JP2008271605A - Communication system, and communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make flexible an arrangement of a transmitter and a receiver and the design of a communication device by increasing the distance between electrodes of the transmitter and receiver electrostatically coupled to each other. <P>SOLUTION: A surface wave of electromagnetic waves radiated from a coupling electrode of a transmitter side is efficiently transmitted through the inside and a surface of a surface wave transmission line composed of a linear member made of a dielectric or magnetic body. Even when the distance between coupling electrodes of the transmitter and receiver is made relatively long, data communication can be performed. The surface wave radiated from the coupling electrode can be guided to an easy-to-use position through the surface wave transmission line to eliminate the need to put the electrodes close to each other, and also to increase the flexibility of mounting of components and layout design of a housing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication system that performs large-capacity data communication between information devices, and in particular, data that does not interfere with other communication systems using an electrostatic field (quasi-electrostatic field) or an induced electric field between information devices. The present invention relates to a communication system that performs communication.

  More particularly, the present invention relates to a communication system that realizes high-capacity transmission of high-frequency signals by electric field coupling, and in particular, by extending the distance between electrodes of a transmitter / receiver that performs electric field coupling, The present invention relates to a communication system that makes the design flexible.

  Recently, when moving data between small information devices such as exchanging data such as images and music with a personal computer, it is possible to use a general-purpose cable such as an AV (Audio Visual) cable or a USB (Universal Serial Bus) cable. The use of a wireless interface is increasing instead of a method using a medium such as a connected data communication or a memory card. According to the latter, it is not necessary to change the connector and route the cable every time data is transmitted, which is convenient for the user. Many information devices equipped with various cableless communication functions have also appeared.

  As a method of transmitting data between small devices without a cable, radio waves that transmit and receive wireless signals using an antenna, such as wireless LAN (Local Area Network) and Bluetooth (registered trademark) communication represented by IEEE 802.11, are used. Communication methods have been developed. For example, a built-in antenna is built in a position that is not covered by the hand holding the grip, and correct image data is received without the built-in antenna being covered by a hand, so an antenna for wireless communication is deployed inside the device Even so, there has been proposed a portable image recording apparatus in which the characteristics inherent to the antenna are exhibited as they are (see, for example, Patent Document 1).

  Many of the conventional wireless communication systems adopt a radio communication system, and propagate signals using a radiation electric field generated when a current is passed through an antenna (antenna). In this case, since a radio wave is emitted from the transmitter side regardless of whether there is a communication partner, there is a problem that it becomes a generation source of an interference radio wave for a nearby communication system. Further, since the antenna on the receiver side receives not only the desired wave from the transmitter but also a radio wave arriving from a distance, it is easily affected by the surrounding interfering radio waves and causes a decrease in reception sensitivity. Further, when there are a plurality of communication partners, it is necessary to perform complicated settings in order to select a desired communication partner. For example, when a plurality of sets of wireless devices perform wireless communication in a narrow range, it is necessary to perform communication by performing division multiplexing such as frequency selection in order to avoid mutual interference. In addition, since radio waves cannot communicate when their polarization directions are orthogonal, it is necessary for the antennas to have the same polarization direction between the transceivers.

  For example, when considering a contactless data communication system at a close distance of several millimeters to several centimeters, the transmitter / receiver is strongly coupled at a short distance, while a signal is transmitted to a long distance to avoid interference with other systems. It is preferable not to arrive. In addition, it is desirable that the devices that perform data communication do not depend on each other's posture (orientation) when they are brought close to each other, and that they are coupled, that is, have no directivity. In addition, in order to perform large-capacity data communication, it is desirable that broadband communication is possible.

  The wireless communication includes a communication method using an electrostatic field or an induction field in addition to the radio wave communication using the radiated electric field. For example, in an existing non-contact communication system mainly used for RFID (Radio Frequency IDentification), an electric field coupling method or an electromagnetic induction method is applied. The electrostatic field and the induction field are inversely proportional to the cube of the distance and the square of the distance, respectively, with respect to the distance from the source. Therefore, in this type of non-contact communication system, the transmission signal attenuates steeply according to the distance. Therefore, when there is no communication partner in the vicinity, a coupling relationship does not occur, so that other communication systems are not disturbed. Further, even when radio waves arrive from a distance, the coupler (coupler) does not receive radio waves, so that it is not necessary to receive interference from other communication systems.

  For example, by forming a communication auxiliary body set in which RFID tags are positioned between a plurality of communication auxiliary bodies, and arranging RFID tags attached to a plurality of products so as to be sandwiched between the communication auxiliary bodies, RFID There has been proposed an RFID tag system that enables stable reading and writing of information even when tags are overlapped (see, for example, Patent Document 2).

  In addition to the apparatus main body and a mounting means for mounting the apparatus main body on the body, the antenna coil and the data communication means for performing data communication with an external communication device through the antenna coil in a non-contact manner. A data communication device using an induction magnetic field in which an antenna coil and data communication means are arranged in an outer case provided on the upper portion of the device body has been proposed (for example, see Patent Document 3). .

  In addition, an antenna coil for data communication with an external device is mounted on a memory card inserted into the portable information device, and an RFID antenna coil is disposed outside the memory card insertion slot of the portable information device. A proposal has been made on a mobile phone having an RFID that secures a communication distance without impairing portability (see, for example, Patent Document 4).

  A conventional RFID system using an electrostatic field or an induction electric field uses a low frequency signal, and therefore has a low communication speed and is not suitable for a large amount of data transmission. On the other hand, the present inventors consider that high-capacity transmission is possible by transmitting a high-frequency signal by electric field coupling.

  However, while the electric field strength of the radiated electric field attenuates gently in inverse proportion to the distance, the electric field strengths of the induction electric field and the electrostatic electric field attenuate sharply in inverse proportion to the square and third power of the distance, that is, the communication distance. Signal attenuation due to Further, since a propagation loss occurs according to the size of the propagation distance with respect to the wavelength, the problem of the propagation loss according to the distance between the electrodes becomes significant when a high frequency signal is propagated by electric field coupling. For this reason, it is necessary to make as close as possible between the coupling electrodes of the transmitter and the receiver. In order to bring the coupling electrodes close enough, it is necessary to perform delicate positioning between the electrodes, and the position must be maintained during data communication, which is not convenient for the user. In addition, it is not possible to perform direct communication between the transceivers at a long distance.

  In addition, when mounting the coupling electrode in the housing of the communication device, it is necessary to place the electrode outside the housing as much as possible in order to reduce the inter-electrode distance during data communication. Will be limited. Of course, it is desirable that the coupling electrode be small and low in cost.

JP 2006-106612 A JP 2006-60283 A JP 2004-214879 A JP 2005-18671 A

  An object of the present invention is to provide an excellent communication system capable of performing data communication without interference with other communication systems using an electrostatic field or an induction field between information devices.

  A further object of the present invention is to provide an excellent communication system capable of realizing high-capacity data transmission of a high-frequency signal by a communication method using an electrostatic field or an induced electric field.

  A further object of the present invention is to provide an excellent communication system capable of extending the distance between coupling electrodes of a transmitter / receiver to make the arrangement between the transmitter / receiver and the design of the communication device flexible.

The present invention has been made in consideration of the above problems, a transmitter circuit unit that generates a high-frequency signal for transmitting data, a transmitter including a high-frequency coupler that transmits the high-frequency signal as an electrostatic field,
A high-frequency coupler, and a receiver including a receiving circuit unit that receives and processes a high-frequency signal received by the high-frequency coupler;
Surface wave propagation means for providing a surface wave transmission line for transmitting surface waves radiated from the high frequency coupler on the transmitter side with low propagation loss;
It is a communication system characterized by comprising.

  However, “system” here refers to a logical collection of a plurality of devices (or functional modules that realize specific functions), and each device or functional module is in a single housing. It does not matter whether or not (hereinafter the same).

  If data such as images and music can be exchanged between personal computers, such as exchanging data with a personal computer, the convenience for the user is enhanced. However, in many wireless communication systems represented by wireless LAN, a radiated electric field generated when a current is passed through an antenna is used, so that radio waves are emitted regardless of whether there is a communication partner. Further, since the radiated electric field attenuates gently in inverse proportion to the distance from the antenna, the signal reaches a relatively long distance. For this reason, it becomes a source of jamming radio waves for nearby communication systems, and the reception sensitivity of the receiver-side antenna also decreases due to the influence of surrounding jamming radio waves. In short, in the radio wave communication system, it is difficult to realize wireless communication limited to a communication partner at a short distance.

