Patent Publication Number: US-2022224159-A1

Title: Wireless power and data transmission apparatus and transmission module

Description:
TECHNICAL FIELD 
     The present disclosure relates to a wireless power and data transmission apparatus and a transmission module. 
     BACKGROUND ART 
     Systems which transmit electric power wirelessly, i.e., contactlessly, and which also transmit data are known. For example, Patent Document 1 discloses an apparatus which wirelessly transmits energy and data between two objects that are capable of relative rotation with respect to each other around an axis of rotation. This apparatus includes two coils of a circular or circular arc shape that perform energy transmission, and two electrical conductors of a circular or circular arc shape that perform data transmission. The two coils are spaced apart in an opposing relationship along the axial direction of the axis of rotation, and perform energy transmission via magnetic field coupling. The two electrical conductors are disposed so as to be coaxial with the two coils. The electrical conductors are spaced apart in an opposing relationship along the axial direction, and perform data transmission via electromagnetic field coupling. Between the two coils and the two electrical conductors, objects for shielding purposes being made of an electrically conductive material are placed. 
     Patent Document 2 discloses a contactless rotary interface which perform differential signal transmission between two pairs of balanced transmission lines that are provided for two cores that are capable of making relative rotations. 
     CITATION LIST 
     Patent Literature 
     [Patent Document 1] Japanese Laid-Open Patent Publication No. 2016-174149 
     [Patent Document 2] Japanese National Phase PCT Laid-Open Publication No. 2010-541202 
     SUMMARY OF INVENTION 
     Technical Problem 
     The present disclosure provides a technique which allows a device in which electric power and data are wirelessly transmitted between two objects undergoing relative rotations with each other to have a smaller radius. 
     Solution to Problem 
     A wireless power and data transmission apparatus according to an embodiment of the present disclosure includes an inner module and an outer module. At least one of the inner module and the outer module is disposed so as to be capable of rotating around an axis. The inner module includes: an annular-shaped first antenna disposed around the axis; and an annular-shaped first communication electrode disposed around the axis, the first communication electrode being at a different position from that of the first antenna regarding a direction along the axis. The outer module includes: an annular-shaped second antenna disposed around the axis, the second antenna performing power transmission or power reception with the first antenna via magnetic field coupling or electric field coupling; and an annular-shaped second communication electrode disposed around the axis, the second communication electrode being at a different position from that of the second antenna regarding the direction along the axis, and the second antenna performing communications with the first communication electrode via electric field coupling. 
     A transmission module according to another embodiment of the present disclosure is for use as the inner module in the wireless power and data transmission apparatus. 
     A transmission module according to still another embodiment of the present disclosure is for use as the outer module in the wireless power and data transmission apparatus. 
     General or specific aspects of the present disclosure may be implemented using an apparatus, a system, a method, an integrated circuit, a computer program, or a storage medium, or any combination of an apparatus, a system, a method, an integrated circuit, a computer program, and/or a storage medium. 
     Advantageous Effects of Invention 
     According to an embodiment of the present disclosure, communication quality can be improved in a system in which electric power and data are wirelessly transmitted between a power transmitting module and a power receiving module. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram schematically showing an example of a robot arm apparatus having a plurality of movable sections. 
         FIG. 2  is a diagram schematically showing a wiring configuration in a conventional robot arm apparatus. 
         FIG. 3  is a diagram showing a specific example of the conventional configuration shown in  FIG. 2 . 
         FIG. 4  is a diagram showing an example of a robot in which power transmission in each joint is achieved wirelessly. 
         FIG. 5  is a diagram showing an example of a robot arm apparatus in which wireless power transmission is applied. 
         FIG. 6  is a cross-sectional view showing examples of a power transmitting module and a power receiving module in a wireless power and data transmission apparatus. 
         FIG. 7  is an upper plan view of the power transmitting module shown in  FIG. 6  as viewed along an axis C. 
         FIG. 8  is a perspective view showing an example configuration of the magnetic core. 
         FIG. 9  is a cross-sectional view showing the configuration of a wireless power and data transmission apparatus according to an illustrative embodiment. 
         FIG. 10A  is a diagram showing the structure along a cross section taken along line A-A in  FIG. 9 . 
         FIG. 10B  is a diagram showing the structure along a cross section taken along line B-B in  FIG. 9 . 
         FIG. 11  is a perspective view showing an exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 12  is a cross-sectional view showing another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 13  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 14  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 15  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 16  is a diagram showing an example of a wireless power and data transmission apparatus which allows the inner module and the outer module to be easily separated. 
         FIG. 17  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 18  is a diagram showing another example of a wireless power and data transmission apparatus which allows the inner module and the outer module to be easily separated. 
         FIG. 19  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 20  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 21  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 22  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 23  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 24  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 25  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 26  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 27  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 28  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 29  is a cross-sectional view showing still another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 30A  is a diagram showing another exemplary configuration of the communication electrodes and the communication circuits. 
         FIG. 30B  is a diagram showing still another exemplary configuration of the communication electrodes and the communication circuits. 
         FIG. 31A  is a diagram showing still another exemplary configuration of the communication electrodes and the communication circuits. 
         FIG. 31B  is a diagram showing still another exemplary configuration of the communication electrodes and the communication circuits. 
         FIG. 32A  is an example method of terminating each communication electrode. 
         FIG. 32B  is another example method of terminating each communication electrode. 
         FIG. 33  is a diagram showing examples of magnetic field intensity distribution. 
         FIG. 34  is a block diagram showing the configuration of a system that includes a wireless power and data transmission apparatus. 
         FIG. 35A  is a diagram showing an exemplary equivalent circuit for a transmission coil and a reception coil. 
         FIG. 35B  is a diagram showing another exemplary equivalent circuit for a transmission coil and a reception coil. 
         FIG. 36A  is a diagram showing an example configuration of a full-bridge type inverter circuit. 
         FIG. 36B  is a diagram showing an example configuration of a half-bridge type inverter circuit. 
         FIG. 37  is a diagram showing another exemplary configuration of a wireless power and data transmission apparatus. 
         FIG. 38  is a block diagram showing the configuration of a wireless power transmission system including two wireless power feeding units. 
         FIG. 39A  is a diagram showing a wireless power transmission system which includes one wireless power feeding unit. 
         FIG. 39B  is a diagram showing a wireless power transmission system which includes two wireless power feeding units. 
         FIG. 39C  shows a wireless power transmission system which includes three or more wireless power feeding units. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Findings Providing the Basis of the Present Disclosure) 
     Prior to describing embodiments of the present disclosure, findings providing the basis of the present disclosure will be described. 
       FIG. 1  is a diagram schematically showing an example of a robot arm apparatus having a plurality of movable sections (e.g., joints). Each movable section is constructed so as to be capable of rotation or expansion/contraction by means of an actuator that includes an electric motor (hereinafter simply referred to as a “motor”). In order to control such an apparatus, it is required to individually supply electric power to the plurality of motors and control them. Supply of electric power from a power source to the plurality of motors has conventionally been achieved through connection via a large number of cables. 
       FIG. 2  is a diagram schematically showing connection between component elements in such a conventional robot arm apparatus. In the configuration shown in  FIG. 2 , electric power is supplied from a power source to a plurality of motors via wired bus connections. Each motor is controlled by a control device (controller) not shown. 
       FIG. 3  is a diagram showing a specific example of the conventional configuration shown in  FIG. 2 . A robot in this example has two joints. Each joint is driven by a servo motor M. Each servo motor M is driven with a three-phase AC power. The controller includes as many motor driving circuits  900  as there are motors M to be controlled. Each motor driving circuit  900  includes a converter, a three phase inverter, and a control circuit. The converter converts alternating current (AC) power from a power source into direct current (DC) power. The three phase inverter converts the DC power which is output from the converter into a three-phase AC power, and supplies it to the motor M. The control circuit controls the three phase inverter to supply necessary electric power to the motor M. The motor driving circuit  900  obtains information concerning rotary position and rotational speed from the motor M, and adjusts the voltage of each phase based on this information. Such a configuration allows the operation of each joint to be controlled. 
     However, in this configuration, a large number of cables need to be provided, as adapted to the number of motors. This causes accidents due to snagging of cables, which leads to the problems of limited ranges of motion and difficulty in changing parts. There also arises a problem in that repetitive bending of cables may deteriorate the cables, or even disrupt them. For improved safety and vibration control, there is a desire to internalize cables within the arm. Doing so would however require a large number of cables to be accommodated in the joints, which poses constraints on the assembly of the robot and the automation of the production steps. Therefore, the inventors have sought to reduce the number of cables in a movable section of a robot arm by applying a wireless power transmission technique. 
       FIG. 4  is a diagram showing an example configuration of a robot in which power transmission in each joint is achieved wirelessly. In this example, unlike in the example of  FIG. 3 , a three phase inverter and a control circuit to drive each motor M are provided within the robot, rather than in an external controller. In each joint, wireless power transmission is performed through magnetic field coupling between a transmission coil and a reception coil. In each joint, this robot includes a wireless power feeding unit and a miniature motor. Each miniature motor  700 A,  700 B includes a motor M, a three phase inverter, and a control circuit. Each wireless power feeding unit  600 A,  600 B includes a power transmitting circuit, a transmission coil, a reception coil, and a power receiving circuit. The power transmitting circuit includes an inverter circuit. The power receiving circuit includes a rectifier circuit. The power transmitting circuit in the left wireless power feeding unit  600 A shown in  FIG. 4 , which is connected between a power source and the transmission coil, converts the supplied DC power into AC power, and supplies it to the transmission coil. The power receiving circuit converts the AC power which the reception coil has received from the transmission coil into DC power, and outputs it. The DC power which has been output from the power receiving circuit is supplied not only to the miniature motor  700 A, but also the power transmitting circuit in the wireless power feeding unit  600 B in any other joint. In this manner, electric power is also supplied to the miniature motors  700 B driving the other joints. 
