Power transmission device, control method for power transmission device, and storage medium

Abstract

[Problem] To provide a technique that enables power transmission control on the basis of detection of a device capable of communication via a communication antenna in a power transmission device including a plurality of power transmission coils for wireless power transmission and the communication antenna. [Solution] A power transmission device (100) is provided with a plurality of power transmission coils (209) and a near field communication (NFC) antenna (213). At least one NFC antenna (213) is disposed in each power transmission area corresponding to the power transmission coil group. When an NFC antenna (213) used to detect an NFC tag is an NFC antenna disposed in a power transmission area in which power is being transmitted using a power transmission coil (209), the power transmission device (100) stops the power transmission process in S704.

Description

Technical Field

[0001] The present disclosure relates to technologies for wireless power transmission. Background Art

[0002] A standard established by the Wireless Power Consortium, a standardization organization, as a wireless charging standard (hereinafter referred to as the WPC standard) is widely known. In Patent Document 1, a power transmission device and a power reception device based on the WPC standard are disclosed. In the WPC standard, magnetic induction is used for power transmission, power reception, and their control communication.

[0003] As one of wireless communication methods, a near field communication (NFC) method is known. The NFC tag does not include a battery and is driven by the energy of electromagnetic waves transmitted when communicating with a communication partner. In the case of performing the above-described wireless power transmission to the NFC tag, it is necessary to avoid damage to the antenna element or the like of the NFC tag.

[0004] In the WPC standard, in parallel with processing related to power transmission or reception, the power transmission device detects an NFC tag by communication based on a standard for NFC (NFC standard). Based on the detection result of the NFC tag, it is determined whether to stop power transmission or reception. Patent Document 2 discloses a wireless charging pad that includes a plurality of power transmission coils and can efficiently charge an electronic device using most of its charging surface.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-56959

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2018-186699 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] In the related art, in the case where the power transmission device includes a plurality of power transmission coils, control for appropriately performing tag detection cannot be satisfactorily established. In the WPC standard, an appropriate control method in the case where an NFC tag is detected in association with a power transmission device including a plurality of power transmission coils has not been studied. Therefore, there is a possibility that control for stopping or restricting power transmission or reception may be performed unnecessarily depending on the position of the power reception device or the NFC tag placed on the power transmission device or depending on the power transmission or reception state.

[0011] An object of the present disclosure is to provide a technology that enables power transmission control in a power transmission device including a plurality of power transmission coils for wireless power transmission and a communication antenna, based on detection of a communicable device via the communication antenna.

[0012] Solution to the problem

[0013] A power transmission device according to the present disclosure includes: a power transmission component configured to perform power transmission using a plurality of power transmission coils; a first detection component configured to detect a power reception device using the power transmission coils; a communication antenna disposed in an area where power transmission can be performed using the power transmission coils; a second detection component configured to detect a communicable device via the communication antenna; and a control component configured to control power transmission from the power transmission component using the power transmission coil used to detect the power reception device. When power is being transmitted to the power reception device via the power transmission coil in an area where the antenna used by the second detection component to detect the device is disposed, the control component performs control to limit power transmission from the power transmission component.

[0014] Effect of the invention

[0015] According to the present disclosure, a technology can be provided that enables power transmission control in a power transmission device including a plurality of power transmission coils for wireless power transmission and a communication antenna, based on detection of a communicable device via the communication antenna. Description of the drawings

[0016] Figure 1 is a diagram illustrating an example of the configuration of a wireless power transmission system according to an embodiment.

[0017] Figure 2 is a block diagram illustrating an example of the configuration of a power transmission device.

[0018] Figure 3 is a block diagram illustrating an example of the configuration of a power reception device.

[0019] Figure 4 of (A) to Figure 4 of (D) is a diagram illustrating an example of the configuration structure of a power transmission coil group.

[0020] Figure 5 is a diagram illustrating an example of the configuration of a power transmission coil and an NFC antenna according to a first embodiment.

[0021] Figure 6 is a flowchart illustrating a processing flow performed by a power transmission device according to an embodiment.

[0022] Figure 7It is a flowchart illustrating the NFC tag detection process according to the first embodiment.

