Power receiving device and communication device based on wireless power feeding method

Abstract

To provide a mechanism for efficiently and wirelessly supplying power to drive a device.SOLUTION: A power receiving device includes: a power receiving antenna that receives, from multiple directions, microwaves transmitted from a power transmitting device, based on a wireless power feeding method configured to operate at a frequency of 900 MHz or more, and thereby whose power receiving state changes; and a controller that transmits to the power transmitting device, as feedback information, information regarding pseudo electric field intensity calculated from multiple voltage values measured at different timings for a voltage generated based on the microwaves received by the power receiving antenna.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power receiving device and a communication device for wireless power supply to a device that consumes power built in a machine such as a multi-joint robot.

Background Art

[0002] In fields such as factory automation (FA), the Internet of Things (IoT), and home appliances, various machines are used. Generally, although machines used in FA and the like are wireless for data communication lines, there are many cases where the power supply lines are not wireless.

[0003] As the background art in this technical field, there is Japanese Unexamined Patent Application Publication No. 2014-29326 (Patent Document 1). This publication describes, "A force sensor that detects an external force, comprising an exterior part (2), a pressing member (1) disposed on the exterior part, a sensor part that detects the force applied to the pressing member, a slip ring part through which power supply or signal transmission is performed via a non-rotating side contact (6) and a rotating side contact (7), wherein both the force sensor part and the slip ring part are housed inside the exterior part, and power supply or signal transmission is performed between the slip ring part and the force sensor part." (See the abstract).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 shows an example of supplying power to a sensor built into the tip side of a multi-joint robot, particularly a robot arm. In this example, it is disclosed that power transmitted from an external power source is supplied to the sensor via a power line arranged in the robot arm (see FIG. 9 of Patent Document 1). However, Patent Document 1 does not consider wireless power supply to the sensor. Therefore, the present invention provides a mechanism for efficiently wirelessly supplying power for driving a device built into a machine such as a multi-joint robot.

Means for Solving the Problem

[0006] To solve the above problems, for example, the configuration described in the claims is adopted.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a mechanism for efficiently wirelessly supplying power for driving a device. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Figure 30

Mode for Carrying Out the Invention

Examples

[0009] FIG. 27 is a diagram showing a case where power is supplied from a power source 34 to a device 30 that consumes power and is built into the tip side of an articulated robot 100 via a wiring 32 arranged inside the articulated robot 100. A plurality of joints J1a, J1b, J2a, J2b, and J2c are provided in the robot arm portion 90 and / or the robot hand portion 80 of the articulated robot 100. By moving these plurality of joints, the articulated robot 100 performs highly flexible operations such as grasping and moving a workpiece W.

[0010] When the wiring 32 is provided inside to supply power to the sensor 30 built into the articulated robot 100, problems such as the burden on the wiring 32, disconnection of the wiring 32, or maintenance of the wiring 32 may occur due to the movement of the joints J1a, J1b, J2a, J2b, and J2c of the articulated robot 100. In addition, in a machine that performs highly flexible operations such as the articulated robot 100, there is a problem that the space for adding the wiring 32 is limited because various components such as actuators are generally incorporated inside.

[0011] Therefore, in order to avoid the problems of the above wiring 32, it is considered to supply power to the sensor 30 by wireless power supply. However, there are specific problems in wirelessly wiring the power supply wiring of the machine 100. For example, in wireless power supply, since relatively small-capacity power is transmitted, the capacity of the power transmitted to the device 30 becomes a problem. If sufficient power cannot be transmitted, it is not preferable because the types and usage modes of the devices 30 used are limited.

[0012] In addition, in wireless power supply, impedance matching inconsistency becomes a problem. Impedance matching inconsistency refers to a state where impedance matching cannot be achieved. From the perspective of energy transmission, impedance matching inconsistency is not preferable because it causes inefficiency.

[0013] FIG. 1 is an example of a diagram schematically showing a power transmission device 1 and a power reception device 10 for performing wireless power supply to a device 30 that consumes power built into the tip side of a machine 100 used in fields such as FA (factories, etc.), IoT (building management systems, etc.), and home appliances.

[0014] "Articulated robot" The machine 100 illustrated in FIG. 1 is, for example, an industrial robot (including machine tools) or a household robot (including home appliances). The machine 100 can be used for various applications such as gripping, lifting (pick), placing (place), assembling, painting, and welding of workpieces or parts W. Preferably, the machine 100 is an articulated robot that performs highly flexible operations.

[0015] The multi-joint robot 100 generally has a plurality of (at least two) axes or joints J1a, J1b, J2a, J2b, J2c (see Fig. 1) in order to operate the robot arm portion 90 and / or the robot hand portion 80 with a high degree of freedom. Generally, the more axes or joints J1a, J1b, J2a, J2b, J2c the multi-joint robot 100 has, the higher the degree of freedom of movement becomes, but accordingly, more precise control is required. On the other hand, the fewer axes or joints J1a, J1b, J2a, J2b, J2c the multi-joint robot 100 has, the simpler the mechanism becomes and the less likely it is to malfunction.

[0016] In Fig. 1, the joints J1a, J1b of the robot arm portion 90 corresponding to the human arm portion and the joints J2a, J2b, J2c of the robot hand portion 80 corresponding to the human hand portion are schematically shown. The multi-joint robot 100 performs functions such as rotation and displacement at each joint J1a, J1b, J2a, J2b, J2c. Generally, the multi-joint robot 100 has a plurality of axes from about 2 to 8 axes implemented. Also, generally, the robot hand portion 80 has a plurality of fingers (fingers) from about 2 to 5 fingers implemented. In this embodiment, it is not limited by the number, shape, function, etc. of the joints or fingers of the multi-joint robot 100.

[0017] The multi-joint robot 100 can be configured in various ways for the mechanism that moves the plurality of joints of the robot arm portion 90. For example, a serial mechanism that moves the plurality of joints of the robot arm portion 90 in order, a parallel (parallel link) mechanism that moves the plurality of joints at once, etc. can be used. The multi-joint robot 100 may be, for example, a vertical multi-joint robot or a horizontal multi-joint robot. The multi-joint robot 100 is not limited to a robot arm or a robot hand, and may also be, for example, a gantry robot.

[0018] The robotic hand part 80 shown in FIG. 1 is also called a chuck. The chuck moves a plurality of fingers in a predetermined direction (for example, the vertical direction, etc.) by an actuator to open and close in order to grasp a workpiece or a part W (see J2a, J2b, J2c in FIG. 1). Conventionally, a device 30 may be mounted to detect the position of the mechanical movement of this chuck (for example, the upper position or the lower position, etc.). Also, a device 30 may be mounted to detect whether or not this chuck is grasping the part W. In the former case, control is performed to open and close the chuck in a predetermined direction. In the latter case, the hardness of the part W (for example, hard or soft, etc.) is detected, and chuck control and the like corresponding thereto are performed.

[0019] As shown in FIG. 1, when a device 30 that consumes power is built into the machine 100, power supply to the device 30 becomes necessary. In this embodiment, a power transmission device 1 having a power transmission antenna 2 for wirelessly powering the device 30 is provided outside the machine 100. Also, a power reception device 10 having a power reception antenna 12 is provided inside or on the machine. Preferably, the power reception device 10 is built into the machine 100, wirelessly receives the energy E transmitted from the power transmission device 1, and is physically connected to the device 30 so as to supply power to the device 30. Therefore, the necessity of wiring for supplying power to the device 30 inside the articulated robot 100 is eliminated or minimized.

[0020] "Sensor" As the device 30 built into the articulated robot 100 illustrated in FIG. 1, for example, a sensor 30 is used. FIG. 28 illustrates that the required amount of power differs depending on the type of the sensor 30. The power consumption of the sensor is approximately calculated. Assuming that the voltage between the capacitors is 3.3V, the amount of power at full charge is described, and the amount of power is calculated assuming that the sensor operates continuously for 1 hour. Preferably, the sensor 30 incorporated in the multi-joint robot 100 is a small, lightweight, and low-power consumption sensor. For example, the sensor 30 is a sensor used for detecting mechanical movements of a chuck, tactile states, etc. For example, the sensor 30 may be a proximity sensor, an MR sensor, a Hall element, a position sensor, or the like.

[0021] The proximity sensor 30 is a sensor that reacts when the workpiece W approaches. For example, the proximity sensor 30 has a cylindrical or thin plate-shaped body, with a detection surface provided on one end side of this body, and a cable extending from the opposite side of this body. The detection surface can be provided at an appropriate location on the robot hand part 80 and is configured to react when the workpiece W approaches.

[0022] There are various types of proximity sensors known. For example, there are those that react when a metal approaches. There are also various types of detection distances for the proximity sensor 30. For example, there are those that detect in units of mm. The proximity sensor 30 has the advantages of no wear or other deterioration due to being non-contact, having waterproof and dustproof properties, and being difficult to break. In particular, the type that reacts to metal has the advantages of being less affected by dust, water droplets, etc., and having few false detections.

[0023] The sensor 30 may also be an MR (Magnetic Resistance) sensor or a magnetic sensor. The MR sensor 30 is a sensor that measures the magnitude and direction of a magnetic field (magnetic field). There are various types known depending on the purpose, such as the strength of the measurement target magnetic field, whether it is AC or DC, and the measurement environment. For example, the MR sensor 30 measures the magnitude of the magnetic field using the magnetoresistance effect in which the electrical resistance of a solid changes due to a magnetic field.

[0024] The sensor 30 may also be a Hall element. The Hall element 30 is a sensor that measures magnetic flux density using the Hall effect. The Hall effect refers to the phenomenon in which an electromotive force appears in a direction perpendicular to both the current and the magnetic field when a magnetic field is applied perpendicular to the flowing current in an object. The Hall element 30 includes sensors that output an analog voltage proportional to the magnetic flux density and sensors that output a digital output.

[0025] The sensor 30 may be a displacement sensor, an inspection sensor, a discrimination sensor, a measurement sensor, a length measuring sensor, a vibration sensor, a microphoto sensor, a pressure sensor, a flow sensor, a temperature and humidity sensor, a human presence sensor, a wear sensor, an acceleration sensor, a strain sensor, a force sensor, or the like. Furthermore, the sensor 30 may be a CMOS sensor, a photoelectric sensor, a laser sensor, an ultrasonic sensor, a touch sensor, a linear cage, a potentiometer, an image sensor, a color sensor, a LiDAR sensor, a TOF sensor, a seismic sensor, a gyro sensor, an inclination sensor, a rotation sensor, an angle sensor, a tachometer, a load cell, a fall sensor, a torque sensor, a liquid level sensor, a leak / water detection sensor, a non-contact temperature sensor, a current sensor, a power sensor, an electrostatic sensor, or an isolator, or the like.

[0026] The sensor 30 may be configured to appropriately detect the work W according to the color, shape, inclination, thickness, transparency, etc. of the work W to be detected. For example, the sensor 30 may be configured to detect a black work, a metal work, a thin work, a transparent work, or the like. Furthermore, the sensor 30 may be a combination of a plurality of sensors based on the characteristics of the work W to be detected. Preferably, the device 30 is a low power consumption type sensor with a power consumption of 100 mWh or less. More preferably, the device 30 is a low power consumption type sensor with a power consumption of several tens of mWh or less. Even more preferably, the device 30 is a low power consumption type sensor with a power consumption of 10 mWh or less.