       FIG. 5  is a diagram showing an example of a robot arm apparatus in which the above-described wireless power transmission is applied. This robot arm apparatus has joints J 1  to J 6 . Among these, the above-described wireless power transmission is applied to the joints J 2  and J 4 . On the other hand, conventional wired power transmission is applied to the joints J 1 , J 3 , J 5 , and J 6 . The robot arm apparatus includes: a plurality of motors Ml to M 6  which respectively drive the joints J 1  to J 6 ; motor control circuits Ctr 3  to Ctr 6  which respectively control the motors M 3  to M 6  among the motors M 1  to M 6 ; and two wireless power feeding units (intelligent robot harness units; also referred to as IHUs) IHU 2  and IHU 4  which are respectively provided in the joints J 2  and J 4 . Motor control circuits Ctr 1  and Ctr 2  which respectively drive the motors M 1  and M 2  are provided in a control device  650  which is external to the robot. 
     The control device  650  supplies electric power to the motors M 1  and M 2  and the wireless power feeding unit IHU 2  in a wired manner. At the joint J 2 , the wireless power feeding unit IHU 2  wirelessly transmits electric power via a pair of coils. The transmitted electric power is then supplied to the motors M 3  and M 4 , the control circuits Ctr 3  and Ctr 4 , and the wireless power feeding unit IHU 4 . The wireless power feeding unit IHU 4  also wirelessly transmits electric power via a pair of coils in the joint J 4 . The transmitted electric power is supplied to the motors M 5  and M 6  and the control circuits Ctr 5  and Ctr 6 . With such a configuration, cables for power transmission can be eliminated in the joints J 2  and J 4 . 
     In such a system, in each wireless power feeding unit, not only power transmission but also data transmission may be performed. For example, signals for controlling each motor, or signals that are fed back from each motor, may be transmitted between a power transmitting module and a power receiving module within the wireless power feeding unit. Alternatively, in the case where a camera is mounted at the tip of the robot arm, data of images that are taken with the camera may be transmitted. In the case where a sensor is mounted at the tip, etc., of the robot arm, a group of data representing information obtained by the sensor may be transmitted Such a wireless power feeding unit, which simultaneously performs power transmission and data transmission, will be referred to as a “wireless power and data transmission apparatus” in the present specification. 
       FIG. 6  is a cross-sectional view showing an example configuration of a power transmitting module  400  and a power receiving module  500  of the wireless power and data transmission apparatus.  FIG. 7  is an upper plan view of the power transmitting module  400  shown in  FIG. 6  as viewed along an axis C. The power receiving module  500  also has a similar structure to the structure shown in  FIG. 7 . At least one of the power transmitting module  400  and the power receiving module  500  can make a relative rotation around the axis C by means of an actuator not shown. 
     The power transmitting module  400  in the example of  FIG. 6  includes: a transmission coil  410 ; communication electrodes including two electrodes  420   a  and  420   b  functioning as differential transmission lines; a magnetic core  430 ; a communication circuit  440 ; and a housing  490  accommodating these. In the following description, two electrodes or lines functioning as differential transmission lines may be collectively referred to as a “differential transmission line pair”. 
     As shown in  FIG. 7 , the transmission coil  410  has a circular shape around the axis C. The two electrodes  420   a  and  420   b  have a circular arc shape (or a slitted circular shape) around the axis C. The two electrodes  420   a  and  420   b  adjoin one another via an interspace. The communication electrodes  420  and the transmission coil  410  are located on the same plane. On the outside of the transmission coil  410 , the communication electrodes  420  is located so as to surround the transmission coil  410 . The transmission coil  410  is accommodated in the magnetic core  430 . 
     In the configuration shown in  FIGS. 6 and 7 , with respect to the axis C, the transmission coil  410  and the reception coil  510  are disposed on the inner side of the radius, whereas the communication electrodes  420  and  520  are disposed on the outer side of the radius. Contrary to this configuration, a configuration may be possible in which the communication electrodes  420  and  520  are disposed on the inner side of the radius and in which the transmission coil  410  and the reception coil  510  are disposed on the outer side of the radius. 
       FIG. 8  is a perspective view showing an example configuration of the magnetic core  430 . The magnetic core  430  shown in  FIG. 8  includes an inner peripheral wall and an outer peripheral wall in a concentric arrangement, and a bottom portion connecting the two. The magnetic core  430  is made of a magnetic material. Between the inner peripheral wall and the outer peripheral wall of the magnetic core  430 , the transmission coil  410  in a wound-around form is disposed. As shown in  FIG. 7 , the magnetic core  430  is disposed so that its center coincides with the axis C. The outer peripheral wall of the magnetic core  430  is located between the transmission coil  410  and the electrode  420   a.  As shown in  FIG. 6 , the magnetic core  430  is disposed so that an open portion that is opposite to its bottom is opposed to the power receiving module  200 . 
     Input/output terminals of the communication circuit  440  are connected to one end  421   a  of the electrode  420   a  and one end  421   b  of the electrode  420   b  shown in  FIG. 7 . During transmission, the communication circuit  440  supplies two signals which are opposite in phase but equal in amplitude to the one end  421   a  of the electrode  420   a  and the one end  421   b  of the electrode  420   b.  During reception, the communication circuit  440  receives two signals which have been sent from the one end  421   a  of the electrode  420   a  and the one end  421   b  of the electrode  420   b.  Through differential arithmetics of the two signals, the communication circuit  440  is able to demodulate the transmitted signal. The other ends of the electrodes  420   a  and  420   b  may be connected to ground (GND), for example. 
     Thus, the two electrodes  420   a  and  420   b  function as differential transmission lines. Since data transmission via differential transmission lines is less susceptible to electromagnetic noises, communication quality can be improved. In the example of  FIG. 6 , the communication circuit  440  may be disposed at positions opposed to the two electrodes  420   a  and  420   b.    
     The transmission coil  410  is connected to a power transmitting circuit not shown. The power transmitting circuit supplies AC power to the transmission coil  410 . The power transmitting circuit may include an inverter circuit to convert DC power into AC power, for example. The power transmitting circuit may include a matching circuit for impedance matching purposes. The power transmitting circuit may also include a filter circuit to suppress electromagnetic noise. 
     Except for the portion opposed to the housing  490  of the power receiving module  500 , the housing  490  may be made of an electrically conductive material. The housing  490  suppresses leakage of an electromagnetic field to the outside of the power transmitting module  400 . 
     The power receiving module  500  may be similar in configuration to the power transmitting module  400 . The power receiving module  500  includes: a reception coil  510 ; a communication electrode including two electrodes  520   a  and  520   b  functioning as differential transmission lines; a magnetic core  530 ; a communication circuit  540 ; and a housing  590  accommodating these. These component elements are similar in configuration to the corresponding component elements of the power transmitting module  400 . 
     The reception coil  510 , the two electrodes  520   a  and  520   b,  and the magnetic core  530  may have structures similar to the structures described in  FIG. 7  and  FIG. 8 . The communication circuit  540  is connected to one end of each of the two electrodes  520   a  and  520   b,  to perform transmission or reception of two signals which are opposite in phase but equal in amplitude. The communication circuit  540  may be disposed in the housing  590  as shown in  FIG. 6 . 
     In the example of  FIG. 6 , the reception coil  510  is opposed to the transmission coil  410 . The communication electrodes  520   a  and  520   b  on the power-receiving side are respectively opposed to the communication electrodes  420   a  and  420   b  on the power-transmitting side. The transmission coil  410  and the reception coil  510  perform power transmission via magnetic field coupling. The communication electrodes  420   a  and  420   b  and the communication electrodes  520   a  and  520   b  perform data transmission via coupling between the electrodes. Data transmission may be started from either one of the power transmitting module  400  and the power receiving module  500 . 
     With the above configuration, between the power transmitting module  400  and the power receiving module  500 , electric power and data can simultaneously be transmitted wirelessly. Although a differential transmission line pair is used in the above configuration, communication electrodes which perform single-ended transmission may alternatively be used. 
     The inventors have found a problem with the aforementioned configuration in that the dimension of the device along a perpendicular direction to the axis is increased by the fact that an antenna for power transmission purposes and a communication electrode flank each other along a perpendicular direction to the axis, thus making it different to realize a smaller radius. In applications to a joint of a robot device as shown in  FIG. 1 , smaller radii are required depending on where it is employed, which makes it difficult to adopt a structure as shown in  FIG. 6  and  FIG. 7 . 
     Based on the above thoughts, the inventors have arrived at the configurations of embodiments of the present disclosure described below. 
     A wireless power and data transmission apparatus according to an embodiment of the present disclosure includes an inner module and an outer module. At least one of the inner module and the outer module is disposed so as to be capable of rotating around an axis. The inner module includes an annular-shaped first antenna disposed around the axis, and an annular-shaped first communication electrode disposed around the axis. The first communication electrode is at a different position from that of the first antenna regarding a direction along the axis. The outer module includes an annular-shaped second antenna disposed around the axis, the second antenna performing power transmission or power reception with the first antenna via magnetic field coupling or electric field coupling and an annular-shaped second communication electrode disposed around the axis. The second antenna performs power transmission or power reception with the first antenna via magnetic field coupling or electric field coupling. The second communication electrode is at a different position from that of the second antenna regarding the direction along the axis, and the second antenna performs communications with the first communication electrode via electric field coupling. 