[0023] Figure 8 It is a sequence diagram illustrating the operations of the device according to the first embodiment.

[0024] Figure 9 It is a diagram illustrating an example of the configuration of the power transmission coil and the NFC antenna according to the second embodiment.

[0025] Figure 10 It is a flowchart illustrating the NFC tag detection process according to the second embodiment.

[0026] Figure 11 It is a sequence diagram illustrating the operations of the device according to the second embodiment. Detailed Description of the Invention

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. An example of a wireless power transmission system based on the WPC standard will be described, and an example of a near field communication (NFC) tag as an electronic tag will be described. Not all of the multiple features in the embodiments of the present disclosure are necessary for the present disclosure, and multiple features can be arbitrarily combined.

[0028] [First Embodiment]

[0029] Figure 1 It is a diagram illustrating an example of the structure of the wireless power transmission system according to the first embodiment. The wireless power transmission system according to the present embodiment includes a power transmission device 100 and a power reception device 101. In Figure 1 it, a first power reception device 101a and a second power reception device 101b are illustrated as the power reception devices.

[0030] The power transmission device 100 has a function of simultaneously charging the first power reception device 101a and the second power reception device 101b placed within its power transmission range. In Figure 1 it, an example in which two power reception devices are placed on the power transmission device is illustrated, but the present disclosure is not limited thereto. For example, the power transmission device 100 can charge one power reception device. Alternatively, the power transmission device 100 can simultaneously charge three or more power reception devices.

[0031] In the present embodiment, the state in which the power reception device is placed on the power transmission device (hereinafter referred to as the "placed state") includes the following states. For example, the placed state includes a state in which the power reception device is mounted on the surface within the power transmission range of the power transmission device.

[0032] The method described in the present embodiment can be applied at least in a state where the power reception device is included in the power transmission range of the power transmission device. For example, the power reception device and the power transmission device can be in a non-contact state.

[0033] The surface of the power transmission device on which the power receiving device is placed in the placement state is not limited to a horizontal plane, and may be a vertical plane, an inclined plane, or a curved surface. In the following description, for simplicity of notation, the power transmission device may be referred to as TX, and the power receiving device may be referred to as RX. Details of TX and RX will be described later with reference to Figure 2 and Figure 3 to illustrate the detailed structures of TX and RX.

[0034] In the wireless power transmission system, wireless power transmission using the electromagnetic induction method for non-contact charging is performed based on the WPC standard. Non-contact wireless power transmission for charging is performed between the power receiving coil of RX and the power transmission coil of TX.

[0035] The wireless power transmission method (non-contact power transmission method) is not limited to the method specified in the WPC standard, and other electromagnetic induction methods, magnetic resonance methods, electric resonance methods, microwave methods, or methods using lasers, etc. may be used. In this embodiment, wireless power transmission is used for non-contact charging, and wireless power transmission may be performed as an application other than non-contact charging.

[0036] In the WPC standard, the magnitude of the power guaranteed when RX receives power from TX is defined by the value of the guaranteed power (hereinafter referred to as "GP"). GP indicates the following power value: Even when the positional relationship between RX and TX changes and the power transmission efficiency between the power receiving coil and the power transmission coil decreases, this power value is guaranteed to be output to the load of RX such as a charging circuit.

[0037] For example, the GP value is 15 (watts). In this case, even when the positional relationship between the power receiving coil and the power transmission coil changes and the power transmission efficiency decreases, TX supplies power to RX by performing control so that 15 watts can be output to the load in RX. GP is determined through negotiation between RX and TX.

[0038] In the WPC standard, a method for TX to detect the presence of an object other than the power receiving device in the surrounding environment of TX (such as near the power transmission coil, etc.) is specified. This object may be referred to as a foreign object. More specifically, the first method is a foreign object detection method based on the change in the quality factor (Q value, Q factor) associated with the power transmission coil in TX.

[0039] The second method (power loss method) is a foreign object detection method based on the difference between the power transmitted by TX and the power received by RX. The first method is performed before power transmission (in the negotiation phase or the re-negotiation phase). The second method is performed during power transmission (in the power transmission phase) based on the data for which the calibration process has been performed.