  On the other hand, in a communication system using an electrostatic field or an induced electric field, a coupling relationship does not occur when there is no communication partner nearby. In addition, the electric field strengths of the induction electric field and the electrostatic field are steeply attenuated in inverse proportion to the square and the cube of the distance, respectively. That is, an unnecessary electric field is not generated and the electric field does not reach far, so that it does not disturb other communication systems. Further, even when radio waves arrive from a distance, the coupling electrode does not receive radio waves, so that it is not necessary to receive interference from other communication systems.

  In addition, the conventional contactless communication system using an electrostatic field or an induction electric field uses a low-frequency signal and thus is not suitable for a large amount of data transmission. However, the present inventors use this type of high-frequency signal. It is considered that large-capacity data transmission is possible even in this non-contact communication system.

  However, the electric field strengths of the induction electric field and the electrostatic electric field are attenuated sharply in inverse proportion to the square and the third power of the distance, respectively, and there is a problem that the propagation loss is large due to the short wavelength when a high frequency signal is used. For this reason, the coupling electrodes of the transmitter and the receiver need to be as close as possible, and communication over a long distance cannot be performed. In addition, in order to bring the coupling electrodes sufficiently close to each other, it is necessary to perform delicate positioning between the electrodes, and since the position must be maintained during data communication, it is convenient for the user. Absent.

  Therefore, the communication system according to the present invention employs a communication method for transmitting a high-frequency signal by electric field coupling, but the surface wave propagation means transmits the surface wave radiated from the coupling electrode on the transmitter side. Therefore, data transmission is possible without sufficiently bringing the electrodes of the transceiver close to each other or performing delicate positioning.

  The surface wave propagation means is composed of, for example, a surface wave transmission line made of a linear member made of a dielectric material or a magnetic material, and along the traveling direction of the longitudinal wave among electromagnetic waves radiated from the coupling electrode on the transmitter side. Arranged. Such a surface wave transmission line efficiently propagates a surface wave through and through the surface of the transmission line. Therefore, compared to a case where a surface wave is propagated in a free space where no surface wave transmission line is disposed, Propagation loss can be reduced by interposing the surface wave transmission line between the couplers. Further, when performing non-contact transmission, the user does not have to directly contact the coupling electrodes with each other between the transceivers.

The surface wave transmission line is made of, for example, a dielectric having a dielectric constant ε larger than the dielectric constant ε _{0 of} air. In such a case, the surface wave of the dielectric travels parallel to the boundary surface, and complete reflection occurs at the boundary surface. Therefore, when a surface wave is incident on the inside of the dielectric at an appropriate angle, reflection is repeated at two boundaries, and the surface wave is efficiently propagated without loss.

  The surface wave transmission line is made of a dielectric material having a higher dielectric constant toward the inner side, such as covering the surface of a dielectric material having a higher dielectric constant with another dielectric layer having a lower dielectric constant. Also good. In such a case, it is possible to suppress the proportion of surface waves radiated to the outside as transmitted waves while propagating along the surface wave transmission line, and to transmit signals more efficiently. For example, the surface wave transmission line may be embedded in a rack made of another dielectric having a lower dielectric constant.

Alternatively, the surface wave transmission line can be made of, for example, a magnetic material having a permeability μ larger than the permeability μ _{0 of} air. In such a case, the surface wave of the magnetic material travels parallel to the boundary surface, and complete reflection occurs at the boundary surface. Therefore, when a surface wave is incident on the inside of the magnetic body at an appropriate angle, reflection is repeated at two boundaries, and the surface wave is efficiently propagated without loss.

  By forming the surface wave transmission line with a dielectric material having a higher permeability toward the inside, such as covering the surface of a magnetic material having a high magnetic permeability with another magnetic material layer having a lower magnetic permeability, During propagation along the surface wave transmission line, the ratio of surface waves radiated to the outside as transmitted waves can be suppressed, and signals can be transmitted more efficiently. For example, the surface wave transmission line may be embedded in a rack made of another magnetic material having a lower magnetic permeability.

  In addition, the surface wave transmission line can be constituted by a plurality of dielectric bodies (or magnetic bodies) separated in the middle instead of a single dielectric body (or magnetic body). That is, since the middle of the surface wave transmission line can be electrically disconnected and used in a non-contact state, it can be applied as non-contact communication in which there is no physical contact between devices or between a device and a member. In such a case, the separated dielectric bodies (or magnetic bodies) do not have to be in contact with each other, but in order to reduce loss, the distance between the dielectric bodies (or magnetic bodies) is small, and the signal is transmitted. It is desirable to be placed at a position where they face each other.

  In addition, in the layout in the case where the transmitter / receiver circuit unit and the coupling electrode are mounted on the main board in the communication device, if nothing is placed in front of the electrode housed deep inside the case, radiation is emitted from the electrode. The signal is dispersed in the air in the housing and lost. On the other hand, by installing a dielectric or magnetic material to be a surface wave transmission line in front of the coupling electrode, the electromagnetic wave signal radiated from the coupling electrode is guided to the surface of the housing by the surface wave transmission line. Efficient signal transmission is possible.

  Here, the transmitter connects a high-frequency signal transmission path for transmitting a high-frequency signal generated by the transmission circuit unit to a substantially center of the electrode of the high-frequency coupler through a resonance unit that resonates at a predetermined frequency. Yes. The receiver is connected to a high-frequency signal transmission path for transmitting a high-frequency signal to the receiving circuit section through a resonance section that resonates at a predetermined frequency at substantially the center of the electrode of the high-frequency coupler.

  The resonating unit can be formed of a lumped constant circuit. Specifically, the resonance unit includes a parallel inductor connected between the signal line of the high-frequency transmission line and the ground, and a series inductor connected between the signal line and the electrode of the high-frequency transmission line. Alternatively, the resonance unit can be configured by a distributed constant circuit. Specifically, a conductor pattern (also referred to as “stub”) having a length depending on the wavelength used is formed on a printed circuit board on which the coupler is mounted, and this acts as a resonance part.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding communication system which can perform data communication without interference with another communication system using an electrostatic field or an induction electric field between information apparatuses can be provided.

  In addition, according to the present invention, it is possible to provide an excellent communication system capable of realizing high-capacity data transmission of a high-frequency signal by a communication method using an electrostatic field or an induced electric field.

  Further, according to the present invention, it is possible to provide an excellent communication system capable of extending the distance between the coupling electrodes of the transceiver to make the arrangement between the transceivers and the design of the communication device flexible. .

  In the communication system according to the present invention, the surface wave radiated from the coupling electrode on the transmitter side is efficiently transmitted by the surface wave propagation means with low propagation loss. There is no need to directly contact each other's coupling electrodes, and data communication by electric field coupling is possible even at a long distance.

  Further, according to the communication system according to the present invention, it is not necessary to perform fine alignment between the electrodes in order to sufficiently bring the electrodes to be electrically coupled to each other, and the electrodes are disposed outside the housing in the housing of the communication device. This eliminates the need to do so, increasing the degree of freedom in housing layout design.

  The communication system according to the present invention can be used in a non-contact state between the coupling electrode of the transceiver and the surface wave transmission line provided by the surface wave propagation means, or in the middle of the surface wave transmission line. Therefore, it can be applied as non-contact communication in which there is no physical contact between devices or between a device and a member.

  In the communication device according to the present invention, the surface wave radiated from the coupling electrode can be guided to a position where it can be easily used by the surface wave transmission line. Therefore, it is not necessary to dispose the coupling electrode near the outside of the communication device casing, so that the degree of freedom in mounting components and designing the layout of the casing is increased.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

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

  The present invention relates to a communication system that performs data transmission between information devices using an electrostatic field or an induced electric field. According to a communication method based on an electrostatic field or an induced electric field, when there is no communication partner nearby, there is no coupling relationship and no radio waves are emitted, so that other communication systems are not disturbed. Further, even when radio waves arrive from a distance, the coupler does not receive radio waves, so that it is not necessary to receive interference from other communication systems.

  In the conventional radio communication using an antenna, the electric field strength of the radiated electric field is inversely proportional to the distance, whereas in the induced electric field, the electric field strength is inversely proportional to the distance squared, and in the static electric field, the electric field strength is inversely proportional to the cube of the distance. Therefore, according to the communication method based on electric field coupling, it is possible to configure a weak radio having a noise level for other radio systems in the vicinity, and it is not necessary to obtain a license from the radio station.

  An electrostatic field that varies with time may be referred to as a “quasi-electrostatic field”. In this specification, however, the electrostatic field is collectively referred to as an “electrostatic field”.

  Conventional communication using an electrostatic field or an induction field uses a low-frequency signal and is not suitable for transmitting a large amount of data. On the other hand, in the communication system according to the present invention, high-capacity transmission is possible by transmitting a high-frequency signal by electric field coupling. Specifically, by applying a communication method using a high frequency and a wide band, such as UWB (Ultra Wide Band) communication, to the electric field coupling, it is possible to realize weak data and large capacity data communication.