     With the above configuration, regarding the direction along the axis, the first communication electrode is at a different position from that of the first antenna, and the second communication electrode is at a different position from that of the second antenna. In other words, the first antenna and the first communication electrode are not on the same plane, and also the second antenna and the second communication electrode are not on the same plane. With such a structure, the size of the device along a perpendicular direction to the axis can be reduced, thereby realizing an even smaller radius. 
     In the present specification, an “annular shape” refers to a shape that is schematically a circular shape. A slitted circular shape, such as a circular arc shape, is also encompassed within an annular shape. 
     One of the inner module and the outer module functions as a power transmitting module, whereas the other functions as a power receiving module. In the case where the inner module functions as a power transmitting module, the first antenna functions as a transmission antenna, while the second antenna functions as a reception antenna. Conversely, in the case where the outer module functions as a power transmitting module, the second antenna functions as a transmission antenna, while the first antenna functions as a reception antenna. 
     Each of the first antenna and the second antenna may be a coil to perform power transmission or power reception via magnetic field coupling, or an electrode or an electrode group to perform power transmission or power reception via electric field coupling. In the present specification, the term “antenna” is used as a notion encompassing a coil and an electrode or an electrode group that may be used for power transmission. A transmission antenna is connected to a power transmitting circuit that outputs AC power. A reception antenna converts received AC power into another form of AC power or DC power for use by a load. 
     Each of the first communication electrode and the second communication electrode may be configured to perform one or both of transmission and reception. In the case where the first communication electrode performs transmission, the second communication electrode performs reception. Conversely, in the case where the second communication electrode performs transmission, the first communication electrode performs transmission. Each of the power transmitting module and the power receiving module may include two communication electrodes, i.e., for transmission purposes and for reception purposes. In that case, full duplex communication may be achieved, where transmission from the power-transmitting side to the power-receiving side and transmission from the power-receiving side to the power-transmitting side are concurrently performed. 
     Each of the first communication electrode and the second communication electrode may include a differential transmission line pair as described above, for example. Alternatively, each of the first communication electrode and the second communication electrode may include one transmission line for performing single-ended transmission. Each communication electrode is connected to a respectively corresponding communication circuit (i.e., a transmission circuit or a reception circuit). 
     The diameter of the first communication electrode and the diameter of the first antenna may be equal or different. Similarly, the diameter of the second communication electrode and the diameter of the second antenna may be equal or different. In the latter case, when viewed in the direction along the axis, the position of the first communication electrode differs from the position of the first antenna, and the position of the second communication electrode differs from the position of the second antenna. 
     The inner module may further include a first electrically-conductive shield between the first antenna and the first communication electrode. The outer module may further include a second electrically-conductive shield between the second antenna and the second communication electrode. 
     By providing these electrically-conductive shields, the electromagnetic interference between each antenna and each communication electrode can be further reduced. Herein, “electromagnetic interference” means: interference due to a magnetic field; interference due to an electric field; or interference due to a combination thereof. By providing electrically-conductive shields, influences of a magnetic field or an electric field occurring from each antenna during power transmission that are exerted on the a signal voltage on each communication electrode can be reduced, whereby communication quality can be improved. Owing to the interference suppressing effect based on electrically-conductive shields, the distance between the first antenna and the first communication electrode and the distance between the second antenna and the second communication electrode may be shortened. Note that it may be only one of the inner module and the outer module that includes an electrically-conductive shield. Each of the first electrically-conductive shield and the second electrically-conductive shield has an annular shape, for example. Each of the first electrically-conductive shield and the second electrically-conductive shield may be disposed around the axis. 
     When viewed in the direction along the axis, a mid position between the first antenna and the second antenna may be different from a mid position between the first communication electrode and the second communication electrode. Furthermore, when viewed in the direction along the axis, at least one of the first electrically-conductive shield and the second electrically-conductive shield may overlap the mid position between the first antenna and the second antenna. With such configurations, the electromagnetic interference between each antenna and each communication electrode can be further suppressed. 
     Regarding the direction along the axis, the first electrically-conductive shield may be at a different position from a position of the second electrically-conductive shield. Furthermore, when viewed in the direction along the axis, the first electrically-conductive shield and the second electrically-conductive shield may partially overlap. Such configurations provide an improved shielding performance, thereby allowing the electromagnetic interference between each antenna and each communication electrode to be further suppressed. 
     In one embodiment, each module is structured so that sliding one of the inner module and the outer module in the direction along the axis allows the one of the inner module and the outer module to be attached or detached. With such a structure, assembly and detachment of the inner module and the outer module can be facilitated. 
     For example, in one embodiment, regarding the direction along the axis, the first electrically-conductive shield is located between the second electrically-conductive shield and one of the second antenna and the second communication electrode. Regarding the direction along the axis, the second electrically-conductive shield is located between the first electrically-conductive shield and one of the first communication electrode and the first antenna. In a cross section containing the axis, an outer peripheral edge of the first electrically-conductive shield may be is located inside of the one of the second antenna and the second communication electrode, and an inner peripheral edge of the second electrically-conductive shield may be located outside of the one of the first communication electrode and the first antenna. As used herein, the “inner peripheral edge” means a portion of the given member that is located the innermost, whereas the “outer peripheral edge” means a portion of the given member that is located the outermost. With such a structure, when the inner module or the outer module is slid along the axial direction, they can be easily detached or attached, without interfering with each other. 
     Furthermore, in a cross section containing the axis, the outer peripheral edge of the first electrically-conductive shield may be located outside of the inner peripheral edge of the second electrically-conductive shield. Such a structure can reconcile a high interference suppressing effect based on the overlap between the first electrically-conductive shield and the second electrically-conductive shield and the ease of attachment and detachment. 
     The wireless power and data transmission apparatus may further include an actuator to rotate the at least one of the inner module and the outer module around the axis. Such an actuator may have an electric motor and a mechanism to transmit the motive force of the electric motor to the inner module or the outer module, for example. 
     The wireless power and data transmission apparatus may further include: a power transmitting circuit that is connected to one of the first antenna and the second antenna to output AC power; and a power receiving circuit that is connected to the other of the first antenna and the second antenna to convert received AC power into another form of electric power. 
     The wireless power and data transmission apparatus may further include a first communication circuit that is connected to one of the first communication electrode and the second communication electrode; and a second communication circuit that is connected to the other of the first communication electrode and the second communication electrode. 
     The present disclosure also encompasses a transmission module for use as the inner module or the outer module in any of the above wireless power and data transmission apparatuses. The transmission module may include at least one of the actuator, the power transmitting circuit, the power receiving circuit, the first communication circuit, and the second communication circuit mentioned above. 
     The wireless power and data transmission apparatus may be used as a wireless power feeding unit in a robot arm apparatus as shown in  FIG. 1 , for example. The wireless power and data transmission apparatus is applicable to not only a robot arm apparatus, but also any apparatus that includes a rotary mechanism. 
     In the present specification, a “load” means any device that may operate with electric power. Examples of “loads” include devices such as motors, cameras (imaging devices), light sources, secondary batteries, and electronic circuits (e.g., power conversion circuits or microcontrollers). A device which includes a load and a circuit to control the load may be referred to as a “load device”. 
     Hereinafter, more specific embodiments of the present disclosure will be described. Note however that unnecessarily detailed descriptions may be omitted. For example, detailed descriptions on what is well known in the art or redundant descriptions on what is substantially the same configuration may be omitted. This is to avoid lengthy description, and facilitate the understanding of those skilled in the art. The accompanying drawings and the following description, which are provided by the present inventors so that those skilled in the art can sufficiently understand the present disclosure, are not intended to limit the scope of claims. In the following description, identical or similar constituent elements are denoted by identical reference numerals. 
     Embodiments 
     A wireless power transmission data transmission apparatus according to an illustrative embodiment of the present disclosure will be described. The wireless power and data transmission apparatus may be used as a component element in an industrial robot that is used at a factory, a site of engineering work, etc., as shown in  FIG. 1 , for example. Although the wireless power and data transmission apparatus may also be used for other purposes, e.g., supplying power to electric automobiles, the present specification will mainly describe its applications to industrial robots. 
       FIG. 9  is a cross-sectional view schematically showing an example configuration of a wireless power and data transmission apparatus according to an illustrative embodiment of the present disclosure.  FIG. 9  shows an example of a cross-sectional structure of the wireless power and data transmission apparatus along a plane containing the axis C.  FIG. 10A  is a diagram showing the structure along a cross section taken along line B-B in  FIG. 9 .  FIG. 10B  is a diagram showing the structure along a cross section taken along line C-C in  FIG. 9 . 
     As shown in  FIG. 9 , the wireless power and data transmission apparatus includes an inner module  100  and an outer module  200 . One or both of the inner module  100  and the outer module  200  is/are configured so as to be capable of rotating around the axis C by means of an actuator not shown. One of the inner module  100  and the outer module  200  functions as a power transmitting module. The other of the inner module  100  and the outer module  200  functions as a power receiving module. In the following description, an example will be described where the outer module  200  is a power transmitting module and the inner module  100  is a power receiving module. Conversely to this example, the inner module  100  may be a power transmitting module while the outer module  200  may be a power receiving module. 
