JP5487222B2 - Composite antenna and communication device using the same - Google Patents

Description

  The present invention relates to a composite antenna that combines an antenna that performs communication by a change in a magnetic field and an antenna that performs communication by a change in an electric field, and a communication device using the composite antenna.

  In recent years, with the spread of wireless communication technology, opportunities for communication between communication devices using a wireless interface have increased regardless of wired connection such as an AV (Audio Visual) cable or a USB (Universal Serial Bus) cable. Yes. There are various communication media used by the wireless interface, and wireless interfaces using a radiation field and a near field have been put into practical use.

  In particular, the communication system using the near field is designed so that communication can be performed when the distance between the transmitting antenna and the receiving antenna is close because the attenuation of the radio signal is large. Since communication can be performed only when the antennas are close to each other, interference due to radio signals of other users using the same communication method can be avoided. Therefore, the communication method using the near field can perform simple communication because there is no need to perform an authentication process or an encryption / decryption process assuming interference with other users.

  In the near field, for example, a communication method using an induction magnetic field is a communication system that has a function of an electronic ticket for transportation by communicating between a ticket gate and a communication device or a card, or communication with an electronic register. It is used for various purposes such as those that have a function of electronic payment by communicating with a device (see, for example, Patent Document 1). On the other hand, in the near field, the communication method using an induced electric field and an electrostatic field (hereinafter simply referred to as an induced electric field) dominant in near field communication using an electric field preserved music and video content. It is used for various purposes such as an electronic device having a storage device and an electronic device having a playback device that has a function of transferring content by performing communication (for example, see Patent Document 2). reference).

  In recent years, a communication method for performing communication at such a short distance is generally referred to as non-contact communication, and in recent years, in view of simplicity of processing at the time of use and easy understanding of intuitive operation of performing communication by contacting a communication device, It is a communication method that has become widespread. In addition, non-contact communication is being applied to small communication devices that can be carried because of the feature of contacting communication devices.

JP 2002-64403 A JP 2008-182714 A

  The communication method using the induction magnetic field and the communication method using the induction electric field have different applications. Therefore, there is a demand to provide a service combining two antennas by installing a composite antenna using two communication systems in a communication device. For example, a service is conceivable in which electronic payment is performed using an antenna using an induced magnetic field, and content whose payment has been completed is transferred to a communication device using an antenna using an induced electric field.

  By the way, in a portable communication device, it is necessary to configure the communication device as small as possible in order to improve portability. Therefore, the electronic device mounted in the communication apparatus is not only configured to be small, but also must be disposed at a close position. The antenna using the induction magnetic field and the antenna using the induction electric field need to be provided in close proximity in the communication device. For this reason, when using an antenna using an induction magnetic field, there is a possibility that magnetic flux may be input to the antenna using an induction electric field.

  An antenna using an induction electric field or the like is generally composed of a flat metal plate called a coupler element. When magnetic flux is input to the metal plate, an induced electromotive force is generated in the metal plate in accordance with Faraday's law of electromagnetic induction, and current flows. Since this current flows like a vortex around the metal plate, it is generally called an eddy current. A magnetic flux is generated according to the eddy current flowing in the metal plate, and this magnetic field is generated in a direction that cancels the magnetic flux input to the metal plate.

  Therefore, when an antenna using an induced magnetic field and an antenna using an induced electric field are arranged close to each other, the induced electromotive force generated in the antenna using the induced magnetic field is attenuated by the magnetic flux from the antenna using the induced electric field. To do. As a result, there is a problem that sufficient induction current does not flow to the antenna using the induction magnetic field, and communication cannot be performed satisfactorily.

  The present invention has been made to solve the above problems, and by suppressing eddy currents generated in an antenna using an induced electric field or the like, an antenna using an induced magnetic field and an antenna using an induced electric field or the like are provided. An object of the present invention is to provide a composite antenna arranged close to each other and a communication device using the same.

According to the embodiment, the composite antenna includes a conductor that couples the first modulated wave with an electromagnetic wave belonging to an electrostatic field or an induced electric field, and the conductor has the same area by a notch at a position where the edge is divided. A first antenna having a shape in which a plurality of portions are combined; and a second antenna including a conductor that couples the second modulated wave with an electromagnetic wave belonging to an induced magnetic field.

  According to another embodiment, a communication device includes a conductor that couples the first modulated wave with an electromagnetic wave belonging to an electrostatic field or an induction electric field, and the conductor has the same notch by a notch at a position that divides the edge. A first antenna having a shape in which a plurality of areas are combined, and a first reception circuit that receives the first modulated wave from the first antenna and generates a first reception signal And a second antenna comprising a conductor for coupling the second modulated wave with an electromagnetic wave belonging to the induced magnetic field, and receiving the second modulated wave from the second antenna and receiving a second received signal And a second receiving circuit unit to be generated.

  ADVANTAGE OF THE INVENTION According to this invention, the composite antenna which reduced the interference generate | occur | produced when the antenna using an electrostatic field, an induction electric field, etc., and the antenna using an induction magnetic field were made to approach, and a communication apparatus using the same are provided. it can.

