのみ発信することができる。 Further, in the installation side communication apparatus 1, transmission and reception are switched by the transmission / reception switching SW8. In FIG. 1, the contact point of the transmission / reception switching SW8 indicates the transmission state. In this transmission, for example, when the transmission from the transmission unit 6 is communication by a packet system, a carrier wave for communication may be output only when the packet output from the transmission unit 6 is executed. For example, a carrier wave may be transmitted only at the time of communication by sending a signal notifying the start of transmission to the transmission unit 6 before outputting a packet from the processing apparatus 2 on the installation side and transmitting a signal for notifying the end of transmission after outputting the packet. it can.

本実施の形態の構成において、設置側通信装置１の送受信電極１０に絶縁体１１を介して人体５が触れていない場合は、リアクタンス部Ｘ_ｓ７からみた送受信電極１０の負荷は、送受信電極１０と大地グランド１４との間の浮遊容量Ｃ_ｓｇ１２のみとなる。人体５が送受信電極１０に絶縁体１１を介して触れた場合には、送受信電極１０の負荷はＣ_ｓｇ１２と人体５と大地グランド１４との間の浮遊容量Ｃ_ｂ１３との和となる。そこで、リアクタンス部Ｘ_ｓ７のリアクタンス値をＣ_ｓｇ１２とＣ_ｂ１３とを加算した合成容量Ｃ_ｓｇ＋Ｃ_ｂで共振が発生する値にすると、人体５が触れない場合には送受信電極１０に印加される電圧は低く、人体５が触れた場合には高くすることができる。 In the configuration of the present embodiment, when the human body 5 does not touch the transmission / reception electrode 10 of the installation side communication device 1 via the insulator 11, the load of the transmission / reception electrode 10 viewed from the reactance part X _s 7 is the transmission / reception electrode 10. And stray capacitance C _sg 12 between the ground and the ground 14. When the human body 5 touches the transmission / reception electrode 10 via the insulator 11, the load on the transmission / reception electrode 10 is the sum of the C _sg 12 and the stray capacitance C _b 13 between the human body 5 and the earth ground 14. Therefore, when the reactance value of the reactance part X _s 7 is set to a value at which resonance occurs in the combined capacitance C _sg + C _{b obtained} by adding C _sg 12 and C _b 13, the reactance value is applied to the transmission / reception electrode 10 when the human body 5 does not touch. The applied voltage is low and can be increased when the human body 5 touches it.

また、図２に示すように、２体の人体５が送受信電極１０に絶縁体１１を介して同時に触れた場合には、リアクタンス部Ｘ_ｓ７との間で共振が発生可能な浮遊容量値よりも負荷が大きくなるため信号Ｖ_ｓｇ２２は小さくなる。図２に示すようにＣ_ｓｇ１２のみではＶ_ｓｇ２２の値は低くなり、Ｃ_ｓｇ１２＋Ｃ_ｂ１３において最高値となり、さらにＣ_ｓｇ１２＋２Ｃ_ｂ１３においては再び低くなる。すなわち、人体５が２体である場合は２Ｃ_ｂ１３となるのでＶ_ｓｇ２２は低いものとなる。 In addition, as shown in FIG. 2, when two human bodies 5 touch the transmitting / receiving electrode 10 through the insulator 11 at the same time, the stray capacitance value that can generate resonance with the reactance part X _s 7 is obtained. Since the load increases, the signal V _sg 22 decreases. The value of _C sg 12 alone is _V sg 22 as shown in FIG. 2 is lowered _becomes a maximum value in the _C sg 12 ₊ C b 13, becomes again lower in yet _C sg 12 + _2C b 13. That, _V sg 22 since the _2C b 13 if the human body 5 is 2-body becomes low.