  UWB communication uses a very wide frequency band of 3.1 GHz to 10.6 GHz, and can realize high-capacity wireless data transmission of about 100 Mbps despite a short distance. UWB communication is a communication technology originally developed as a radio wave communication method using an antenna. For example, in IEEE 802.15.3, a data transmission method having a packet structure including a preamble as an access control method for UWB communication. Has been devised. In addition, Intel Corporation is considering a wireless version of USB that is widely used as a general-purpose interface for personal computers as a UWB application.

  In addition, UWB communication allows data transmission exceeding 100 Mbps without occupying a transmission band of 3.1 GHz to 10.6 GHz, and considering the ease of making an RF circuit, 3.1-4. A transmission system using a 9 GHz UWB low band is also actively developed. The present inventors consider that a data transmission system using UWB low band is one of effective wireless communication technologies installed in mobile devices. For example, it is possible to realize high-speed data transmission in a short-distance area such as an ultra-high-speed short-range DAN (Device Area Network) including a storage device.

  According to the UWB communication system using an electrostatic field or an induced electric field, the present inventors can perform data communication using a weak electric field, and can transfer a large amount of data such as moving images and music data for one CD at high speed. I think it can be transferred in a short time.

  FIG. 19 shows a configuration example of a contactless communication system using an electrostatic field or an induced electric field. The illustrated communication system includes a transmitter 10 that transmits data and a receiver 20 that receives data.

  The transmitting and receiving electrodes 13 and 23 of the transmitter 10 and the receiver 20 are arranged to face each other with a distance of, for example, about 3 cm, and can be coupled to each other. The transmission circuit unit 11 on the transmitter side generates a high-frequency transmission signal such as a UWB signal based on transmission data when a transmission request is generated from a higher-order application, and the signal propagates from the transmission electrode 13 to the reception electrode 23. Then, the receiving circuit unit 21 on the receiver 20 side demodulates and decodes the received high-frequency signal and passes the reproduced data to the upper application.

  According to a communication method using a high frequency and a wide band like UWB communication, it is possible to realize ultrahigh-speed data transmission of about 100 Mbps at a short distance. In addition, when UWB communication is performed by electric field coupling instead of radio wave communication, the electric field strength is inversely proportional to the cube of the distance or the square of the distance, so the electric field strength (radio wave strength) at a distance of 3 meters from the radio equipment is By suppressing the frequency to a predetermined level or less, it is possible to obtain a weak radio that does not require a radio station license, and a communication system can be configured at low cost. In addition, when data communication is performed at an extremely short distance by the electric field coupling method, the signal quality is not deteriorated by the reflecting objects present in the vicinity, and it is not necessary to consider the prevention of hacking and ensuring the confidentiality on the transmission line. There are advantages such as.

  On the other hand, since the propagation loss increases according to the propagation distance with respect to the wavelength, it is necessary to sufficiently suppress the propagation loss when a high-frequency signal is propagated by electric field coupling. In a communication system that transmits high-frequency broadband signals such as UWB signals by electric field coupling, even ultra-short-distance communication of about 3 cm is equivalent to about one-half wavelength for the used frequency band of 4 GHz, so it is ignored. It is a length that cannot be done. In particular, the problem of characteristic impedance is more serious in a high-frequency circuit than in a low-frequency circuit, and the influence of impedance mismatch becomes apparent at the coupling point between the electrodes of the transceiver.

  In conventional contactless communication using frequencies in the kHz or MHz band, the propagation loss in space is small, so the transmitter and receiver are equipped with a coupler consisting only of electrodes, and the coupling part simply operates as a parallel plate capacitor. Even in this case, desired data transmission can be performed. On the other hand, in the case of non-contact communication using a high frequency in the GHz band, the propagation loss in space increases, so it is necessary to suppress the reflection of signals between the coupling electrodes of the transceiver and improve the transmission efficiency. is there. In the communication system shown in FIG. 19, even if the high-frequency signal transmission line connecting the transmission circuit unit 11 and the transmission electrode 13 is a coaxial line with impedance matching of 50Ω, for example, If the impedance at the coupling portion between the coupling electrodes 23 on the receiving side is mismatched, the signal is reflected to cause a propagation loss.

  Therefore, as shown in FIG. 20, the high-frequency couplers disposed in each of the transmitter 10 and the receiver 20 include plate-like coupling electrodes 13 and 23, parallel inductors 12A and 22A, and series inductors 12B and 22B. It is configured by connecting to a high-frequency signal transmission line. When such a high-frequency coupler is disposed facing each other as shown in FIG. 21, the two electrodes operate as one capacitor and operate like a band-pass filter as a whole. High-frequency signals can be efficiently transmitted between the two. Here, the high-frequency signal transmission line indicates a coaxial cable, a microstrip line, a coplanar line, or the like.

  In the contactless communication system shown in FIG. 19, when transmitting a high-frequency signal such as UWB by electric field coupling, the essential conditions for the high-frequency coupler are as follows.

(1) There is an electrode for coupling by an electric field.
(2) There is a parallel inductor for coupling with a stronger electric field.
(3) In the frequency band used for communication, the inductor and capacitor constants are set so that impedance matching can be achieved when the coupler is placed face to face.

As shown in FIG. 21, the band-pass filter composed of a pair of high-frequency couplers whose electrodes face each other has its pass frequency f ₀ determined by the inductance of the series inductor and the parallel inductor and the capacitance of the capacitor constituted by the electrodes. can do. FIG. 22 shows an equivalent circuit of a bandpass filter composed of a set of high frequency couplers. If the characteristic impedance R [Ω], the center frequency f ₀ [Hz], the phase difference between the input signal and the passing signal is α [radian] (π <α <2π), and the capacitance of the capacitor constituted by the electrodes is C / 2. The constants of the parallel and series inductances L ₁ and L ₂ constituting the band-pass filter can be obtained by the following equations according to the operating frequency f ₀ .

Further, when the coupler alone functions as an impedance conversion circuit, an equivalent circuit thereof is as shown in FIG. In the illustrated circuit diagram, an impedance conversion circuit that converts the characteristic impedance from R ₁ to R ₂ by selecting the parallel inductance L ₁ and the series inductance L ² in accordance with the operating frequency f ₀ so as to satisfy the following equation. Can be configured.

  FIG. 24 shows the result of measuring the propagation loss while changing the distance by placing the antenna, the coupler (when there is a parallel inductor), and the coupler (when there is no parallel inductor) facing each other.

  The coupler (with a parallel inductor) is strongly coupled and has a small propagation loss at a short distance of up to about 1 cm. However, it has a characteristic that it rapidly attenuates as the distance increases and does not cause interference to the surroundings. It has become. In contrast, the propagation loss of the antenna does not increase as much as the coupler (with the parallel inductor) even when the distance is increased, and thus the antenna may become an interference signal to other wireless systems. Further, in a coupler that does not have a parallel inductor, the propagation efficiency is poor, and the propagation loss is large even when the communication partner is nearby.

  The coupling electrode of the high frequency coupler is connected to a high frequency transmission line such as a coaxial cable, a microstrip line, or a coplanar line. The “high frequency coupler” referred to in the present specification solves a problem peculiar to a high frequency circuit.

  As described above, in the non-contact communication system shown in FIG. 19, a communication device that performs UWB communication uses the high-frequency coupler shown in FIG. 20 instead of using an antenna in a conventional radio communication system wireless communication device. As a result, it is possible to realize ultra-short distance data transmission having unprecedented characteristics.

  Here, the resonance part 12 (or high frequency transmission line) which consists of a series inductor etc. shall be connected to the center of the electrode 13 for transmission. This is because, by connecting a high-frequency transmission line to the center of the electrode, current flows evenly in the electrode 13, and unnecessary radio waves are not radiated on the front surface of the electrode 13 in a direction substantially perpendicular to the electrode surface (see FIG. 18A), when the resonance part 12 is connected to a position having an offset from the center of the electrode 13, an unequal current flows in the electrode 13 and operates like a microstrip antenna to radiate unnecessary radio waves. (See FIG. 18B).

  FIG. 25 shows an actual configuration example of the high-frequency coupler shown in FIG. In the illustrated example, the high frequency coupler on the transmitter 10 side is shown, but the receiver 20 side is similarly configured. In the figure, an electrode 13 is disposed on the upper surface of a cylindrical dielectric 15 and is electrically connected to a signal line on a printed circuit board 17 through a through hole 16 penetrating through the dielectric 15. In the illustrated high-frequency coupler, for example, after a through hole is formed in a cylindrical dielectric having a desired height, a conductor pattern to be a coupling electrode is formed on the upper end surface of the cylinder, and a through hole is formed in the through hole. It can be manufactured by filling the conductor with a conductor and mounting the dielectric on the printed circuit board by reflow soldering or the like.