The figure which shows the structure of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which shows the mode of generation | occurrence | production of the cancellation magnetic field of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which shows the mode of generation | occurrence | production of an eddy current of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which shows the simulation model of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which showed the reflective characteristic in the simulation model of FIG. 4 of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which shows another simulation model of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which showed the reflective characteristic in the simulation model of FIG. 6 of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which showed the other structure of the electric field receiving antenna of the composite antenna which concerns on the 1st Embodiment of this invention. The figure which shows the structure of the composite antenna which concerns on the 2nd Embodiment of this invention. The figure which shows the circuit structure of the electric field receiving antenna of the composite antenna which concerns on the 2nd Embodiment of this invention. The figure which shows the structure which added the magnetic sheet of the composite antenna in this embodiment. The figure which shows the structure which separated the position of the feeding point of the composite antenna in this embodiment.

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

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a composite antenna according to the first embodiment.

(Composite antenna configuration)
The receiver 1 forming the composite antenna of the present embodiment is integrally configured by combining an antenna that uses an induced electric field or the like and an antenna that uses an induced magnetic field. An antenna that uses an induced electric field or the like includes a receiving electrode 2 made of a flat metal conductor and a receiving circuit unit 3 that performs signal processing on a current generated from the receiving electrode 2. An antenna that uses an induced magnetic field includes a receiving loop 5 that is a loop of a thin metal conductor disposed so as to surround the outside of the receiving electrode 2, and a receiving circuit unit 6 that performs signal processing on the current generated from the receiving loop 5. Composed.

  In addition, a transmitter 7 serving as a first transmission means that communicates with the receiver 1 is coupled to the reception electrode 2 of the receiver 1 to transmit an induction electric field and the like, and the transmission electrode 8 is supplied with electric power. The transmission circuit unit 9 is configured to be supplied. Further, the transmitter 10 serving as the second transmission means is opposed to the reception loop 5 of the receiver 1 and generates a magnetic flux according to the applied electrical signal, and according to the applied electrical signal. The transmission circuit unit 12 supplies power to the transmission loop 11.

  When the receiver 1 and the transmitter 7 configured as described above perform communication, the reception electrode 2 and the transmission electrode 8 are coupled to face each other, and high-frequency modulated power is transmitted from the transmission circuit unit 9 of the transmitter 7. Feed to electrode 8. Specifically, 1 GHz to 100 GHz is used as the high frequency. Then, an electric field component that is parallel and orthogonal to the traveling direction of the electric field modulated at high frequency is induced from the transmitting electrode 8, and this electric field propagates in the direction of the receiving electrode 2 of the receiver 1. The electric field applied to the receiving electrode 2 is input to the receiving circuit unit 3 as a high-frequency modulated current and is subjected to signal processing by the receiving circuit unit 3. In the so-called near field, most of the field is occupied by an induced electric field or the like and an electric field belonging to a quasi-electrostatic field. Attenuates in proportion to. Therefore, the receiving electrode 2 of the receiver 1 and the transmitting electrode 8 of the transmitter 7 are coupled to each other only when they are sufficiently close to each other, for example, 3 cm or less, and communication cannot be performed.

  On the other hand, when the receiver 1 and the transmitter 10 communicate with each other, the reception loop 5 and the transmission loop 11 are brought close to each other, and the low-frequency modulated power from the transmission circuit unit 12 of the transmitter 10 is sent to the transmission loop 11. Apply. Specifically, 10 MHz to 20 MHz is used as the low frequency. Then, a magnetic field is generated from the current flowing in the transmission loop 11, and a part of the magnetic field generated from the transmission loop 11 is applied to the reception loop 5 of the receiver 1. The magnetic flux density in the reception loop 5 changes due to the change in the magnetic field generated from the transmission loop 11. Due to this change in magnetic flux density, an induced current is generated in the receiving loop 5 based on Faraday's law of electromagnetic induction. This induced current is input to the receiving circuit unit 6 and is subjected to signal processing by the receiving circuit unit 6.

  Since the magnetic field radiated from the transmission loop 11 of the transmitter 10 attenuates according to the distance, it is necessary to perform communication in a state where the transmission loop 11 and the reception loop 5 are close to each other. The distance at which the transmission loop 11 and the reception loop 5 can communicate varies depending on the size of each loop and the amount of power input to the transmission loop 11. For example, in the case of an antenna for carrying out admission ticket processing for transportation facilities, a sufficient induced current is generated only when the antenna is sufficiently close to 10 cm or less, and communication cannot be performed. Each circuit in FIG. 1 is installed by a grounding point (not shown).

(Reduce eddy currents by forming slits)
FIG. 2 is a diagram showing how magnetic flux is generated when the receiver 1 and the transmitter 10 communicate with each other. As described above, the reception loop 5 of the receiver 1 generates an induced current when the magnetic flux 20 generated from the transmission loop 11 of the transmitter 10 is applied. When the induced current is input to the receiving circuit unit 6, the transmitting circuit unit 12 of the transmitter 10 and the receiving circuit unit 6 of the receiver 1 communicate with each other.