     The inner module  100  includes a first antenna  110 , a first communication electrode  120 , a first magnetic core  130 , and a dielectric member  150 , as well as a metal housing  190  supporting these. The outer module  200  includes a second antenna  210 , a second communication electrode  220 , a second magnetic core  230 , and a dielectric member  250 , as well as a metal housing  290  supporting these. Although not shown in  FIG. 9  to  FIG. 10B , the inner module  100  may further include a power receiving circuit that is connected to the first antenna  110  and a first communication circuit that is connected to the first communication electrode  120 . Similarly, the outer module  200  may further include a power transmitting circuit that is connected to the second antenna  210  and a second communication circuit that is connected to the second communication electrode  220 . 
     Each of the first antenna  110  and the second antenna  210  in the present embodiment is an annular-shaped coil disposed around the axis C. For simplicity,  FIG. 9  illustrates the coils as having two turns and one layer; however, the number of turns and the number of layers in each coil may be arbitrary. The second antenna  210  is located outside the first antenna  110 . In the present embodiment, the first antenna  110  functions as a reception antenna, whereas the second antenna  210  functions as a transmission antenna. The transmission antenna is connected to a power transmitting circuit not shown. The power transmitting circuit supplies AC power to the transmission antenna. The reception antenna is connected to a power receiving circuit not shown. The power receiving circuit converts the AC power received by the reception antenna into another form of electric power required by a load such as a motor. During operation, the first antenna  110  and the second antenna  210  are magnetically coupled through electromagnetic induction. As a result, electric power is wirelessly transmitted from the first antenna  110  to the second antenna  210 . 
     The first magnetic core  130  is an annular-shaped magnetic body having a dent on its outer periphery. The second magnetic core  230  is an annular-shaped magnetic body having a dent on its inner periphery. The first antenna  110  is accommodated in the dent of the first magnetic core  130 , whereas the second antenna  210  is accommodated in the dent of the second magnetic core  230 . The magnetic cores  130  and  230  are disposed so that the outer peripheral portion of the first antenna  110  and the inner peripheral portion of the second antenna  210  are opposed to each other. 
     Each of the first communication electrode  120  and the second communication electrode  220  in the present embodiment is an annular-shaped transmission line disposed around the axis C. As shown in  FIG. 9 , the first communication electrode  120  is at a position away from the first antenna  110  in a direction along the axis C. Similarly, the second communication electrode  220  is at a position away from the second antenna  210  in a direction along the axis C. In the present embodiment, the first communication electrode  120  is supported by the dielectric member  150 , whereas the second communication electrode  220  is supported by the dielectric member  250 . The first communication electrode  120  and the second communication electrode  220  are opposed to each other. A gap exists between the first communication electrode  120  and the second communication electrode  220 , so that signals are transmitted via this gap. Even when the inner module  100  or the outer module  200  rotates around the axis C, the first communication electrode  120  and the second communication electrode  220  are kept opposed to each other. 
     The first communication electrode  120  is connected to a first communication circuit not shown. The second communication electrode  220  is connected to a second communication circuit not shown. Each of the first communication circuit and the second communication circuit may include a circuit element such as a modulation circuit or a demodulation circuit for performing signal transmission or reception. 
     As shown in  FIG. 10A , the first communication electrode  120  has a slitted circular shape. One end  121  of the first communication electrode  120  is connected to a terminal of the first communication electrode. The other end of the first communication electrode  120  is terminated. Similarly, the second communication electrode  220  has a slitted circular shape. One end  221  of the second communication electrode  220  is connected to a terminal of the second communication electrode. The other end of the second communication electrode  220  is terminated. During signal transmission, a signal is input from one of the first communication circuit and the second communication circuit, and the signal is transmitted to the other of the first communication circuit and the second communication circuit via the communication electrodes  120  and  220 . Signal transmission between the inner module  100  and the outer module  200  is thus realized. 
       FIG. 11  is a perspective view showing an exemplary internal structure of the wireless power and data transmission apparatus when cut along a plane containing the axis C. In this example, each of the first antenna  110  and the second antenna  210  is a coil having  16  turns and  1  layer. As shown in the figure, the first antenna  110  and the second antenna  210  are in a concentric arrangement. A gap exists between the first antenna  110  and the second antenna  210 . Similarly, the first communication electrode  120  and the second communication electrode  220  are in a concentric arrangement. A minute gap exists between the first communication electrode  120  and the second communication electrode  220 . 
     The dimensions of each antenna  110 ,  210  and each communication electrode  120 ,  220  are not particularly limited. However, there may be cases where a hollow structure is needed for incorporation into a robot, for example, and they may be set to the following dimensions. The diameter of the first antenna  110  may be set to a value of e.g. not less than 67 mm and not more than 72 mm. The diameter of the second antenna  210  is greater than the diameter of the first antenna  110 , and may be set to a value which is e.g. 93 mm or less. The diameter of the first communication electrode  120  may be set to a value of e.g. not less than 67 mm and not more than 72 mm. The diameter of the second communication electrode  220  is greater than the diameter of the first communication electrode  120 , and may be set to a value which is e.g. 93 mm or less. The interval between the first antenna  110  and the second antenna  210  (i.e., the size of the gap along a perpendicular direction to the axis C) may be set to a value of e.g. not less than 1 mm and not more than 3 mm. The interval between the first communication electrode  120  and the second communication electrode  220  may be set to a value of e.g. not less than 1 mm and not more than 3 mm. However, the aforementioned numerical ranges are merely examples, and each dimension may be outside the respective numerical range. 
     In the example shown in  FIG. 9 , each of the first communication electrode  120  and the second communication electrode  220  includes a single transmission line that performs single-ended transmission. However, the present disclosure is not limited to this example. For example, the communication electrode of each module may include two transmission lines, i.e., a differential transmission line pair, that function as differential transmission lines. 
       FIG. 12  is a cross-sectional view showing an exemplary configuration where each communication electrode includes a differential transmission line pair. In this example, the first communication electrode  120  includes two electrodes  120   a  and  120   b  constituting a differential transmission line pair. The second communication electrode  220  includes two electrodes  220   a  and  220   b  constituting a differential transmission line pair. The electrodes  120   a  and  120   b  are arranged in the direction along the axis C. Similarly, the electrodes  220   a  and  220   b  are arranged in the direction along the axis C. The electrodes  220   a  and  220   b  are respectively opposed to the electrodes  120   a  and  120   b.  The two electrodes  120   a  and  120   b  of the first communication electrode  120  are connected to a first communication circuit not shown. The two electrodes  220   a  and  220   b  of the second communication electrode  220  are connected to a second communication circuit not shown. When the first communication circuit performs transmission, the first communication circuit supplies two signals of mutually opposite phases (hereinafter referred to as “differential signals”) respectively to the two electrodes  120   a  and  120   b  of the first communication electrode  120 . The differential signals are transmitted from the electrodes  120   a  and  120   b  to the electrodes  220   a  and  220   b,  and received by the second communication circuit. Through processing including differential arithmetics of the received signals, the second communication circuit is able to demodulate the transmitted signal. 
     In the case where differential transmission is employed as in the example of  FIG. 12 , influences of electromagnetic noises are counteracted, whereby communication quality can be improved. 
     Next, other exemplary configurations for the wireless power and data transmission apparatus will be described. 
       FIG. 13  is a cross-sectional view showing an example of a wireless power and data transmission apparatus that includes a plurality of electrically-conductive shields. In this example, the inner module  100  includes a first electrically-conductive shield  160  between the first antenna  110  and the first communication electrode  120 . The outer module  200  further includes a second electrically-conductive shield  260  between the second antenna  210  and the second communication electrode  220 . Each of the first electrically-conductive shield  160  and the second electrically-conductive shield  260  has an annular shape, and is disposed around the axis C. The first electrically-conductive shield  160  and the second electrically-conductive shield  260  are disposed on the same plane. Each electrically-conductive shield  160 ,  260  is a plate of metal, for example. As in this example, by disposing the electrically-conductive shields  160  and  260 , influences of electromagnetic fields occurring from the antennas  110  and  210  during power transmission on the signals transmitted between the communication electrodes  120  and  220  can be reduced. This may allow the coils  110  and  210  and the communication electrodes  120  and  220  to be disposed at shorter intervals, for example. 
     The electrically-conductive shields do not need to be plate-shaped, but may have any shape. 
     Each electrically-conductive shield may be made of a metal such as copper or aluminum, for example. Otherwise, the following configurations may be employed as electrically-conductive shields or alternatives thereof.
     a configuration obtained by coating side walls made of an electrical insulator with an electrically conductive paint (e.g., a silver paint or a copper paint)   a configuration obtained by attaching an electrically conductive tape (e.g., a copper tape or an aluminum tape) on side walls made of an electrical insulator   an electrically conductive plastic (i.e., a material including a metal filler kneaded in a plastic)   

     Any of these may exhibit a similar function to that of the aforementioned electrically-conductive shield. Such configurations will collectively be referred to as “electrically-conductive shields”. 
     Each electrically-conductive shield according to the present embodiment has a ring structure that conforms along the antennas  110  and  210  and the communication electrodes  120  and  220 . Each electrically-conductive shield may have a structure with a gap to create a C shape (i.e., a circular arc shape), as does each communication electrode  120 ,  220 . In that case, too, losses of energy due to an eddy current can be reduced. Each electrically-conductive shield may have a polygonal or elliptical shape, for example. A plurality of metal plates may be placed together to compose a shield. Furthermore, each electrically-conductive shield may have one or more apertures or slits. Such a configuration allows losses of energy due to an eddy current to be reduced. 