  By appropriately adjusting the height from the circuit mounting surface of the printed circuit board 17 to the electrode 13, that is, the length of the through-hole 16, according to the wavelength used, the through-hole 16 has an inductance, and is substituted for the series inductor 12B. Can do. The signal line is connected to the ground 18 via a chip-like parallel inductor 12A. Although not shown, the parallel inductance can be replaced with a wiring pattern on a printed board instead of a chip. This type of inductance consists of a distributed constant circuit and is also referred to below as a “stub”.

  The dielectric 15 and the through hole 16 have a role of avoiding the coupling between the electrode 13 and the ground 18 and a role of forming the series inductor 12B. By taking a sufficient height from the circuit mounting surface of the printed circuit board 17 to the electrode 13 to constitute an inductance equivalent to the series inductor 12B, electric field coupling between the ground 18 and the electrode 13 can be avoided, and a high frequency coupler can be obtained. The function (that is, the electric field coupling action with the high frequency coupler on the receiver side) is secured. However, when the height of the dielectric 15 is large, that is, when the distance from the circuit mounting surface of the printed circuit board 17 to the electrode 13 becomes a length that cannot be ignored with respect to the wavelength used, the series inductor 12B, that is, the resonance unit 12 acts as an antenna. Has the harmful effect of emitting radio waves. In this case, the radiated radio wave due to the behavior of the antenna in the resonance unit 12 of the high frequency coupler is less attenuated with respect to the distance than the electrostatic field or the induced electric field, so that the electric field strength at a distance of 3 meters from the radio equipment is below a predetermined level. It becomes difficult to suppress to weak radio. Therefore, the height of the dielectric 15 avoids coupling with the ground 18 and sufficiently obtains the characteristics as a high-frequency coupler, configures the series inductor 12B necessary for acting as a resonance circuit, The condition is that the resonance part composed of the series inductor 12B does not increase the function as an antenna.

  In general, metal prevents the antenna from efficiently radiating radio waves, so that a metal such as a ground cannot be disposed in the vicinity of the radiating element of the antenna. On the other hand, in the communication system according to the present embodiment, the high frequency coupler does not deteriorate in characteristics even if a metal is disposed on the back side of the electrode 13. Further, by appropriately selecting the constants of the series inductor 12B and the parallel inductor 12A, it can be made smaller than the conventional antenna. In addition, since the electrostatic field does not have a polarization like an antenna, a certain communication quality can be ensured even if the direction is changed.

  In the field of radio wave communication, as shown in FIG. 5, a “capacitance loaded type” antenna is widely known in which a metal is attached to the tip of an antenna element to provide a capacitance and the height of the antenna is shortened. At first glance, the coupler is similar in structure to the coupler shown in FIG. Here, the difference between the coupler used in the transceiver in this embodiment and the capacity loaded antenna will be described.

The capacity loaded antenna shown in FIG. 5 radiates radio waves in the directions B ₁ and B ₂ around the radiating element of the antenna, but the A direction is a null point that does not radiate radio waves. When the electric field generated around the antenna is examined in detail, the radiation electric field attenuated in inverse proportion to the distance from the antenna, the induced electric field attenuated in inverse proportion to the square of the distance from the antenna, and the distance from the antenna 3 An electrostatic field that decays in inverse proportion to the power is generated. Since the induced electric field and the electrostatic field are attenuated more rapidly depending on the distance than the radiated electric field, only the radiated electric field is discussed in a normal wireless system, and the induced electric field and the electrostatic field are often ignored. Therefore, even the capacitively loaded antenna shown in FIG. 5 generates an induced electric field and an electrostatic field in the direction A, but is rapidly used in radio communication because it attenuates quickly in the air. Absent.

Next, consider the electromagnetic field generated at the coupling electrode on the transmitter side. FIG. 16 shows an electromagnetic field generated by a minute dipole. In FIG. 26, this electromagnetic field is mapped onto the coupling electrode. As shown in the figure, the electromagnetic field is roughly divided into an electric field component (transverse wave component) E _θ that vibrates in a direction perpendicular to the propagation direction and an electric field component (longitudinal wave component) E _R that vibrates in a direction parallel to the propagation direction. . Further, a magnetic field Hφ is generated around the minute dipole. The following equation represents the electromagnetic field due to a small dipole, but since an arbitrary current distribution can be considered as a continuous collection of such small dipoles, the electromagnetic field induced thereby has similar properties (for example, (See Yasunori Mushiaki, “Antenna / Radio Wave Propagation” (Corona, pp. 16-18, first published on February 28, 1961)).

As can be seen from the above equation, the transverse wave component of the electric field includes a component that is inversely proportional to the distance (radiated electric field), a component that is inversely proportional to the square of the distance (induced electric field), and a component that is inversely proportional to the cube of the distance (electrostatic field). ). Further, the longitudinal wave component of the electric field is composed of only a component inversely proportional to the square of the distance (inductive electric field) and a component inversely proportional to the cube of the distance (electrostatic field), and does not include the component of the radiated electromagnetic field. Further, the electric field E _R becomes maximum in the direction in which | cos θ | = 1, that is, in the direction of the arrow in FIG.

In the radio communications are widely used in wireless communication, radio wave emitted from an antenna is a transverse wave E _theta oscillating in the perpendicular direction its traveling direction, the radio wave can not communicate with the direction of polarization is orthogonal. In contrast, electromagnetic waves emitted from the coupling electrode in a communication system utilizing an electrostatic field or an induced electric field, in addition to the transverse wave E _theta, including longitudinal wave E _R which oscillates in the traveling direction. The longitudinal wave E _R is also called “surface wave”. A surface wave can also propagate through the inside of a medium such as a conductor, a dielectric material, or a magnetic material (described later).

In a non-contact communication system, a signal can be transmitted via any component of a radiated electric field, an electrostatic field, and an induced electric field. However, a radiated electric field that is inversely proportional to distance can cause interference to other systems that are relatively far away. Therefore, to suppress the component of the radiation field, in other words, while suppressing the transverse wave E _theta comprising the components of the radiation field, the non-contact communication is preferred utilizing longitudinal wave E _R not containing component of the radiation field.

From the viewpoint described above, the high frequency coupler according to the present embodiment has the following devices. First, it can be seen from the above-described three equations showing the electromagnetic field that E _θ = 0 and the E _R component takes a maximum value when θ = 0 °. That is, E _θ is maximized in a direction perpendicular to the direction of current flow, and E _R is maximized in a direction parallel to the direction of current flow. Therefore, to maximize E _R perpendicular front direction with respect to the electrode surface, it is desirable to increase the vertical direction of the current component to the electrode. On the other hand, when the feeding point is offset from the center of the electrode, the current component in the direction parallel to the electrode increases due to this offset. Then, the front direction of the E _theta component of the electrode according to the current component is increased. Therefore, in the high-frequency coupler according to the present embodiment, the feeding point substantially at the center position of the electrode as shown in FIG. 18A (described above), is the E _R component is set to be maximum.

Of course, not only the radiated electric field but also the static electric field and the induced electric field are generated even in the conventional antenna, and electric field coupling occurs when the transmitting and receiving antennas are brought close to each other. Not right. In contrast, the high-frequency coupler shown in Figure 20, to enhance transmission efficiency create a stronger electric field E _R at a predetermined frequency, the electrode and the resonance unit for coupling is formed.

When the high frequency coupler shown in FIG. 20 is used alone on the transmitter side, a longitudinal wave electric field component E _R is generated on the surface of the coupling electrode, but the transverse wave component E _θ including the radiation electric field is changed to E _R. Since it is relatively small, almost no radio waves are emitted. That is, no disturbing wave to other neighboring systems is generated. Also, most of the signal input to the high frequency coupler is reflected by the electrode and returns to the input end.

On the other hand, when one set of high-frequency couplers is used, that is, when the high-frequency couplers are arranged at a short distance between the transmitter and the receiver, the coupling electrodes are coupled mainly by a quasi-electrostatic field component to form one capacitor. It works like a bandpass filter and is in a state where impedance matching is achieved. Therefore, most of the signal / power is transmitted to the other party in the passing frequency band, and the reflection to the input end is small. The “short distance” here is defined by the wavelength λ, and corresponds to the distance d between the coupling electrodes being d << λ / 2π. For example, when the use frequency f ₀ is 4 GHz, the distance between the electrodes is 10 mm or less.

