JP2012064996A - Electric field communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the intensity of an electric field signal induced by an electric field transmission medium and improve a receiving sensitivity.SOLUTION: An electric field communication device has: a first electrode 11 arranged on an outer surface of a housing 10; a second electrode 12 electrically connected to a terminal of a communication circuit, to which a potential to be a reference for a potential is inputted, and arranged on the outer surface of the housing separately from the first electrode; and a first dielectric body 13 and a second dielectric body 14 arranged on respective surfaces of the first and second electrodes respectively and that have a specific dielectric constant larger than a predetermined specific dielectric constant and a thickness larger than a predetermined thickness.

Description

  The present invention relates to an electric field communication technique for transmitting and receiving data using an electric field.

  According to Patent Documents 1 and 2, an electric field communication technique is disclosed in which an electric field is induced in an electric field transmission medium such as a human body and data communication is performed using the induced electric field. Hereinafter, an external configuration of the electric field communication apparatus having such a technique will be described.

  FIG. 7 is an external view of a conventional electric field communication device viewed from a perspective direction. The electric field communication device 100 is externally arranged with a housing 10 that stores therein a communication circuit (not shown) that performs electric field communication, and is electrically connected to the communication circuit and disposed on one surface of the housing 10. The first electrode 11 is connected to the communication circuit, and the second electrode 12 is disposed on the other surface of the housing 10 facing the one surface. .

  This electric field communication device 100 detects the electric field generated between the two electrodes when either the first electrode 11 or the second electrode 12 contacts the human body, for example, and converts it into an electrical signal for data. Send and receive. Either the first electrode 11 or the second electrode 12 serves as an input / output potential for inputting and / or outputting a data potential to the communication circuit, and the other serves as a reference potential for the input / output potential.

  The first electrode 11 and the second electrode 12 are generally made of a good metal conductor, and are electrically connected to other components (for example, the communication circuit and other electric circuits) constituting the electric field communication device 100. Therefore, the surface of each electrode is covered with a thin insulator such as an insulating film. For example, an insulating film such as a polypropylene film or a polyethylene film is attached. The dielectric constant of the insulator used in this way is about 2 to 3, and its thickness is generally about 0.3 mm or less, and a thinner one is preferable. By covering the surface of each electrode with an insulator, direct human contact with each electrode exposed to the outside is prevented and both electrodes are protected.

JP 2001-352298 A JP 2010-81082 A

  As described above, even if a conventional insulator is interposed between each electrode and the electric field transmission medium, the electric field communication performance is not deteriorated, but the electric field induced in the electric field transmission medium from each electrode. There is a problem that the reception sensitivity is low because of the low intensity.

  The present invention has been made in view of the above, and it is an object of the present invention to increase the strength of an electric field signal induced in an electric field transmission medium and improve reception sensitivity.

  The electric field communication device according to claim 1, wherein an electric field communication device that induces an electric field based on data to be transmitted in an electric field transmission medium and transmits / receives data using the electric field includes a communication circuit for electric field communication. The housing is electrically connected to the terminal of the communication circuit to which the potential as the data is inputted and outputted, and is a reference with respect to the first electrode disposed on the outer surface of the housing. A second electrode that is electrically connected to a terminal of the communication circuit to which a potential is input, and that is spaced apart from the first electrode and disposed on an outer surface of the housing; the first electrode; and the first electrode And a plurality of dielectrics each having a relative dielectric constant larger than a predetermined relative dielectric constant and a thickness larger than a predetermined thickness.

  According to the present invention, a plurality of dielectrics disposed on the respective surfaces of the first electrode and the second electrode, each having a relative dielectric constant greater than a predetermined relative dielectric constant and a thickness greater than a predetermined thickness Therefore, it is possible to increase the strength of the electric field signal induced in the electric field transmission medium and improve the reception sensitivity.

  The electric field communication device according to claim 2 is the electric field communication device according to claim 1, wherein the dielectric has a relative dielectric constant of 4 or more and a thickness of 0.5 mm or more. .

  According to the present invention, since the dielectric according to claim 1 has a relative dielectric constant of 4 or more and a thickness of 0.5 mm or more, the strength of the electric field signal induced in the electric field transmission medium is further increased. In addition, the reception sensitivity can be improved reliably.

  The electric field communication apparatus according to a third aspect is the electric field communication apparatus according to the first or second aspect, wherein the dielectric is a glass epoxy resin.

  ADVANTAGE OF THE INVENTION According to this invention, the intensity | strength of the electric field signal induced by an electric field transmission medium can be increased, and a receiving sensitivity can be improved.