そこで、出力強度や受信限界強度を人体５が１体のみで送受信電極１０に絶縁体１１を介して触れた時の電気的な条件に合わせてに設定することにより、たとえば２体の人体５が同時に触れるような場合には通信を不能にすることができる。リアクタンス部Ｘ_ｓ７のリアクタンス値をこのように設定することにより、個人認証のためのＩＤ情報の誤認識を防止でき、さらに電界通信システムの周囲への電磁波の放射を必要最小限度に抑えることができる。なお、設置側通信装置１の入力部９は送信時にはリアクタンス部Ｘ_ｓ７の共振に影響を与えないように送受信電極１０との間で送受切替ＳＷ８により電気的に切り離されている。 Therefore, by setting the output intensity and the reception limit intensity according to the electrical conditions when only one human body 5 touches the transmission / reception electrode 10 via the insulator 11, for example, two human bodies 5 When touching at the same time, communication can be disabled. By setting the reactance value of the reactance part X _s 7 in this way, it is possible to prevent erroneous recognition of ID information for personal authentication, and to further suppress the radiation of electromagnetic waves around the electric field communication system to the minimum necessary level. it can. Note that the input unit 9 of the installation side communication device 1 is electrically disconnected from the transmission / reception electrode 10 by the transmission / reception switching SW 8 so as not to affect the resonance of the reactance unit X _s 7 during transmission.

＜第２の実施の形態＞
人体５が携帯している携帯端末側通信装置４は、人体５が送受信電極１０に絶縁体１１を介して触れていなくても人体５の周囲にある設置側通信装置１から放射される信号（電磁波）で意図しない動作をする場合がある。 <Second Embodiment>
The mobile terminal-side communication device 4 carried by the human body 5 is a signal radiated from the installation-side communication device 1 around the human body 5 even when the human body 5 does not touch the transmission / reception electrode 10 via the insulator 11 ( (Electromagnetic waves) may cause unintended operation.

図３には、設置側通信装置１と、携帯端末側通信装置４を持った人体５と、が大地グランド１４に接地しつつ互いに離れており、回路グランド７０と送受信電極１０との間に浮遊容量Ｃ_ｒ２０が存在している。携帯端末側通信装置４では受信部２４と、送受信電極３１と、絶縁体３０とを備えて人体５に接触している。 In FIG. 3, the installation-side communication device 1 and the human body 5 having the mobile terminal-side communication device 4 are separated from each other while being grounded to the ground ground 14, and are floating between the circuit ground 70 and the transmission / reception electrode 10. A capacity C _r 20 is present. The mobile terminal side communication device 4 includes a receiving unit 24, a transmission / reception electrode 31, and an insulator 30 and is in contact with the human body 5.

この図３に示すように、携帯端末側通信装置４を持った人体５が設置側通信装置１に近づいたとき、携帯端末側通信装置４の回路グランド７０と設置側通信装置１の送受信電極１０が近づく場合がある。このとき携帯端末側通信装置４の回路グランド７０と設置側通信装置１の送受信電極１０との間に浮遊容量Ｃ_ｒ２０が形成され、両者が近づくほどこのＣ_ｒ２０の値は大きくなる。 As shown in FIG. 3, when the human body 5 having the mobile terminal side communication device 4 approaches the installation side communication device 1, the circuit ground 70 of the mobile terminal side communication device 4 and the transmission / reception electrodes 10 of the installation side communication device 1. May approach. At this time, a stray capacitance C _r 20 is formed between the circuit ground 70 of the mobile terminal side communication device 4 and the transmission / reception electrode 10 of the installation side communication device 1, and the value of this C _r 20 increases as the two approaches.

このとき携帯端末側通信装置４の受信部２４で受信する信号Ｖ_ｒｃｖ２３は以下の式で表される。 At this time, the signal V _rcv 23 received by the receiving unit 24 of the mobile terminal side communication device 4 is expressed by the following equation.

Ｖ_ｒｃｖ＝｛Ｚ_ｒｃｖ／（１／ｊωＣ_ｒ＋１／ｊωＣ_ｂ＋Ｚ_ｒｃｖ）｝Ｖ_ｓｇ（１）
上式（１）でＶ_ｓｇ２２は送受信電極１０に印加される信号、Ｚ_ｒｃｖ２６は携帯端末側通信装置４の受信部２４の入力インピーダンス、ωは信号の角周波数、ｊは−１の平方根である。この信号が受信部２４の受信限界強度Ｖ_{ｒｃｖ，ｔｈ}を超えるとデータが携帯端末側処理装置４に入力され意図しない動作が起きる可能性が有るため、受信限界強度Ｖ_{ｒｃｖ，ｔｈ}を越えないように受信部２４を設計する必要がある。 V _rcv = {Z _rcv / (1 / jωC _r + 1 / jωC _b + Z _rcv )} V _sg (1)
In the above equation (1), V _sg 22 is a signal applied to the transmitting / receiving electrode 10, Z _rcv 26 is the input impedance of the receiving unit 24 of the mobile terminal side communication device 4, ω is the angular frequency of the signal, and j is the square root of −1. It is. If this signal exceeds the reception limit strength V _{rcv, th} of the receiving unit 24, data may be input to the mobile terminal side processing device 4 and an unintended operation may occur, so that the reception limit strength V _{rcv, th} is not exceeded. It is necessary to design the receiving unit 24.