Also, when placing the EFC medium distance between the transmitter and the receiver are on the periphery of the coupling electrode of the transmitter, the electrostatic field is attenuated, the longitudinal wave electric field E _R mainly composed of an induced electric field is generated . Longitudinal wave electric field E _R is received by the coupling electrode of the receiver, the signal is transmitted. However, in comparison with the case where both couplers are arranged at a short distance, in the high frequency coupler on the transmitter side, the ratio of the input signal reflected by the electrode and returning to the input end becomes higher. The “medium distance” here is defined by the wavelength λ, the distance d between the coupling electrodes is about 1 to several times larger than λ / 2π, and the distance between the electrodes is 10 to 40 mm when the use frequency f ₀ is 4 GHz. At the time.

  By the way, in a communication system using an electrostatic field or an induction field, the electric field strength is rapidly attenuated in inverse proportion to the cube of the distance and the square of the distance, so that the communication range is limited to an extremely short distance. . Further, when a high-frequency signal such as UWB communication is used, the problem of a large propagation loss due to the short wavelength is further added. For this reason, it is necessary to make the transmitter and receiver electrodes (couplers) as close as possible, and communication over a long distance cannot be performed. Further, in order to bring the electrodes sufficiently close to each other, it is necessary to perform delicate alignment between the electrodes, and the position must be maintained during data communication, which is not convenient for the user.

  On the other hand, in the communication system according to the present invention, a surface wave transmission line made of a dielectric or magnetic material is disposed between the coupling electrode on the transmitter side and the coupling electrode on the receiver side, Among the electromagnetic waves radiated from the coupling electrode, the surface wave can be efficiently propagated through and inside the surface wave transmission line. Therefore, even if the coupling electrodes of the transmitter and the receiver are separated from each other by a relatively long distance, the surface wave radiated by the electric field coupling can be transmitted with low propagation loss, and data communication can be performed. It is no longer necessary to make the bonding electrodes directly contact each other.

Of the transmission waves using an electromagnetic field, those having a phase velocity v smaller than the light velocity c are called slow waves, and those having a larger phase velocity v are called fast waves. Surface waves are equivalent to the former slow waves. In an infinitely long transmission line with a slow wave structure, energy is concentrated in the transmission line, and no external radiation is generated (for example, “New Millimeter Wave” written by Tsuyoshi Teshirogi, edited by Tsutomu Yoneyama) Technology "(see Ohm, P119). Here the surface wave to say, among the electric field generated from the coupling electrode, which corresponds to a longitudinal wave E _R which is a component that vibrates in the direction of propagation and parallel to the direction (above).

  A mechanism in which electromagnetic waves propagate along the surface of a conductor, dielectric, or magnetic material is known as, for example, “Gobo Line” or “G Line” (for example, US Pat. No. 2,685,068, US Pat. No. 2,921,277). See the description).

  For example, Japanese Patent Laid-Open No. 2003-115707 discloses a surface wave transmission line using a dielectric made of a thermoplastic polymer as a medium. Japanese Laid-Open Patent Publication No. 7-175987 discloses a surface wave transmission line in which a dielectric or dielectric fiber with low high-frequency loss is brought together with a predetermined periodic structure so that the electromagnetic field distribution range can be controlled to some extent. Proposals have been made. For details of the mechanism of the surface wave transmission line for propagating electromagnetic waves, refer to, for example, Masamitsu Nakajima “Microwave Engineering” (Morokushi Publishing, pages 182 to 190).

  In addition, electromagnetic surface waves propagating through one ferrite rod magnetized in the axial direction have been extensively studied, and there are three types of surfaces: “dynamic”, “surface (surface mode)”, and “volume (stereoscopic mode)”. It has already been clarified that a wave mode exists. The dynamic mode exists in a frequency range where the ferrite can be regarded as a mere dielectric, and is a forward wave. On the other hand, the surface mode and the three-dimensional mode are modes in which electric power is collected near the surface of the ferrite rod or in the center, respectively, and is mainly backwave. Of these modes, the surface mode is applied to the resonator, and the three-dimensional mode is applied to the delay line and Faraday rotator. (Study on surface waves propagating through two parallel ferrite rods by Toshiaki Akira "checking).

  FIG. 3 shows a configuration example of a non-contact communication system in which a surface wave transmission line is interposed between high-frequency coupling electrodes of a transceiver. The illustrated communication system includes a transmitter 10 that transmits data, a receiver 20 that receives data, and a surface wave transmission line that transmits surface waves radiated from a transmitting electrode 13 on the transmitter 10 side with low propagation loss. 30. The surface wave transmission line 30 is made of a dielectric material or a magnetic material, and is disposed along the traveling direction of the surface wave radiated from the transmitting electrode 13.

  The transmission circuit unit 11 on the transmitter 10 side generates a high-frequency transmission signal such as a UWB signal based on transmission data when a transmission request is issued from a higher-level application. The signal output from the transmission circuit unit 11 resonates at the resonance unit 12 and is radiated from the transmitting electrode 13 as a surface wave in the front direction from the electrode.

  The surface wave radiated from the transmitting electrode 13 is efficiently propagated through the surface wave transmission line 30 and is input from the receiving electrode 23 on the receiver 20 side to the receiving circuit unit 21 via the resonance unit 22. . The receiving circuit unit 21 demodulates and decodes the received high-frequency signal and passes the reproduced data to the upper application.

  When the surface wave emitted from the transmitting electrode 13 is incident from the end face of the surface wave transmission line 30, it propagates to the receiving side without loss while repeating reflection every time it reaches the boundary surface with the outside (described later). . Therefore, the signal can efficiently propagate from the transmitting electrode 13 to the receiving electrode 23 due to the intervention of the surface wave transmission line 30. Further, in order to increase the incident angle of the surface wave radiated from the transmitting electrode 13 and reduce the ratio of the transmitted wave radiated to the outside, the end face of the surface wave transmission line 30 made of a dielectric or magnetic material is used for the transmission. Desirably, the electrode 13 is disposed on the front surface so as to be substantially perpendicular to the electrode surface.

  In FIG. 4, the structural example of the surface wave transmission part (high frequency coupler) of the transmitter 10 is shown. It should be understood that the configuration of the surface wave receiving portion on the receiver 20 side is the same.

  As shown in the figure, a resonance portion and an electrode of a linear conductor having a predetermined length are attached to the tip portion of the high-frequency signal line made of a coaxial cable. The resonance unit 12 and the transmitting electrode 13 as a whole are designed to have a length of a quarter wavelength of a predetermined frequency, thereby resonating at a predetermined frequency and generating a surface wave of that frequency. be able to. Normally, the generated surface wave is abruptly attenuated in the air as the distance increases. However, the resonance part 12 is connected to the center of the transmitting electrode 13 at the tip, and the radiation surface of the electrode is almost at the front of the electrode. By installing the surface wave transmission line 30 made of a dielectric or magnetic material in the vertical direction, the surface wave transmitted from the transmitting electrode 13 is captured by the surface wave transmission line 30 made of a dielectric or magnetic material, and the surface wave is transmitted. It can be a transmitter (or a high frequency coupler).

  A surface wave transmission line 30 made of a dielectric material or a magnetic material is disposed in front of the transmitting electrode 13 where the strength of the induced electric field and the electrostatic field is large, at a position perpendicular to the electrode surface. Then, when the induced electric field and the electrostatic field generated in the vicinity of the electrode 13 are captured by the end face of the surface wave transmission line 30, they propagate through the transmission line 30 and are input to the receiving electrode 23 on the receiver 20 side. . That is, by transmitting the electromagnetic field radiated from the electrode 13 on the transmitter 10 side as a surface wave in the surface wave transmission line 30, data communication using the surface wave can be enabled.

  FIG. 6 shows another configuration example of the surface wave transmission portion of the transmitter 10. It should be understood that the configuration of the surface wave receiving portion on the receiver 20 side can be similarly configured.

  The surface wave transmitting part and the receiving part are each provided with a resonance part 12 by a lumped constant circuit using a coil or a capacitor instead of a linear conductor. In the example illustrated in FIG. 6, the resonance unit 12 includes a parallel inductor 12 </ b> A connected between the signal line of the high-frequency transmission line from the transmission circuit unit 11 and the ground, and a series inductor 12 </ b> B connected between the signal line and the electrode. Therefore, a strong electric field is generated in front of the electrode, and surface waves can be generated efficiently.

  In a transceiver, when a pair of high-frequency couplers as shown in FIG. 6 are arranged facing each other with a surface wave transmission line interposed, two electrodes operate as one capacitor, and the bandpass as a whole.・ It works like a filter. Here, by adjusting the constant of the series inductor 12B, the constant of the parallel inductor 12A, and the constant of the capacitor formed of the electrodes 13 and 23, it is possible to design the impedance in the coupling portion to be continuous. (As described above).