[0027] "Wireless power supply" There are several types of wireless power supply. In this embodiment, preferably, wireless power supply is performed between the power transmission device 1 and the power reception device 10 by the microwave method. In the microwave method, energy or power can be transmitted over a relatively long distance. Therefore, even when the sensor 30 to be powered is built into the multi-joint robot 100 and its position is frequently changed, the necessary power can be sent to the sensor 30 from a remote location. However, in the microwave method, there is an upper limit to the capacity of the energy that can be transmitted. For example, when performing wireless power supply by the microwave method, power with a capacity of about 1 mW can be transmitted at a distance of about 1 m.

[0028] Referring again to FIG. 28, when the sensor 30 is a proximity sensor, a seismic sensor, or a temperature and humidity sensor, it can be handled with relatively low-capacity (1 mW to 10 mW) power. When the sensor 30 is a pressure sensor or an angle sensor, power with a larger capacity (10 mW to 100 mW) is required. When the sensor 30 is a color sensor, a laser sensor, etc., even larger-capacity (100 mW to 1000 mW) power is required. Therefore, when based on the microwave method, ensuring the power sent to the sensor 30 becomes a problem.

[0029] FIG. 2 is a diagram generally showing schematically the power consumption required for various types of devices 30. For example, as shown by reference numeral D1, the power capacity required to operate edge computing (such as a microcomputer, a terminal, a processing device, etc.) is relatively large, whereas, as shown by reference numeral D2, the power capacity required to operate a sensor can be relatively small. As shown by reference numeral D3, the power capacity required to operate a wireless communication IC is not as large as D1, but is larger than D2. Research and development on miniaturization and large capacity of these electronic components are being advanced in various fields, and as can be understood from FIG. 2, the power consumption required for these is showing a decreasing trend year by year. However, the values such as D2 are approximated, and as exemplified in FIG. 28, the required power varies depending on the type of the sensor 30.

[0030] As shown by symbol D4, when a wireless communication IC is connected to the device 30 to be powered, the required power capacity increases. Examples of wireless communication ICs include protocols having physical layers such as Bluetooth (registered trademark), ZigBee (registered trademark), Sub-GHz (frequency band less than 1 GHz or less than 1 GHz), Wi-Fi (registered trademark), IO-Link (registered trademark), Thread, multi-standard, WIRED, IEEE802.15.1, and IEEE802.15.4, etc., which are short-range wireless communication standards. When a wireless communication IC is combined with the sensor 30, for example, about 10 to 30 mW of power may be required during data transmission and reception. Note that the sensor 30 may be a sensor having a wireless communication function (for example, a SAW sensor or a surface acoustic wave filter, etc.) even if it is not connected to the wireless communication IC.

[0031] When performing wireless power supply by the microwave method, there is an upper limit to the capacity of the energy to be transmitted. Therefore, when the type of the sensor 30 to be powered requires a relatively large capacity (see Fig. 28), or when the sensor 30 is connected to a wireless communication IC (see Fig. 2), or when there are two or more sensors 30 to be powered, etc., the transmitted power becomes a problem. Therefore, in this embodiment, a battery management system 21 is combined and used for the wireless power supply by the microwave method (see Fig. 1). The battery management system 21 is a system that charges a battery by wireless power supply and drives the system (device 30) with the power. Fig. 1 schematically illustrates that the energy or power E transmitted from the power transmission antenna 2 of the power transmission device 1 is received by the power reception antenna 12 of the power reception device 10, and after this energy E is stored in the battery in the battery management system 21, it is sent to the sensor 30.

[0032] As illustrated in FIGS. 28 and 2, the power consumption is approximately determined for each device 30 (sensor, wireless communication IC, edge computing), and there are limitations for devices 30 that can be driven without using a battery. Also, as illustrated in FIG. 2, the power consumption of each device 30 has been decreasing year by year. That is, by combining and using the battery management system 21 for wireless power supply, more types of devices 30 can be driven compared to a system that does not use a battery, and the target range is increasing year by year. Therefore, in this embodiment, it is important to combine the battery management system 21 with wireless power supply.

[0033] In FIG. 1, the power receiving device 10 is housed on the tip side of the multi-joint robot 100 (such as the tip side of the robot arm 90 or the tip side of the robot hand 80). Among the multi-joint robot 100 composed of various components, there is relatively more space inside the fingers of the robot hand 80. For this reason, it is preferable to house the power receiving device 10 including the power receiving antenna 12, the battery management system 21, and the sensor 30 in this space. At this time, relatively large and bulky components may be configured to be flexible and wound up and stored in the space of the finger. Also, some components may be arranged at a location away from the finger (for example, the base of the finger of the robot hand part 80 or a wider location nearby). Also, some components can protrude outside the machine 100 as necessary. Preferably, the separation distance between components is kept short to minimize the wiring length.

[0034] One power transmission device 1 may transmit energy E to one power receiving device 10. Alternatively, one power transmission device 1 may transmit energy E to a plurality of power receiving devices 10. When a plurality of power receiving devices 10 are provided in the machine 100, the power receiving devices 10 may be provided in the spaces of the plurality of fingers of the robot hand 80, respectively. Alternatively, sensors 30 may be mounted in the spaces of the respective fingers of the robot hand 80, and the power receiving antenna 12 and / or the battery management system 21 for supplying power to each sensor 30 may be provided in the space at the base of the finger.

[0035] "Power receiving antenna" FIG. 3 is an example of a plan view showing a configuration example of the power receiving antenna 12. The power receiving antenna 12 is a power receiving element having the function of receiving a radio frequency (RF) signal or electromagnetic wave transmitted from the power transmission device 1. This power receiving antenna 12 is formed, for example, in a thin plate shape with a front size of 12 cm × 12 cm and a thickness of 0.5 mm. However, the size can be changed to about 13 cm × 13 cm or 14 cm × 14 cm. Also, the thickness can be changed to about 1 mm.

[0036] Referring to FIG. 3, the power receiving antenna 12 is composed of a plurality of antenna parts 110, 120, 130, 140, 150, 160 so as to receive energy E (see FIG. 1) from a plurality of directions. The antenna part is also called a rectenna and is an element that rectifies and converts microwaves into direct current. These antenna parts 110, 120, 130, 140, 150, 160 form a substantially thin plate-shaped antenna 12 having an appropriate size as a whole. The antenna 12 can be configured in multiple layers. For example, the antenna parts 110 to 160 may be placed on a flexible substrate to have flexibility (able to be bent or rolled).

[0037] In the example shown in FIG. 3, five antenna parts 110, 120, 130, 140, 150 are arranged on the front side, and one antenna part 160 is arranged on the back side. Further, connection parts (DC connections) 171, 172, 173, 174, 175 connecting the antenna parts 110, 120, 130, 140, 150 on the front side and the antenna part 160 on the back side are arranged between them.

[0038] On the surface side, one antenna portion 110, 120, 130, 140 is arranged along each side of the square shape. Each antenna portion 110, 120, 130, 140 extends with a predetermined length so as to be able to receive power preferably at the four sides, and is arranged to be orthogonal to each other. Each antenna portion 110, 120, 130, 140 has, for example, portions 111, 121, 131, 141 that extend linearly along each side, and portions that are bent inward and extend at both ends in order to secure received power. Therefore, the antenna portions 110, 120, 130, 140 are not limited to the length of each side of the square shape, and receive energy with a relatively long length including the portions curved inward. For example, at the corner side of the square, each antenna portion has first bent portions 112, 113, 122, 123, 132, 133, 142, 143 that are bent inward at an angle of about 45 degrees, and second bent portions 114, 115, 124, 125, 134, 135, 144, 145 that are bent inward at an angle of about 90 degrees. Each antenna portion can further have a third bent portion (not shown).

[0039] Furthermore, on the central side of the square shape where each antenna portion 110, 120, 130, 140 is arranged, when viewed from the surface side, an antenna portion 150 that extends linearly obliquely (at 45 degrees) from the upper right to the lower left of the square shape is arranged. These five antenna portions 110, 120, 130, 140, 150 on the surface side are arranged so that adjacent ones do not contact each other and the interval between adjacent ones does not become too wide. Therefore, each antenna portion is arranged to avoid loss due to electromagnetic coupling caused by the proximity of the antennas. Furthermore, with this arrangement configuration, electromagnetic energy can be received by the antenna from any angle.

[0040] Furthermore, on the back side, an antenna portion 160 extending linearly in an oblique manner is similarly disposed. The antenna portion 160 on the back side extends in a mirror image relationship with respect to the antenna portion 150 on the front side and is disposed so as to apparently intersect at the center of the rectangular shape. When viewed from the front side, this antenna portion 160 extends linearly in an oblique manner from the upper left to the lower right of the rectangular shape.

[0041] Furthermore, connection portions 171, 172, 173, 174, 175 for connecting the six antenna portions 110, 120, 130, 140, 150, 160 to each other are provided to synthesize DC components. For example, when viewed from the front side, the connection portions 171, 172, 173, 174, 175 linearly connect the central portions 111, 121, 131, 141 of the four antenna portions 110, 120, 130, 140 extending along each side of the rectangular shape in one stroke, and also connect the central portions of the two antenna portions 150, 160 extending linearly in an oblique manner. Rectifiers 14a, 14b, 14c, 14d, 14e are provided at these connection locations respectively. These multiple rectifiers 14a, 14b, 14c, 14d, 14e can be considered to constitute one rectifier 14 as a whole.

[0042] Thus, the power receiving antenna includes a plurality of antennas, and these antennas are arranged along the four sides of a substantially rectangular shape and / or the diagonals of a slightly rectangular shape. Thus, the energy received by the power receiving antenna 12 composed of the plurality of antenna portions 110 to 160 is sent to a rectifier 14 that is functionally connected to the power receiving antenna 12. The rectifier 14 is an element having a rectifying action that allows current to flow only in one direction. The power receiving antenna 12 and the rectifier 14 may be integrally formed, and convert the RF (electromagnetic wave) received by the power receiving antenna 12 into DC (direct current voltage).

[0043] In the prior art, when antennas are configured by juxtaposing a plurality of antenna units, interference may occur between adjacent antenna units, which may have an adverse effect (radio wave interference) on the power reception function. Also, in order to avoid this interference, a relatively large space may be provided between adjacent antenna units, resulting in the antenna being made too large as a whole. In this embodiment, by arranging the six antenna units 110 to 160 as described above, these antenna units 110 to 160 are arranged in a compact manner as a whole, and interference between adjacent antenna units is avoided so that each antenna unit 110 to 160 can suitably receive power.

[0044] FIG. 4 is an example of a diagram showing the simulation results of the power reception states of the antenna units 110 to 160. In FIG. 4, the horizontal axis represents the frequency (GHz), and the vertical axis represents the power reception efficiency or the radiation efficiency (magnitude). As can be understood from FIG. 4, assuming that the radiation efficiency of a perfect (ideal) antenna unit is 100%, it was confirmed that all the antenna units 110 to 160 exhibit a radiation efficiency exceeding 90%, particularly at a frequency of 0.9 to 0.92 GHz. The results in FIG. 4 are based on three-dimensional electromagnetic field simulation. Therefore, it can be expected that the antenna 12 illustrated in FIG. 3 shows good reception results in each direction (up and down, left and right, front and back) of the X-axis, Y-axis, and Z-axis in a three-dimensional space. Note that the positions, numbers, sizes, and shapes of the antenna units 110 to 160 and the rectifiers 14a to 14e are not limited to the configuration shown in FIG. 3.