一方、図４に示すように、人体５が設置側通信装置１の送受信電極１０に触れたときに携帯端末側通信装置４の受信部２４で受信する信号は以下の式で表される。 On the other hand, as shown in FIG. 4, a signal received by the receiving unit 24 of the mobile terminal side communication device 4 when the human body 5 touches the transmission / reception electrode 10 of the installation side communication device 1 is expressed by the following equation.

Ｖ_ｒｃｖ＝｛Ｚ_ｒｃｖ／（１／ｊωＣ_ｇｒｃｖ＋Ｚ_ｒｃｖ）｝Ｖ_ｂ，ｍ（２）
上式（２）でＶ_ｂ，ｍは人体に印加される信号、Ｃ_ｇｒｃｖは携帯端末側通信装置４の回路グランド７０と大地グランド１４との間の浮遊容量である。この信号に関しては通信を行うのに受信限界強度Ｖ_{ｒｃｖ，ｔｈ}以上にする必要があるため、
｛Ｚ_ｒｃｖ／（１／ｊωＣ_ｒ＋１／ｊωＣ_ｂ＋Ｚ_ｒｃｖ）｝Ｖ_ｓｇ＜Ｖ_{ｒｃｖ，ｔｈ}＜｛Ｚ_ｒｃｖ／（１／ｊωＣ_ｇｒｃｖ＋Ｚ_ｒｃｖ）｝Ｖ_ｂ，ｍ（３）
となるようにシステムを設計する。 V _rcv = {Z _rcv / (1 / jωC _grcv + Z _rcv )} V _{b, m} (2)
In the above equation (2), V _{b, m} is a signal applied to the human body, and C _grcv is a stray capacitance between the circuit ground 70 and the ground 14 of the mobile terminal side communication device 4. Since this signal needs to have a reception limit strength V _{rcv, th} or higher for communication,
{Z _rcv / (1 / jωC _r + 1 / jωC _b + Z _rcv )} V _sg <V _{rcv, th} <{Z _rcv / (1 / jωC _grcv + Z _rcv )} V _{b, m} (3)
Design the system so that

そして、式（３）を変形し、
１＜（１＋１／ｊωＣ_ｒＺ_ｒｃｖ＋１／ｊωＣ_ｂＺ_ｒｃｖ）（Ｖ_{ｒｃｖ，ｔｈ}／Ｖ_ｓｇ）＜｛（Ｃ_ｇｒｃｖ／Ｃ_ｒ＋Ｃ_ｇｒｃｖ／Ｃ_ｂ＋ｊωＣ_ｇｒｃｖＺ_ｒｃｖ）／（１＋ｊωＣ_ｇｒｃｖＺ_ｒｃｖ）｝（Ｖ_ｂ，ｍ／Ｖ_ｓｇ）（４）
として考察する。Ｃ_ｂ１３はＣ_ｇｒｃｖに比べて非常に大きいためＣ_ｇｒｃｖ／Ｃ_ｂは無視でき、同様にωＣ_ｇｒｃｖＺ_ｒｃｖも無視できるため、式（４）は以下のようになる。 Then, transform equation (3),
1 <(1 + 1 / jωC r Z rcv + 1 / jωC b Z rcv) (V rcv, th / V sg) <{(C grcv / C r + C grcv / C b + jωC grcv Z rcv) / (1 + jωC grcv Z rcv) } (V _{b, m} / V _sg ) (4)
Consider as follows. Since C _b 13 is much larger than C _grcv , C _grcv / C _b can be ignored. Similarly, _{ωC grcv} Z _rcv can also be ignored. Therefore, equation (4) is as follows.

