JP2015130607A - Communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device in which transmission power is reduced and downsizing and thinning are easy.SOLUTION: A communication device comprises a substrate, a line having inductive reactance, a communication part, and a variable capacitance element. The substrate includes a ground part and a dielectric part laminated on the ground part, and a first surface includes the ground part and a second surface on the side opposite to the first surface includes the dielectric part. The line is provided on the second surface side. The communication part is provided on the second surface and connected to one end of the line and the ground part. The variable capacitance element has a conductor connected to the other end of the line and electrostatic capacitance between the conductor part and the ground part is variable when a human body touches or comes close to the conductor part.

Description

  Embodiments described herein relate generally to a communication device.

  The human body can be used as a part of the signal transmission path. For example, there is a biological communication apparatus in which an electromagnetic field generated between a signal electrode and a ground propagates on the surface of a human body.

  However, when the distance between the signal electrode and the ground is narrow, the capacity of the signal electrode increases, so that the reflection loss increases and it is difficult to efficiently generate an electromagnetic field on the human body surface.

  If the impedance is matched by bringing the ground into contact with the human body, the transmission efficiency is improved. However, if the signal electrode and the ground are brought into contact with each other at the same time, the potential difference is reduced, so that reception sensitivity may be lowered. In order to solve this, if the structure is such that the signal electrode on the receiving side is not in contact with the ground, the configuration on the receiving side and the transmitting side is different, and the communication apparatus becomes complicated.

Japanese Patent Laid-Open No. 10-229357

  Provided is a communication device that can reduce transmission power and can be easily reduced in size and thickness.

  The communication device according to the embodiment includes a substrate, a line having inductive reactance, a communication unit, and a variable capacitance element. The substrate includes a ground portion and a dielectric portion laminated on the ground portion, the first surface includes the ground portion, and the second surface opposite to the first surface is The dielectric part is included. The line is provided on the second surface side. The communication unit is provided on the second surface and is connected to one end of the line and the ground unit. The variable capacitance element has a conductor portion connected to the other end of the line, and a static electricity between the conductor portion and the ground portion by bringing a human body into contact with or close to the conductor portion. Capacitance can be changed.

1 is a schematic perspective view of a communication device according to a first embodiment. It is a block diagram of the communication system using the communication apparatus of 1st Embodiment. 1 is an equivalent circuit diagram of a communication device according to a first embodiment. It is a schematic diagram showing the modification of the place which attaches a communication apparatus. It is a model perspective view of the communication apparatus concerning a comparative example. It is a block diagram of the communication system of a comparative example. It is the equivalent circuit schematic of the communication apparatus of a comparative example. FIG. 8A is a graph showing the dependence of the voltage standing wave ratio on the frequency in the first embodiment, and FIG. 8B is a graph showing a comparison of the voltage standing wave ratio when the contact state is changed. . FIG. 9A is a schematic perspective view of a communication apparatus according to the second embodiment, and FIG. 9B and FIG. 9C are schematic views of a line used in the modification. FIG. 10A is a schematic perspective view of a communication apparatus according to the third embodiment, and FIG. 10B is an equivalent circuit diagram. FIG. 11A is a schematic perspective view of a communication apparatus according to the fourth embodiment, and FIG. 11B is an equivalent circuit diagram. It is a model perspective view of the communication apparatus concerning 5th Embodiment. It is a model perspective view of the communication apparatus concerning 6th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the drawings are schematic or conceptual, and the size ratio between the parts is not necessarily the same as the actual one. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a schematic perspective view of a communication apparatus according to the first embodiment.
The communication device 100 includes a substrate 103, a communication unit 104, an inductor unit 107, and a variable capacitance element 109.

  The substrate 103 includes a ground part 102 and a dielectric part 101 stacked on the ground part 102. The ground portion 102 is made of a conductor having a reference potential, for example, a metal layer such as copper or gold. The dielectric part 101 can be made of, for example, a glass epoxy resin. The substrate 103 includes a first surface 103a including the ground portion 102, and a second surface 103b provided on the opposite side of the first surface 103a and including the dielectric portion 101.