The surface wave incident on the surface acoustic wave transmission line made of a dielectric is promoted in the propagation direction (that is, the receiver side) while being repeatedly reflected every time it reaches the boundary surface with the outside. FIG. 1 illustrates how a surface wave propagates inside a surface wave transmission line made of a dielectric. However, it is assumed that the dielectric constant ε of the dielectric is larger than the dielectric constant ε ₀ of the air surrounding the surface wave transmission line.

When electromagnetic waves (surface waves) enter the boundary between two media having different dielectric constants, refraction similar to that in optics occurs. When the incident angle θi is equal to the critical angle theta _c represented by the following formula, the refraction angle theta _t is equal to [pi / 2, the transmitted wave of the dielectric will proceed in parallel with the boundary surface. When the incident angle θ _i is larger than that, complete reflection occurs at the boundary surface. Therefore, when an electromagnetic wave is incident on the inside of the dielectric plate at an appropriate angle, the electromagnetic wave (surface wave) is propagated efficiently without being repeatedly reflected at the two boundaries.

FIG. 2 illustrates how a surface wave propagates in a surface wave transmission line made of a magnetic material. However, it is assumed that the magnetic permeability μ of the magnetic material is larger than the magnetic permeability μ ₀ of the air surrounding the surface wave transmission line. When electromagnetic waves (surface waves) are incident on the boundary between two media having different magnetic permeability, refraction similar to that in optics occurs. That is, when the incident angle θ _i becomes equal to the critical angle θ _c expressed by the following equation, the refraction angle θ _t becomes equal to π / 2, and the transmitted wave travels parallel to the boundary surface. When the incident angle θ _i is larger than that, complete reflection occurs at the boundary surface. Therefore, when an electromagnetic wave is incident on the inside of the magnetic plate at an appropriate angle, the electromagnetic wave (surface wave) is repeatedly reflected at the two boundaries and propagates efficiently without loss as in the case shown in FIG. Is done.

  As shown in FIG. 27, the present inventors perform high-frequency signal transmission by interposing a surface wave transmission line made of a dielectric (or magnetic material) between two opposing high-frequency couplers 1 and 2. The electromagnetic field distribution generated around the surface wave transmission line was obtained by simulation using the finite element method. However, the surface wave transmission line is assumed to be a dielectric having a relative permittivity of 10, a relative permeability of 10, and an electric conductivity of 0 [Siemens / m], and its cross-sectional area is 6 mm × 6 mm and the length is 49.6 mm. The gap between both end faces of the surface wave transmission line and the coupling electrode was set to 50 mm, and the operating frequency was 4.5 GHz. The high-frequency coupler is composed of a coupling electrode having an area of 20 mm × 42 mm, a thickness of 0.8 mm, a dielectric constant of 3.4, and an area of 11 mm × 11 mm and a height of 3 mm. It is composed of a stub (described above) having a width of 20 mm and a width of 3 mm. The longitudinal direction of the surface wave transmission line, that is, the signal transmission direction is taken as the z axis, and the plane parallel to the electrode of the coupling electrode is taken as the xy plane.

  28A to 28F show changes in the electric field distribution in the zx plane when the high-frequency signal is transmitted through the surface wave transmission line in the configuration shown in FIG. Show. As shown in the figure, it can be seen that a surface wave having an amplitude in the direction perpendicular to the surface of the surface wave transmission line made of a dielectric propagates from the high frequency coupler 1 toward the high frequency coupler 2.

  In addition, it is known that a magnetic field is generated by a temporal change of an electric field. FIGS. 29A to 29F show changes in the magnetic field distribution in the xy plane when the high frequency signal is transmitted through the surface wave transmission line in the configuration shown in FIG. Show.

  FIG. 30 schematically shows an electric field distribution and a magnetic field distribution generated around the surface acoustic wave transmission line made of a dielectric based on FIGS. As described above, the surface wave propagating through the transmission line includes a surface mode in which energy is collected near the surface of the transmission line and a three-dimensional mode in which energy is collected in the center of the transmission line. As can be seen from FIG. 30, the energy of the surface wave propagating through the surface acoustic wave transmission line made of a dielectric is near the central axis (solid mode) where the longitudinal wave component propagates and near the surface (surface) where the transverse wave component propagates. Mode). That is, an electric field perpendicular to the surface of the dielectric is generated near the surface of the dielectric, and a longitudinal electric field (including the above-described total reflection component) that vibrates in a direction substantially parallel to the traveling direction in the central portion of the dielectric. Further, a signal propagates by generating a magnetic field so as to be wound around the central axis of the dielectric in accordance with these two types of electric field changes.

  At this time, when the direction and strength of current and magnetism change (alternating current) and a suitable magnetic field that interacts with the electric field is generated, the magnetic field is generated when there is an electric field, and the electric field is generated when there is a magnetic field. Thus, it is expected that the surface wave signal propagates far away while alternately changing the form of energy between the electric field and the magnetic field. On the other hand, in the case of a magnetic substance having a relative dielectric constant of 1 for the surface wave transmission line, only the electric field component is generated from the high-frequency coupler, making it difficult to capture the signal.

FIG. 31 shows a state where a longitudinal wave electric field E _R generated on the surface of the coupling electrode of the high frequency coupler is transferred as a surface wave at the end of the surface wave transmission line made of a dielectric. When the longitudinal wave electric field E _R generated on the surface of the coupling electrode is incident from the end face of the surface wave transmission line, the longitudinal wave component propagates in a three-dimensional mode near the central axis of the surface wave transmission line as shown in FIG. 31A. When a longitudinal wave electric field E _R generated on the surface of the coupling electrode is perpendicularly incident from the outer periphery near the end of the surface wave transmission line, the transverse wave component is generated near the surface of the surface wave transmission line as shown in FIG. 31B. Propagate by surface mode.

  Thus, when a surface wave propagates on a surface wave transmission line made of a dielectric, both a three-dimensional mode and a surface mode exist, and energy is transmitted by both the three-dimensional mode and the surface mode. Therefore, in order to receive the surface wave emitted from the high frequency coupler without loss, the size of the end face of the surface wave transmission line (the thickness of the transmission line) is sufficiently larger than the size of the coupling electrode. It is thought that it is preferable.

Figure 32, in the configuration shown in FIG. 27 shows the results of the propagation loss S ₂₁ when changing the size of the transceiver each coupling electrode was determined by simulation using the finite element method. However, the surface wave transmission line is assumed to be a dielectric having a relative permittivity of 10, a relative permeability of 10, and an electric conductivity of 0 [Siemens / m], and its cross-sectional area is 6 mm × 6 mm and the length is 49.6 mm. The gap between both end faces of the surface wave transmission line and the coupling electrode was set to 50 mm, and the operating frequency was 4.5 GHz. The high-frequency coupler is composed of a square coupling electrode having an area of 20 mm × 42 mm, a thickness of 0.8 mm, and a dielectric constant of 3.4 mm, and a height of 3 mm. The resonance part is 20 mm long and has a width. The length of one side of the coupling electrode is variable. From the figure, it can be said that the propagation loss S ₂₁ is substantially constant when the thickness of the surface wave transmission line does not change.

Further, in FIG. 33, in the configuration shown in FIG. 27, the propagation loss S ₂₁ when varying the thickness of the surface-wave transmission line shows the results obtained in the simulation by the finite element method. However, the frequency used is 4.5 GHz. The surface wave transmission line is assumed to be a dielectric having a relative permittivity of 10, a relative permeability of 10, and an electric conductivity of 0 [Siemens / m], and its length is 49.6 mm. And the gap between the coupling electrodes was set to 50 mm, and the cross-sectional area was variable. The high-frequency coupler is composed of a coupling electrode having an area of 20 mm × 42 mm, a thickness of 0.8 mm, and a dielectric constant of 3.4, and an area of 11 mm × 11 mm and a height of 3 mm. It is assumed that the stub is composed of 20 mm and a width of 3 mm (described above). From the figure, it can be seen that the propagation loss S ₂₁ changes depending on the thickness of the surface wave transmission line.

In addition, FIG. 34 shows a result obtained by simulating the propagation loss S ₂₁ when the relative permittivity and the relative permeability of the surface wave transmission line are changed in the configuration shown in FIG. 27 by a finite element method simulation. . However, the frequency used is 4.5 GHz, and the high-frequency coupler is a coupling electrode having an area of 20 mm × 42 mm, a thickness of 0.8 mm, a dielectric constant of 3.4 and an area of 11 mm × 11 mm and a height of 3 mm. It is assumed that the resonance part is composed of a stub (described above) having a length of 20 mm and a width of 3 mm. The surface wave transmission line has a cross-sectional area of 6 mm × 6 mm and a length of 49.6 mm, and the gap between both end faces of the surface wave transmission line and the coupling electrode is set to 50 mm. From the figure, it can be seen that the propagation loss S ₂₁ changes depending on the relative permittivity and relative permeability of the surface wave transmission line.