１＜（１＋１／ｊωＣ_ｒＺ_ｒｃｖ＋１／ｊωＣ_ｂＺ_ｒｃｖ）（Ｖ_{ｒｃｖ，ｔｈ}／Ｖ_ｓｇ）＜（Ｃ_ｇｒｃｖ／Ｃ_ｒ）（Ｖ_ｂ，ｍ／Ｖ_ｓｇ）（５）
式（５）でＶ_ｂ，ｍ／Ｖ_ｓｇは人体５が設置側通信装置１の送受信電極１０に絶縁体１１を介して触れたときと触れない場合の信号の比であり、本実施の形態によれば１より大きく設計することにより、Ｃ_ｒが概ねＣ_ｇｒｃｖぐらいの大きさであれば１＜（Ｃ_ｇｒｃｖ／Ｃ_ｒ）（Ｖ_ｂ，ｍ／Ｖ_ｓｇ）を満たすことができる。すなわちＺ_ｒｃｖを適切に小さく設定することにより式（５）を満たすことができ、設置側通信装置１に触れていない人体５が設置側通信装置１に接近しても通信が行われず、しかしながら触れたときには通信ができる電界通信システムを構築することができる。 1 <(1 + 1 / jωC _r Z _rcv + 1 / jωC _b Z _rcv ) (V _{rcv, th} / V _sg ) <(C _grcv / C _r ) (V _{b, m} / V _sg ) (5)
In the formula (5), V _{b, m} / V _sg is a ratio of signals when the human body 5 touches the transmission / reception electrode 10 of the installation side communication device 1 via the insulator 11 and does not touch it. According to by increasing design than 1, it is possible to meet if the magnitude of _{C r} is about approximately _{_{_{C grcv 1 <(C grcv /}}} C r) (V b, m / V sg). That is, by setting Z _rcv appropriately small, Equation (5) can be satisfied, and communication is not performed even if the human body 5 not touching the installation side communication device 1 approaches the installation side communication device 1, however, touching It is possible to construct an electric field communication system that can communicate with each other.

なお、すでに示した図１では送受切替ＳＷ８で送受信電極１０とリアクタンス部Ｘ_ｓ７および入力部９を切替可能に接続しているが、図５のようにリアクタンス部７と送信部６、入力部９を切替可能に接続するように配置しても良い。この送受信切替ＳＷ８は図３、４に示した設置側通信装置１においても適用可能である。 In FIG. 1 already shown, the transmission / reception electrode 10 is connected to the reactance unit X _s 7 and the input unit 9 by the transmission / reception switch SW8, but the reactance unit 7, the transmission unit 6, and the input unit are switched as shown in FIG. You may arrange | position so that 9 may be connected so that switching is possible. This transmission / reception switching SW8 is also applicable to the installation side communication apparatus 1 shown in FIGS.

＜第３の実施の形態＞
次の図６には、第１および第２の実施の形態の変形例を示している。この図６に示す第３の実施の形態では、大地グランド１４から回路グランド４４が浮遊した第１の携帯端末側通信装置３０と、同じく大地グランド１４から浮遊した第２の携帯端末側通信装置３２と、の間の通信を行う。なお、図５においては簡単のため第１の携帯端末側通信装置３０から第２の携帯端末側通信装置３２への通信に必要な要素のみ記載している。 <Third Embodiment>
FIG. 6 shows a modification of the first and second embodiments. In the third embodiment shown in FIG. 6, the first mobile terminal side communication device 30 in which the circuit ground 44 floats from the ground ground 14 and the second mobile terminal side communication device 32 that also floats from the ground ground 14. And communicate with each other. In FIG. 5, only elements necessary for communication from the first mobile terminal side communication device 30 to the second mobile terminal side communication device 32 are shown for simplicity.

本実施の形態においては、回路グランド４４と人体５との間の浮遊容量Ｃ_ｂｇ３９と、回路グランド４４と送受信電極３６との間の浮遊容量Ｃ_ｓｇ３８と、を利用して、人体５が触れたときに信号を大きくする。そして、リアクタンス部Ｘ_ｓ３５のリアクタンス値をＣ_ｓｇ＋Ｃ_ｂｇで共振の発生する値にして、人体５が触れない場合には送受信電極３６に印加される電圧を低くし、人体５が触れた場合には高くしている。 In the present embodiment, the human body 5 is configured using the stray capacitance C _bg 39 between the circuit ground 44 and the human body 5 and the stray capacitance C _sg 38 between the circuit ground 44 and the transmission / reception electrode 36. Increase the signal when touched. When the reactance value of the reactance part X _s 35 is set to a value at which resonance occurs at C _sg + C _bg , the voltage applied to the transmission / reception electrode 36 is lowered when the human body 5 is not touched, and the human body 5 is touched To be high.