It is the external view which looked at the electric field communication apparatus from the perspective direction. It is the top view which looked at the cross section by the code | symbol 50 shown in FIG. 1 from the upper direction. It is the side view which looked at the cross section with the code | symbol 51 shown in FIG. 1 from the horizontal direction. This is an embodiment in the case where a person possesses the electric field communication device 100. It is an example of measurement data of electric field strength when changing the dielectric constant and thickness of a dielectric. It is another Example in case a human possesses the electric field communication apparatus 100. It is the external view which looked at the conventional electric field communication apparatus from the perspective direction.

  Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different modes and should not be construed as being limited to the description of the present embodiment.

  FIG. 1 is an external view of the electric field communication apparatus according to the present embodiment as seen from a perspective direction. FIG. 2 is a top view of the cross section at 50 shown in FIG. 1 as viewed from above. FIG. 3 is a side view of the cross section at 51 shown in FIG. Hereinafter, the configuration of the electric field communication apparatus 100 will be described with reference to FIGS. 1 to 3.

  The external appearance of the electric field communication apparatus 100 is as follows. The casing 10 forming the electric field communication apparatus 100, the first electrode 11, the second electrode 12 disposed opposite to the first electrode 11, and the first electrode 11 includes a first dielectric 13 covering 11 and a second dielectric 14 covering the second electrode 12.

  The housing 10 houses therein a communication circuit 20 that induces an electric field from the first electrode 11 and the second electrode 12 to perform data communication (data transmission / reception) by the electric field.

  The first electrode 11 is electrically connected to the first terminal 21 of the communication circuit 20 through which a potential as data to be transmitted / received is input / output via the first connection line 23, and the outer surface of the housing 10. Is arranged.

  The second electrode 12 is electrically connected via a second connection line 24 to the second terminal 22 of the communication circuit 20 to which a reference potential (for example, ground potential) with respect to a potential as data to be transmitted / received is input. The first electrode 11 is disposed on the outer surface of the housing 10 facing the outer surface. Note that the arrangement relationship between the first electrode 11 and the second electrode 12 does not necessarily have to be opposed to each other, and the electrodes need only be arranged apart from each other.

  The first dielectric 13 is disposed on the surface of the first electrode 11, the second dielectric 14 is disposed on the surface of the second electrode 12, and both dielectrics have a specific dielectric constant. It is characterized in that it is larger than the relative dielectric constant and the thickness (height component in the vertical direction shown in FIG. 1) is thicker than a predetermined thickness. It is preferable to use glass epoxy resin (relative dielectric constant: 4.5) used for a printed circuit board for each dielectric.

  From the above configuration, the relative dielectric constants of the first dielectric 13 and the second dielectric 14 disposed on the surfaces of the first electrode 11 and the second electrode 12 are increased and the thickness thereof is increased. As a result, the strength of the electric field signal induced in the electric field transmission medium can be increased, and the reception sensitivity can be improved.

  In particular, the relative dielectric constant of the first dielectric 13 and the second dielectric 14 is desirably 4 or more. The higher the relative dielectric constant of both dielectrics, the higher the above-mentioned effect. Therefore, there is no upper limit to the relative dielectric constant of each dielectric. However, if the substance that can be used as the dielectric is solid at room temperature or is easy to process, the upper limit is, for example, the relative dielectric constant of about 30 that the titanium oxide ceramic has.

  The thickness of the first dielectric 13 and the second dielectric 14 is preferably 0.5 mm or more. Since the above-mentioned effect obtained as the thickness of both dielectrics is increased, there is no upper limit to the thickness of each dielectric, like the relative dielectric constant. However, as shown in FIG. 5, which will be described later, depending on the type of substance constituting the dielectric, when the thickness exceeds a certain level, the rate of increase in the intensity of the electric field signal gradually decreases, and the above-described effect on the thickness increment is reduced. . Further, when the electric field communication device described in this embodiment is carried, it is not welcomed that the thickness increases. Therefore, if these are the conditions, for example, the upper limit of the thickness is about 7 mm.

  The electric field communication apparatus 100 having such a configuration, like the conventional electric field communication apparatus, induces an electric field based on data to be transmitted in the electric field transmission medium and performs an operation of transmitting and receiving data using the electric field. Since more specific operations are described in detail in Patent Documents 1 and 2, descriptions regarding the operations are omitted.

  Next, the operational effects of the first dielectric 13 and the second dielectric 14 having the above-described features will be described.