  By the way, the magnetic flux 20 applied to the reception loop 5 is also applied to the reception electrode 2 on the antenna side using an induction electric field or the like. When the magnetic flux 20 applied in the receiving electrode 2 changes, an electric field is generated in the receiving electrode 2 in accordance with Faraday's law of electromagnetic induction. Electrons in the receiving electrode 2 move by the generated electric field. As shown in FIG. 2, the electrons in the receiving electrode 2 move around the edge of the receiving electrode 2 when the magnetic flux 20 is applied to the receiving electrode 2 from the upper surface. The movement of electrons that circulate around the edge of the receiving electrode 2 can be regarded as a current. Since this current flows through the edge of the receiving electrode 2 so as to draw an eddy, it is generally called an eddy current. The eddy current 21 generated in the receiving electrode 2 generates a canceling magnetic flux 22 according to Ampere's law. The canceling magnetic flux 22 is generated in a direction opposite to the magnetic flux 20 applied to the receiving electrode 2 as shown in FIG. Since the magnetic flux 20 and the canceling magnetic flux 22 cancel each other, the amount of the magnetic flux 20 applied to the receiving loop 5 decreases as a result. As the amount of magnetic flux 20 applied to the receiving loop 5 of the antenna using the induced magnetic field decreases, the amount of induced current generated in the receiving loop 5 decreases. When the amount of induced current generated in the reception loop 5 decreases, the signal processing by the reception circuit unit 6 cannot be performed. Furthermore, the presence of such a conductor that generates the eddy current 21 in the reception loop 5 also applies to the transmission loop 11 that is disposed in close proximity when the receiver 1 and the transmitter 10 communicate with each other. , Causing a decrease in self-inductance due to eddy currents. Since the decrease of the self-inductance causes a resonance frequency shift of the transmission loop 11, the communication quality between the receiver 1 and the transmitter 10 is deteriorated as a result.

  As described above, the presence of a conductor such as the reception electrode 2 in the reception loop 5 causes various adverse effects when the receiver 1 and the transmitter 10 communicate with each other. It is desirable that there is no.

  Therefore, in this embodiment, a slit is formed in the receiving electrode 2 to divide the eddy current 21. By forming slits in the receiving electrode 2, components that cancel each other out in the divided eddy current 21 are generated, and the total amount of eddy current 21 generated in the receiving electrode 2 decreases. Thereby, the amount of the canceling magnetic flux 22 generated from the eddy current 21 can be reduced.

  FIG. 3 is a diagram showing the slit shape of the receiving electrode 2 and the state of the eddy current 21 generated in the slit shape. For example, as shown in FIG. 3A, the slit is formed with four linear grooves toward the center of the receiving electrode 2 vertically and horizontally from the point where the edge of the receiving electrode 2 is divided into two.

  FIG. 3C shows how the eddy current 21 is generated when the magnetic flux 20 is applied to the receiving electrode 2 in which the slit is formed. In FIG. 3C, the slit is inserted so that the receiving electrode 2 is divided into almost four parts. Therefore, when viewed from the process of generating the induced current, the receiving electrode 2 in which the slit is formed can be regarded as a shape in which four small receiving electrodes are combined.

  FIG. 3B shows how the eddy current 21 is generated when the magnetic flux 20 is applied to the receiving electrode 2 in which no slit is formed. The area of each leaf 2a to 2d of the receiving electrode 2 in FIG. 3C is a quarter of the area of the receiving electrode 2 in FIG. According to Faraday's law of electromagnetic induction, the amount of induced current generated in each leaf 2a-2d of the receiving electrode 2 is proportional to the amount of fluctuation of the magnetic flux 20 input into each leaf 2a-2d. Therefore, the amount of eddy current 21 generated in each of the leaves 2a to 2d of the receiving electrode 2 is a quarter of the eddy current 21 in FIG.

  Here, attention is paid to the eddy current 21 flowing in a place where the leaves 2a to 2d are in contact among the eddy currents 21 generated in the leaves 2a to 2d in FIG. Since the eddy currents 21 flowing at the locations where the leaves 2a to 2d are in contact with each other are flowing in opposite directions, the canceling magnetic fluxes 22 generated from each other cancel each other. If the components of the eddy current 21 that cancel each other are ignored, the eddy current 21 flowing in the receiving electrode 2 having the slits can be regarded as an eddy current 21 flowing in the receiving electrode 2 as shown in FIG. Since the current amount of the eddy current 21 shown in FIG. 3D is weakened by the cancellation of the eddy current 21 described above, it becomes equal to the current amount of the eddy current 21 flowing through the leaves 2a to 2d. As a result, the current amount of the eddy current 21 flowing in the leaves 2a to 2d of the receiving electrode 2 having the slit is weakened by about a quarter of that of the receiving electrode not forming the slit (FIG. 3B). I understand that. The thickness of the arrow line in FIG. 3 (d) and FIG. 3 (b) indicates the difference.

  When the amount of eddy current flowing in the receiving electrode 2 is weakened, the amount of the canceling magnetic flux 22 generated by the receiving electrode 2 is reduced. As a result, even when the magnetic flux 20 is applied to both the reception loop 5 and the reception electrode 2, the amount of the canceling magnetic flux 22 is reduced. It can be performed. Note that the size of the reception electrode 2 is usually configured to be larger than that of the transmission electrode 8. As the size of the receiving electrode 2 is increased, the amount of magnetic flux 20 applied to the receiving electrode 2 is increased, and the generation amount of the eddy current 21 and the canceling magnetic flux 22 is also increased. It is considered that the effect of suppressing the generation of the canceling magnetic flux 22 is great by forming a slit in the receiving electrode 2 where the generation amount of the canceling magnetic flux 22 is large.