次の図７に詳細な構成を示す。人体５が触れる箇所に送（受）信電極３６だけではなく、回路グランド４４もスペーサ（絶縁体）５０を介して配置する。人体５が触れた場合には図７に示すように回路グランド４４と人体５との間に容量Ｃ_ｂｇ３９が形成される。 The detailed configuration is shown in FIG. Not only the transmission / reception electrode 36 but also the circuit ground 44 is arranged via a spacer (insulator) 50 at a location where the human body 5 touches. When the human body 5 touches, a capacitor C _bg 39 is formed between the circuit ground 44 and the human body 5 as shown in FIG.

また、送信電極３６とは逆相の信号が回路グランド４４から人体５へ印加されるが、回路グランド４４と人体５との間の容量Ｃ_ｂｇ３９が障壁となるため、送信電極３６から印加される信号のほうが大きくなる。 In addition, a signal having a phase opposite to that of the transmission electrode 36 is applied from the circuit ground 44 to the human body 5. However, since the capacitance C _bg 39 between the circuit ground 44 and the human body 5 serves as a barrier, the signal is applied from the transmission electrode 36. The signal is larger.

図７の構成では、同じ面に送信電極３６と回路グランド４４を配置しているが、回路グランド４４を反対側などの別の面に配置してもよい。また、スペーサ５０で回路グランド４４と人体５との間の容量Ｃ_ｂｇ３９を調節しているが、スペーサ５０を厚くできない場合には人体５に近接する回路グランド４４の面積で調節しても同じ効果が得られる。 In the configuration of FIG. 7, the transmission electrode 36 and the circuit ground 44 are arranged on the same surface, but the circuit ground 44 may be arranged on another surface such as the opposite side. Further, the capacitance C _bg 39 between the circuit ground 44 and the human body 5 is adjusted by the spacer 50. However, if the spacer 50 cannot be thickened, the same adjustment can be made by adjusting the area of the circuit ground 44 close to the human body 5. An effect is obtained.

なお、本実施の形態においても、図１や図５に示したように送受切替ＳＷ８を設けて双方向通信可能なトランシーバの構成を実現することが可能である。 Also in this embodiment, it is possible to provide a transceiver configuration capable of bidirectional communication by providing the transmission / reception switching SW 8 as shown in FIGS.

＜第４の実施の形態＞
図８に本発明に係る第４の実施の形態の構成図を示す。 <Fourth embodiment>
FIG. 8 shows a configuration diagram of the fourth embodiment according to the present invention.

本実施の形態では人体５が設置側通信装置１の送受信電極１０に絶縁体１１を介して触れている場合において、信号振幅が大きくなった時にのみ送信要求信号等のデータを出力する構成を備えており、送受信電極１０に印加されている信号をモニタするために検波部５１を設けたことを特徴としている。 In the present embodiment, when the human body 5 touches the transmission / reception electrode 10 of the installation side communication device 1 via the insulator 11, a configuration is provided in which data such as a transmission request signal is output only when the signal amplitude increases. In order to monitor a signal applied to the transmission / reception electrode 10, a detection unit 51 is provided.

次に、図８の構成図と図９のタイミングチャートによって動作を説明する。 Next, the operation will be described with reference to the block diagram of FIG. 8 and the timing chart of FIG.

図８に示す設置側処理装置２から定期的に送信開始信号が出力され、送信部６では送信開始信号がＨレベルのときに搬送波Ｖ_ｓｇのみが出力されている。搬送波Ｖ_ｓｇ（ｂ）は図９中に示すタイミングで出力されており、図９中の送信開始信号（ａ）がＨレベルと同じタイミングである。この時点では検波部５１からの検波部出力（ｃ）やデータ（ｄ）は出力されていない。 A transmission start signal is periodically output from the installation side processing device 2 illustrated in FIG. 8, and the transmission unit 6 outputs only the carrier wave V _sg when the transmission start signal is at the H level. The carrier wave V _sg (b) is output at the timing shown in FIG. 9, and the transmission start signal (a) in FIG. 9 is at the same timing as the H level. At this time, the detector output (c) and data (d) from the detector 51 are not output.