Propagation loss S ₂₁ of the surface wave transmission line made of a dielectric depends on the frequency, the relative permittivity of the transmission line, the relative permeability, and the thickness of the surface wave transmission line. In consideration of the simulation results shown in FIGS. 32 to 34, for example, when the frequency is 4.5 GHz, the relative permittivity is 10, the relative permeability is 10, and the thickness of the surface wave transmission line is about 6 mm × 6 mm The signal propagates efficiently with little loss.

  It is known that a surface wave propagates through the surface of a conductor such as a metal wire in addition to the inside of a dielectric or magnetic material. When a surface acoustic wave transmission line made of a magnetic material is used, only the electric field component is generated from the high frequency coupler, and a magnetic material with a relative dielectric constant of 1 cannot capture a signal, so the propagation loss of the surface wave is large. However, a surface acoustic wave can be efficiently transmitted with a magnetic material having a relative dielectric constant greater than 1. Further, when a surface acoustic wave transmission line made of a dielectric is used, an electric field perpendicular to the surface of the dielectric, and an electric field of a longitudinal wave that vibrates in a direction parallel to the traveling direction generated in the central portion of the dielectric, A signal propagates by a magnetic field generated so as to wrap around the central axis of the dielectric.

FIG. 17A shows the relationship between the transmission line length and the propagation loss S ₂₁ when PPS (polyphenylene sulfide resin) as the dielectric, NiZn ferrite as the magnetic material, and a magnet are used for the surface wave transmission line. Yes. However, PPS has a dielectric constant of 5 to 12, a dielectric loss tangent of 0.002 and a diameter of 10 mm, NiZn ferrite has a diameter of 9 mm (inner diameter of 5 mm), and a magnet has a diameter of 6 mm (see FIG. 17B). The propagation loss S ₂₁ of the surface wave transmission line is a surface wave from the high frequency signal line (Port 1) on the transmitter side to the high frequency signal line (Port 2) on the receiver side when the surface wave transmission line is sandwiched between the electrodes. Is a loss in propagation (see FIG. 17C). From FIG. 17A, it can be understood that the propagation loss is reduced by the presence of the surface wave transmission line between the couplers of the transmitter and the receiver as compared with the case where the surface wave is propagated without placing the free space, that is, the surface wave transmission line. Like.

  The shape of the surface wave transmission line 30 made of a dielectric or magnetic material is not particularly limited. For example, it may be any of a plate shape as shown in FIG. 7, a belt shape as shown in FIG. 8, and a line shape as shown in FIG. In addition, if the surface wave transmission line is shaped like a spindle as shown in FIG. 10 and its apex is directed to a specific receiver, the surface wave captured on the bottom surface is propagated from the coupling electrode on the transmitter side. Therefore, efficient propagation can be realized. For example, in the case of performing one-way communication from one communication device to the other communication device, such a transmission line configuration is advantageous.

  As shown in FIG. 11, the surface wave transmission line 30 may be configured to cover the surface of a dielectric having a high dielectric constant with an outer layer 31 of another dielectric having a lower dielectric constant. By doing so, even if the surface wave is transmitted without reflecting the surface of the dielectric having a high dielectric constant, it is reflected on the surface of another dielectric covering the surface and pulled back to the center dielectric layer. It is. That is, the ratio of surface waves radiated to the outside as transmitted waves in the course of propagation through the surface wave transmission line 30 can be suppressed, and signals can be transmitted more efficiently.

  Needless to say, the same effect can be obtained by forming two or more outer layers having different dielectric constants ε (or magnetic permeability μ) as shown in FIG. . In addition, the dielectric constant ε (or magnetic permeability μ) does not change stepwise according to the distance r from the center, but is continuously changed according to the distance r from the center as shown in FIG. Alternatively, even if the magnetic permeability μ) changes, the ratio of surface waves radiated to the outside of the surface wave transmission line 30 as transmitted waves can be similarly suppressed.

  FIG. 13 shows an object made of a dielectric having a high dielectric constant ε (or magnetic permeability μ) and another dielectric (or magnetic substance) having a low dielectric constant ε (or magnetic permeability μ) as the surface wave transmission line 30. It shows a state where it was buried inside. Further, another object that fills a dielectric having a high dielectric constant ε (or magnetic permeability μ) can be configured, for example, as a rack or a member for positioning the coupling electrodes 13 and 23 of the transmitter 10 and the receiver 20. .

  FIG. 14 shows an example in which the surface acoustic wave transmission line 30 is composed of a plurality of dielectric bodies (or magnetic bodies) separated in the middle rather than a single dielectric body (or magnetic body). Since the middle of the surface wave transmission line 30 can be cut off and used in a non-contact state, the communication system according to the present embodiment is applied as non-contact communication in which there is no physical contact between devices or between a device and a member. can do. The separated dielectrics do not have to be in contact with each other, but in order to keep the loss small, it is desirable that the distance between the dielectrics is small and that the surfaces where signals are transmitted face each other face each other. .

  FIG. 15 shows a configuration example of a non-contact communication device using a surface wave transmission line. In the illustrated example, the transmission / reception circuit unit and the coupling electrode are mounted on the main circuit board in the non-contact communication device. If nothing is placed in front of the electrode housed deep inside the housing, the signal radiated from the electrode is dispersed in the air inside the housing and lost. On the other hand, according to the configuration of the communication device shown in FIG. 15, a dielectric or magnetic material serving as a surface wave transmission line is installed in front of the coupling electrode, and the electromagnetic field radiated from the coupling electrode is An efficient signal transmission is possible by inducing a signal to a desired part of the surface of the housing by the transmission line.

  So far, in the communication system shown in FIG. 3, a mechanism for transmitting a signal between a pair of high-frequency couplers by interposing a surface wave transmission line has been described. Here, when a signal is transmitted between two devices, energy transfer is inevitably involved. Therefore, this type of communication system can be applied to power transmission. As described above, the electric field ER generated by the high frequency coupler on the transmitter side propagates on the surface wave transmission line as a surface wave. On the receiver side, the signal received by the high-frequency coupler can be rectified and stabilized to extract power.

  FIG. 35 shows a configuration example when the communication system shown in FIG. 3 is applied to power transmission.

  In the illustrated system, a charger connected to an AC power source and a high-frequency coupler incorporating a wireless communication device can perform power transmission and charging to the wireless communication device via a surface wave transmission line placed between them. it can. However, the high frequency coupler is used only for power transmission.

  When the receiving high-frequency coupler is not near the transmitting high-frequency coupler, most of the power input to the transmitting high-frequency coupler is reflected and returns to the DC / AC inverter side, so that unnecessary radio waves are sent to the outside. Radiating or consuming more power than necessary can be suppressed.

  Moreover, although the example which performs charge to a radio | wireless communication apparatus was given in the figure, you may make it perform the non-contact electric power transmission not only to a radio | wireless machine but the music player or a digital camera, for example.

  FIG. 36 shows another configuration example in which the communication system shown in FIG. 3 is applied to power transmission. The illustrated system is configured to use a high-frequency coupler and a surface wave transmission line for both power transmission and communication.

  Switching of the timing for performing communication and power transmission is performed by a communication / transmission (reception) switching signal sent from the transmission circuit unit. For example, communication and power transmission may be switched at a predetermined cycle. At this time, the power transmission output can be kept optimal by adding the charging state to the communication signal and feeding back to the charger side. For example, when charging is completed, the information is sent to the charger side, and the power transmission output is set to zero. Or you may make it superimpose communication data on electric power.

  The system shown in the figure is configured so that the charger is connected to an AC power source. However, the system is used for other purposes such as sharing power from another mobile phone to a mobile phone having a low battery, for example. Also good.

  The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiment without departing from the gist of the present invention.

  In the present specification, the embodiment applied to a communication system in which a UWB signal is data-transmitted by electric field coupling in a cableless manner has been mainly described, but the gist of the present invention is not limited to this. For example, the present invention can be similarly applied to a communication system that uses a high-frequency signal other than the UWB communication method and a communication system that performs data transmission by electric field coupling using a relatively low frequency signal.

  In the present specification, the embodiment in which the present invention is applied to a system that performs data communication between a pair of high-frequency couplers by interposing a surface wave transmission line has been mainly described. Since transmission of a signal necessarily involves energy transfer, this type of communication system can naturally be applied to power transmission.

  In short, the present invention has been disclosed in the form of exemplification, and the description of the present specification should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims should be taken into consideration.