[0040] On the other hand, a plurality of components constituting the RX (and a product assembled with the RX) or the TX (and a product assembled with the TX) may include essential metal components. There are metal components that may inadvertently generate heat when they are exposed to the power of wireless power transmission using a power transmission coil.

[0041] Such metal components include, for example, a metal frame near the power transmission coil or the power reception coil. A foreign object in the present disclosure is an object that is not a part of either the power reception device and a product assembled with the power reception device or the power transmission device and a product assembled with the power transmission device, and may generate heat when exposed to the power signal transmitted by the power transmission coil.

[0042] An object that is an essential part of the power reception device and a product assembled with the power reception device, or an object that is an essential part of the power transmission device and a product assembled with the power transmission device does not correspond to a foreign object. For example, a paper clip corresponds to a foreign object.

[0043] The communication between the RX and the TX includes communication for power transmission / reception control based on the WPC standard and communication for device authentication. Here, the communication for power transmission / reception control based on the WPC standard will be described.

[0044] In the WPC standard, a plurality of phases including a power transmission phase for performing power transmission and a phase before power transmission are defined, and communication for necessary power transmission / reception control is performed in these phases. Various such phases will be described below.

[0045] The phase before power transmission includes a ping phase, a configuration phase, a negotiation phase, and a calibration phase. In the ping phase, the TX intermittently transmits an analog ping and detects the presence of an object within the power transmission range.

[0046] The analog ping is hereinafter referred to as AP. For example, the TX can detect the power reception device 101 or a conductor sheet or the like placed on the power transmission device 100 by transmitting the AP. Thereafter, the TX transmits a digital ping with a higher power than that of the AP.

[0047] The digital ping is hereinafter referred to as DP. The DP has a power sufficient to start the control unit of the RX placed on the TX. The RX uses a signal strength packet to notify the TX of the magnitude of the received power voltage.

[0048] In this way, the TX identifies that the object detected using the AP is the RX by receiving a response from the RX that has received the DP. When the TX receives a notification indicating the magnitude of the received power voltage from the RX, the TX transitions to the configuration phase.

[0049] Before sending DP, TX measures the quality factor (Q value, Q factor) associated with the power transmission coil. The measurement result is used for foreign object detection processing based on the Q value measurement method. In the configuration stage, TX identifies RX and obtains device configuration information (capability information) from RX.

[0050] Therefore, RX sends an ID packet and a configuration packet to TX. The ID packet includes the identification information of RX, and the configuration packet includes the device configuration information (capability information) of RX.

[0051] TX that has received the ID packet and the configuration packet sends an acknowledgment (ACK) to RX as a response. Then, the configuration stage ends.

[0052] In the negotiation stage, the GP value is determined based on the GP value required by RX or the power transmission capability of TX, etc. In response to a request from RX, TX performs foreign object detection processing based on the Q value measurement method.

[0053] In the WPC standard, a method is specified for performing the same processing as in the negotiation stage again in response to a request from RX after temporarily transitioning to the power transmission stage. The stage to which the power transmission stage transitions and where this processing is performed is called the renegotiation stage.

[0054] In the calibration stage based on the WPC standard, RX notifies TX of a predetermined received power value, and TX performs adjustment for efficient power transmission. The predetermined received power value is, for example, the received power value in the light load state or the received power value in the maximum load state. TX can use the received power value notified by RX for foreign object detection processing based on the power loss method.

[0055] In the power transmission stage, power transmission continues and control is performed for handling errors or stopping power transmission due to full charge, etc. TX and RX perform communication for power transmission / reception control through the following in-band communication, in which signals are superimposed using the same antenna (coil) as in wireless power transmission based on the WPC standard.

[0056] The in-band range in which communication based on the WPC standard can be performed between TX and RX is almost the same as the power transmission range.

[0057] The functional structures of TX and RX will be described below. Figure 2 It is a block diagram illustrating the functional structure of the power transmission device 100 (TX). The power transmission device 100 includes a control unit 201, a power supply unit 202, a first power transmission circuit 203, a first communication unit 204, a second power transmission circuit 205, a second communication unit 206, a memory 207, and a power transmission coil selection unit 208.