       FIG. 14  is a cross-sectional view showing another example of a wireless power and data transmission apparatus that includes a plurality of electrically-conductive shields. In this example, the diameter of the first communication electrode  120  differs from the diameter of the first antenna  110 , and the diameter of the second communication electrode  220  differs from the diameter of the second antenna  210 . Herein, the diameter of the first antenna  110 , or the diameter of the first communication electrode  120 , means the diameter of a circle that is defined by the outer peripheral edge of each. On the other hand, the diameter of the second antenna  210 , or the diameter of the second communication electrode  220 , means the diameter of a circle that is defined by the inner peripheral edge of each. In this example, the width of the second electrically-conductive shield  260  is greater than the width of the first electrically-conductive shield  160 . When viewed from the direction along the axis C, the mid position between the first antenna  110  and the second antenna  210  (i.e., the position of an upper thick broken line in  FIG. 14 ) differs from the mid position between the first communication electrode  120  and the second communication electrode  220  (i.e., the position of a lower thick broken line in  FIG. 14 ). Moreover, when viewed from the direction along the axis C, the second electrically-conductive shield  260  overlaps the mid position between the first antenna  110  and the second antenna  210 . In other words, the inner peripheral edge of the second electrically-conductive shield  260  is inside of the mid position between the antennas  11  and  210 . Contrary to this example, the width of the first electrically-conductive shield  160  may be greater than the width of the second electrically-conductive shield  260 . In that case, the outer peripheral edge of the first electrically-conductive shield  160  may be located outside of the mid position between the antennas  110  and  210 . As in this example, the mid position between the antennas and the mid position between the communication electrodes may be shifted, whereby the interference suppressing effect can be further enhanced. 
       FIG. 15  is a cross-sectional view showing still another example of a wireless power and data transmission apparatus that includes a plurality of electrically-conductive shields. In this example, regarding the direction along the axis C, the position of the first electrically-conductive shield  160  differs from the position of the second electrically-conductive shield  260 . When viewed from the direction along the axis C, the first electrically-conductive shield  160  and the second electrically-conductive shield  260  partially overlap. The outer peripheral edge of the first electrically-conductive shield  160  is outside of the mid position between the communication electrodes  120  and  220 , and reaches over to the mid position between the antennas  110  and  210 . The inner peripheral edge of the second electrically-conductive shield  260  is inside of the mid position between the antennas  110  and  210 , and reaches over to the mid position between the communication electrodes  120  and  220 . The outer peripheral edge of the first electrically-conductive shield  160  may be outside or inside of the mid position between the antennas  110  and  210 . The inner peripheral edge of the second electrically-conductive shield  260  may be inside or outside of the mid position between the communication electrodes  120  and  220 . As in the example of  FIG. 15 , by disposing the plurality of shields  160  and  260  so as to overlap each other, the interference suppressing effect can be further enhanced. 
     The structure shown in  FIG. 15  is characterized in that, although the electrically-conductive shields  160  and  260  protrude from any other portion in this structure, it permits easy assembly and detachment. In this example, regarding the direction along the axis C, the first electrically-conductive shield  160  is located between the second electrically-conductive shield  260  and the second antenna  210 . Regarding the direction along the axis C, the second electrically-conductive shield  260  is located between the first electrically-conductive shield  160  and the first communication electrode  120 . The outer peripheral edge of the first electrically-conductive shield  160  is outside of the inner peripheral edge of the second electrically-conductive shield  260  and yet inside of the second antenna  210  and the second magnetic core  230 . Moreover, the inner peripheral edge of the second electrically-conductive shield  260  is outside of the first communication electrode  120 . With such a structure, even if the inner module  100  or the outer module  200  is slid in the direction along the axis C, each electrically-conductive shield  160 ,  260  will not interfere with any other member. Therefore, as shown in  FIG. 16 , by sliding one of the inner module  100  and the outer module  200  in the direction along the axis C, the module can be easily attached or detached. In the present specification, as shown in  FIG. 16 , a structure that permits easy assembly without allowing interference between members may be referred to as a “nesting structure”. 
       FIG. 17  is a diagram showing another example of a wireless power and data transmission apparatus having a nesting structure. In this example, contrary to the example of  FIG. 15 , the diameter of the first communication electrode  120  is greater than the diameter of the first antenna  110 , the diameter of the second communication electrode  220  is greater than the diameter of the second antenna  210 , and the width of the first electrically-conductive shield  160  is greater than the width of the second electrically-conductive shield  260 . In this example, regarding the direction along the axis C, the first electrically-conductive shield  160  is located between the second electrically-conductive shield  260  and the second communication electrode  220 . Regarding the direction along the axis C, the second electrically-conductive shield  260  is located between the first electrically-conductive shield  160  and the first antenna  110 . The outer peripheral edge of the first electrically-conductive shield  160  is outside of the inner peripheral edge of the second electrically-conductive shield  260  and yet inside of the second communication electrode  220 . Moreover, the inner peripheral edge of the second electrically-conductive shield  260  is outside of the first antenna  110 . With such a structure, too, even if the inner module  100  or the outer module  200  is slid in the direction along the axis C, each electrically-conductive shield  160 ,  260  will not interfere with any other member. Therefore, as shown in  FIG. 18 , the inner module  100  and the outer module  200  can be easily assembled or disassemble. 
     In each example described with reference to  FIG. 13  to  FIG. 18 , each of the communication electrodes  120  and  220  may be composed of a differential transmission line pair as in the example of  FIG. 12 .  FIG. 19  shows one example where the configuration shown in  FIG. 17  is adapted so that the communication electrodes  120  and  220  are composed of differential transmission line pairs. Note that  FIG. 19  and any subsequent cross-sectional view illustrates, within the wireless power and data transmission apparatus, only a portion on one side of the axis C. Utilizing differential transmission allows for reducing signal noise and improve communication quality. 
       FIG. 20  is a cross-sectional view showing another variant of the wireless power and data transmission apparatus. In this example, each of the communication electrodes  120  and  220  includes two differential transmission lines of different widths. The transmission lines that are closer to the antennas  110  and  210  have a smaller width than the width of the transmission lines that are farther from the antennas  110  and  210 . By thus differentiating the two transmission lines in width or area, the level of noise influences on the signal in each line that is associated with wireless power transmission can be adjusted. As a result, the effect of noise suppression based on differential lines can be further improved. 
       FIG. 21  is a cross-sectional view showing another variant of the wireless power and data transmission apparatus. In this example, an electrically conductive member  180  is disposed between the dielectric member  150  and the metal housing  190  of the inner module  100 . Similarly, an electrically conductive member  280  is disposed between the dielectric member  250  and the metal housing  290  of the outer module  200 . Similarly to the communication electrodes  120  and  220 , the electrically conductive members  180  and  280  have an annular plate structure. The communication electrode  120  and the electrically conductive member  180  are located on opposite sides of the dielectric member  150 . Similarly, the communication electrode  220  and the electrically conductive member  280  are located on opposite sides of the dielectric member  250 . The electrically conductive members  180  and  280  are grounded, so that influences of the metal housings  190  and  290  on the signals on the communication electrodes  120  and  220  are alleviated. Such electrically conductive members  180  and  280  may be referred to as “rear-face GND”. Such electrically conductive members  180  and  280  may also be similarly provided in any other embodiment than  FIG. 21  of the present disclosure. 
       FIG. 22  is a cross-sectional view showing still another variant of the wireless power and data transmission apparatus. In this example, the first antenna  110  and the second antenna  210  differ from each other in terms of the number of turns in the coil. In the example shown in  FIG. 22 , the outer coil has more turns than does the inner coil. Conversely to this example, as shown in  FIG. 23 , for example, the inner coil may have more turns than does the outer coil. Such a structure may be adopted when stepping up or stepping down through wireless power transmission. Rather than in terms of the number of turns, the thickness or material of the windings may be made asymmetric between the power-transmitting side and the power-receiving side. 
     In each of the above examples, the communication electrodes  120  and  220  are on the same plane that is perpendicular to the axis C, and mutually opposing faces of the communication electrodes  120  and  220  are parallel to the axis C. The present disclosure is not limited to this positioning. In other words, the mutually opposing faces of communication electrodes  120  and  220  may be inclined from the direction of axis C. For example, as shown in  FIG. 24 , the positioning of the communication electrodes  120  and  220  may be rotated by 90° from the aforementioned positioning. In this example, normal directions of the mutually opposing faces of the communication electrodes  120  and  220  are parallel to the axis C. Moreover, both of the communication electrodes  120  and  220  are located outside of the second antenna  210 . With such positioning, noise on the signals associated with electromagnetic fields occurring from the antennas  110  and  210  can be further reduced. 
     In each of the above examples, only one pair of communication electrodes  120  and  220  is provided. Therefore, bidirectional communication is only possible by way of half duplex communication, where each communication electrode  120 ,  220  alternatively performs transmission or reception. Alternatively, two or more pairs of communication electrodes  120  and  220  may be provided; in that case, full duplex communication becomes possible, that is, transmission from both sides may concurrently occur. 