次に、この搬送波Ｖ_ｓｇはリアクタンス部Ｘ_ｓ７を介して送受信電極１０に印加される。検波部５１では検波回路５３で送受信電極１０に印加された搬送波の振幅を検出し、比較回路５４で固定電圧源５２の基準電圧と比較する。そして共振により基準電圧よりも搬送波の振幅が大きい場合には設置側処理装置２に信号を出力し、これを受けた設置側処理装置２はデータを送信部６に出力する。 Next, the carrier wave V _sg is applied to the transmission / reception electrode 10 via the reactance part X _s 7. In the detection unit 51, the detection circuit 53 detects the amplitude of the carrier wave applied to the transmission / reception electrode 10, and the comparison circuit 54 compares it with the reference voltage of the fixed voltage source 52. When the amplitude of the carrier wave is larger than the reference voltage due to resonance, the signal is output to the installation side processing device 2, and the installation side processing device 2 receiving this outputs the data to the transmission unit 6.

図９に示すように送信開始信号（ａ）が出力されているタイミングに同期して搬送波Ｖ_ｓｇ（ｂ）が出力されているが、共振が生じたことにより搬送波Ｖ_ｓｇ（ｂ）のレベルも高くなり基準電圧を超える。この超えた分の電圧は検波部出力（ｃ）として出力され、この出力に基づいたタイミングでデータ（ｄ）が出力される。 As shown in FIG. 9, the carrier wave V _sg (b) is output in synchronization with the timing at which the transmission start signal (a) is output. However, the level of the carrier wave V _sg (b) is also generated due to the resonance. Increases and exceeds the reference voltage. The excess voltage is output as a detector output (c), and data (d) is output at a timing based on this output.

これにより携帯端末側通信装置４を持った人体５が送受信電極１０に近づいただけでは送信要求信号等のデータが出力されないので通信が行われず、より通信対象の選択性を向上させることができる。 As a result, data such as a transmission request signal is not output only when the human body 5 having the mobile terminal side communication device 4 approaches the transmission / reception electrode 10, so that communication is not performed, and the selectivity of the communication target can be further improved.

＜第５の実施の形態＞
既に説明した第１〜第４の実施の形態では、共振を起こすためのリアクタンス値を固定にしていたが、このリアクタンス値を可変リアクタンスにしてもよい。この可変リアクタンスを用いた構成図を図１０と図１１に示す。 <Fifth embodiment>
In the first to fourth embodiments already described, the reactance value for causing resonance is fixed, but this reactance value may be a variable reactance. Configuration diagrams using this variable reactance are shown in FIGS.

図１０に示す構成では、すでに示した図１の構成と比較して、送受切替ＳＷ８の有無を除きリアクタンス部Ｘ_ｓ７が可変リアクタンス部Ｘ_ｓ７５に変更されている。また、図１１に示す構成では可変リアクタンス部７５のリアクタンス値を可変制御するためのリアクタンス制御部６１も設けられている。リアクタンス制御部６１は設置側処理装置２から出力される起動信号６２により起動する。この起動信号６２は送信部６からデータを送信する際に出力される。 In the configuration shown in FIG. 10, the reactance unit X _s 7 is changed to the variable reactance unit X _s 75 except for the presence / absence of the transmission / reception switching SW 8 as compared with the configuration shown in FIG. In the configuration shown in FIG. 11, a reactance control unit 61 for variably controlling the reactance value of the variable reactance unit 75 is also provided. The reactance control unit 61 is activated by an activation signal 62 output from the installation side processing device 2. The activation signal 62 is output when data is transmitted from the transmission unit 6.

これらの可変リアクタンス部７５は、たとえば、送信信号と共振するためのインダクタと、これに印加された電圧に応じて静電容量が変化する可変容量ダイオードを備えた共振回路をもちいることで実現できる。この共振回路に入力された送信信号を可変容量ダイオードで整流して得られた直流電流に応じて電位差が生じるので、この電位差を可変容量ダイオードのアノードとカソード間に印加するための抵抗器を備えることにより、共振回路のリアクタンス値を可変制御することができる。 These variable reactance units 75 can be realized by using, for example, a resonance circuit including an inductor for resonating with a transmission signal and a variable capacitance diode whose capacitance changes according to a voltage applied thereto. . Since a potential difference is generated according to the direct current obtained by rectifying the transmission signal input to the resonance circuit with the variable capacitance diode, a resistor is provided for applying the potential difference between the anode and the cathode of the variable capacitance diode. As a result, the reactance value of the resonance circuit can be variably controlled.