[0045] The power receiving antenna 12 has an appropriate size so as to cover substantially all directions. Further, the power receiving antenna 12 may be configured to have flexibility. For this reason, for example, in a relatively narrow space such as inside a finger of the robot hand portion 80, the power receiving antenna 12 can be folded and accommodated. Even in this case, the high efficiency of the power receiving antenna 12 can be maintained. Further, the power receiving antenna 12 may be accommodated inside the machine 100, or may be wound around and accommodated in a housing of the main body of the machine or related components (for example, an actuator, etc.) on the upper part of the machine 100. Note that the quadrilateral shape forming the contour of the antenna 12 is not limited to a perfect square shape, and each angle formed by two sides of the quadrilateral is not limited to 90 degrees. Further, the contour of the antenna 12 may be a polygonal shape or a circular shape.

[0046] Therefore, the power receiving situation is optimized by using the power receiving antenna 12 that maximizes the received power obtained from a plurality of antennas and can receive power corresponding to all angles. Conventionally, when dealing with a plurality of antennas (array antennas), high-frequency components were added while performing phase control, etc., so the radiation direction was uniformly determined. In order to enable radio waves to be received at all angles, it was necessary to separate the radiation of each antenna. In this embodiment, each antenna is completely separated at high frequencies, and by adding only the DC components after rectification, it is possible to minimize the radio wave interference between the antennas. Further, there is also an advantage in eliminating radio wave interference between the antennas within a limited range and arranging them while keeping a high antenna efficiency (90% or more).

[0047] "Power receiving circuit" FIG. 5 is an example of a diagram more specifically showing an electric circuit in wireless power feeding performed between the power transmission device 1 and the power receiving device 10 schematically shown in FIG. 1. In this embodiment, the power receiving device 10 is provided in a form including the sensor 30. However, in other embodiments, the power receiving device 10 may be provided in a form not including the sensor 30 and may be connected to the sensor 30 during installation. Referring to FIG. 5, the power transmission device 1 includes a power transmission circuit 6 that generates a radio frequency (RF) signal at least at a frequency within a predetermined frequency range, a power transmission antenna 2 that transmits the RF signal to the outside as electromagnetic energy or electromagnetic wave E, and a controller 4. Preferably, the power transmission device 1 uses the controller 4 to perform control (for example, control of the power transmission direction of the power transmission antenna 2) for effectively performing wireless power supply, the details of which will be described later.

[0048] Referring to FIG. 5, the power reception device 10 includes a power reception antenna 12 (see FIG. 3) that receives an electromagnetic wave (RF signal), a rectifier 14 (see FIG. 3) that is functionally connected to the power reception antenna 12 and converts the electromagnetic wave (RF signal) into a direct current voltage (DC), a first power storage device 16 that is functionally connected to the rectifier 14 and stores the direct current voltage (DC), a second power storage device 20 that is functionally connected to the first power storage device 16 and stores the direct current voltage (DC), and a device (sensor) 30 that is functionally coupled to the second power storage device 20.

[0049] "Power storage device" Referring to FIG. 5, both the first power storage device 16 and the second power storage device 20 are power storage devices that store electricity inside, and together they constitute the battery management system 21 illustrated in FIG. 1. Preferably, the first power storage device 16 is a capacitor, and the second power storage device 20 is a battery 20 having a charger 18.

[0050] The capacitor 16 is an electronic component that stores and discharges electricity (charge) inside. The capacitor 16 stores power particularly for driving the sensor 30. A capacitor 16 having an appropriate capacitance is selected in consideration of the power required for the sensor 30 to be powered. For example, the capacitor 16 is a relatively large-capacity capacitor that can store a large capacitance such as 10 mF or more or 1 F or more. Research and development on miniaturization and large-capacity of the capacitor 16 are being advanced in various fields, and the scope of the present invention is not limited by its specific capacitance, but it has at least a capacitance that enables power supply to the sensor 30.

[0051] For example, capacitor 16 is an electric double layer capacitor or an electric double layer capacitor (EDLC). The electric double layer capacitor 16 uses an electric double layer formed at the interface between a solid (activated carbon electrode) and a liquid (electrolyte) as a substitute for a dielectric. The electric double layer capacitor 16 uses activated carbon with an extremely large surface area as an electrode and has a relatively large capacitance. Since the capacitance of an electric double layer capacitor is ideally proportional to the surface area of the electrodes and inversely proportional to the distance between the electrodes, it is possible to achieve a very large capacitance.

[0052] The electric double layer capacitor 16 has advantages such as no limit on the number of charge and discharge cycles, being maintenance-free, being strong against large current charge and discharge, being usable even in an environment with severe temperature conditions, and being excellent in rapid charge and discharge. The electric double layer capacitor 16 is also called a supercapacitor or an ultracapacitor.

[0053] Capacitor 16 may also be a pseudocapacitor (pseudo capacitor or redox capacitor). A pseudocapacitor is a capacitor that utilizes a Faraday reaction and is an energy storage device having a function similar to that of an electric double layer capacitor (EDLC).

[0054] Capacitor 16 may also be a hybrid capacitor. A hybrid capacitor is a capacitor in which one of the two electrodes uses an electric double layer and the other electrode uses a redox reaction (oxidation-reduction reaction).

[0055] Capacitor 16 may also be a lithium ion capacitor (Li ion capacitor). A lithium ion capacitor has a structure in which the anode is an electric double layer and the cathode is a lithium ion secondary battery. Alternatively, capacitor 16 may be a capacitor using a metal oxide sintered body (ceramic) as a dielectric or a ceramic capacitor. Alternatively, capacitor 16 may be an electric field capacitor or the like.

[0056] The second power storage device 20 is a device for storing electricity inside, specifically a battery. A charger 18 is combined with the battery 20. The charger 18 is an electronic component having the function of charging the battery 20. The charger 18 and the battery 20 are physically connected to each other by a cable or a connector or the like.

[0057] The battery 20 is an electronic component having the function of a battery (chemical battery) that can be repeatedly used multiple times (not just once) by performing charging. The battery 20 is also referred to as a secondary battery, a storage battery, or a rechargeable battery. The battery 20 may be a lithium-ion battery, a nickel-metal hydride, an all-solid-state battery, or the like.

[0058] Considering the power required for the sensor 30 to be powered, a battery 20 with an appropriate capacity is selected. In this embodiment, the power stored in the battery 20 can be limited to about 2V to 5V. However, in other embodiments, the power stored in the battery 20 is not limited to the above values.

[0059] The power storage devices 16 and 20 can store power at a faster speed when their capacity is smaller. Therefore, depending on the type and usage mode of the sensor 30 to be powered, power storage devices 16 and 20 having a suitable charging time and storage capacity are selected. For example, referring back to FIG. 28, when the power supply target is a proximity sensor or the like, a small-capacity capacitor can be used, and when the power supply target is a pressure sensor or the like, a large-capacity capacitor can be used. Also, referring back to FIG. 2, when the power supply target is a proximity sensor and is connected to a wireless IC, a large-capacity capacitor can be used. When the power required to drive the sensor 30 is larger, a secondary battery 20 is required.

[0060] "Impedance mismatch" As shown in FIG. 1, in wireless power supply, an electromagnetic wave or a radio frequency (RF) signal E is transmitted from the power transmission antenna 2 of the power transmission device 1 toward the power reception antenna 12 of the power reception device 10. In the power reception device 10, this RF signal is converted into a direct current (DC) voltage and then the battery 20 (see FIG. 5) of the battery management system 21 is charged. However, in wireless power supply, when the rectifier side (RF side) and the device side (DC side) are connected, impedance mismatch may occur. Impedance mismatch is not preferable because it causes inefficiency from the viewpoint of energy transmission. In particular, when performing wireless power transmission of microwaves, since relatively small power or weak power is handled, a decrease in efficiency can cause a fatal problem.

[0061] Here, the battery 20 is ideally a device that stores charge without consuming power. Since not consuming power means having no resistance component, ideally, even when the RF side and the battery side are connected, the problem of impedance mismatch does not occur. However, actually, since the battery may have a resistance component, the above problem does not completely disappear.

[0062] On the other hand, different from the battery, the sensor 30 is a device that consumes power and thus has a resistance component. Therefore, when this resistance component is coupled to the RF side, impedance mismatch occurs to a greater degree. In this case, there is a risk of suffering disadvantages due to a decrease in the efficiency of the circuit of the sensor 30. In particular, when the sensor 30 operates with relatively small power, this problem of low efficiency becomes more serious.

[0063] Therefore, in this embodiment, when performing wireless power supply in a microwave manner between the power transmission device 1 and the power reception device 10, by using the battery management system 21 (see FIG. 1), sufficient power is transmitted to the device 30, and an electrical circuit (see FIG. 5) is configured so as to avoid the occurrence of impedance mismatch problems on the device 30 side. This is achieved in this embodiment by means (for example, switches SW1 to SW4) for switching the flow of power to the power storage devices 16 and 20 in the electrical circuit shown in FIG. 5.

[0064] "Switches SW1 to SW4" As described above, the power reception circuit of the power reception device 10 shown in FIG. 5 can be divided into two regions based on frequency. That is, it can be divided into two regions: an RF (radio frequency) region including the upstream antenna 12 and rectifier 14 with the capacitor 16 as a boundary, and a DC (direct current, low frequency) region including the downstream charger 18, battery 20, and sensor 30. A plurality of switches SW1 to SW4 are used to selectively supply power to the capacitor 16, battery 20, and sensor 30 so as to avoid or minimize the occurrence of impedance mismatch problems particularly on the sensor 30 side.

[0065] The switches SW1 to SW4 are configured so as to avoid or minimize the occurrence of impedance mismatch, particularly when transmitting the wireless power of microwaves received on the antenna 12 side, preferably to the sensor 30 that handles weak power. The switches SW1 to SW4 are elements that can selectively interrupt the power distribution, and switch between an on state that enables power distribution and an off state that disables power distribution. The switches SW1 to SW4 are not limited to the form illustrated in FIG. 5, and any element that can perform power distribution switching may be used. For example, the switch SW4 may be configured using an LDO (Low Drop-Out regulator).

[0066] In the embodiment shown in FIG. 5, the power reception circuit includes switches SW1 to SW4 arranged as follows. The first switch SW1 is arranged to switch the power distribution between the rectifier 14 and the first power storage device (e.g., a capacitor) 16. The second switch SW2 is arranged to switch the power distribution between the first power storage device 16 and the second power storage devices (e.g., batteries) 18, 20. The third switch SW3 is arranged to switch the power distribution between the first power storage device 16 and the device 30. The fourth switch SW4 is arranged to switch the power distribution between the second power storage devices 18, 20 and the device 30. Here, "switching the power distribution" means switching whether to distribute power or not, that is, switching the switch on or off.

[0067] In the example of FIG. 5, the four switches SW1 to SW4 are shown in the off state (state 0) where the power distribution is interrupted, as indicated by the solid lines. However, each of the switches SW1 to SW4 can shift to the on state that enables power distribution, as indicated by the dashed lines. State 0 corresponds to, for example, the case where the power transmission device 1 has stopped functioning, or even when the power transmission device 1 is functioning, but its power efficiency is poor. The electric circuit of the power receiving device 10 can select any one of at least six different states (states 1 to 6) by switching the four switches SW1 to SW4 on and off, as exemplified below.