  The communication unit 104 is connected to one end of the inductor unit 107 via a signal line 105, a terminal 106, and the like arranged on the second surface 103b. The communication unit 104 is also connected to the ground unit 102. Note that a conductor (not shown) connected to the ground part 102 by a through hole (not shown) provided so as to reach the ground part 102 from the surface of the dielectric part 101 is provided, and the communication part 104 You may connect.

  The terminal 106 includes an outer conductor portion connected to the ground portion 102 and an inner conductor portion connected to the signal line 105. The outer conductor portion and the inner conductor portion are electrically insulated.

  Inductor portion 107 includes a conductive wire 107a and a core 107b. Moreover, the conducting wire 107a has a spiral structure or the like, and a core 107b made of a magnetic material or the like is provided so as to be surrounded by the spiral structure. That is, in the first embodiment, the line having inductive reactance is the inductance portion 107 including a spiral structure. One end of the conductive wire 107 a is connected to the terminal 106, and the other end is connected to the conductor portion 108. Conductive wire 107a is made of a material such as copper.

  The conductor portion 108 is disposed so as to be included inside the ground portion 102 when viewed from above. In FIG. 1, the conductor portion 108 is disposed on the second surface 103b side. The conductor 108 is made of a conductive material such as an electrode used in medical equipment, a conductive sheet such as copper foil, conductive ink, or a transparent conductive material. If conductive ink is used, the conductor portion 108 can be easily configured inside or outside the casing regardless of the structure of the casing. Further, if a transparent conductive material is used, the display content can be recognized even if it is placed on a display or an operation unit.

FIG. 2 is a configuration diagram of a communication system using the communication apparatus according to the first embodiment.
The communication device 100 and the communication device 200 communicate with each other using a part of the human body (living body) 20 as a signal transmission path. One hand of the human body 20 contacts the conductor portion 108 of the communication device 100. The other hand contacts the conductor portion 208 of the communication device 200. It may be in a state where they are close to each other by holding their hands without touching them.

  Note that the close state means that the human body 20 and the conductor portions 108 and 208 can be coupled by an electromagnetic field via a thin sheet or the like without directly contacting the conductor portions 108 and 208. A minute current or the like flows between one region of the human body 20 coupled to the conductor portion 108 and the other region of the human body 20 coupled to the conductor portion 208 to form the first transmission path TL1. In addition, the ground portion 102 and the ground portion 202 are coupled by an electromagnetic field via the atmosphere without passing through the ground, and become the second transmission line TL2. It is assumed that the communication device 100 is a transmission side and the communication device 200 is a reception side. Of course, a communication device capable of transmitting and receiving may be used.

FIG. 3 is an equivalent circuit diagram of the communication apparatus according to the first embodiment.
A signal is transmitted from the communication unit 104 to the conductor unit 108 via the terminal 106 and the inductor unit 107. The inductor unit 107 is represented as a parallel connection circuit of an inductance and a capacitance generated between lines of a spiral structure. The conductor portion 108 forms a capacitor with the ground portion 102.

  In this figure, the communication unit 104 can have either a transmitter or a receiver. In addition, the communication unit 204 can include either a receiver or a transmitter.

  In the first embodiment, the conductor portion 108 is connected to the other end portion of the inductor portion 107. The inductor unit 107 includes a capacitance between the spiral structures, but the capacitor generated between the conductor unit 108 and the ground unit 102 and the inductive reactance of the inductor unit 107 are connected in series.

  A capacitor represented by an equivalent circuit is the variable capacitance element 109. The capacitance (C1) of the variable capacitance element 109 changes depending on the coupling state between the conductor 108 and the human body 20. In the first embodiment, the inductive reactance of the inductor unit 107 is determined so that impedance matching can be obtained with the capacitance C <b> 1 coupled to the human body 20. Thereby, when the human body 20 which is the basis of human body communication contacts the communication apparatus, it can communicate efficiently.