＜第６の実施の形態＞
次の図１２には、第６の実施の形態を示す。本実施の形態では浮遊容量と共振を発生させるために２個のリアクタンスとしてリアクタンス部６５とリアクタンス部６６とを使用している。既に示した図１の構成において、共振時に人体５に印加される信号振幅は以下の式で表され、容量Ｃ_ｂ１３やＣ_ｓｇ１２が大きいほど信号振幅は小さくなる。 <Sixth Embodiment>
Next, FIG. 12 shows a sixth embodiment. In this embodiment, a reactance unit 65 and a reactance unit 66 are used as two reactances in order to generate stray capacitance and resonance. In the configuration of FIG. 1 already shown, the signal amplitude applied to the human body 5 at the time of resonance is expressed by the following formula, and the signal amplitude decreases as the capacitances C _b 13 and C _sg 12 increase.

この式（６）に対し、図１２の構成では共振時の人体に印加される信号振幅は以下の式（７）のようになり、人体５に印加される信号が大きくなる。

In contrast to this equation (6), in the configuration of FIG. 12, the amplitude of the signal applied to the human body at the time of resonance is expressed by the following equation (7), and the signal applied to the human body 5 is increased.

なお、本実施の形態においても図６のように携帯端末側通信装置に適用することや、図８のように検波部５１を設けて共振で信号が大きくなった場合にのみデータを出力する構成を組み合わせてもよい。

Also in this embodiment, the present invention is applied to the mobile terminal side communication device as shown in FIG. 6, or the detector 51 is provided as shown in FIG. 8 to output data only when the signal becomes large due to resonance. May be combined.

＜第７の実施の形態＞
第７の実施の形態においては、図１３のようにリアクタンス部６５と送信部６、入力部９を送受切替ＳＷ６７でもって切替可能に接続するように配置しても良い。この場合、受信時にリアクタンス部６６が受信信号に影響を与えないように送受切替スイッチ６８を設ける。なお、リアクタンス部６５、６６のどちらか一方または両方を可変リアクタンスにしてリアクタンス制御部を設けてもよい。 <Seventh embodiment>
In the seventh embodiment, as shown in FIG. 13, the reactance unit 65, the transmission unit 6, and the input unit 9 may be arranged to be switchably connected by a transmission / reception switching SW 67. In this case, a transmission / reception selector switch 68 is provided so that the reactance unit 66 does not affect the received signal during reception. Note that either one or both of the reactance units 65 and 66 may be variable reactances to provide a reactance control unit.

以上説明した第１〜７の実施の形態によれば、人体が触れた時や、触れた人体が一人の場合にのみ信号を大きくして通信し、誤認識の防止や周囲の電子機器等への影響を低減することができる。 According to the first to seventh embodiments described above, communication is performed with a larger signal only when a human body touches or when the touched human body is alone, to prevent misrecognition and to surrounding electronic devices, etc. Can be reduced.

電界通信システムの第１の実施の形態の構成図を示す。The block diagram of 1st Embodiment of an electric field communication system is shown. 電界通信システムの第１の実施の形態における浮遊容量を説明するためのグラフを示す。The graph for demonstrating the stray capacitance in 1st Embodiment of an electric field communication system is shown. 電界通信システムの第２の実施の形態の構成図を示す。The block diagram of 2nd Embodiment of an electric field communication system is shown. 電界通信システムの第２の実施の形態の構成図を示す。The block diagram of 2nd Embodiment of an electric field communication system is shown. 電界通信システムの第２の実施の形態の構成図を示す。The block diagram of 2nd Embodiment of an electric field communication system is shown. 電界通信システムの第３の実施の形態の構成図を示す。The block diagram of 3rd Embodiment of an electric field communication system is shown. 電界通信システムの第３の実施の形態の構成図を示す。The block diagram of 3rd Embodiment of an electric field communication system is shown. 電界通信システムの第４の実施の形態の構成図を示す。The block diagram of 4th Embodiment of an electric field communication system is shown. 電界通信システムの第４の実施の形態のタイミングチャートを示す。The timing chart of 4th Embodiment of an electric field communication system is shown. 電界通信システムの第５の実施の形態の構成図を示す。The block diagram of 5th Embodiment of an electric field communication system is shown. 電界通信システムの第５の実施の形態の構成図を示す。The block diagram of 5th Embodiment of an electric field communication system is shown. 電界通信システムの第６の実施の形態の構成図を示す。The block diagram of 6th Embodiment of an electric field communication system is shown. 電界通信システムの第７の実施の形態の構成図を示す。The block diagram of 7th Embodiment of an electric field communication system is shown.