[0068] In the example of FIG. 6 (state 1), only the first switch SW1 is turned on, and the other switches SW2 to SW4 are all in the off state. This state 1 corresponds to, for example, a state with good power efficiency and is a state where the capacitor 16 is charged by the power received on the power receiving antenna 12 side. In this state, the output of the rectifier 14 does not flow to the charger 18, the battery 20, and the sensor 30. That is, since there is no connection between the RF side and the DC side (especially the sensor 30), impedance mismatch between them is avoided.

[0069] In the example of FIG. 7 (state 2), only the first switch SW1 and the second switch SW2 are turned on, and all the other switches SW3 to SW4 are in the off state. This state is, for example, a state with good power efficiency, in which the capacitor 16 is charged by the power received on the antenna 12 side, and the battery 20 is charged via the charger 18 by the power stored in the capacitor 16. Note that in order to prevent waste of energy by discarding the power flow, the first switch SW1 is not turned off. In this state, particularly since the third switch SW3 is turned off, the output of the rectifier 14 does not flow to the sensor 30. That is, since there is no connection between the RF side and the DC side (particularly the sensor 30), impedance mismatch between them is avoided.

[0070] In the example of FIG. 8 (state 3), only the fourth switch SW4 is turned on, and all the other switches SW1 to SW3 are in the off state. This state corresponds to, for example, a state with poor power efficiency or a state in which wireless power supply is not performed between the power transmission device and the power reception device. However, since the battery 20 has already been charged (it is not necessary for the charge rate to be 100%), the sensor 30 is powered by that power. In this state, particularly since the third switch SW3 is turned off, the output of the rectifier 14 does not flow to the sensor 30. That is, since there is no connection between the RF side and the DC side (particularly the sensor 30), impedance mismatch between them is avoided.

[0071] In the example of Fig. 9 (State 4), the first switch SW1 and the fourth switch SW4 are turned on, and all the other switches SW2 - SW3 are in the off state. This state corresponds to, for example, a state with good power efficiency, where the capacitor 16 is being charged by the power received on the antenna 12 side. However, since the battery 20 has already been charged, it is powering the sensor 30 with its power. In this state, especially because the third switch SW3 is turned off, the output of the rectifier 14 does not flow to the sensor 30. That is, since there is no connection between the RF side and the DC side (especially the sensor 30), impedance mismatch between them is avoided.

[0072] In the example of Fig. 10 (State 5), the first switch SW1, the second switch SW2, and the fourth switch SW4 are turned on, and only the third switch SW3 is in the off state. This state corresponds to, for example, a state with good power efficiency, where the charging of the capacitor 16 by the power received on the antenna 12 side is complete. The battery 20 is chargeable and is powering the sensor 30 with its power. In this state, especially because the third switch SW3 is turned off, the output of the rectifier 14 does not flow to the sensor 30. That is, since there is no connection between the RF side and the DC side (especially the sensor 30), impedance mismatch between them is avoided.

[0073] In the example of Fig. 11 (State 6), the first switch SW1 and the third switch SW3 are turned on. This state corresponds to, for example, a state with good power efficiency, where the capacitor 16 is charged by the power received on the antenna 12 side, and the sensor 30 is powered by the power stored in the capacitor 16. In this state, the sensor 30 is powered by the power of the capacitor 16 instead of the power of the battery 20. At this time, it is possible to turn off the second switch SW2. In this state, since the first switch SW1 and the third switch SW3 are turned on, as a result, the output of the rectifier 14 flows to the sensor 30, and thus there is a connection between the RF side and the DC side (especially the sensor).

[0074] In the example of state 6 shown in FIG. 11, a problem of impedance mismatch may occur due to the connection between the RF side and the DC side (especially the sensor). However, this problem occurs only in state 6 among all the illustrated states 1 to 6. By not selecting this state 6 or by limiting its frequency or duration even if state 6 is selected, the problem of impedance mismatch can be avoided or minimized as a whole. The example of state 6 shown in FIG. 11 has not only demerits but also merits. For example, by enabling power supply to the sensor 30 from both the battery 20 and the capacitor 16, diversity can be imparted to the system. Also, by selecting state 6, there is also an aspect of dealing with the problem of charging loss to the battery.

[0075] Therefore, in this embodiment, by appropriately controlling the four switches SW1 to SW4, the power state inside the power receiving device 20 is distinguished. As a result, the problem of reduction in power receiving efficiency due to impedance mismatch can be avoided or minimized, the problem of increase in power consumption of the sensor system can be dealt with, and the power supply wiring to the sensor system becomes unnecessary. Furthermore, depending on the usage situation, in addition to power supply to the sensor 30 from the battery 20, it is also possible to directly supply power to the sensor 30 from the capacitor 16. Therefore, the user can obtain benefits such as reduction in maintenance and management costs of the sensor system, reduction in cost of the sensor system, and reduction in environmental devices due to the extended life of the system.

[0076] FIG. 29 is an example of a diagram showing each state of the power receiving circuit of the power receiving device in FIG. 5. In FIG. 29, in states 0 to 2, the sensor 30 is in an off (when not in use) state, and in states 3 to 6, the sensor 30 is in an on (when in use) state. In each of the states 0 to 6, voltage values v1 and v2 before and after the capacitor 16 are particularly transmitted to the controller 40.

[0077] "Monitoring of Power Receiving Situation" When wireless power supply is provided to the device 30 of the machine 100 operating with FA or the like, if the power transmission direction of the power transmission antenna 2 of the power transmission device 1 and the power reception direction of the power reception antenna 12 of the power reception device 10 are not optimized, a situation may occur where sufficient power supply cannot be performed (see reference symbol E in FIG. 1). For example, when the power reception antenna 12 is built into a robot arm / robot hand and the position, angle, height, etc. of the power reception antenna 12 change with a high degree of freedom as the robot arm / robot hand moves, the power transmission situation between the power transmission device 1 and the power reception device 10 can vary in various ways. In FA or the like, there were cases where the power reception situation of the power reception device 10 could not be grasped promptly.

[0078] The power reception situation of the power reception device 10 can be grasped by various means. For example, when the time required for charging the capacitor 16 is short and power can be transmitted to the battery 20 in a short period, based on the voltage value and time, the controller 40 can understand the power reception situation of the power reception device 10. This is because the shorter the time required for charging the capacitor 16, the greater the power received by the power reception antenna 12. Conversely, the longer the time required for charging the capacitor 16, the smaller the power received by the power reception antenna 12. It is also possible to perform other electrical inspections. In the first embodiment, a means SW5 for monitoring the power reception situation of the power reception antenna 12 more quickly and easily is provided in the power reception device 10.

[0079] Referring to FIG. 5 again, the power reception circuit of the power reception device 10 includes, in addition to the above four switches SW1 to SW4, a further switch SW5 for switching the power distribution at the output side of the rectifier 14 (between the rectifier 14 and the first switch SW1), and this switch SW5 is functionally coupled to a light-emitting diode (LED) 22. For example, this switch SW5 is physically connected to the LED 22 by a cable or a connector or the like.

[0080] When the above switch SW5 is turned on, the voltage on the rectifier 14 side flows through the switch SW5 to the LED22, and when the power thereof exceeds a predetermined value, the lamp of the LED22 is configured to light up. It is assumed that the lighting of the LED22 can be visually confirmed from the outside of the machine 100 (see FIG. 1). Therefore, based on the lighting of this LED22, the user (for example, an inspector) can easily grasp the power reception status of the power receiving device 10 without performing an electrical inspection.

[0081] The intensity of the light emitted by the LED22 is approximately proportional to the amount of current flowing. In order to prevent waste of the available power in wireless power supply, it is preferable to minimize the lighting frequency or period of the LED22. For example, only the switch SW5 is turned on and the other switches SW1 to SW4 are turned off so as to minimize the influence on the power supply operation before or after the start of use of the power receiving device 10.

[0082] For example, referring to FIG. 1, although power E is being transmitted from the power transmission device 1 to the power receiving device 10, if the LED22 (see FIG. 5) of the power receiving device 10 does not light up (or the lighting is weak), it can be presumed that the power transmission direction of the power transmission antenna 2 of the power transmission device 1 and the power reception direction of the power reception antenna 12 of the power receiving device 10 are not suitably matched, or the transmission of the energy E is being obstructed by some means. In this case, as will be described later, it is considered to perform beam forming of the power transmission antenna 2 of the power transmission device 1. Or, among a plurality of beams of the power transmission antenna 2, it is possible to consider splitting and emitting two or three or more of them.

Embodiment

[0083] FIGS. 12 to 14 show a second embodiment in which a partial modification is made to the first embodiment of the power receiving device 10 illustrated in FIGS. 5 to 11. Example 2 is basically configured in the same way as Example 1, and the differences are only the rearrangement of the four switches SW1 to SW4 in Example 1 and their control. Since the other components of the power transmission device 1, the power reception device 10, and the machine 100 can be configured in the same way as in Example 1, in order to avoid duplication of description, the details of these other components are omitted.

[0084] In Example 2, the four switches SW11 to SW14 are arranged as follows. The first switch SW11 is arranged so as to be able to selectively interrupt the reception of power between the rectifier 14 and the charger 18 / battery 20. The second switch SW12 is arranged so as to be able to selectively interrupt the reception of power between the rectifier 14 and the capacitor 16. The third switch SW13 is arranged so as to be able to selectively interrupt the reception of power between the capacitor 16 and the sensor 30. The fourth switch SW14 is arranged so as to be able to selectively interrupt the reception of power between the battery 20 and the sensor 30.

[0085] In FIG. 12, the four switches SW11 to SW14 can be switched between an on state and an off state as indicated by solid lines and broken lines. In FIG. 12, all of the four switches SW11 to SW14 are in the off state where the reception of power is interrupted. This state corresponds to, for example, a state where the power efficiency of the power transmission device 1 is poor or a state where wireless power supply is not performed between the power transmission device 1 and the power reception device 10. In this case, the output of the rectifier 14 does not flow to the capacitor 16, the battery 20, and the sensor 30.

[0086] Referring to FIG. 13, in state 1 of the second embodiment, only the first switch SW11 and the third switch SW13 are turned on simultaneously, and the second switch SW12 and the fourth switch SW14 are turned off simultaneously. This state 1 is, for example, in a state with good power efficiency and corresponds to a state where the battery 20 is charged by the power received on the antenna 12 side. Further, when the charging of the capacitor 16 has been completed in advance, it corresponds to a state where the sensor 30 is powered by the output thereof. In this state, the output of the rectifier 14 only flows to the battery 20 and does not flow to the capacitor 16 and the sensor 30. That is, since there is no connection between the RF side and the DC side (especially the sensor), no impedance mismatch occurs between them.

[0087] Referring to FIG. 14, in state 2 of the second embodiment, only the second switch SW12 and the fourth switch SW14 are turned on simultaneously, and the first switch SW11 and the third switch SW13 are turned off simultaneously. This state 2 is, for example, in a state with good power efficiency and corresponds to a state where the capacitor 16 is charged by the power received on the antenna 12 side. Further, when the charging of the battery 20 has been completed in advance, it corresponds to a state where the sensor 30 is powered by the output thereof. In this state, the output of the rectifier 14 only flows to the capacitor 16 and does not flow to the battery 20 and the sensor 30. That is, since there is no connection between the RF side and the DC side (especially the sensor), no impedance mismatch occurs between them.