  Although an example in which a slit is formed in the receiving electrode 2 has been described here, a slit having the same shape as that formed in the receiving electrode 2 may be formed in the transmitting electrode 8 of the transmitter 7.

  When the transmitter 7 and the transmitter 10 are integrally formed, the transmission electrode 8 of the transmitter 7 receives the magnetic flux transmitted from the transmission loop 11 of the transmitter 10, and an eddy current is generated in the transmission electrode 8. Occur. The eddy current generated in the transmission electrode 8 cancels out the magnetic flux similarly to the eddy current generated in the reception electrode 2 of the receiver 1. Therefore, by forming a slit in the transmission electrode 8 of the transmitter 7, generation of eddy current and cancellation magnetic flux is suppressed, and communication between the transmission circuit unit 12 of the transmitter 10 and the reception circuit unit 6 of the transmitter 7 is performed. Can do. When the transmitter 7 and the transmitter 10 are integrally formed, the distance between the transmission loop 11 of the transmitter 10 which is a magnetic flux generation source and the transmission electrode 8 of the transmitter 7 becomes very short. Therefore, the magnetic flux density input to the transmission electrode 8 also increases, and the amount of cancellation magnetic flux generated increases. It is considered that the effect of suppressing the generation of the canceling magnetic flux is large by forming the slit in the transmission electrode 8 having a large amount of the canceling magnetic flux.

(Resonance frequency shift of receiving electrode with slit)
Next, it is shown by simulation that the receiving electrode 2 in which the slit is formed has an effect of suppressing the generation of the eddy current 21 as compared with that in which the slit is not formed. FIG. 4 shows a simulation model in which the reception unit 1 that combines the reception loop 5 and the reception electrode 2 and the transmission units 7 and 10 that combine the transmission loop 11 and the transmission electrode 8 face each other. The size of each component of the receiving unit 1 and the transmitting units 7 and 10 and the facing distance between the receiving unit 1 and the transmitting units 7 and 10 are as shown in FIG. 4A shows a simulation model in which no slit is formed in the transmission electrode 8, and FIGS. 4B to 4E show simulation models in which a slit is formed. 4B to 4E, there are four types of slit lengths of 2 mm to 8 mm, respectively.

  As described above, the magnetic flux generated by the transmission loop 11 of the transmitter 10 is input to the transmission electrode 8 of the transmission unit 7. Since the transmission electrode 8 generates a canceling magnetic flux, the magnetic flux and the canceling magnetic flux cancel each other. Therefore, the amount of magnetic flux generated by the transmission loop 11 of the transmitter 10 is smaller than when the transmission electrode 8 is not present. Here, the transmission loop 11 can be regarded as an inductor. Therefore, the product of the amount of current injected into the transmission loop 11 and the self-inductance of the transmission loop 11 is proportional to the amount of magnetic flux generated by the transmission loop 11. The amount of magnetic flux generated by the transmission loop 11 has decreased due to the insertion of the transmission electrode 8, but this can be regarded as a decrease in inductance of the transmission loop 11. By the way, the resonance frequency of the transmission loop 11 of the transmitter 10 and the reception loop 5 of the receiver 1 is inversely proportional to the product of the inductance and capacitance of both. Therefore, it can be considered that insertion of the transmission electrode 8 of the transmission unit 7 reduces the apparent inductance of the transmission loop 11, and as a result, the resonance frequency increases.

  FIG. 5 shows a reflection spectrum of power in the transmission circuit unit 12 when a signal having a frequency of 10 to 20 MHz is radiated from the transmission loop 11 of the transmitter 10. It can be seen that the increase in the resonance frequency in FIGS. 5B to 5E in which the slits are formed is suppressed as compared with FIG. 5A in which the slits are not formed. Considering the increase in the resonance frequency caused by the insertion of the transmission electrode 8 in the transmission loop 11 described above, it can be understood that the decrease in inductance of the transmission electrode 8 is suppressed by the formation of the slit. Therefore, it can be said that the generation of eddy current is suppressed by the formation of the slit.

(Restriction condition of slit shape)
It has been stated that the slit has an effect of suppressing the generation of eddy currents and canceling magnetic fluxes regardless of whether the slit is formed on the reception electrode 2 or the transmission electrode 8. However, a portion where the metal conductor is separated by the slit width occurs due to the formation of the slit. The portion where the metal conductors are separated operates as a capacitor. Therefore, the formation of the slit causes a change in capacitance components of the reception electrode 2 and the transmission electrode 8. In particular, in order for the receiving electrode 2 and the transmitting electrode 8 to be coupled, the receiving electrode 2 needs to be impedance matched. If the slit formed in the receiving electrode 2 has a large capacitance component, the impedance of the receiving electrode 2 changes and impedance matching cannot be achieved. Therefore, the reception electrode 2 and the transmission electrode 8 do not resonate and communication cannot be performed.

  For these reasons, when a slit is formed in the reception electrode 2 of the reception unit 1, it is necessary to maintain a capacitance to such an extent that the reception electrode 2 and the transmission electrode 8 resonate. The capacitance that varies when formed on the receiving electrode 2 increases in proportion to the width of the slit. The simulation shows that the resonance state between the receiving electrode 2 and the transmitting electrode 8 in the high frequency region changes due to the formation of the slit.