In this way, the impedance Z _L viewed from the one end of the line having inductive reactance to the variable capacitive element 109 (in a state coupled to the human body 20) on the load side, and the impedance of the communication device 104 Can be matched in-band.

  The signal electrode generates and receives not only the electric field perpendicular to the surface of the human body 20 by the conductor 108 but also a magnetic field perpendicular to the surface of the human body 20 by the inductor 107 having a spiral structure. Electric power can be reduced.

FIG. 4 is a schematic diagram illustrating a modified example of the attachment location of the communication device.
For example, the communication unit 104 including a transmitter can be provided in the chest, and the communication unit 204 including a receiver can be provided in the abdomen. In this way, it is easy to configure a wearable biosensor. Further, the communication device according to the first embodiment can transmit ID information (identification information), an audio signal, and the like.

FIG. 5 is a schematic perspective view of a communication device according to a comparative example.
FIG. 6 is a configuration diagram of a communication system of a comparative example.
FIG. 7 is an equivalent circuit diagram of the communication device of the comparative example.
In the comparative example, communication is performed using a signal electrode formed by only the conductor portion 408. Therefore, the equivalent circuit shown in FIG. 7 is represented only by the capacitance 601 in which the conductor portion 408 is generated in the ground portion 402. The capacitance 601 is inversely proportional to the distance between the conductor portion 408 and the ground portion 402. For this reason, when the interval is narrow, the capacitance of the signal electrode is increased. As a result, a signal input from the terminal 406 to the conductor portion 408 is reflected and is not transmitted to the communication device 500, resulting in a loss.

8A is a graph showing the dependence of the voltage standing wave ratio on the frequency, and FIG. 8B is a graph showing a comparison of the voltage standing wave ratio when the contact state is changed.
The vertical axis represents the voltage standing wave ratio, and the horizontal axis represents the frequency (MHz).
In FIG. 8A, the voltage standing wave ratio was measured in a state where the human body 20 was in contact with the conductor portion 108. In the comparative example, the voltage standing wave ratio was as high as 8 or more in the band to be used.

  A voltage standing wave VSWR (VSWR: Voltage Standing Wave Ratio) is expressed by Equation (1) using a voltage reflection coefficient Γ.

Further, the reflection loss L _REF (dB)) is expressed by Expression (2) using the voltage reflection coefficient Γ.

In the comparative example, since the voltage standing wave ratio is 8 or more, the reflection loss L _REF increases to 4 dB or more. For this reason, it is difficult to reduce transmission power. On the other hand, in the first embodiment, the voltage standing wave ratio can be made close to 1 at the frequency f. For this reason, the reflection loss L _REF can be reduced to near zero.

In the first embodiment, as shown in FIG. 8B, in the non-contact state between the conductor 108 and the human body 20, the voltage standing wave ratio is approximately 4.1 in the vicinity of 11.7 MHz, The reflection loss L _REF is large. On the other hand, in the coupled state, the voltage standing wave ratio is approximately 1.3 in the vicinity of 10.6 MHz, the impedance matching is well taken, and the reflection loss L _REF can be reduced. In addition, the transmission power of the first embodiment was 9.7 dB higher than the transmission power of the comparative example. The received power of the first embodiment can be 1.6 dB lower than the received power of the comparative example.

(Second Embodiment)
FIG. 9A is a schematic perspective view of a communication apparatus according to the second embodiment, and FIGS. 9B and 9C are schematic views of an inductive reactance line used in the modification.
As shown in FIG. 9A, in the communication device 800 according to the second embodiment, the inductor unit 807 includes a conducting wire 807a and a magnetic body 807b such as ferrite. The conducting wire 807a has a folded meander structure and is provided on the magnetic body 807b. That is, the line having inductive reactance is the inductor portion 807 including a meander structure. One end of the conducting wire 807 a is connected to the terminal 106. In addition, the other end of the conductive wire 807a is connected to the conductor portion.

  Thus, by providing the meander-shaped portion on the magnetic body 807b, a planar shape can be obtained. In addition, since the magnetic body 807b is a magnetic sheet that can be easily bent, it can be attached to a side surface or the like on the inner side of the housing, and mounting becomes easy.