[0088] In the second embodiment, by switching between state 1 (FIG. 13) in which the switch SW11 and the switch SW13 are turned on simultaneously and state 2 (FIG. 14) in which the switch SW12 and the switch SW14 are turned on simultaneously at appropriate times and periods, the output of the rectifier 14 can always be made to flow to either the capacitor 16 or the battery 20, and during that time, the sensor 30 can be operated by the other one that is being charged. Therefore, the output of the rectifier 14 is always being used and no energy is wasted.

[0089] In Embodiment 2, two switches SW12 and SW13 are provided between the rectifier 14 and the sensor 30. Since at least one of the switches is always in the off state, the output 14 of the rectifier does not directly flow to the sensor 30. In Embodiment 2, the state corresponding to State 6 (FIG. 11) of Embodiment 1 does not occur. Therefore, impedance mismatch between the RF side and the DC side (especially the sensor) is always avoided.

[0090] However, the states of the electric circuit shown in FIG. 12 are not limited to the states illustrated in FIGS. 13 and 14. For example, only one of the switch SW11 and the switch SW12 may be turned on for a predetermined period, and all other switches may be turned off to charge only the capacitor 16 or the battery 20. Also, turning on the two switches shown in FIGS. 13 and 14 simultaneously does not have to be exactly simultaneous. Depending on the embodiment, the switch SW11 and the switch SW13 may be turned on with a time difference. Also, the switch SW12 and the switch SW14 may be turned on with a time difference. Also in this embodiment, a switch SW15 and an LED 22 are provided as means for monitoring the power reception status. Also, the values of the voltages v1 and v2 in the power reception circuit are transmitted to the controller 40.

Embodiment

[0091] FIG. 15 shows Embodiment 3 in which a partial modification is made to Embodiment 2 of the power reception device 10 illustrated in FIGS. 12 to 14. Embodiment 3 is basically configured in the same manner as Embodiment 2, and the difference is only the combination of the capacitor 16 and the battery 20 in Embodiment 2. Since the other components of the power transmission device 1, the power reception device 10, and the machine 100 can be configured in the same manner as in Embodiment 1, the details of these other components are omitted to avoid duplication of description.

[0092] In Example 2, the power of the capacitor 16 to be charged is only used for the operation of the sensor and not for charging the battery. The capacitor 16 and the battery 20 are used alternately (complementarily) to operate the sensor. Therefore, both the capacitor 16 and the battery 20 serve the common function as electrical storage devices for storing electricity.

[0093] In Example 3, the power receiving device 10 uses a combination of two capacitors 16a and 16b instead of a combination of the capacitor 16 and the battery 20 as a battery management system for supplying power to the sensor 30. The capacitors 16a and 16b may both be of the same type and / or capacitance. The capacitors 16a and 16b may have different types and / or capacitances.

[0094] The four switches SW21 to SW24 are arranged as follows. The first switch SW21 is arranged so as to be able to selectively interrupt the reception of power between the rectifier 14 and the capacitor 16a. The second switch SW22 is arranged so as to be able to selectively interrupt the reception of power between the capacitor 16a and the sensor 30. The third switch SW23 is arranged so as to be able to selectively interrupt the reception of power between the rectifier 14 and the capacitor 16b. The fourth switch SW24 is arranged so as to be able to selectively interrupt the reception of power between the capacitor 16b and the sensor 30.

[0095] In Example 2, by turning on one set of two switches and turning off the other set of two switches simultaneously among the four switches, either one of the two electrical storage devices 16 and 20 is charged, and the sensor 30 is powered by the power of the other. In Example 3, when charging either or both of the two capacitors 16a and 16b and supplying power to the sensor 30 with the power, the four switches SW21 to SW24 may be switched on and off in various combinations.

[0096] For example, any one of the following states 0 to 6 can be selected. In state 0, all of the four switches SW21 to SW24 are turned off. In state 1, only the capacitor 16a is charged by turning on only the switch SW21. In state 2, the sensor 30 is powered by the power of the capacitor 16a by turning on only the switches SW21 and SW22. In state 3, only the capacitor 16b is charged by turning on only the switch SW23. In state 4, the sensor 30 is powered by the power of the capacitor 16b by turning on only the switches SW23 and SW24. In state 5, the capacitors 16a and 16b are charged by turning on only the switches SW21 and SW23. In state 6, the sensor 30 is powered by the power of the capacitors 16a and 16b by turning on all of the switches SW21 to SW24.

[0097] As shown in Examples 1 and 2, when the battery 20 is used as the power storage device, the power stored in the battery may be limited to 2V or 4V. On the other hand, as shown in Example 3, when the capacitors 16a and 16b are used as the power storage device, the power stored in the capacitor may be, for example, 5V or less. Therefore, when powering the sensor 30 from the capacitor, there is an advantage that it is more resistant to over-discharge than powering the sensor 30 from the battery. Therefore, when the power for powering the sensor 30 is relatively small and resistance to over-discharge is required, Example 3 can be considered.

[0098] In addition, in Example 3 illustrated in FIG. 15, two capacitors 16a and 16b are used in parallel. On the other hand, in other examples, it is possible to use three or more capacitors in parallel. Also, in other examples, it is possible to use two or more capacitors in series. However, when capacitors are connected in series (stacked vertically in two stages), in the case of polarized capacitors, there is a possibility of destruction, so pay attention to the connection direction.

Example

[0099] FIG. 16 illustrates Example 4 in which a partial modification is made to Example 1 of the power receiving device 10 illustrated in FIG. 5. Example 4 is basically configured in the same manner as Example 1, and the difference is that for the first power storage device 16, one capacitor 16 is changed to two capacitors 16c and 16d. Since the other components of the power transmission device 1, the power receiving device 10, and the machine 100 can be configured in the same manner as in Example 1, the details of these other components are omitted to avoid duplication of description.

[0100] Referring to FIG. 16, the capacitor 16c is provided on the downstream side of the rectifier 14 and on the upstream side of the first switch SW31. The capacitor 16c is always connected to the rectifier 14, but there is no problem in terms of the function of the capacitor 16c. The capacitor 16d is provided on the downstream side of the first switch SW31 and on the upstream side of the sensor 30.

[0101] The four switches SW31 to SW34 are arranged as follows. The first switch SW31 is arranged so as to be able to selectively interrupt the reception of power between the rectifier 14 (capacitor 16c) and the capacitor 16d. The second switch SW32 is arranged so as to be able to selectively interrupt the reception of power between the capacitor 16d and the charger 18 / battery 20. The third switch SW33 is arranged so as to be able to selectively interrupt the reception of power between the capacitor 16d and the sensor 30. The fourth switch SW34 is arranged so as to be able to selectively interrupt the reception of power between the battery 20 and the sensor 30.

[0102] In the power receiving circuit of Embodiment 4 shown in FIG. 16, the output from the rectifier 14 is first dropped into the capacitor 16c. The power stored in this capacitor 16c is further stored in the battery 20 or the capacitor 16d, and the power storage devices 20 and 16d supply power to the sensor 30. In each state, the switches SW31 to SW34 are operated so as to avoid impedance mismatch caused by connecting the rectifier 14 side and the sensor 30 side.

[0103] By appropriately switching the four switches SW31 to SW34, the state of the charging circuit of the power receiving device 20 can be switched to various states. In particular, in the power receiving circuit of Embodiment 4 shown in FIG. 16, since two capacitors 16c and 16d are arranged separately from the battery 20, it is possible to optimize the charging of the battery 20 and the power supply to the sensor 30 by these two capacitors 16c and 16d.

[0104] FIG. 30 shows the switching states of the four switches SW31 to SW34 shown in FIG. 16. Similarly in Embodiment 4, in order to visually confirm the power receiving state of the power receiving device 10, the switch SW35 and the LED 22 are provided so that the operator can grasp the radio wave reception state. Furthermore, in order to transmit the voltage values v2 and v3 of the power receiving device 10 to the wireless communication IC, the switches SW36 to SW37 are provided. These voltage values are detected by a VD (Voltage Detector) or the like.

[0105] Referring to FIG. 30, in state 0, all the switches SW31 to SW37 are turned off. This state corresponds to the case where no radio wave is transmitted from the power transmission device 1 or the radio wave reception state of the power receiving device 10 is poor. Or only the switch SW35 is turned on. This state corresponds to the case of checking the power reception status of the power receiving device 10. Therefore, since the power storage device (capacitor) 16c is always connected to the rectifier 14, it is always charged, but the stored power does not flow to other elements such as the power storage device (capacitor) 16d and the power storage device (battery) 20.

[0106] In state 1, only the switch SW31 is turned on, and all other switches SW32 to SW37 are turned off. This state corresponds to a state where the power transmission efficiency from the power transmission device 1 to the power reception device 10 is good. For this reason, the power stored in the power storage device 16c flows to the power storage device 16d, but this corresponds to a state where the power storage device 16d is not yet fully charged. If the power storage device 16d is a capacitor, the charging time can be short.

[0107] In state 2, only the switch SW32 is turned on, and all other switches SW31, SW33 to SW37 are turned off. This state corresponds to a state where the power transmission efficiency from the power transmission device 1 to the power reception device 10 is good. For this reason, due to the power stored in the power storage device 16c, the power storage device 16d is fully charged, and this corresponds to a state where the stored power is flowing to the power storage device 20. Normally, the battery 20 can store more power inside than the capacitor 16d. Therefore, until the battery 20 is fully charged, the above states 1 and 2 may be repeated to repeat the power storage and power transmission of the capacitors 16c and 16d.

[0108] Up to states 1 and 2, the sensor 30 is in the off state. After state 3, the sensor 30 is in the on state. In state 3, only the switch SW34 is turned on, and all other switches SW31 to SW33, SW35 to SW37 are turned off. In this state, it corresponds to a state where the sensor 30 is powered by the power stored in the battery 20. Also, the capacitor 16c is charged by the output of the rectifier 14.

[0109] In state 4, only switch SW31 and switch SW34 are turned on, and all other switches SW32 to SW33, SW35 to SW37 are turned off. In this state, the power stored in the power storage device 16c flows to the power storage device 16d, and the sensor 30 is powered by the power stored in the power storage device 20. Also in this case, the charging and discharging of the capacitors 16c and 16d may be repeated by repeating the above states 3 and 4.

[0110] In state 5, only switch SW33 is turned on, and all other switches SW31 to SW32, SW34 to SW37 are turned off. In this state, the sensor 30 is powered by the power stored in the power storage device (capacitor) 16d. At this time, since switch SW31 is turned off, the output of the rectifier does not flow directly to the sensor 30, so the RF side and the DC side are not directly connected. That is, in this embodiment, impedance mismatch caused by directly connecting the rectifier 14 side and the sensor 30 side as in state 6 (FIG. 11) of Embodiment 1 is prevented.