  FIG. 6 shows another model of simulation in which the receiving unit 1 that combines the receiving loop 5 and the receiving electrode 2 and the transmitting units 7 and 10 that combine the transmitting loop 11 and the transmitting electrode 8 face each other. . The size of each component of the receiving unit 1 and the transmitting units 7 and 10 and the facing distance between the receiving unit 1 and the transmitting units 7 and 10 are as shown in FIG. 6 (F) to 6 (I), slits having different shapes are formed in the receiving electrode 2 of the receiving unit 1.

  FIG. 7A shows a power reflection spectrum in the transmission circuit unit 12 when a signal having a frequency of 15 to 20 MHz is radiated from the transmission loop 11 of the transmission unit 10. Reflection spectrum waveforms (F) to (I) in FIG. 7 correspond to different slits in FIGS. 6 (F) to (I). From the reflection spectrum waveforms (F) to (I) of FIG. 7A, it can be seen that the increase in the resonance frequency is suppressed as the slit width increases with reference to FIG. 6F where the slit width is narrow.

  On the other hand, FIG. 7B shows a power reflection spectrum in the transmission circuit unit 9 when a signal having a frequency of 4.5 to 5 GHz is radiated from the transmission electrode 8 of the transmission unit 7. The reflection spectrum waveforms (F) to (I) in FIG. 7 (b) correspond to different slits in FIGS. 6 (F) to (I). From the reflection spectrum waveforms (F) to (I) of FIG. 7 (b), it can be seen that FIG. 6 (F), which has a small increase in capacitance due to the slit, is resonating because the amount of reflection decreases in the high frequency region. However, in FIG. 6G in which the slit width is increased, the reflection amount is increased as compared with FIG. 6F. Further, in FIGS. 6 (H) and (I) with the increased slit width, it can be seen that most of the input power is reflected and not resonated.

  As described above, when a slit is formed in the receiving electrode 2, an increase in resonance frequency is suppressed by the slit and generation of a canceling magnetic flux is suppressed, but the capacitance of the receiving electrode 2 changes as the width of the slit increases. Therefore, the transmission electrode 8 and the reception electrode 2 do not resonate and cannot communicate. Specifically, in order for the transmission electrode 8 and the reception electrode 2 to communicate, it is necessary to keep the amount of reflected power at −2 dB or less compared to the transmission power. In order to suppress the amount of reflected power to −2 dB or less compared to the transmission power, the magnitude of the influence caused by the capacitance generated from the slit is small in the frequency domain in which the receiver 1 and the transmitter 7 communicate with each other. Therefore, it is necessary to narrow the width of the slit in order to be within a predetermined range that is sufficiently large in the frequency region in which the transmitter 10 and the transmitter 10 communicate. In order to satisfy this condition, it is necessary to form the width of the slit so that it is 1/100 or less of the wavelength used for communication between the receiver 1 and the transmitter 7. However, there is a limit to the width of the slit at a location where the metal plate divided by the slit can effectively cause capacitive coupling. That is, as long as the width of the slit as a whole is 1/100 or less of the wavelength, a region having a width of 1/100 or more of the wavelength may be provided in a part of the slit. For example, the slit opening provided on the edge of the metal plate may have a width of 1/100 or more of the wavelength, and the region where the width of the slit is 1/100 or more of the wavelength is the inner side of the metal plate. You may have it.

(Various variations of flat electrode)
In the present embodiment, the case has been described in which slits are formed in a cross shape in the rectangular receiving electrode 2 and transmitting electrode 8 as shown in FIG. However, the shape of the metal conductor and the shape of the slit are not limited to this in order to achieve the purpose of dividing the path through which the eddy current flows and generating a canceling component. FIGS. 8F to 8J show various modifications of the slits formed in the reception electrode 2 and the transmission electrode 8.

  For example, as shown in FIG. 8F, the metal conductor may have a shape other than a rectangle. For example, a circle, an ellipse, a polygon, or a shape obtained by cutting a part from the polygon may be used. For example, as shown in FIG. 8 (g), the direction in which the slit is formed does not have to go to the center of the metal conductor, and may be formed at a different angle. For example, as shown in FIG. 8H, the slit is not necessarily formed at the center of the edge of the metal conductor. For example, the slit is formed at the top of the metal conductor or at a position away from the center of the edge. It doesn't matter.

  For example, as shown in FIG. 8 (i), the number of slits need not be four, and for example, eight slits may be formed. For example, as shown in FIG. 8 (j), the slit shape does not have to be a rectangle, for example, a triangle, an ellipse, a polygon, a shape obtained by combining another polygon with a polygon, or a non-circular shape. You can take these. In the receiving electrode 2, the metal conductor does not have to be composed of a single flat plate. For example, as shown in FIG. 8E, a slit that is interrupted at the center of the metal conductor may be connected to form the reception electrode 2 as four divided metal conductors. Further, although the metal conductor is described as having a flat plate shape, the metal conductor may have a three-dimensional structure such as a structure in which a step is provided in the metal conductor together with a slit, or a structure in which the metal conductor is bent.

  Further, when the metal conductor is rectangular, the resonance frequency between the reception electrode 2 and the transmission electrode 8 is determined by the length of the long side, and the bandwidth is determined by the length of the short side. When the metal conductor is rectangular, its antenna characteristics can be easily calculated.