FIG. 1 is a diagram illustrating a state in which a surface wave propagates in a surface wave transmission line made of a dielectric material. FIG. 2 is a diagram showing how a surface wave propagates in a surface wave transmission line made of a magnetic material. FIG. 3 is a diagram illustrating a configuration example of a communication system according to an embodiment of the present invention. FIG. 4 is a diagram illustrating a configuration example of a surface wave transmission portion of the transmitter 10. FIG. 5 is a diagram illustrating a configuration example of a capacity loaded antenna. FIG. 6 is a diagram illustrating another configuration example of the surface wave transmission portion of the transmitter 10. FIG. 7 is a diagram illustrating an example of a surface wave transmission line configured in a plate shape. FIG. 8 is a diagram showing an example of a surface acoustic wave transmission line configured in a band shape. FIG. 9 is a diagram illustrating an example of a surface acoustic wave transmission line configured in a linear shape. FIG. 10 is a diagram showing an example of a surface wave transmission line configured in a spindle shape. FIG. 11 is a diagram showing a configuration example in which the surface of a dielectric having a high dielectric constant as a surface wave transmission line is covered with another dielectric layer having a lower dielectric constant. FIG. 12 is a diagram illustrating a configuration example of a surface acoustic wave transmission line whose permittivity continuously changes according to the distance r from the center. FIG. 13 is a diagram showing a state in which a dielectric having a high dielectric constant is embedded as another surface acoustic wave transmission line in another dielectric having a low dielectric constant. FIG. 14 is a diagram illustrating an example in which the surface acoustic wave transmission line is configured by a plurality of dielectric bodies (or magnetic bodies) separated in the middle instead of a single dielectric body (or magnetic body). FIG. 15 is a diagram illustrating a configuration example of a contactless communication device using a surface wave transmission line. FIG. 16 is a diagram showing an electric field component (longitudinal wave component) ER that vibrates in a direction parallel to the propagation direction. FIG. 17A is a diagram showing the relationship between the transmission line length and the propagation loss when PPS (polyphenylene sulfide resin) as the dielectric, NiZn ferrite as the magnetic material, and a magnet are used in the surface wave transmission line, respectively. FIG. 17B is a diagram illustrating a material used as a surface acoustic wave transmission line. FIG. 17C is a diagram for explaining the propagation loss. FIG. 18A is a diagram illustrating a state of a current flowing through an electrode when a high-frequency transmission line is connected to the center of the electrode of the high-frequency coupler. FIG. 18B is a diagram illustrating a state in which an unequal current flows in the electrode and radiates unnecessary radio waves when the high-frequency transmission line is connected to a position having an offset from the center of the electrode of the high-frequency coupler. FIG. 19 is a diagram illustrating a configuration example of a contactless communication system using an electrostatic field or an induction field. FIG. 20 is a diagram illustrating a configuration example of a high-frequency coupler disposed in each of the transmitter 10 and the receiver 20. FIG. 21 is a diagram showing a state in which the high-frequency couplers shown in FIG. 20 are arranged to face each other and a bandpass filter is configured as a whole. FIG. 22 is a diagram showing an equivalent circuit of a bandpass filter including a set of high-frequency couplers. FIG. 23 is a diagram showing an equivalent circuit when the high-frequency coupler shown in FIG. 20 functions as an impedance conversion circuit. FIG. 24 is a diagram showing the results of measuring the propagation loss while changing the distance by placing the antenna, the coupler (when there is a parallel inductor), and the coupler (when there is no parallel inductor) facing each other. 25 is a diagram showing an actual configuration example of the high-frequency coupler shown in FIG. FIG. 26 is a diagram showing a state in which the electromagnetic field generated by the minute dipole is mapped onto the coupling electrode. FIG. 27 is a diagram showing a state in which a high-frequency signal is transmitted by interposing a surface wave transmission line made of a dielectric between two high-frequency couplers 1 and 2 facing each other. FIG. 28A is a diagram showing a change in the electric field distribution in the zx plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 28B is a diagram showing a change in the electric field distribution in the zx plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 28C is a diagram showing a change in the electric field distribution in the zx plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 28D is a diagram showing a change in the electric field distribution in the zx plane for a half cycle at 1/12 cycle intervals when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 28E is a diagram showing a change in the electric field distribution in the zx plane for a half cycle at 1/12 cycle intervals when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 28F is a diagram showing a change in the electric field distribution in the zx plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 29A is a diagram showing a change in the magnetic field distribution in the xy plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 29B is a diagram showing a change in the magnetic field distribution in the xy plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 29C is a diagram showing a change in the magnetic field distribution in the xy plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 29D is a diagram showing a change in the magnetic field distribution in the xy plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted via a surface wave transmission line in the configuration shown in FIG. It is. FIG. 29E is a diagram showing a change in the magnetic field distribution in the xy plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 29F is a diagram showing a change in the magnetic field distribution in the xy plane for a half cycle at a 1/12 cycle interval when a high frequency signal is transmitted through a surface wave transmission line in the configuration shown in FIG. It is. FIG. 30 is a diagram schematically showing an electric field distribution and a magnetic field distribution generated around a surface wave transmission line made of a dielectric. Figure 31A is a diagram field E _R of the longitudinal waves generated in the surface of the coupling electrode of the high-frequency coupler showing how possess as a surface wave at an end of the surface-wave transmission line made of a dielectric. Figure 31B is a diagram field E _R of the longitudinal waves generated in the surface of the coupling electrode of the high-frequency coupler showing how possess as a surface wave at an end of the surface-wave transmission line made of a dielectric. Figure 32, in the configuration shown in FIG. 27 is a diagram showing the result obtained by simulation using the finite element method the propagation loss S ₂₁ when varying the size of the transceiver each of the coupling electrode. Figure 33, in the configuration shown in FIG. 27 is a diagram showing the result obtained by simulation using the finite element method the propagation loss S ₂₁ when varying the thickness of the surface-wave transmission line. FIG. 34 is a diagram showing a result of obtaining a propagation loss S ₂₁ by simulation using the finite element method when the relative permittivity and relative permeability of the surface wave transmission line are changed in the configuration shown in FIG. FIG. 35 is a diagram illustrating a configuration example when the communication system illustrated in FIG. 3 is applied to power transmission. FIG. 36 is a diagram illustrating another configuration example in which the communication system illustrated in FIG. 3 is applied to power transmission.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Transmitter 11 ... Transmission circuit part 12 ... Resonance part 12A ... Parallel inductor 12B ... Series inductor 13 ... Transmitting electrode 20 ... Receiver 21 ... Reception circuit part 22 ... Resonance part 23 ... Reception electrode 30 ... Surface wave transmission line 31 ... Outer layer

Claims (13)

A transmitter circuit unit that generates a high-frequency signal for transmitting data; a transmitter including a high-frequency coupler that transmits the high-frequency signal as an electrostatic magnetic field;
A high-frequency coupler, and a receiver including a receiving circuit unit that receives and processes a high-frequency signal received by the high-frequency coupler;
Surface wave propagation means for providing a surface wave transmission line for transmitting surface waves radiated from the high frequency coupler on the transmitter side with low propagation loss;
A communication system comprising: The high-frequency signal is a UWB signal that uses an ultra-wideband.
The communication system according to claim 1. The surface wave transmission line is composed of a dielectric having a dielectric constant ε greater than the dielectric constant ε _{0 of} air.
The communication system according to claim 1. The surface wave transmission line is composed of a dielectric having a larger dielectric constant toward the inner side.
The communication system according to claim 3. The surface wave transmission line is embedded in another dielectric having a low dielectric constant.
The communication system according to claim 3. The surface wave transmission line is composed of a magnetic material having a permeability μ larger than the permeability μ _{0 of} air.
The communication system according to claim 1. The surface wave transmission line is composed of a magnetic material having a larger permeability toward the inside,
The communication system according to claim 6. The surface wave transmission line is embedded in another magnetic body having a lower magnetic permeability,
The communication system according to claim 6. The surface wave transmission line is composed of a plurality of dielectric bodies (or magnetic bodies) separated in the middle,
The communication system according to claim 1. The receiver rectifies the high-frequency signal received by the high-frequency coupler and generates power.
The communication system according to claim 1. A device housing;
A communication circuit unit for processing a high-frequency signal that transmits data, a resonance unit that resonates a high-frequency signal that is output from the communication circuit unit at a desired frequency, and a central portion that are housed in the device casing. A coupling electrode connected to the resonance part;
A surface wave transmission line disposed on the front surface of the coupling electrode in a direction substantially perpendicular to the electrode surface;
The surface wave transmission line captures an electromagnetic field generated near the front of the coupling electrode, and transmits the inside of the line as a surface wave.
A communication device. The surface wave transmission line captures the surface wave radiated from the coupling electrode and guides it to a desired site on the surface of the housing.
The communication device according to claim 11. The resonance unit includes a series inductor and a parallel inductor.
The communication device according to claim 11.