[0058] The power transmission device 100 further includes a power transmission coil group 210, an NFC communication unit 211, an NFC antenna selection unit 212, and an NFC antenna 213.

[0059] The power transmission coil group 210 includes a plurality of power transmission coils 209a, 209b,.... The TX includes a plurality of NFC antennas 213a, 213b,.... In the following description, the plurality of power transmission coils or the plurality of NFC antennas are referred to as the power transmission coil 209 or the NFC antenna 213 when they do not need to be distinguished.

[0060] The control unit 201 controls the entire power transmission device 100. The control unit 201 includes, for example, one or more processors such as a central processing unit (CPU) or a microprocessing unit (MPU). The control unit 201 may include an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA) configured to perform the processes described later.

[0061] The power supply unit 202 includes a power supply for supplying power for the operations of the control unit 201, the first power transmission circuit 203, the second power transmission circuit 205, and the NFC communication unit 211. The power supply unit 202 includes, for example, a wired power receiving circuit or a battery that is supplied with power from a commercial power supply.

[0062] The first power transmission circuit 203 and the second power transmission circuit 205 generate an AC voltage and an AC current in any of the power transmission coils 209 included in the power transmission coil group 210. For example, the first power transmission circuit 203 and the second power transmission circuit 205 use a switching circuit having a half-bridge or full-bridge configuration using field effect transistors (FETs) to convert the DC voltage supplied from the power supply unit 202 into an AC voltage.

[0063] In this case, the first power transmission circuit 203 and the second power transmission circuit 205 include gate drivers for controlling the ON / OFF (turn-on / turn-off) of the FETs.

[0064] The first communication unit 204 performs control communication for wireless power transmission based on the WPC standard with the communication unit ( Figure 3 303 in) of the power receiving device according to a control command from the control unit 201. For example, the first communication unit 204 performs load modulation of the AC voltage or AC current generated by the first power transmission circuit 203, and transmits a signal of communication data to the power receiving device by superimposing the signal of the communication data on the transmitted wave (electromagnetic wave).

[0065] The first communication unit 204 receives the signal of the communication data transmitted from the power receiving device by demodulating the AC voltage or AC current modulated by the communication unit ( Figure 3 303 in) of the power receiving device.

[0066] Through this process, control communication for wireless power transmission based on the WPC standard is achieved. Similar to the first communication unit 204, the second communication unit 206 achieves control communication by modulating or demodulating the load of the AC voltage or AC current generated by the second power transmission circuit 205 according to a control command from the control unit 201 and transmitting and receiving communication data.

[0067] The memory 207 is connected to the control unit 201 and stores information related to the states of the power transmission device 100 or the respective components of the wireless power transmission system and the overall state. For example, the memory 207 stores identification information of a plurality of power transmission coils and NFC antennas required for power transmission control and communication control, or identification information of a power transmission area to be described later.

[0068] Any one or more of the plurality of power transmission coils 209 constituting the power transmission coil group 210 are connected to the first power transmission circuit 203 or the second power transmission circuit 205 via the power transmission coil selection unit 208.

[0069] The power transmission coil selection unit 208 connects any one or more of the power transmission coils constituting the power transmission coil group 210 to the first power transmission circuit 203 or the second power transmission circuit 205 according to a control command from the control unit 201.

[0070] The control unit 201 can control the power transmission coil selection unit 208 so that the first power transmission circuit 203 or the second power transmission circuit 205 is connected to any one or more of the power transmission coils. The switching of the connection between the first power transmission circuit 203 and the second power transmission circuit 205 and the power transmission coils performed by the power transmission coil selection unit 208 will be described later.

[0071] The first power transmission circuit 203 and the second power transmission circuit 205 according to the present embodiment can operate independently to simultaneously transmit power for charging at most one power receiving device. That is, the power transmission device 100 can simultaneously charge at most two power receiving devices.

[0072] The NFC communication unit 211 uses the NFC method, which is a short-range wireless communication method, to communicate with other NFC devices. It is assumed that the other NFC devices include NFC tags. The power transmission device 100 can use the NFC communication unit 211 to detect the presence of NFC tags.