  9B and 9C, a line having inductive reactance is realized by providing a zigzag line pattern 822 on a magnetic body 820 such as ferrite. FIG. 9B is a schematic plan view, and FIG. 9C is a schematic cross-sectional view along the line AA.

(Third embodiment)
FIG. 10A is a schematic perspective view of a communication apparatus according to the third embodiment, and FIG. 10B is an equivalent circuit diagram.
In the communication device 900, a line having inductive reactance further includes a chip inductor unit 901. The chip inductor unit 901 is connected in series between the inductor unit 107 and the terminal 106. By providing the chip inductor 901 part, the shape of the inductor part 107 for obtaining a desired inductive reactance can be reduced.

(Fourth embodiment)
FIG. 11A is a schematic perspective view of a communication apparatus according to the fourth embodiment, and FIG. 11B is an equivalent circuit diagram.
A chip capacitor 1101 is provided in parallel with the variable capacitance element 109. That is, one end of the chip capacitor 1101 is connected to the conducting wire 107 a of the inductor unit 107 via the terminal 1102. The other end is connected to a through hole 1103 connected to the ground portion 102. For this reason, a desired capacitive reactance can be obtained even if the size of the conductor portion 108 is limited due to mounting requirements.

(Fifth embodiment)
FIG. 12 is a schematic perspective view of a communication apparatus according to the fifth embodiment.
The inductor unit 107 includes two spiral structures that are connected in series and orthogonal to each other. In this way, a diversity effect can be obtained with respect to the magnetic field, and transmission / reception gain can be improved.

(Sixth embodiment)
FIG. 13 is a schematic perspective view of a communication apparatus according to the sixth embodiment.
The conductor portion can be provided on at least one of the first surface 103 a side and the second surface 103 b side of the substrate 103. In the sixth embodiment, the conductor portion 1409 is also provided on the side opposite to the conductor portion 108 (the first surface side) with respect to the substrate 103. In the equivalent circuit, two variable capacitance elements are connected in parallel to the end of the inductor unit 107. For this reason, even if the human body 20 is in contact with or close to either the upper surface or the lower surface of the communication device 1400, a desired capacitance can be obtained between the conductor portion and the ground portion 102.

  According to the first to sixth embodiments, the line having inductive reactance and the conductor portion are connected in series. In addition, the variable capacitance element 109 and a line having inductive reactance are connected in series. The capacitance C1 of the variable capacitance element changes when the human body 20 is in contact with or close to the conductor portion. By changing the capacitance C1 of the variable capacitance element 109, the impedance of the communication unit can be matched with the impedance of the variable capacitance element 109 viewed from one end of the line. For this reason, transmission power can be reduced.

  Similarly, by providing the communication device on the reception side with a line having inductive reactance and a variable capacitance element, impedance matching can be achieved on the reception side as well. For this reason, transmission power can be further reduced in the entire communication system.

  Such a communication device can be used for a biosensor, a contact sensor, a tablet PC, an NFC (Near Field Communication) compatible IC card, and the like.

  Note that the present invention is not limited to the above-described embodiment, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

20 human body (living body), 100, 800, 900, 1100, 1300, 1400 communication device, 101 dielectric unit, 102, 202 ground unit, 103 substrate, 103a first surface, 103b second surface, 104, 204 communication Part, 107 inductor part, 108, 208, 1409 conductor part, 109 variable capacitance element, C1 (variable capacitance element) capacitance

If the impedance is matched by bringing the ground into contact with the human body, the transmission efficiency is improved. However, if the signal electrode and the ground are brought into contact with the human body at the same time, the potential difference is reduced, so that the reception sensitivity may be lowered. In order to solve this problem, if the structure is such that the signal electrode on the reception side and the ground are not in contact with the human body at the same time , the configuration is different between the reception side and the transmission side, and the communication device becomes complicated.