[0111] From state 0 to state 5, the wireless communication IC is in the off state. After state 6, the wireless communication IC is in the on state. In state 6, only switches SW34 and SW36 are turned on, and all other switches SW31 to SW33, SW35, SW37 are turned off. In this state, it corresponds to the state where power is supplied from the power storage device (battery) 20 to the wireless communication IC50 in state 3. This value is transmitted to the controller 40 of the power receiving device 10 and the controller (host computer) 4 of the power transmitting device 1.

[0112] Note that the controller 40 can have a wireless communication function. Also, it is possible to include the wireless communication IC50 in the controller 40. Basically, both or either one of the controller 40 and the wireless communication IC50 exhibits the wireless communication function of the present invention. By combining the controller 40 and / or the wireless communication IC 50 with the sensor 30, the detection result of the sensor 30 can be transmitted to the outside. However, when a SAW sensor is used as the sensor 30, the detection result of the sensor 30 can be transmitted to the outside by the wireless communication function of the SAW sensor without using the controller 40 and / or the wireless communication IC 50. In this way, the power receiving device 10 can be configured to supply power required for the wireless communication function in addition to the power required for the device 30.

[0113] In state 7, only the switches SW31, SW34, and SW36 are turned on, and all the other switches SW32, switch SW33, SW35, and SW37 are turned off. In this state, it corresponds to the state where power is supplied from the power storage device (battery) 20 to the wireless communication IC 50 in state 4. This value is transmitted to the controller 40 of the power receiving device 10 and the controller 4 of the power transmitting device 1.

[0114] In state 8, only the switches SW33 and SW37 are turned on, and all the other switches SW31, switch SW32, SW34 to SW36 are turned off. In this state, it corresponds to the state where power is supplied from the power storage device (capacitor) 16d to the wireless communication IC 50 in state 5. This value is transmitted to the controller 40 of the power receiving device 10 and the controller 4 of the power transmitting device 1.

[0115] In any of states 1 to 8, the output of the rectifier does not flow directly to the sensor 30, so the RF side and the DC side are not directly connected. That is, impedance mismatch between the RF side and the DC side (especially the sensor 30) is avoided. The voltage value transmitted to the wireless communication IC 50 in states 6 to 8 is used for the controller 40 and / or the controller 4 to grasp the power reception status of the power receiving device 10.

[0116] In Example 4 illustrated in FIG. 16, three power storage devices 16c, 16d, and 20 are used. Preferably, two of these (16c, 16d) are large-capacity capacitors and one (20) is a battery. However, depending on the embodiment, all three of these may be capacitors (not shown). Similarly in this case, details of the power receiving circuit based on the switching of switches SW31 to SW37 can be referred to FIG. 30.

Example

[0117] FIG. 17 illustrates Example 6 in which a partial modification is made to Example 4 of the power receiving device 10 illustrated in FIG. 16. Example 5 is basically configured in the same manner as Example 4, and the differences in components are the deletion of capacitor 16c and the deletion of switches SW31 and SW33. Since the other components of the power transmission device 1, the power receiving device 10, and the machine 100 can be configured in the same manner as in Example 4, in order to avoid duplication of description, details of these other components are omitted.

[0118] In Example 5, as the power storage device, a combination of one capacitor 16c and a battery 20 is used, and the number of switches incorporated in the power receiving circuit is minimized. As a result, the mounting area of the power receiving device 10 is minimized, the complication of control is avoided, and the operation cost is suppressed. Furthermore, by removing switches SW31 and SW33, the power receiving circuit is configured so as to prevent impedance mismatch as much as possible while satisfying the requirements of practical application examples.

[0119] Generally, when the number of elements that require operations such as switches in the electric circuit of the power receiving device 10 increases, the overall power consumption increases. Although the power required for the switch is small, since the amount of power transmitted by wireless power transmission is limited, it is not preferable that the power consumption increases in a form that does not contribute to the power supply of the sensor. Also, generally, it is not preferable that the control of the power receiving device 10 is complicated due to an increase in components. Therefore, in Example 5, both coping with switch impedance mismatch and simplifying the control of the power receiving circuit are achieved.

[0120] That is, in Example 5, unlike Examples 1 to 4, even if impedance mismatch occurs at about 5% or 10% of the whole, if the influence given is small, it is the policy to ignore it. In order to prevent 100% complete impedance mismatch, rather than performing control of a complicated power receiving circuit, by performing control of a simplified power receiving circuit, reduction of implementation cost is aimed at.

[0121] In the power receiving circuit of Example 5 illustrated in FIG. 17, the output of the rectifier 14 is first dropped into the capacitor 16d. At this time, a switch for switching power distribution between the rectifier 14 and the capacitor 16d is deleted. For this reason, the capacitor 16d can be constantly charged, but it does not cause any particular inconvenience thereby.

[0122] A switch SW32 is arranged between the capacitor 16d and the battery 20 (charger 18) so that the state of charging the capacitor 16d and the state of charging the battery 20 with the stored power can be switched. Therefore, while the capacitor 16d is being charged, the switch SW32 is turned off, and while the capacitor 16d is charged and power is transmitted to the battery 20, the switch SW32 is turned on.

[0123] A switch SW34 is arranged between the battery 20 and the sensor 30 so that the state of charging the battery 20 and the state of charging the sensor 30 with the charged power can be switched. Therefore, while the battery 20 is being charged, the switch SW34 is turned off, and while the battery 20 is charged and power is transmitted to the sensor 30, the switch SW34 is turned on.

Example

[0124] FIG. 18 illustrates Example 6 in which a partial modification is made to Example 5 of the power receiving device 10 illustrated in FIG. 17. Example 6 is basically configured in the same manner as Example 5, and the difference is only the change of the switch SW34 to an LDO. Since the other components of the power transmission device 1, the power reception device 10, and the machine 100 can be configured in the same manner as in Example 4, in order to avoid duplication of description, the details of these other components are omitted.

[0125] In Example 6, an LDO is arranged between the battery 20 and the sensor 30 instead of the switch SW34. By operating this LDO, without using a mechanical switch, the state of charging the battery 20 and the state of charging the sensor 30 with the charged power are switched. Also in Example 6, similar to Example 5, in order to prevent 100% complete impedance mismatch from occurring, rather than performing control of a complicated power reception circuit, by performing control of a simplified power reception circuit, the implementation cost is reduced.

[0126] An LDO is also called a low-loss regulator. This is a series regulator that can operate with an extremely small difference between the input voltage and the output voltage. By operating the LDO, substantially the same function as a switch can be achieved.

[0127] "Optimization of Impedance Matching" In each of the electric circuits of the above Examples 1 to 6, it is possible to further optimize the impedance matching. FIG. 19 is an example of a diagram schematically showing the state of optimization of impedance matching of an electric circuit, with the input power (input power) on the horizontal axis and the efficiency of the power reception circuit on the vertical axis.

[0128] As illustrated in FIG. 19(1), in the power reception circuit of the power reception device 10, when the RF region and the DC region are connected and an impedance matching mismatch occurs, the efficiency deteriorates. As illustrated in FIG. 19(2), in the above case, when the impedance matching mismatch is avoided, the deterioration of the efficiency can be improved. However, even in this case, as illustrated in (3) of FIG. 19, it is difficult to achieve high efficiency if impedance matching is not optimized. Therefore, the present invention provides means not only for avoiding impedance matching mismatches but also for enabling optimization of impedance matching.

[0129] With reference to FIGS. 20(A) and (B), means for optimizing impedance matching will be exemplified. Note that the electric circuit in FIG. 20(B) is simplified for explanation purposes, but the following explanation is applicable to each of the above-described embodiments (particularly, Embodiments 5 and 6).

[0130] The electric circuit shown simplified in FIG. 20(B) includes a rectifier, a switch, a power storage device (capacitor) indicated by symbol Z1, and the combined impedance of a power supply circuit and a device (sensor) indicated by Z2. In the state shown in FIG. 20(B), the switch is in the off position where power distribution is not performed. In this case, the output of the rectifier is connected only to the impedance Z1 of the capacitor. When the switch is in the on position where power distribution is performed with respect to the state shown in FIG. 20(B), the combined impedance Z2 of the impedance Z1 of the capacitor, the power supply circuit, and the sensor is connected in parallel to the output of the rectifier.

[0131] On the left side of FIG. 20(A), the impedance Za when the switch is turned on is exemplified. At this time, impedance mismatch occurs and the power is at a low value. On the right side of FIG. 20(A), the impedance Zc when the switch is turned off is exemplified (Zc = Z1). At this time, no impedance mismatch occurs, but impedance optimization has not been performed. Therefore, if the value when impedance optimization is performed is Zb, the value of Zc is larger than Za but smaller than Zb.

[0132] Here, when the ratio when the switch is on is "D"%, and the ratio when the switch is off is "(1 - D)%", the load impedance Z of the rectifier can be defined as follows. Z = (Z1 / / Z2) × (1 - D) + Z1 × D In the above formula, the symbol " / / " is a simplified mathematical expression for calculating parallel values. For example, in the calculation of the parallel value of resistors, similar to the fact that the mathematical expression 1 / (1 / R1 + 1 / R2) can be simplified and written as R1 / / R2.

[0133] Referring to Fig. 20(B), when the switch is switched on and off at high speed, from the perspective of the rectifier, seemingly, the state with only impedance Z1 and the state where Z1 and Z2 are connected in parallel are alternately switched. At this time, the time connected to Z2 is adjusted. For example, the switch is switched at 1 millisecond intervals. At that time, the impedance seen from the rectifier appears to draw a mountain-shaped (convex) curve as schematically illustrated in Fig. 20(A). This has been confirmed by simulation.

[0134] Therefore, when adjusting the impedance by rapidly switching Z1 and Z2, as schematically shown in Fig. 20(A), it is equivalent to changing the impedance like Za, Zb, Zc. At that time, if the on-off ratio of the switch is adjusted so that seemingly the impedance of Zb can be created from the perspective of the rectifier, it is considered that the output power is maximized. Note that the power when the switch is moved at high speed is about microwatts, and the power loss due to the switch is small.

[0135] Thus, in the present invention, impedance matching is optimized by adjusting the charging time of the capacitor and the duty ratio connected to the power supply circuit. For this purpose, the state averaging method for obtaining the equivalent impedance with respect to Z1 and Z2 is applied. As a result, in the present invention, not only impedance matching mismatch is avoided simply by switching the switch, but also the impedance seen from the rectifier is seemingly averaged by switching the switch on and off at high speed, thereby enabling optimization of impedance matching.

[0136] In particular, in the electric circuits illustrated in Examples 5 and 6, by applying the state averaging method, it is possible to improve the efficiency of the power receiving circuit as a whole for the power receiving device. When applying the electric circuit illustrated in FIG. 20(B) to the power receiving circuits of Examples 5 and 6 illustrated in FIGS. 16 or 17, the wiring of the electric circuit may be changed so that the capacitor and the sensor are connected in parallel to the rectifier. In this way, by switching the second switch SW32 (FIGS. 16 and 17) at high speed and appropriately determining the on / off ratio of the second switch SW32, the state averaging method is applied to the large resistance and the small resistance (Z1, Z2) as seen from the rectifier 14, thereby optimizing the impedance.

[0137] In addition, when applying the electric circuit illustrated in FIG. 20(B) to Examples 1 to 6, the electric circuit can be modified according to the embodiment. For example, in the electric circuit of FIG. 20(B) illustrated for the optimization of impedance matching, a DC-DC converter may be used for the element of Z2. In this case, the impedance matching is optimized by adjusting the two impedances inside the DC-DC converter with a switch. The DC-DC converter is a device that converts direct current to direct current and is an element used to convert to a required voltage or stabilize it. Also, an LDO or a sensor may be connected to the element of Z2. In this case, the LDO can be used as the switch.