       FIG. 25  is a diagram showing an example of a wireless power and data transmission apparatus that is capable of full duplex communication. Broken line arrows in  FIG. 25  schematically represent directions of communication at a given moment. In this example, the inner module  100  includes two communication electrodes  120 A and  120 B, whereas the outer module  200  includes two communication electrodes  220 A, and  220 B. The inner communication electrodes  120 A and  120 B are arranged in the direction along the axis C, and the outer communication electrodes  220 A and  220 B are also arranged in the direction along the axis C. The inner communication electrodes  120 A and  120 B are respectively opposed to the outer communication electrodes  220 A and  220 B. With such a structure, each module is able to concurrently perform transmission and reception, whereby full duplex communication can be realized. 
       FIG. 26  is a diagram showing another example of a wireless power and data transmission apparatus that is capable of full duplex communication. In this example, distance from the axis C (indicated by both arrows in  FIG. 26 ) differs between the pair of communication electrodes  120 B and  220 B that are relatively close to the antennas  110  and  210  and the pair of communication electrodes  120 A and  220 A that are relatively far from the antennas  110  and  210 . The mid position between the communication electrodes  120 B and  220 B is outside of the mid position between the antennas  110  and  210 , whereas the mid position between the communication electrodes  120 A and  220 A is outside of the mid position between the communication electrodes  120 B and  220 B. As in this example, the distance from the axis C may be varied from electrode pair to electrode pair. By doing so, the path length of each electrode can be adjusted to an appropriate length, and the noise on the transmitted signal can be further reduced. 
       FIG. 27  is a diagram showing still another example of a wireless power and data transmission apparatus that is capable of full duplex communication. In this example, the orientations of the two communication electrodes  120 A and  120 B in the inner module  100  differ by 90°, and the orientations of the two communication electrodes  220 A and  220 B in the outer module  200  also differ by 90°. The communication electrodes  120  and  220  that are relatively close to the antennas  110  and  210  (referred to as the “first electrode pair”) are disposed so that their normal directions coincide with a perpendicular direction to the axis C. The communication electrodes  120  and  220  that are relatively far from the antennas  110  and  210  (referred to as the “second electrode pair”) are disposed so that their normal directions are oriented in a parallel direction to the axis C. With such positioning, crosstalk between the signals to be transmitted between the first electrode pair and the signals to be transmitted between the second electrode pair can be suppressed. In this example, the mid position between the first electrode pair is outside of the first antenna  110  and inside of the second antenna  210 . The second electrode pair is outside of the second antenna  210 . Without being limited to such positioning, the positioning of the electrode pairs may be arbitrarily selected. 
     In each of the above examples, each of the inner module  100  and the outer module  200  includes only one antenna for power transmission purposes. Without being limited to such a configuration, each module may include two or more antennas. For example, a plurality of antennas corresponding to electric powers of different magnitude may be mounted on each module. 
       FIG. 28  is a diagram showing an example where each module includes two antennas for power transmission purposes. In this example, the inner module  100  includes two antennas  110 A and  110 B, whereas the outer module  200  includes two antennas  210 A and  210 B. The inner two antennas  110 A and  110 B are arranged in the direction along the axis C. The coil of the antenna  110 B that is relatively far from the communication electrodes  120  and  220  has a cross-sectional area which is greater than the cross-sectional area of the coil of the antenna  110 A that is relatively close to the communication electrodes  120  and  220 . Similarly, the outer antennas  210 A and  210 B are arranged in the direction along the axis C. The coil of the antenna  210 B has a cross-sectional area which is greater than the cross-sectional area of the coil of the antenna  210 A. The antennas  110 A and  210 A are used for the purpose of transmitting a relatively small electric power. The antennas  110 B and  210 B are used for the purpose of transmitting a relatively large electric power. In this example, when viewed from the direction along the axis C, the mid position between the antennas  110 A and  210 A coincides with the mid position between the antennas  110 B and  210 B. On the other hand, the mid position between the electrodes  120  and  220  differs from the mid position between the antennas  110 A and  210 A and from the mid position between antennas  110 B and  210 B. In this example, the antennas  110 A and  210 A for transmitting a small electric power are disposed closer to the communication electrodes  120  and  220  than are the antennas  110 B and  210 B for transmitting a large electric power. Such a structure allows for suppressing the noise that is mixed in the signal that is being exchanged during power transmission. 
       FIG. 29  is a diagram showing another example where each module includes two antennas for power transmission purposes. In this example, the mid position between the antennas  110 A and  210 A and the mid position between the antennas  110 B and  210 B as viewed from the direction along the axis C differ from each other. The mid position between the former is outside of the mid position between the latter, and the mid position between the communication electrodes  120  and  220  is located further outside. As in this example, the gap position may differ among the respective pairs, i.e., the antennas  110 A and  210 A, the antennas  110 B and  210 B, and the communication electrodes  120  and  220 . Such a structure allows for further suppressing the noise that is mixed into the signals to be exchanged between the communication electrodes. 
     The configuration of each of the above examples is only an example, and the present disclosure is not limited to these configurations. For example, in the examples illustrated in  FIG. 13  to  FIG. 29 , the number of electrically-conductive shields is not limited to two, but may be 0, 1, or 3 or more. The positioning of the electrically-conductive shields is not limited to the illustrated positioning, either; their positioning may be changed depending on the required shielding property. Each antenna is not limited to a coil, and any electrode pair that performs wireless power transmission or power reception of electric power via e.g. electric field coupling (or capacitive coupling) may be utilized as an antenna. In such a configuration, the electrode pair of each antenna may be disposed in a manner similar to the communication electrodes. As the electrodes for power transmission purposes, electrodes which are larger in width or area than the electrodes (transmission lines) for communications purposes may be used. Furthermore, among the above-described examples, in any example where each communication electrode is a transmission line (electrode) for single-ended transmission, a differential transmission line pair (electrode pair) may be used instead. Conversely, in any example where each communication electrode is a differential transmission line pair (electrode pair), a transmission line for single-ended transmission may be used instead. In each of the above-described examples, the structures of the metal housings  190  and  290 , the magnetic cores  130  and  230 , and the dielectric members  150  and  250  are merely examples; depending on the required characteristics, their configuration may be altered. 
     Next, examples of the configuration and connection of the communication electrodes and communication circuits will be described more specifically. 
       FIG. 30A  is a diagram schematically showing an exemplary configuration of the communication electrodes and communication circuits in the case where half duplex communication via single-ended transmission is to be performed. The inner module  100  includes a first communication circuit  140  that is connected to the first communication electrode  120 . The outer module  200  includes a second communication circuit  240  that is connected to the second communication electrode  220 . The first communication circuit  140  includes a transmission circuit  141 , a reception circuit  142 , and a switch (SW)  143 . The switch  143  is connected to one end of the first communication electrode  120 . The switch  143  is also connected to the transmission circuit  141  and the reception circuit  142 . In response to a control signal from a first control circuit not shown, the switch  143  is able to switch between a state where one end of the communication electrode  120  and the transmission circuit  141  are electrically connected and a state where the other end of the communication electrode  120  and the reception circuit  142  are electrically connected. The other end of the communication electrode  120  is grounded via a resistor. The second communication circuit  240  includes a transmission circuit  241 , a reception circuit  242 , and a switch  243 . The switch  243  is connected to one end of the second communication electrode  220 . The switch  243  is also connected to the transmission circuit  241  and the reception circuit  242 . In response to a control signal from a second control circuit not shown, the switch  243  is able to switch between a state where one end of the communication electrode  220  and the transmission circuit  241  are electrically connected and a state where the other end of the communication electrode  220  and the reception circuit  242  are electrically connected. The other end of the communication electrode  220  is grounded via a resistor. Each control circuit may be a circuit including a processor, e.g., a microcontroller. When transmitting a signal from the inner module  100  to the outer module  200 , the switch  143  electrically connects the transmission circuit  141  and the communication electrode  120 , and the switch  243  electrically connects the reception circuit  242  and the communication electrode  220 . Conversely, when transmitting a signal from the outer module  200  to the inner module  100 , the switch  243  electrically connects the transmission circuit  241  and the communication electrode  220 , and the switch  143  electrically connects the reception circuit  142  and the communication electrode  120 . Such a configuration can achieve half duplex communication via single-ended transmission. 
       FIG. 30B  is a diagram schematically showing an exemplary configuration of the communication electrodes and communication circuits in the case where full duplex communication via single-ended transmission is to be performed. In this example, the communication circuit  140  of the inner module  100  is connected to the two communication electrodes  120 A and  120 B of the inner module  100 . The communication circuit  240  of the outer module  200  is connected to the two communication electrodes  220 A and  220 B of the outer module. The communication circuit  140  of the inner module includes a transmission circuit  141  that is connected to the communication electrode  120 B and a reception circuit  142  that is connected to the communication electrode  120 A. The communication circuit  240  of the outer module  200  includes a transmission circuit  241  that is connected to the communication electrode  220 A, and a reception circuit  242  that is connected to the communication electrode  120 B. In this example, each of the communication circuits  140  and  240  does not include a switch. When transmitting a signal from the inner module  100  to the outer module  200 , the transmission circuit  141  inputs the signal to the communication electrode  120 B, and the reception circuit  242  receives the signal having been transmitted via the communication electrodes  120 B and  220 B. Conversely, when transmitting a signal from the outer module  200  to the inner module  100 , the transmission circuit  241  inputs the signal to the communication electrode  220 A, and the reception circuit  142  receives the signal having been transmitted via the communication electrodes  220 A and  120 A. The operation of the transmission circuit  141  and the reception circuit  142  is controlled by a first control circuit not shown, whereas the operation of the transmission circuit  241  and the reception circuit  242  is controlled by a second control circuit not shown. Such a configuration can achieve full duplex communication via single-ended transmission. 