The communication device according to the embodiment includes a substrate, a line having inductive reactance, a communication unit, and a variable capacitance element. The substrate includes a ground portion and a dielectric portion laminated on the ground portion, the first surface includes the ground portion, and the second surface opposite to the first surface is The dielectric part is included. The line is provided on the second surface side. The communication unit is provided on the second surface and is connected to one end of the line and the ground unit. The variable capacitance element has a conductor portion connected to the other end portion of the line, and when a human body is in contact with or close to the conductor portion, a static electricity between the conductor portion and the ground portion is formed. Capacitance can be changed.

1 is a schematic perspective view of a communication device according to a first embodiment. It is a block diagram of the communication system using the communication apparatus of 1st Embodiment. 1 is an equivalent circuit diagram of a communication device according to a first embodiment. It is a schematic diagram showing the modification of the place which attaches a communication apparatus. It is a model perspective view of the communication apparatus concerning a comparative example. It is a block diagram of the communication system of a comparative example. It is the equivalent circuit schematic of the communication apparatus of a comparative example. It is a graph showing the voltage standing wave ratio dependence with respect to the frequency in 1st Embodiment. FIG. 9A is a schematic perspective view of a communication apparatus according to the second embodiment, and FIG. 9B and FIG. 9C are schematic views of a line used in the modification. FIG. 10A is a schematic perspective view of a communication apparatus according to the third embodiment, and FIG. 10B is an equivalent circuit diagram. FIG. 11A is a schematic perspective view of a communication apparatus according to the fourth embodiment, and FIG. 11B is an equivalent circuit diagram. It is a model perspective view of the communication apparatus concerning 5th Embodiment. It is a model perspective view of the communication apparatus concerning 6th Embodiment.

FIG. 8 is a graph showing the dependence of the voltage standing wave ratio on the frequency.
The vertical axis represents the voltage standing wave ratio, and the horizontal axis represents the frequency (MHz).
In FIG. 8, the voltage standing wave ratio was measured in a state where the human body 20 was in contact with the conductor portion 108. In the comparative example, the voltage standing wave ratio was as high as 8 or more in the band to be used.

In the comparative example, since the voltage standing wave ratio is 8 or more, the reflection loss L _REF increases to 4 dB or more. On the other hand, in the first embodiment, the voltage standing wave ratio can be made close to 1 at the frequency f. For this reason, the reflection loss L _REF can be reduced to near zero.

Also, the transmission power of the first embodiment could 9.7dB higher than the transmission power of the comparative example. Received power of the first embodiment could 1.6dB rather higher than the received power of the comparative example.

Claims (12)

A ground portion and a dielectric portion laminated on the ground portion, wherein the first surface includes the ground portion, and the second surface opposite to the first surface is the dielectric portion. Including a substrate;
A line provided on the second surface side and having an inductive reactance;
A communication unit provided on the second surface and connected to one end of the line and the ground unit;
It has a conductor part connected to the other end of the line, and the capacitance between the conductor part and the ground part can be changed by bringing a human body into contact with or close to the conductor part. A variable capacitance element;
A communication device comprising:   The impedance of the variable capacitance element side viewed from the one end of the line within the band of the communication unit can be matched with the impedance of the communication unit by changing the capacitance. The communication apparatus according to 1.   The communication device according to claim 1, wherein the line includes two regions intersecting each other and connected in series.   The communication device according to claim 3, wherein the two regions of the line are orthogonal to each other.   The communication device according to claim 1, wherein the line is disposed outside the ground portion when viewed from above.   The communication device according to claim 1, wherein the line has a spiral structure.   The communication device according to claim 6, wherein the line includes a magnetic body extending along a central axis of the spiral structure in the spiral structure.   The communication device according to claim 6, wherein the first conductor portion is capable of contacting or approaching the human body such that the central axis of the spiral structure is parallel to the surface of the human body.   The communication device according to claim 1, wherein the line has a meander structure.   The communication device according to claim 9, wherein the meander structure is formed on a magnetic body.   The communication device according to claim 1, wherein the conductor portion is provided on at least one of the first surface side and the second surface side.   The communication device according to claim 11, wherein the variable capacitance element is disposed inside the ground portion when viewed from above.

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