[0073] The NFC communication unit 211 is connected to any one or more than one NFC antenna via the NFC antenna selection unit 212. The control unit 201 determines which NFC antenna 213 the NFC communication unit 211 is to be connected to by controlling the NFC antenna selection unit 212. The NFC antenna selection unit 212 switches the connection between the NFC communication unit 211 and the NFC antenna 213 according to a control command from the control unit 201.

[0074] In Figure 2 In the illustrated example, each constituent unit is illustrated as a separate block element. Each constituent unit is the control unit 201, the power supply unit 202, the first power transmission circuit 203, the first communication unit 204, the second power transmission circuit 205, the second communication unit 206, the memory 207, the power transmission coil selection unit 208, the power transmission coil group 210, the NFC communication unit 211, and the NFC antenna selection unit 212.

[0075] The present disclosure is not limited to this example, and two or more than two block elements may be incorporated into one chip or the like, and one block element may be divided into a plurality of block elements.

[0076] Figure 3 is a block diagram illustrating the functional structure of the RX (the first power receiving device 101a and the second power receiving device 101b). In the present embodiment, the first power receiving device 101a and the second power receiving device 101b have the same functional structure.

[0077] The power receiving devices are simply referred to as the power receiving device 101 when they are not distinguished. Here, the first power receiving device 101a and the second power receiving device 101b may be different types of devices. Figure 3 The illustrated power receiving device 101 includes a control unit 301, a power receiving unit 302, a communication unit 303, a memory 304, a power receiving coil 305, a charging unit 306, and a battery 307.

[0078] The control unit 301 controls the entire power receiving device 101. The control unit 301 includes, for example, one or more than one processors such as a CPU or an MPU. The control unit 301 may include an ASIC or an FPGA configured to perform the processing to be described later. The control unit 301 may be started by receiving predetermined power from the power transmission device 100.

[0079] The power receiving unit 302 receives the AC voltage and the AC current generated in the power receiving coil 305 from any power transmission coil 209 constituting the power transmission coil group 210. The power receiving unit 302 converts the AC voltage and the AC current into a DC voltage and a DC current for operating the control unit 301, the charging unit 306, and the like.

[0080] The communication unit 303 performs control communication for wireless power transmission based on the WPC standard with the first communication unit 204 or the second communication unit 206 of the power transmission device 100 according to a control command from the control unit 301.

[0081] The communication unit 303 transmits communication data to the power transmission device 100 by modulating the AC voltage and AC current received by the power receiving coil 305. The communication unit 303 receives communication data transmitted from the power transmission device 100 by demodulating the AC voltage and AC current modulated by the power transmission device 100.

[0082] The charging unit 306 charges the battery 307 based on the DC voltage and DC current supplied from the power receiving unit 302. The memory 304 is connected to the control unit 301 and stores information for indicating the state of each component or the overall state of the power receiving device 101 or the wireless power transmission system.

[0083] In Figure 3 the illustrated example, the control unit 301, the power receiving unit 302, the communication unit 303, the memory 304, and the charging unit 306 are illustrated as independent component blocks. The present disclosure is not limited to this example, and two or more component blocks may be integrated into one chip or the like, or one component block may be divided into multiple component blocks.

[0084] In addition to the charging function by wireless power transmission, the power receiving device 101 and the power transmission device 100 according to the present embodiment may also have a function of executing an application. For example, the power receiving device 101 is a smart phone, and the power transmission device 100 is an accessory device for charging the battery of the smart phone (power receiving device 101).

[0085] Alternatively, the power receiving device 101 and the power transmission device 100 may be storage devices such as a hard disk device or a memory device, or may be information processing devices such as a personal computer (PC). The power receiving device 101 and the power transmission device 100 may be image input devices such as a camera device (such as a still camera and a video camera) or a scanner, or may be image output devices such as a printer, a copier, or a projector.

[0086] Alternatively, the power transmission device 100 may be a smart phone. In this case, the power receiving device 101 may be another smart phone or a wireless earphone. The power transmission device 100 may be a charger installed in a vehicle console or the like.