       FIG. 31A  is a diagram schematically showing an exemplary configuration of the communication electrodes and communication circuits in the case where half duplex communication via differential transmission is to be performed. In this example, the communication circuit  140  of the inner module  100  includes a transmission circuit  145  and a reception circuit  146  for differential transmission purposes, and a switch  147 . The communication circuit  240  of the outer module  200  includes a transmission circuit  245  and a reception circuit  246  for differential transmission purposes, and a switch  247 . In response to a control signal from a first control circuit not shown, the switch  147  switches between a state where the communication electrodes  120   a  and  120   b  and the transmission circuit  145  are connected and a state where the communication electrodes  120   a  and  120   b  and the reception circuit  146  are connected. In response to a control signal from a second control circuit not shown, the switch  247  switches between a state where the communication electrodes  220   a  and  220   b  and the transmission circuit  245  are connected and a state where the communication electrodes  220   a  and  220   b  and the reception circuit  246  are connected. The transmission circuits  145  and  245  each output differential signals from two terminals thereof. The reception circuits  246  and  246  each perform necessary processing, e.g., differential arithmetics, to the differential signals having been input to their respective two terminals, to demodulate a signal therefrom. Via the switch  147 , one end of the communication electrodes  120   a  and  120   b  is connected to the two terminals of the transmission circuit  145  or to the two terminals of the reception circuit  146 . The other end of the communication electrodes  120   a  and  120   b  is grounded via a resistor. Similarly, via the switch  247 , one end of the communication electrodes  220   a  and  220   b  is connected to the two terminals of the transmission circuit  245  or to the two terminals of the reception circuit  246 . The other end of the communication electrodes  220   a  and  220   b  is grounded via a resistor. When transmitting a signal from the inner module  100  to the outer module  200 , the switch  147  electrically connects the transmission circuit  145  and the communication electrodes  120   a  and  120   b,  and the switch  247  electrically connects the reception circuit  246  and the communication electrodes  220   a  and  220   b.  Conversely, when transmitting a signal from the outer module  200  to the inner module  100 , the switch  247  electrically connects the transmission circuit  245  and the communication electrodes  220   a  and  220   b,  and the switch  147  electrically connects the reception circuit  146  and the communication electrodes  120   a  and  120   b.  Such a structure can achieve half duplex communication via differential transmission. 
       FIG. 31B  is a diagram schematically showing an exemplary configuration of the communication electrodes and communication circuits in the case where full duplex communication based on differential signals is to be performed. In this example, the inner module  100  includes a pair of communication electrodes  120 Aa and  120 Ab, which constitute a differential transmission line pair, and a pair of communication electrodes  120 Ba and  120 Bb, which constitute another differential transmission line pair. The outer module  200  includes a pair of communication electrodes  220 Aa and  220 Ab, which constitute a differential transmission line pair, and a pair of communication electrodes  220 Ba and  220 Bb, which constitute another differential transmission line pair. The communication electrodes  120 Aa and  120 Ab are respectively opposed to the communication electrodes  220 Aa and  220 Ab. The communication electrodes  120 Ba and  120 Bb are respectively opposed to the communication electrodes  220 Ba and  220 Bb. The communication circuit  140  of the inner module  100  includes a transmission circuit  145  and a reception circuit  146  for differential transmission purposes, but does not include a switch. The communication circuit  240  of the outer module  200  includes a transmission circuit  245  and a reception circuit  246  for differential transmission purposes, but does not include a switch. When transmitting a signal from the inner module  100  to the outer module  200 , the transmission circuit  145  inputs differential signals to the communication electrodes  120 Ba and  120 Ba, and the reception circuit  242  demodulates the signal having been transmitted via the communication electrodes  120 Ba,  120 Bb,  220 Ba and  220 Bb. Conversely, when transmitting a signal from the outer module  200  to the inner module  100 , the transmission circuit  245  inputs differential signals to the communication electrodes  220 Aa and  220 Ab, and the reception circuit  146  demodulates the signal having been transmitted via the communication electrodes  220 Aa,  220 Ab,  120 Aa and  120 Ab. The operation of the transmission circuit  145  and the reception circuit  146  is controlled by a first control circuit not shown, whereas the operation of the transmission circuit  245  and the reception circuit  246  is controlled by a second control circuit not shown. Such a configuration can achieve full duplex communication via differential transmission. 
     Now, example methods of terminating each differential transmission line will be described. 
       FIG. 32A  shows a first example of a method of terminating each differential transmission line. In this example, as in the examples of  FIG. 30A  to  FIG. 31B , one end of each differential transmission line is connected to a terminal of a communication circuit. On the other hand, the other end of each differential transmission line is connected to a terminator. These resistors are connected to each other, this node being grounded. The resistance values of the resistors are set to values that will make the reflection at the terminal ends as small as possible. Thus, a configuration may be adopted where the differential transmission lines are terminated with two resistors, a midpoint between which is grounded. With such a configuration, the termination resistance value can be set to an appropriate value for each line, whereby the potential reference for the terminal ends of the differential lines can be made common. 
       FIG. 32B  shows a second example of a method of terminating each differential transmission line. In this example, an end of each differential transmission line is connected to one terminator. In this example, one resistor employed between the differential lines achieves termination, whereby the number of parts can be reduced. 
     Thus, with wireless power and data transmission apparatuses according to embodiments of the present disclosure, in each module, antennas for power transmission purposes and communication electrodes are disposed while being shifted in a direction along the axis of rotation. As compared to any configuration in which an antenna and a communication electrode flank each other along a perpendicular direction to the axis C (i.e., a radial direction), such a structure allows the device to have a smaller radius. When the mid position between the inner antenna and the outer antenna and the mid position between the inner communication electrode and the outer communication electrode are shifted from each other, data transmission noise associated with wireless power transmission can be reduced. Furthermore, when at least one electrically-conductive shield is disposed between the antenna and the communication electrode in at least one of the inner module and the outer module, noise can be further reduced. 
       FIG. 33  is a diagram showing results of an analysis which was performed in order to confirm the effects of noise suppression with electrically-conductive shields. In  FIG. 33 , (a) shows an example of a magnetic field intensity distribution based on a configuration having no shields disposed. In  FIG. 33 , (b) shows an example of a magnetic field intensity distribution based on a configuration in which two shields are disposed on the same plane. In  FIG. 33 , (c) shows an example of a magnetic field intensity distribution based on a configuration in which two shields are disposed with an overlap. In  FIG. 33 , denser region represent lower magnetic field intensities, while sparser regions represent higher magnetic field intensities. In this analysis, each of the communication electrodes  120  and  220  is composed of a differential transmission line pair. The outer antenna  210  is a transmission coil, whereas the inner antenna  110  is a reception coil. The noise intensity of the signal that is output from the outer communication electrode  220  when an AC power of  40  MHz is input to the transmission coil is analyzed with respect to each of the three configurations of (a) to (c) of  FIG. 33 . Assuming that an input power of the antenna  210  (input port) is Pi=1 [W] and that an output power of the communication electrode  220  is Po[W], a noise attenuation ΔN is expressed by the following equation. 
       Δ N [dB]=10 log( Po/Pi )
 
     This noise attenuation AN was calculated for each of the configurations of (a) to (c) of  FIG. 33 . The numerical value in each of the diagrams (a) to (c) of  FIG. 33  represents the noise attenuation AN under the respective configuration. The noise attenuations under the configurations of (a) to (c) of  FIG. 33  were, respectively, −70 dB, −121 dB, and −161 dB. It was confirmed from these results that disposing the electrically-conductive shields  160  and  260  realize a great noise attenuation, and that disposing the electrically-conductive shields  160  and  260  with an overlap achieves an even greater noise attenuation. 
     Next, exemplary configurations of systems including wireless power and data transmission apparatuses according to embodiments of the present disclosure will be described. In the following description, it is assumed that electric power is transmitted from the inner module  100  to the outer module  200 . In the following description, the inner module  100  may be referred to as the “power transmitting module  100 ”, the outer module  200  as the “power receiving module  200 ”, the first antenna  110  as the “transmission coil  110 ”, and the second antenna  210  as the “reception coil  210 ”. The system described below will similarly be applicable in the case where the inner module  100  is a power receiving module and the outer module  200  is a power transmitting module. 
       FIG. 34  is a block diagram showing the configuration of a system including the wireless power and data transmission apparatus. This system includes a power source  20 , a power transmitting module  100 , a power receiving module  200 , and a load  300 . The load  300  in this example includes a motor  31 , a motor inverter  33 , and a motor control circuit  34 . Without being limited to a device having the motor  31 , the load  300  may be any device that operates with electric power, e.g., a battery, a lighting device, or an image sensor. The load  300  may be an electrical storage device, e.g., a secondary battery or a capacitor for electrical storage purposes, that stores electric power. The load  300  may include an actuator including the motor  31  that causes the power transmitting module  100  and the power receiving module  200  to undergo a relative movement (e.g., rotation or linear motion). 