  FIG. 4 shows an embodiment in the case where a person possesses the electric field communication device 100. The electric field signal generated by the electric field communication device 100 is induced in the human body 1 through the first capacitor 30 coupled between the first electrode 11 and the human body 1 that are close to the human body side. In order to transmit the electric field signal induced in the human body 1 to the communication partner electrode 32 laid on the floor or passage, the potential of the second electrode 12 on the space side is stabilized (ideally fixed). It is necessary to be. This is because when the potential of the second electrode 12 on the space side is indefinite, the electric field signal generated from the electric field communication device 100 is radiated to the space with the potential on the human body side as a reference.

  The reference potential of the electric field signal induced in the human body is the ground potential, and the potential is determined by the second capacitor 31 coupled between the second electrode 12 on the space side and the ground 3. By increasing the second capacitance 31, the potential of the second electrode 12 becomes more stable, and the electric field signal induced in the human body can be increased.

  FIG. 5 is an example of measurement data of the electric field strength when the dielectric constant and thickness of the dielectric are changed. As the material constituting the insulator, foamed polystyrene having a relative dielectric constant of about 1, foamed polypropylene having a relative dielectric constant of about 1.5, and glass epoxy having a relative dielectric constant of about 4.5 are used. Each thickness is changed, and an electric field signal having a frequency of 5 MHz and an amplitude of about 18 Vp-p is transmitted from the electric field communication device 100 and transmitted to the receiving electrode installed on the floor via the simulated human body 1, and the receiving electrode The intensity of the electric field generated in the above is measured. From this measurement result, it can be understood that the electric field strength increases as the relative dielectric constant of the dielectric increases and as the thickness of the dielectric increases.

  For this reason, in the present embodiment, a dielectric having a relative dielectric constant larger than that of the prior art and thicker than that of the prior art is disposed on each surface of the first electrode 11 and the second electrode 12. As a result, the coupling between the human body 1 and the first electrode 11 and the coupling between the earth 3 and the second electrode 12 are strengthened, and the potential of the second electrode 12 is stabilized. As a result, the human body The electric field signal induced by the can be increased.

  In addition, as shown in FIG. 6, if the electric field communication apparatus 100 is utilized in the vicinity of the metal door 5 having a ground potential, the above effect can be further enhanced. This is because the distance between the second electrode 12 and the ground 3 is reduced, and thus the proportion of the high dielectric material occupied between the second electrode 12 and the ground 3 is increased.

  Further, the first dielectric 13 and the second dielectric 14 can be used as an auxiliary electrode for assisting the first electrode 11 and the second electrode 12.

  According to the present embodiment, each of the first electrode 11 and the second electrode 12 is disposed on each surface, the relative dielectric constant is larger than the predetermined relative dielectric constant, and the thickness is larger than the predetermined thickness. Since the first dielectric 13 and the second dielectric 14 are included, the coupling between the human body 1 and the first electrode and the coupling between the ground 3 and the second electrode 12 are enhanced. The intensity of the electric field signal induced in the human body 1 can be increased and the reception sensitivity can be improved.

  According to the present embodiment, the first electrode 11 and the second electrode 12 have a relative dielectric constant of 4 or more and a thickness of 0.5 mm or more, so that the electric field signal induced in the human body 1 The strength can be further increased, and the receiving sensitivity can be reliably improved.

DESCRIPTION OF SYMBOLS 1 ... Human body 3 ... Ground 5 ... Metal door 10 ... Housing 11 ... 1st electrode 12 ... 2nd electrode 13 ... 1st dielectric 14 ... 2nd dielectric 20 ... Communication circuit 21 ... 1st Terminal 22 ... Second terminal 23 ... First connection line 24 ... Second connection line 30 ... First capacity 31 ... Second capacity 32 ... Communication partner electrode 100 ... Electric field communication device

Claims (3)

In an electric field communication apparatus that induces an electric field based on data to be transmitted in an electric field transmission medium and transmits and receives data using the electric field.
A housing containing a communication circuit for electric field communication;
A first electrode electrically connected to a terminal of the communication circuit to which the potential as the data is input and output, and disposed on the outer surface of the housing;
A second electrode that is electrically connected to a terminal of the communication circuit to which a reference potential is input with respect to the potential, and is disposed on the outer surface of the housing apart from the first electrode;
A plurality of dielectrics disposed on each surface of the first electrode and the second electrode, each having a relative dielectric constant greater than a predetermined relative dielectric constant and a thickness greater than a predetermined thickness;
An electric field communication device comprising: The dielectric is
2. The electric field communication device according to claim 1, wherein the relative dielectric constant is 4 or more and the thickness is 0.5 mm or more. The dielectric is
The electric field communication device according to claim 1, wherein the electric field communication device is a glass epoxy resin.

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