[0138] "Optimization of power receiving status" In each of the electric circuits of the above-described Examples 1 to 6, it is possible to further observe the electric field strength. For example, in the electric circuit of Example 1 illustrated in FIG. 5, by turning on only the switch SW5 and observing the lighting state of the LED 22, the user can grasp the power supply status of the power receiving device 10. Furthermore, in each of Examples 1 to 6, the power receiving device 1 may grasp the power receiving status on the side of the power receiving device 10 by transmitting the voltage value of the power receiving circuit as a feedback signal to the power transmitting device 1. Based on this, optimization of the power receiving status of the power receiving device 10 becomes possible.

[0139] The feedback control described below is applicable to each of Embodiments 1 to 6. Hereinafter, it will be described based on the power receiving circuit of Example 4 shown in FIG. 16. For example, in the power receiving circuit of FIG. 16, let the value of the power sent to the first capacitor 16c be v1 upstream of the first switch SW31, and the value of the power sent to the second capacitor 16d be v2 downstream of the first switch SW31. The displacement of the voltage value at this time is schematically illustrated in FIG. 21.

[0140] FIG. 21 schematically shows a graph when the voltage values of v1 and v2 of the power receiving circuit of Example 4 shown in FIG. 16 are taken on the vertical axis and time is taken on the horizontal axis. In FIG. 21, between time t0 and time t1, all of the switches SW31 to SW35 of the power receiving circuit of Example 4 shown in FIG. 16 are turned off, and the energy output from the rectifier 14 is all sent to the first capacitor 16c. During this period, the voltage value v1 of the first capacitor 16c continues to rise.

[0141] At time t1, when the voltage value v1 of the first capacitor 16c reaches Vth1, the switch SW31 is turned on. Vth1 is the threshold for turning on the switch SW31. At this time, the first capacitor 16c is sufficiently charged. The value of Vth1 and t1 can vary depending on the type of capacitor 16c used.

[0142] At time t1, when switch SW31 is switched from off to on, the energy stored in the first capacitor 16c starts to flow into the second capacitor 16d. Between t1 and t2, the power stored in the second capacitor 16d continues to increase. Time t2 corresponds to the time when the voltage of v1 is supplied to v2 and they become equal in potential. Thereafter, between time t2 and time t3, the voltage value v2 of the second capacitor 16d continues to rise.

[0143] At time t3, when the voltage value v2 of the second capacitor 16d reaches Vth2, switch SW31 is turned on. Vth1 is the threshold for turning on switch SW32. At this time, the second capacitor 16d is sufficiently charged. The value of Vth2 and t2 can vary depending on the type of capacitor 16d used.

[0144] In FIG. 21, by observing the time from t1 to t3, it becomes possible to pseudo - observe the reception intensity of the power receiving device 10. Note that the time from t1 to t2 is not used for observing the reception intensity, but is described to approximate the graph of FIG. 21 to the voltage waveform of the actual application example. The voltage value of v1 and the voltage value of v2 are transmitted to the controller 40 of the power receiving device 10. The controller 40 measures the time from Vth1 to Vth2, measures the rising speed of v2, and pseudo - observes the electric field strength at this time.

[0145] Therefore, the controller 40 transmits these values as a feedback signal fs to the power transmission device 1. The power transmission device 1 pseudo - observes the reception intensity on the power receiving device 10 side based on the value of the feedback signal fs. The controller 4 of the power transmission device 1 can perform control to optimize the transmission direction of the transmission antenna 2 based on this result. In this way, the electric field strength is pseudo - observed by the rising speed of v2. In addition, the power reception state of the power receiving device 10 may be observed using each value of v1, v2, v3 (see FIG. 16), etc.

[0146] FIG. 22 is a diagram showing a flow when the power receiving device 10 transmits a feedback signal fs to the power transmitting device 1. As illustrated on the right side of FIG. 22, in the power receiving device 10, the energy received by the power receiving antenna 12 is sent to the rectifier 14 and then sent to the battery 20. At this time, values such as v1 and v2 are sent to the controller 40 of the power receiving device 10. These values are sent to the power transmitting device 1 as the feedback signal fs by the wireless communication IC 50 connected to the controller 40. Note that, as described above, the power receiving antenna 12 is configured to be able to receive power well in a three-dimensional space (see FIGS. 3 and 4). Therefore, in order to optimize wireless power feeding when the power receiving situation is poor, controlling the power transmitting antenna 2 is effective.

[0147] As illustrated in the center of FIG. 22, a wireless communication 5 is connected to the controller 4 of the power transmitting device 1, and the feedback signal fs is configured to be sent to the controller 4. As illustrated on the left side of FIG. 22, the power transmitting device 1 is provided with a transmission circuit having a signal generator 6a and an amplifier 6b, and is configured such that energy is sent from the power transmitting antenna 2 to the surroundings. Therefore, the controller 4 can control the RF switch 3 and thus control the power transmitting antenna 2 based on the feedback signal fs.

[0148] FIG. 23 is a diagram schematically showing the control of the power transmitting antenna 2 performed by the controller 4 of the power transmitting device 1. The controller 4 is a small computer (such as a microcomputer), for example, a single-board computer equipped with an ARM processor. The transmitting antenna 2 includes a plurality of antenna parts 2a, 2b, 2c, 2d, 2e, and is configured such that the output from the RF source 6 is sent to these parts.

[0149] Each of the antenna parts 2a, 2b, 2c, 2d, 2e is independently controlled by the controller 4 via the RF switches 3a, 3b. The controller controls the antenna 2 so that energy is sent to the outside only from the optimal antenna units 2c and 2d among the plurality of antenna units 2a, 2b, 2c, 2d, and 2e, for example. The power transmission antenna can be configured to split a beam into two or three or more beams and transmit them. Thereby, the controller 4 of the power transmission device 1 performs control for optimizing wireless power supply. Further, the power transmission device 1 may transmit an se signal (sensor enable signal) to the power reception device 10 with respect to the feedback signal fs in FIG. 16. The power reception device 10 may switch each state based on this se signal.

[0150] "Beamforming" As described above, in the first to sixth embodiments, as illustrated in FIG. 23, the power transmission device 1 can perform beamforming by a reconfigurable antenna by selecting and controlling any of the plurality of antenna units 2a to 2e constituting the power transmission antenna 2. Hereinafter, with reference to FIGS. 24 and 25, the beamforming of the power transmission antenna 2 will be described more specifically.

[0151] Referring to FIG. 24, an RF source (high-frequency source) 202 having a function of transmitting an RF signal to the antenna 200 is shown. This corresponds to the RF signal sent from the signal generator 6a through the amplifier 6b to the transmission antenna 2 illustrated in FIG. 22, or the RF source 6 illustrated in FIG. 23. The antenna 200 is composed of a plurality of antenna units 210, 220, 230, 240, and 250, which correspond to the antenna units 2a, 2b, 2c, 2d, and 2e illustrated in FIG. 23. Each of the antenna units 210 to 250 is arranged concentrically and nested, and each extends circumferentially. Therefore, each of the antenna units 210 to 250 radiates energy circumferentially around it.

[0152] Referring to FIG. 24, each of the antenna units 210, 220, 230, 240, 250 has switch units (components for creating a phase difference) 212, 222, 232, 242, 252 and 214, 224, 234, 244, 254 so as to equally divide one circumference into two semi - circles. These switch units control the phase of the electromagnetic wave. On the right side of FIG. 24, a configuration example of one of the above - mentioned switch units, 254, is shown enlarged. As shown in this figure, an LC circuit is provided in each switch unit. The LC circuit is an electric circuit composed of an inductor L and a capacitor C and is a kind of resonant circuit. The LC circuit is configured to generate a signal of a specific frequency. Further, a short (Short) is incorporated in this LC circuit. By switching, these components (L, C, Short) are selected.

[0153] Referring to FIG. 24, the LC circuit is provided with a switch SW for switching the power distribution of the current flowing through the circuit. The switch SW can select any one of three cases: when the current flows only through the inductor L, when the current flows only through the capacitor C, and when the current does not flow through either of them (Short) between the inductor L and the capacitor C in the LC circuit. Each of the antenna units 210 - 250 can function independently of the switch units 212 - 252 and 214 - 254. Since each switch can be switched in three ways, when N switches are used, theoretically, 3^N combinations are possible. For example, when five switches are used, theoretically, 243 (3^5) combinations are possible. Therefore, the antenna 200 enables complex control such that the superposition of waves is focused at a short distance by individually controlling the constituent antenna units 210 - 250.

[0154] FIG. 25 illustrates a cross - section along the X - X line of the antenna 200 shown in FIG. 24, and is a diagram illustrating two different power - transmission states (A) and (B) based on the operation of the above - mentioned switch unit. For example, in the state of (A) in FIG. 25, the switch sections 212 to 252 and 214 to 254 that equally divide each antenna section 210 to 250 into two are selected to be in the same state as each other. That is, the switch sections 212 to 252 are, in order, in the states of C1, C2, C3, L1, and L2. C is a capacitor, L is an inductor, and the numerical values represent the degree of flowing power. Similarly, the switch sections 214 to 254 are, in order, in the states of C1, C2, C3, L1, and L2. Therefore, in the state of (A) in FIG. 26, in each antenna section 210 to 250, the two semi-circular portions send energy equally to the surroundings and condense it evenly in the vertical direction and at a shallow angle in the front direction.

[0155] On the other hand, in the state of (B) in FIG. 25, the switch sections 212 to 252 and 214 to 254 that equally divide each antenna section 210 to 250 into two make the two semi-circular portions in different states from each other. That is, the switch sections 212 to 252 are, in order, in the states of L5, C2, Short, Short, and C3. On the other hand, the switch sections 214 to 254 are, in order, in the states of L5, L4, L3, L1, and L2. Therefore, in the state of (B) in FIG. 25, in each antenna section 210 to 250, the two semi-circular portions send energy to the surroundings so as to be different from each other, and condense it unevenly in the vertical direction and at a shallow angle in the diagonal direction.

[0156] For example, assume that in the state of (A) in FIG. 25, a feedback signal indicating that the power reception state of the power reception antenna 12 of the power reception device 10 is not good is sent to the power transmission device 1. At this time, if the controller 4 of the power transmission device 1 determines that beam forming of the power transmission antenna 2 / 200 is necessary, it controls the switch sections 212 to 252 and 214 to 254 in FIG. 24 to switch the power transmission direction of the power transmission antenna 200 to, for example, the state of (B) in FIG. 25.

[0157] As described above, the reconfigurable metasurface of the power transmission antenna 2 / 200 of the power transmission device 1 is configured. However, this shape and configuration are not limited to those shown in the drawings. For example, in the illustrated embodiment, a plurality of circular antenna portions are arranged concentrically and nested, but this shape is not limited to circular. Also, in the illustrated embodiment, a plurality of circular antenna portions are bisected into two semi-circular portions, but they may be divided into three or four or more equal parts to enable finer control. Further, although the illustrated power transmission antenna is configured in a planar shape, in other embodiments, the antenna portions 210 to 250 may not be arranged on the same plane.