  Further, by forming slits in the metal conductor, the path of induced current flowing in the metal conductor increases. Thereby, the resonant frequency of the receiving electrode 2 and the transmitting electrode 8 can be reduced. In general, the resonance frequency of the reception electrode 2 and the transmission electrode 8 increases as the size is reduced. Therefore, by forming the slit and lowering the resonance frequency, the reception electrode 2 and the transmission electrode 8 can be made smaller than the reception electrode 2 and the transmission electrode 8 having the same resonance frequency without forming the slit. it can.

  Further, the AC current flowing in the conductor has a characteristic of flowing on the surface of the conductor, and the amount of the current is attenuated as it goes from the conductor surface to the inside of the conductor. The depth at which this amount of current is 1 / e compared to the conductor surface is called the skin depth, and the skin depth can be calculated from the magnetic permeability and conductivity of the conductor and the frequency of the current flowing in the conductor. The amount of current flowing in the conductor configured to be thinner than the skin depth is reduced. Therefore, by configuring the receiving electrode 2 and the transmitting electrode 8 with a thickness thinner than the skin depth calculated from the modulated wave radiated from the transmitting loop 11, the eddy current flowing in the receiving electrode 2 and the transmitting electrode 8 can be reduced. The amount can be reduced. In addition, description is abbreviate | omitted about the calculation method of the resonant frequency of the receiving electrode 2 and the transmitting electrode 8, and the calculation method of the skin depth in a conductor.

(Second embodiment)
FIG. 9 is a diagram illustrating a configuration of the receiver 30 using the composite antenna according to the second embodiment.

  As in the first embodiment, the composite antenna receiver 30 is configured by combining an antenna that uses an induced electric field and an antenna that uses an induced magnetic field. An antenna that uses an induced electric field or the like includes an electric field receiving loop 31 that has a plurality of loops formed of thin metal conductors, and a receiving circuit unit 3 that processes a current generated from the electric field receiving loop 31.

  On the other hand, an antenna using an induction magnetic field includes a reception loop 5 formed of a loop of a thin metal conductor disposed so as to surround the outside of the electric field reception loop 31, and a reception circuit that performs signal processing on a current generated from the reception loop 5. The unit 6 is configured. Since the configurations of the transmitter 7 and the transmitter 10 are the same as those in the first embodiment, description thereof will be omitted.

  When the receiver 30 and the transmitter 7 communicate with each other, the reception electrode 2 of the receiver 30 and the transmission electrode 8 of the transmitter 7 face each other, and the electric frequency modulated from the transmission circuit unit 9 of the transmitter 7 is transmitted. A signal is applied to the transmission electrode 8. Then, an electric field modulated at a high frequency is induced from the transmission electrode 8. The electric field radiated from the transmission electrode 8 is applied to the electric field reception loop 31 of the receiver 30. By the way, it can be considered that the magnetic field is applied to the electric field receiving loop 31 according to Maxwell's law concerning the electric field and the magnetic flux density. The magnetic field input to the electric field receiving loop 31 generates an induced current in accordance with Faraday's law of electromagnetic induction. Since this induced current is generated according to the high-frequency signal transmitted by the transmission circuit unit 9, the reception circuit unit 3 can determine the signal transmitted from this induced current. The detailed configuration of the antenna using an induction electric field and the like and the signal transmission / reception method are the same as those in the first embodiment, and thus description thereof is omitted.

  FIG. 10 is a diagram showing a state of connection between the electric field receiving loop 31 of the receiver 1 and the receiving circuit 3. Here, as an example, a case will be described in which the electric field receiving loop 31 is composed of two loops, a first electric field receiving loop 31 (a) and a second electric field receiving loop 31 (b). The number of loops constituting the electric field receiving loop 31 is not limited to two, and a plurality of loops may be combined.

  The first electric field receiving loop 31 (a) and the second electric field receiving loop 31 (b) are each provided with a notch, and both ends of the notch are connected to the plus side terminal and the minus side terminal of the receiving circuit unit 3. It is connected. The upper end of the first electric field receiving loop 31 (a) is connected to the plus side terminal of the receiving circuit unit 3, and the lower end is connected to the minus side terminal. On the other hand, the upper end of the second electric field receiving loop 31 (b) is connected to the plus side terminal of the receiving circuit unit 3 via the capacitor 32 (a) and to the minus side terminal via the inductor 33 (a). . On the other hand, the lower end of the second electric field receiving loop 31 (b) is connected to the plus side terminal of the receiving circuit unit 3 via the inductor 33 (b) and to the minus side terminal via the capacitor 32 (b). .

  When a high frequency modulated magnetic field signal is applied to the electric field receiving loop 31 of FIG. 10, induced currents are generated in the first electric field receiving loop 31 (a) and the second electric field receiving loop 31 (b), respectively. . Since the direction in which the magnetic flux is applied to the two loops is the same, the induced current is generated in the same direction, for example, the counterclockwise direction of the loop in FIG. The induced currents generated in the first electric field receiving loop 31 (a) flow into the positive terminal and the negative terminal of the receiving circuit 3, respectively. On the other hand, the induced current generated in the second electric field receiving loop 31 (b) passes through the inductors 33 (a) and (b) and the capacitors 32 (a) and (b).