     The power transmitting module  100  includes a transmission coil  110 , communication electrodes  120  (electrodes  120   a  and  120   b ), a power transmitting circuit  13 , and a power transmission control circuit  14 . The power transmitting circuit  13 , which is connected between the power source  20  and the transmission coil  110 , converts the DC power which is output from the power source  20  into AC power, and outputs it. The transmission coil  110  sends the AC power which is output from the power transmitting circuit  13  into space. The power transmission control circuit  14  may be an integrated circuit including a microcontroller unit (MCU, hereinafter also referred to as a “micon”) and a gate driver circuit, for example. By switching the conducting/non-conducting states of the plurality of switching elements included in the power transmitting circuit  13 , the power transmission control circuit  14  controls the frequency and voltage of the AC power which is output from the power transmitting circuit  13 . The power transmission control circuit  14  includes a communication circuit  140 . The communication circuit  140 , which is connected to the electrodes  120   a  and  120   b,  also handles exchanges of signals via the electrodes  120   a  and  120   b.    
     The power receiving module  200  includes a reception coil  210 , communication electrodes  220  (electrodes  220   a  and  220   b ), a power receiving circuit  23 , and a power reception control circuit  125 . The reception coil  210  electromagnetically couples with the transmission coil  110 , and receives at least a portion of the electric power which has been transmitted from the transmission coil  110 . The power receiving circuit  23  includes a rectifier circuit that converts the AC power which is output from the reception coil  210  into e.g. DC power and outputs it. The power reception control circuit  24  includes a communication circuit  240 . The communication circuit  240 , which is connected to the electrodes  220   a  and  220   b,  also handles exchanges of signals via the electrodes  220   a  and  220   b.    
     The load  300  includes the motor  31 , the motor inverter  33 , and the motor control circuit  34 . Although the motor  31  in this example is a servo motor which is driven with a three-phase current, it may be any other kind of motor. The motor inverter  33  is a circuit that drives the motor  31 , including a three-phase inverter circuit. The motor control circuit  34  is a circuit, e.g., an MCU, that controls the motor inverter  33 . By switching the conducting/non-conducting states of the plurality of switching elements that are included in the motor inverter  33 , the motor control circuit  34  causes the motor inverter  33  to output a three-phase AC power as desired. 
       FIG. 35A  is a diagram showing an exemplary equivalent circuit for the transmission coil  110  and the reception coil  210  in the wireless power feeding unit  100 . As shown in the figure, each coil functions as a resonant circuit having an inductance component and a capacitance component. By ensuring that the resonant frequencies of two coils opposing each other have close values, electric power can be transmitted with a high efficiency. The transmission coil  110  receives AC power supplied from the power transmitting circuit  13 . Owing to a magnetic field that is generated with this AC power from the transmission coil  110 , electric power is transmitted to the reception coil  210 . In this example, the transmission coil  110  and the reception coil  210  both function as series resonant circuits. 
       FIG. 35B  is a diagram showing another exemplary equivalent circuit for the transmission coil  110  and the reception coil  210  in the wireless power feeding unit  100 . In this example, the transmission coil  110  functions as a series resonant circuit, whereas the reception coil  210  functions as a parallel resonant circuit. In another possible implementation, the transmission coil  110  may constitute a parallel resonant circuit. 
     Each coil may be a planar coil or a laminated coil formed on a circuit board, or a wound coil in which a litz wire, a twisted wire, or the like made of a material such as copper or aluminum is used, for example. Each capacitance component in the resonant circuit may be realized by a parasitic capacitance of the coil, or a capacitor having a chip shape or a lead shape may be separately provided, for example. 
     The resonant frequency f 0  of the resonant circuit is typically set to be equal to the transmission frequency f 1  during power transmission. It is not necessary for the resonant frequency f 0  of each of the resonant circuit to be exactly equal to the transmission frequency f 1 . The resonant frequency f 0  of each may be set to a value in the range of about 50 to about 150% of the transmission frequency f 1 , for example. The frequency f 1  of the power transmission may be e.g. 50 Hz to 300 GHz; 20 kHz to 10 GHz in one example; 20 kHz to 20 MHz in another example; and 80 kHz to 14 MHz in still another example. 
       FIGS. 36A and 36B  are diagrams showing exemplary configurations for the power transmitting circuit  13 .  FIG. 36A  shows an exemplary configuration of a full-bridge type inverter circuit. In this example, by controlling ON or OFF of the four switching elements S 1  to S 4  included in the power transmitting circuit  13 , the power transmission control circuit  14  converts input DC power into an AC power having a desired frequency f 1  and voltage V (effective values). In order to realize this control, the power transmission control circuit  14  may include a gate driver circuit that supplies a control signal to each switching element.  FIG. 36B  shows an exemplary configuration of a half-bridge type inverter circuit. In this example, by controlling ON or OFF of the two switching elements S 1  and S 2  included in the power transmitting circuit  13 , the power transmission control circuit  14  converts input DC power into an AC power having a desired frequency f 1  and voltage V (effective values). The power transmitting circuit  13  may be different in structure from the configurations shown in  FIG. 36A  and  FIG. 36B . 
     The power transmission control circuit  14 , the power reception control circuit  24 , and the motor control circuit  34  can be implemented as circuits including a processor and a memory, e.g., microcontroller units (MCU). By executing a computer program which is stored in the memory, various controls can be performed. The power transmission control circuit  14 , the power reception control circuit  24 , and the motor control circuit  34  may be implemented in special-purpose hardware that is adapted to perform the operation according to the present embodiment. The power transmission control circuit  14  and the power reception control circuit  24  also function as communication circuits. The power transmission control circuit  14  and the power reception control circuit  24  are able to transmit signals or data to each other via the communication electrodes  120  and  220 . 
     The motor  31  may be a motor that is driven with a three-phase current, e.g., a permanent magnet synchronous motor or an induction motor, although this is not a limitation. The motor  31  may any other type of motor, such as a DC motor. In that case, instead of the motor inverter  33  (which is a three-phase inverter circuit), a motor driving circuit which is suited for the structure of the motor  31  is to be used. 
     The power source  20  may be any power source that outputs DC power. The power source  20  may be any power source, e.g., a mains supply, a primary battery, a secondary battery, a photovoltaic cell, a fuel cell, a USB (Universal Serial Bus) power source, a high-capacitance capacitor (e.g., an electric double layer capacitor), or a voltage converter that is connected to a mains supply, for example. 
     In the above embodiments, coils are used as antennas; instead of coils, however, electrodes which transmit electric power via electric field coupling (also referred to as capacitive coupling) may be used. For example, as shown in  FIG. 37 , the power transmitting module  100  may include a transmission electrode  110 E, and the power receiving module  200  may include a reception electrode  210 E. In this case, each of the transmission electrode  110 E and the reception electrode  210 E may be split into two subportions, such that AC voltages which are opposite in phase are applied to the two subportions. 
     A wireless power transmission system according to another embodiment of the present disclosure includes a plurality of wireless power feeding units and a plurality of loads. The plurality of wireless power feeding units are connected in series, and each supply electric power to one or more loads connected thereto. 
       FIG. 38  is a block diagram showing the configuration of a wireless power transmission system including two wireless power feeding units. This wireless power transmission system includes two wireless power feeding units  10 A and  10 B and two loads  300 A and  300 B. The number of wireless power feeding units and the number of loads are not limited two, but may each be three or more. 
     Each power transmitting module  100 A,  100 B is similar in configuration to the power transmitting module  100  in the above-described embodiment. Each power receiving module  200 A,  200 B is similar in configuration to the power receiving module  200  in the above-described embodiment. The loads  300 A and  300 B receive electric power supplied from the power receiving modules  200 A and  200 B, respectively. 
       FIGS. 39A to 39C  are schematic diagrams showing different types of configuration for the wireless power transmission system according to the present disclosure.  FIG. 39A  shows a wireless power transmission system which includes one wireless power feeding unit  10 .  FIG. 39B  shows a wireless power transmission system in which two wireless power feeding units  10 A and  10 B are provided between a power source  20  and a terminal load  300 B.  FIG. 39C  shows a wireless power transmission system in which three or more wireless power feeding units l 0 A to  10 X are provided between a power source  20  and a terminal load device  300 X. The technique according to the present disclosure is applicable to any of the implementations of  FIGS. 39A to 39C . The configuration shown in  FIG. 39C  is suitably applicable to an electrically operated apparatus such as a robot having many movable sections, as has been described with reference to  FIG. 1 , for example. 
     In the configuration of  FIG. 39C , the configuration according to the above-described embodiment may be applied to all of the wireless power feeding units  10 A to  10 X, or the above-described configuration may be applied to only some of the wireless power feeding units. 
     INDUSTRIAL APPLICABILITY 
     The technique according to the present disclosure is suitably applicable to an electrically operated apparatus such as a robot, a monitor camera, an electric vehicle, or a multicopter to be used in a factory or a site of engineering work, for example. 
     REFERENCE SIGNS LIST 
       10  wireless power feeding unit 
       13  power transmitting circuit 
       14  power transmission control circuit 
       23  power receiving circuit 
       24  power reception control circuit 
       31  motor 
       33  motor inverter 
       34  motor control circuit 
       20  power source 
       100  inner module 
       110  first antenna 
       120  first communication electrode 
       130  magnetic core 
       140  first communication circuit 
       150  dielectric member 
       160  first electrically-conductive shield 
       190  metal housing 
       200  power receiving module 
       210  second antenna 
       220  second communication electrode 
       230  magnetic core 
       240  second communication circuit 
       250  dielectric member 
       260  second electrically-conductive shield 
       290  metal housing 
       300  load 
       600  wireless power feeding unit 
       650  control device 
       700  miniature motor 
       900  motor driving circuit