[0087] Reference will be made to Figure 4 of (A) to Figure 4 of (D) to describe the configuration structure of the power transmission coil group 210 of the power transmission device 100. Figure 4 of (A) toFigure 4 shows the state in a top view of the power transmission coil group 210 schematically, and illustrates an example of the arrangement of a plurality of power transmission coils on a two-dimensional plane (xy plane).

[0088] Here, the actual plurality of power transmission coils may also be arranged in a three-dimensional space including the height direction (z direction). The power transmission coils 400 to 411 correspond to the plurality of power transmission coils 209 that make up the power transmission coil group 210.

[0089] Figure 4 of (A) and Figure 4 of (B) are diagrams showing the state in a top view of a part of the power transmission coil group 210. In Figure 4 of (A), an example of the arrangement of six circular coils is illustrated as the power transmission coils 400 to 405. The power transmission coils 400, 401, and 402 are arranged such that their peripheral portions are in partial contact with two other power transmission coils.

[0090] Similarly, the power transmission coils 403, 404, and 405 are arranged such that their peripheral portions are in partial contact with two other power transmission coils. Similarly, the power transmission coils 402, 403, and 405 are arranged such that their peripheral portions are in partial contact with two other power transmission coils.

[0091] Figure 4 of (B) illustrates an example of the arrangement of six circular coils as the power transmission coils 406 to 411. Figure 4 The arrangement of the power transmission coils 406 to 411 illustrated in of (B) corresponds to the arrangement obtained by laterally inverting the arrangement of the power transmission coils 400 to 405 illustrated in Figure 4 of (A).

[0092] For convenience, the power transmission coils 406 to 411 are illustrated by adding hatching (vertical lines) to the circles corresponding to the respective power transmission coils to distinguish them from the power transmission coils 400 to 405. This also applies to Figure 4 of (C) and Figure 4 of (D).

[0093] In Figure 4 of (B), the power transmission coils 409, 410, and 411 are arranged such that their peripheral portions are in partial contact with two other power transmission coils. Similarly, the power transmission coils 406, 407, and 408 are arranged such that their peripheral portions are in partial contact with two other power transmission coils.

[0094] Similarly, the power transmission coils 408, 409, 411 are arranged such that their peripheral portions are in partial contact with two other power transmission coils.

[0095] Figure 4Figure (C) is a diagram showing the state in a top view of the entire power transmission coil group 210. The power transmission coil group 210 has Figure 4 the structure in which the power transmission coils 400 to 405 illustrated in (A) are superimposed on Figure 4 the power transmission coils 406 to 411 illustrated in (B).

[0096] Figure 4 Figure (D) is a diagram showing the positional relationship between a part of the power transmission coil group 210 (the power transmission coils 400, 401, 410, and 411). Since the power transmission coil 400 and the power transmission coil 410 are superimposed in the top view and the power transmission coil 401 and the power transmission coil 410 are superimposed in the top view, these power transmission coils are considered to be "overlapping each other".

[0097] On the other hand, the power transmission coil 400 and the power transmission coil 411 are not superimposed in the top view. The distance 412 indicates the distance (denoted by D) between the outer shape portions of the power transmission coil 400 and the power transmission coil 411. That is, the power transmission coil 400 and the power transmission coil 411 are separated by the distance D in the top view.

[0098] Among a plurality of power transmission coils adjacent to each other, the first power transmission coil is referred to as coil A, and the second power transmission coil is referred to as coil B. The electromagnetic wave associated with the power transmission power of coil A and the in-band communication signal transmitted and received between the communication units of TX and RX can be superimposed on the electromagnetic wave associated with the power transmission power of coil B and the in-band communication signal transmitted and received between the communication units of TX and RX.

[0099] This phenomenon is referred to as "interference" in the present disclosure. The interference between a plurality of power transmission coils and the non-interference between a plurality of power transmission coils are defined as follows. When coil A satisfies condition (1) or (2) with respect to coil B, the two power transmission coils are considered to be "not interfering with each other".

[0100] (1) No fluctuation in the voltage amplitude or current amplitude or frequency of the modulation signal transmitted and received by coil A is observed from coil B.