  In general, in an AC circuit, the inductors 33 (a) and (b) function as low-pass filters that do not pass high frequencies, and the capacitors 32 (a) and (b) function as high-pass filters that do not pass low frequencies. Therefore, the induced current generated in the second electric field receiving loop 31 (b) flows into the plus terminal and the minus terminal of the receiving circuit unit 3 through the capacitor 32 (a) and the capacitor 32 (b), respectively. As a result, the induced current flowing in the first electric field receiving loop 31 (a) and the induced current flowing in the second electric field receiving loop 31 (b) flow to the receiving circuit unit 3 with the same polarity. Therefore, a current flows in the circuit, and the receiving circuit unit 3 can perform signal processing using the flowing current.

  On the other hand, when a low-frequency modulated magnetic field signal is applied to the electric field receiving loop 31, induced currents are generated in the two loops, and the induced current generated in the first electric field receiving loop 31 (a) is Then, it flows into the plus terminal and the minus terminal of the receiving circuit unit 3. The induced currents generated in the second electric field receiving loop 31 (b) flow into the inductors 33 (a) and (b) and the capacitors 32 (a) and (b), respectively. The low-frequency modulated induction current passes through the inductors 33 (a) and (b) rather than the capacitors 32 (a) and (b). Therefore, the induced current generated in the second electric field receiving loop 31 (b) flows into the plus terminal and the minus terminal of the receiving circuit unit 3 through the inductor 33 (a) and the inductor 33 (b), respectively. As a result, the induced current flowing in the first electric field receiving loop 31 (a) and the induced current flowing in the second electric field receiving loop 31 (b) flow into the receiving circuit unit 3 with opposite polarities. .

  Accordingly, since the two induced currents cancel each other, no current is generated in the circuit. As a result, even if a low-frequency modulated magnetic field signal is input to the electric field receiving loop 31, no induced current is generated, so that the canceling magnetic flux 22 is not generated. Therefore, even when the receiver 30 and the transmitter 10 communicate with each other, the receiving circuit unit 10 can correctly receive the signal.

  In the second embodiment, an example in which the antenna using the electric field of the receiver 30 is configured by a metal conductor thin wire has been described. However, the transmission electrode 8 in the transmitter 7 may be configured by a thin metal conductor having the same configuration as the electric field reception loop 31. When the transmitter 7 and the transmitter 10 are configured integrally like the receiver 30, there is a situation where the transmission electrode 8 cancels out due to the magnetic flux transmitted from the transmission loop 11. Conceivable. By configuring the transmission electrode 8 with the metal conductor fine wire having the above-described configuration, it is possible to perform communication between the receiver 30 and the transmitter 10 while suppressing the generation of the canceling magnetic flux.

(Magnetic shield)
FIG. 11 is a configuration diagram of the receiver 1 in which the magnetic sheet 40 is inserted below the reception loop 5. The magnetic sheet 40 is made of a material having high magnetic permeability such as ferrite.

  When the transmitter 10 and the receiver 1 communicate with each other, the magnetic flux 20 output from the transmission loop 11 of the transmitter 10 is applied to the reception loop 5 of the receiver 1. Here, since the magnetic sheet 40 has a high magnetic permeability, the magnetic flux 20 that has passed through the reception loop 5 remains in the magnetic sheet 40. Although a GND pattern (not shown) is disposed below the magnetic sheet 40, the amount of the magnetic flux 20 applied to the GND pattern can be reduced by the magnetic flux 20 remaining on the magnetic sheet 40. By reducing the amount of the magnetic flux 20 applied to the GND pattern, the amount of eddy current generated in the GND pattern can be suppressed. By suppressing the generation amount of eddy current, the generation amount of cancellation magnetic flux can be suppressed, and as a result, the communication performance of the reception loop 5 can be maintained.

  Conventionally, when a magnetic material such as the magnetic sheet 40 is used as a magnetic shield, the magnetic material is arranged up to the inside of the receiving loop 5 to exhibit the effect of converging the magnetic flux applied from the outside. However, in the decoding antenna of the present application, the magnetic sheet 40 has a so-called “B” shape and is disposed at the lower part of the receiving loop 5. Thereby, the structure in which the magnetic sheet 40 does not adjoin the receiving electrode 2 can be taken. Since the magnetic sheet 40 is a magnetic substance and has a high loss in the high frequency region, the magnetic sheet 40 and the receiving electrode 2 are not close to each other, so that the transmitting electrode 8 and the receiving electrode 2 communicate in the high frequency region. However, communication can be performed without being affected by the loss of the magnetic sheet 40.

  In addition, in FIG. 11, the receiving electrode 2 showed the example comprised from the flat metal conductor which formed the slit. However, even if the electric field receiving loop 31 is used instead of the receiving electrode 2, the same effect of the invention can be obtained. Further, the case where the magnetic sheet 40 is formed below the reception loop 5 has been described. However, the magnetic sheet 40 may be formed above the transmission loop 11. In the case where the transmitter 7 and the transmitter 10 are configured integrally, there may be a situation in which the transmission electrode 8 cancels out due to the magnetic flux transmitted from the transmission loop 11 and generates a magnetic flux. The magnetic flux input from the transmission loop 11 to the transmission electrode 8 is absorbed by the magnetic sheet 40 disposed on the upper part of the transmission loop 11. Thus, communication between the receiver 1 and the transmitter 10 can be performed while suppressing the amount of eddy current generated in the transmission electrode 8 and the generation of the canceling magnetic flux.