Explanation of symbols

１設置側通信装置
２設置側処理装置
３携帯端末側処理装置
４携帯端末側通信装置
５人体
６送信部
７リアクタンス部Ｘｓ
８送受切替ＳＷ
９入力部
１０送受信電極
１１絶縁体 DESCRIPTION OF SYMBOLS 1 Installation side communication apparatus 2 Installation side processing apparatus 3 Portable terminal side processing apparatus 4 Portable terminal side communication apparatus 5 Human body 6 Transmitting part 7 Reactance part Xs
8 Send / Receive switch SW
9 Input part 10 Transmission / reception electrode 11 Insulator

Claims

An electric field communication system in which an electric field based on information to be transmitted is induced in an electric field transmission medium and information is transmitted using the induced electric field,
Transmitting means for modulating the information to be transmitted with an AC signal having a predetermined frequency to generate and output a transmission signal;
An electrode for transmitting the transmission signal to the electric field transmission medium;
A combined capacitance C _sg + C _b , which is arranged between the transmitting means and the electrode, and _combines the capacitance C _sg between the electrode and the ground, and the stray capacitance C _b between the electric field transmission medium and the ground. Reactance means for causing the transmission signal to resonate with
An electric field communication system comprising:

The transmitting means normally outputs only a carrier wave,
A detector for monitoring the carrier wave applied to the electrode;
2. The transmission signal is modulated by the carrier wave and output when the detection output output from the detection unit increases due to resonance with the combined capacitance C _sg + C _b in the reactance means . The electric field communication system described.

An electric field communication system in which an electric field based on information to be transmitted is induced in an electric field transmission medium and information is transmitted using the induced electric field,
Transmitting means for modulating and transmitting information to be transmitted with an AC signal having a predetermined frequency, and generating a transmission signal;
An electrode for transmitting the transmission signal to the electric field transmission medium;
Between the combined capacitance C _bg + C _sg obtained by combining the stray capacitance C _bg between the circuit ground of the transmitting unit and the electric field transmission medium and the stray capacitance C _sg between the circuit ground and the electrode. Reactance means disposed between the transmitting means and the electrode to resonate a transmitted signal;
An electric field communication system comprising:

Arranged between the electrode and the ground,
The electric field communication system according to claim 3, further comprising second reactance means for resonating the transmission signal between the reactance means and the combined capacitance C _bg + C _sg .

The reactance means includes
Electric field communication system according to claim 1, characterized in that the variable reactance means reactance value is variably controlled by reactance control unit.

6. The electric field communication system according to claim 1, further comprising receiving means for receiving an electric field based on information to be received induced in the electric field transmission medium via the electrodes.

The electric field communication system according to claim 6, further comprising a switch for separating the reactance means from the electrode so as not to affect the received signal received by the reception means.

A transmission device that induces an electric field based on information to be transmitted in an electric field transmission medium, transmits information using the induced electric field, and a reception device that receives an electric field based on information to be received induced in the electric field transmission medium And an electric field communication system for performing communication between and
The transmitter is
Transmitting means for modulating and transmitting information to be transmitted with an AC signal having a predetermined frequency, and generating a transmission signal;
A transmission electrode for transmitting the transmission signal to an electric field transmission medium;
Reactance means disposed between the transmission means and the transmission electrode to resonate the transmission signal between the transmission electrode and a capacitance between the ground and the ground,
The receiving device is:
A receiving electrode for receiving the transmission signal transmitted to the electric field transmission medium;
Receiving means for converting information to be received into an electric signal, demodulating it, generating a received signal, and outputting the received signal;
A stray capacitance C _r between the transmission electrode of the transmitter and the circuit ground of the receiving device,
_Stray capacitance C _grcv between the circuit ground and the ground of the receiver;
A stray capacitance C _b between the electric field transmission medium and the earth ground,
A transmission signal V _sg applied to the transmission electrode;
The input impedance Z _rcv of the receiver of the receiver;
A reception limit strength signal V _{rcv, th} received by the receiving unit of the receiving device;
A signal V _{b, m} applied to the human body ;
The relationship between the imaginary number j and the angular frequency ω is
1 <(1 + 1 / jωC r Z rcv + 1 / j ω C b Z rcv) (V rcv, th / V sg) <(C grcv / C r) (V b, m / V sg)
An electric field communication system.