[0158] As described above, a reconfigurable transmitter is configured. In the illustrated embodiment, each switch is selected from three options: L, C, and Short. However, in other embodiments, it may be selected from two options: L and C. In this case, if N switches are used, a total of 2^N combinations are possible. Therefore, the power transmission antenna is composed of a plurality of antenna portions, and at this time, each antenna portion is provided with a switch that can create a phase difference of two or three options. When a total of N switches are used, beamforming of 2^N or 3^N combinations is enabled. Furthermore, these switches may be a combination of those that enable selection from three options: L, C, and Short, and those that enable selection from two options: L and C. As described above, the power transmission antenna is composed of a plurality of antenna portions, and at this time, each antenna portion is provided with a switch that can create a phase difference of two or three options. When a total of N switches are used, beamforming of 2^N and / or 3^N combinations is enabled.

[0159] Conventionally, in medium- and long-distance wireless power supply, when the receiving device is mobile, the transmitter always needs to transmit the maximum electromagnetic energy. That is, beam forming of the transmitter is required according to the situation. Generally, as a method, beam forming is performed by controlling the phase of each antenna using an array antenna. However, with this configuration, there are problems such as only one direction for the beam forming direction, high cost, and limitations of the beam angle. In this embodiment, in order to solve such problems, the received intensity is fed back, and a switch for turning on and off parasitic elements and GND arranged around the antenna is provided to configure a system in which the transmission power is always maximized with a beam pattern corresponding to the number of switches and a wide beam angle. The beam angle can also form patterns that radiate respectively toward, for example, two or three receiving devices.

[0160] "Electric field strength" As described above, in Embodiments 1 to 6, the controller 4 of the power transmission device 1 performs beam forming of the power transmission antenna 2. Therefore, it is preferable to know in advance the electric field strength in each case of the power reception device 10. For example, the controller 4 of the power transmission device 1 stores the power reception status of the power reception device 10 in each case where the robot arm unit 90 and / or the robot hand unit 80 operates in, for example, FA (see FIG. 1).

[0161] Therefore, for example, under various situations, the voltage value of the power reception device 10 may be actually measured at each position of the robot arm unit 90 and / or the robot hand unit 80 that operates with a high degree of freedom. Alternatively, using computer simulation, VR (Virtual Reality) system, etc., the voltage on the power reception device 10 side may be pseudo-determined at each position of the robot arm unit 90 and / or the robot hand unit 80 that operates with a high degree of freedom under various situations. The controller 4 stores in advance these variously changing voltage values and the positions of the robot arm unit 90 and / or the robot hand unit 80, etc., and may store them in, for example, a table or a database.

[0162] The controller 4 of the power transmission device 1 can estimate the position, orientation, etc. of the power reception antenna 12 at that time by using the feedback signal fs from the controller 40 of the power reception device 1 with respect to the above table, database, etc. Therefore, the controller 4 of the power transmission device 1 can perform control (beamforming) of the power transmission antenna 2 so that energy can be sent more favorably to the estimated power reception antenna 12. There are various methods for grasping in advance the electric field distribution at the FA (factory site) where the power reception device 10 is used by actual measurement. FIG. 26 is a diagram schematically illustrating the measurement of the electric field distribution by tracking the light of the LED 22 of the power reception device 10.

[0163] As described above, in the first to sixth embodiments, the LED 22 is provided in order to easily check the power reception status of the power reception antenna 12. By continuously tracking the lighting status of this LED 22, the electric field distribution when the machine 100 operates in various ways can be grasped. For example, a camera is installed near the machine 100, and the lighting status of the LED 22 is continuously photographed as a still image. For example, when the shutter speed of the camera is short, the lighting of the LED 22 is photographed as a dot, but when the shutter speed of the camera becomes longer, the lighting of the LED 22 can be photographed as a line. In the latter case, the trajectory of the light can be recorded in one picture.

[0164] For example, in FIG. 26, the articulated robot 100 can move in the vertical direction as illustrated by the vertical arrow. Also, the articulated robot 100 can move in the left - right direction as illustrated by the horizontal arrow. Further, the articulated robot 100 may perform angled movement, rotational movement, etc. As a result of continuously observing and recording the lighting status of the LED 22 in each case of the articulated robot 100 that performs highly - free - degree operations, the electric field distribution of the power reception device 10 can be actually measured. Note that it is possible to track the trajectory of the light of the LED 22 using a video.

[0165] Note that although the light emitted by LED22 is actually very weak, it is possible to track the weak light by turning off the ambient light to create darkness. According to the operating state of each joint of the multi-joint robot 100, in each case, by observing and aggregating the lighting intensity of the light emitted by LED22, the electric field distribution can be obtained. The power transmission device 1 may perform beamforming for optimizing wireless power supply by combining the above feedback signal fs after storing this electric field distribution in advance.

[0166] By mounting LED22 on the power receiver as described above, it is possible to visually grasp the received power according to the presence or absence of lighting and the lighting intensity. However, when the power receiving system (e.g., robot hand, robot arm, etc.) operates, the power receiving location and the received power change, so the state of LED22 changes. In order to continuously record these states, by taking a long exposure with a camera, the intensity of LED22 and the trajectory of the operation of the power receiving system can be recorded, and it is possible to grasp at what state and to what extent power is being received.

[0167] As described above, by grasping the electric field intensity, storing the results, and mapping the data, the electric field distribution can be mapped. For example, the data is stored in the storage device within the power transmission device 1. Thereby, it is possible to grasp in advance the electric field distribution at the FA site where the product is actually used, and it is possible to understand whether the environment is suitable for wireless power transmission during actual use.

[0168] Referring to FIG. 1 again, when the power supply to the sensor 30 is made wireless, it may be necessary to periodically replace the secondary battery. In particular, since FA has a high operating frequency per day, it is considered that the replacement frequency of the secondary battery is high. Therefore, it is necessary to periodically manage the battery management system 21 that uses wireless power supply and is unique to FA and uses wireless communication with the sensor 30.

[0169] In each of the above-described Examples 1 to 6, when the battery 20 is used, it may be possible to predict battery failures. Generally, a battery deteriorates and thus has a limited lifespan. Therefore, it is useful if the degree of deterioration can be grasped and failure prediction can be performed. In the present invention, the degree of deterioration can be grasped based on changes in charging efficiency. The charging efficiency is monitored regularly, and when compared with the start of operation, if it is significantly deteriorated or the predicted failure time is approaching, the battery is replaced. This may be realized by the controller 4 of the power transmission device 1 and / or the controller 40 of the power reception device 10, etc. Furthermore, the present invention illustrated in Examples 1 to 6 compacts the entire power reception device 10 relatively, and preferably accommodates it together on the tip side of the machine tool 100. For this reason, wiring inside the machine tool 100 is made unnecessary or minimized, and access from the outside is facilitated. As a result, power supply to the sensor 30 is ensured and maintainability is enhanced.

[0170] "Magnetic resonance method" As described above, in Examples 1 to 6, radiative wireless power supply is performed based on the microwave method that can supply relatively small power (e.g., 1 m, 1 mW) over a relatively long distance. In addition, for wireless power supply, non-radiative types such as the magnetic resonance method that can supply relatively large power (e.g., 1 cm, 5 W) over a relatively short distance are known. In the case of the microwave method, when a reduction in efficiency due to impedance mismatch occurs between the sensor operating with relatively small-capacity power, it can become a major problem. On the other hand, in the case of the magnetic resonance method, when a reduction in efficiency due to impedance mismatch occurs between the sensor operating with relatively small-capacity power, realistically, the reduction in efficiency can be considered within a negligible range.

[0171] However, even in the case of wireless power supply based on the magnetic resonance method, similar to the microwave method, RF (electromagnetic wave) is converted into DC (direct current voltage). When the RF region and the DC region are coupled, impedance mismatch may occur. Therefore, in order to efficiently receive RF power, impedance matching technology is required. Since this problem itself is the same for both the magnetic resonance method and the microwave method, in order to solve this problem, it is possible to apply Examples 1 to 6 to the magnetic resonance method. However, the effect of its application is more realistic in the case of the microwave method than in the case of the magnetic resonance method. Therefore, Examples 1 to 6 are very useful when performing wireless power supply based on the microwave method.

Explanation of Signs

[0172] 1 Power transmission device 2 Power transmission antenna 4 Controller (host computer) 10 Power reception device 12 Power reception antenna 14 Rectifier 16 Energy storage device (capacitor) 20 Energy storage device (battery) 30 Device (sensor) 40 Controller 50 Wireless communication IC 80 Robot hand part 90 Robot arm part 100 Machine (multi-joint robot) 200 Power transmission antenna

Claims

1. A power receiving device, a power receiving antenna that receives microwaves from a power transmitting device based on a wireless power feeding method configured to operate at a frequency of 900 MHz or more from a plurality of directions and changes the power receiving state; A power receiving device having a controller that transmits information regarding a pseudo electric field intensity calculated from multiple voltage values ​​measured at different times for a voltage generated based on the microwaves received by the power receiving antenna to the power transmitting device as feedback information.

2. a rectifier for converting the electromagnetic waves received by the power receiving antenna into a DC voltage; a first storage device operatively connected to the rectifier; a second storage device operatively connected to the rectifier and the first storage device via a switch; The controller transmits, as the feedback information to the power transmitting device, information regarding a pseudo electric field intensity calculated from a plurality of voltage values ​​measured at different times with respect to the voltage of the first power storage device when the switch is in an off state. The power receiving device according to claim 1 .

3. The power receiving device of claim 1, characterized in that the controller transmits information regarding the pseudo electric field strength calculated based on a threshold voltage value and the time required to reach the threshold voltage value as the feedback information to the power transmitting device.

4. a rectifier for converting the electromagnetic waves received by the power receiving antenna into a DC voltage; a power storage device and a sensor operatively connected to the rectifier via a switch, and The controller uses the switch to disconnect the rectifier side from the power storage device and the sensor side, thereby suppressing impedance mismatch between the rectifier side and the power storage device and the sensor side. The power receiving device according to claim 1 .

5. 2. The power receiving device according to claim 1, further comprising a light emitting diode for indicating a power receiving state.

6. The power receiving device according to claim 5 , wherein the power receiving state is an amount of current flowing through the light emitting diode.

7. a rectifier for converting the electromagnetic waves received by the receiving antenna into a direct current voltage, the rectifier being operatively connected to the light emitting diode via a switch; The controller turns on the switch to enable confirmation of the power receiving status. The power receiving device according to claim 5 .

8. 1. A communication device, comprising: a controller that receives, as feedback information from the power receiving device, information regarding pseudo electric field intensity calculated from multiple voltage values ​​measured at different times for a voltage generated based on microwaves received by a power receiving antenna whose power receiving state changes as a result of receiving microwaves at a frequency of 900 MHz or more from multiple directions in order to identify the power receiving state of the power receiving device; A communication device having the above configuration.

9. The power receiving device further includes a power transmitting antenna for transmitting power to the power receiving device based on a wireless power supply method, The communication device according to claim 8 , wherein the controller controls the power transmitting antenna based on the feedback information.

10. The communication device according to claim 8, characterized in that the controller receives, as the feedback information, information calculated based on the time required to reach a threshold voltage value as information regarding the pseudo electric field strength from the power receiving device.

Images