  In the embodiments described so far, the case where the receiver 1 and the transmitter 10 communicate with each other has been described. However, even when the receiver 1 and the transmitter 7 communicate with each other, a situation in which an antenna using an induced electric field or the like interferes with an antenna using an induced magnetic field can be considered. When an antenna using an induced electric field radiates electromagnetic waves, when the length of the reception loop 5 or the transmission loop 11 is an integral multiple of a half wavelength of the electromagnetic waves, the reception loop 5 or the transmission loop 11 resonates with the electromagnetic waves. End up. Resonance of the reception loop 5 or the transmission loop 11 can be suppressed by setting the length of one loop of the reception loop 5 or the transmission loop 11 to be equal to or less than half the wavelength of the electromagnetic wave radiated from the transmission electrode 8.

  Further, when a signal is supplied by connecting a transmission circuit to the antenna, current is concentrated at the connection point. When two transmitting antennas are combined like the transmitter shown in FIG. 4 or FIG. 6, the current concentrates because the feeding point of the transmission electrode 8 and the feeding point of the transmission loop 11 are close to each other. 8 or a situation in which an unintended current flows out to the transmission loop 11 can be considered. FIG. 12 shows a configuration diagram of the transmitters 7 and 10 in which the positions of the feeding points are separated. By setting the positions of the two feeding points apart from each other, current concentration can be avoided and a situation in which an unintended current flows out to the transmission electrode 8 or the transmission loop 11 can be prevented.

  With the above configuration, when using an antenna that uses an induced magnetic field in a composite antenna in which an antenna that uses an induced magnetic field and an antenna that uses an induced electric field, etc. are arranged close to each other and a communication device using the same, induction is performed. Suppresses the generation of eddy currents in antennas that use electric fields. Thereby, generation | occurrence | production of the cancellation magnetic flux which generate | occur | produces from an eddy current can be suppressed, and the antenna using an induction magnetic field can be used.

  In the present embodiment, the reception loop 5 and the transmission loop 11 are arranged so as to surround the reception electrode 2 and the transmission electrode 8. However, even if the receiving electrode 2 and the receiving loop 5 are partly arranged so as to overlap each other, or the receiving electrode 2 is arranged outside the receiving loop 5, the same effect of the invention can be obtained. By arranging the reception loop 5 and the transmission loop 11 so as to surround the outside of the reception electrode 2 and the transmission electrode 8, the area occupied by the two antennas can be reduced, and the communication device mounting the composite antenna can be reduced in size. can get.

  The present invention is not limited to the embodiment described above, and the constituent elements may be modified as long as they do not depart from the gist of the invention. Various inventions may be formed by proper combinations of a plurality of constituent elements disclosed in the above embodiments. For example, some components may be excluded from all the components shown in each embodiment.

DESCRIPTION OF SYMBOLS 1 Receiver 2 Reception electrode 3, 6 Reception circuit part 5 Reception loop 7, 10 Transmitter 8 Transmission electrode 9, 12 Transmission circuit part 11 Transmission loop 20 Magnetic flux 21 Eddy current 22 Canceling magnetic flux 31 Electric field reception loop 32 Capacitor 33 Inductor 40 Magnetic Sheet

Claims (11)

A conductor for coupling the first modulated wave with an electromagnetic wave belonging to an electrostatic field or an induction electric field is provided, and the conductor has a shape in which a plurality of parts having the same area are combined by a notch at a position where the edge is divided. A first antenna,
A second antenna comprising a conductor that couples the second modulated wave with an electromagnetic wave belonging to an induced magnetic field;
A composite antenna comprising: 2. The composite antenna according to claim 1, wherein the notch includes a linear notch formed to have a width equal to or less than 1/100 of the wavelength of the first modulated wave.   The composite antenna according to claim 1, wherein the first antenna is configured to have a thickness equal to or less than a skin depth at a frequency of the second modulated wave.   4. The composite antenna according to claim 1, wherein the second antenna includes a member having magnetism on a surface opposite to a direction in which the second modulated wave is received. 5.   The conductor of the second antenna is substantially loop-shaped, and the length of the loop-shaped conductor is configured to be equal to or less than half of the wavelength of the first modulated wave. The composite antenna according to claim 4.   The composite antenna according to claim 1, wherein the second antenna surrounds the first antenna.   The composite antenna according to any one of claims 1 to 6, wherein the notch is formed toward a central portion of a conductor of the first antenna.   The composite antenna according to any one of claims 1 to 6, wherein the notch is formed at a different angle with respect to an edge of a conductor of the first antenna.   The composite antenna according to any one of claims 1 to 8, wherein a plurality of portions of the conductor of the first antenna are connected to a central portion of the conductor of the first antenna.   The composite antenna according to any one of claims 1 to 8, wherein the conductor of the first antenna is divided into the plurality of portions by the notch. A composite antenna according to any one of claims 1 to 10,
A first receiving circuit unit connected to the first antenna included in the composite antenna and processing a current generated from the first antenna;
A second antenna comprising a conductor that couples the second modulated wave with an electromagnetic wave belonging to an induced magnetic field;
A communication device comprising: a second receiving circuit unit that is connected to the second antenna included in the composite antenna and processes a current generated from the second antenna.

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