[0101] (2) A fluctuation in the voltage amplitude or current amplitude or frequency of the modulation signal transmitted and received by coil A is observed from coil B, and the observed level is equal to or less than a predetermined value (threshold), and the demodulation performance in the case of demodulating the modulation signal in the communication unit for coil B is not affected.

[0102] The definition of "interfering with each other" between two power transmission coils can be derived from the negative conditions of condition (1) and condition (2). When condition (3) is satisfied, it indicates that the two power transmission coils "interfere with each other".

[0103] (3) From coil B, fluctuations in the voltage amplitude or current amplitude, or fluctuations in the frequency, of the modulation signal transmitted and received by coil A are observed, and the observed level is equal to or greater than a predetermined value (threshold), and it affects the demodulation performance when the communication unit demodulates the modulation signal in coil B.

[0104] In a power transmission coil with electromagnetic coupling (i.e., the coupling coefficient is not zero), the first power transmission coil is referred to as coil A, and the second power transmission coil is referred to as coil B. When coil A satisfies condition (4) or (5) with respect to coil B, the two power transmission coils are considered "not interfering with each other".

[0105] (4) No voltage is induced in coil B that is caused by the high-frequency voltage or high-frequency current applied to coil A, or fluctuations or frequency fluctuations based on the high-frequency voltage or high-frequency current.

[0106] (5) The voltage level in coil B caused by the high-frequency voltage or high-frequency current applied to coil A, or fluctuations or frequency fluctuations based on the high-frequency voltage or high-frequency current, is equal to or less than a predetermined value (threshold).

[0107] When condition (6) is satisfied, it indicates that the two power transmission coils "interfere with each other".

[0108] (6) The voltage level in coil B caused by the high-frequency voltage or high-frequency current applied to coil A, or fluctuations or frequency fluctuations based on the high-frequency voltage or high-frequency current, is greater than a predetermined value (threshold).

[0109] When the two power transmission coils interfere with each other, the degree of interference varies according to the positional relationship between the two power transmission coils. In this embodiment, it is defined that the two power transmission coils do not interfere with each other when they are separated by a predetermined distance D (see 412 in (D) of Figure 4 ) or more.

[0110] For example, power transmission coil 400 and power transmission coil 411 do not interfere with each other. Power transmission coil 400 and power transmission coil 410 overlap with power transmission coil 401 and power transmission coil 410 respectively, and are not separated by a distance D or more.

[0111] Therefore, power transmission coil 400 and power transmission coil 410 interfere with each other, and power transmission coil 401 and power transmission coil 410 interfere with each other. The predetermined value (threshold) or distance D can be defined in the WPC standard.

[0112] The predetermined distance D for determining that the two power transmission coils do not interfere with each other can vary according to the definition of the distance between the power transmission coils. For example, when the distance between the power transmission coils is defined as the distance between the reference points (e.g., the center of gravity) of the power transmission coils and this distance is the shortest distance between the power transmission coils, the predetermined distance D can vary.

[0113] A plurality of power transmission coils can be arranged on a two-dimensional plane and can also be arranged in a three-dimensional space (e.g., in the height direction). According to the present embodiment, under any conditions, control described later can be performed based on the definition of a predetermined distance D without interference according to the same method as described above.

[0114] When a plurality of power transmission coils having the predetermined positional relationship described above transmit power simultaneously, the power transmission coils interfere with each other, and thus there is a possibility of affecting power transmission or control communication from each power transmission coil.

[0115] Therefore, when the power transmission device 100 according to the present embodiment selects a power transmission coil to be connected to the first power transmission circuit 203 and the second power transmission circuit 205, control is performed so that the power transmission coils do not interfere with each other. That is, the control unit 201 causes the power transmission coil selection unit 208 to perform control for selecting power transmission coils separated by a predetermined distance D or more from among a plurality of power transmission coils. Therefore, appropriate power transmission can be performed using a plurality of power transmission coils.

[0116] Alternatively, in addition to the method based on the determination of the predetermined distance D, there is also a method for selecting power transmission coils so that a plurality of power transmission coils do not interfere with each other. Specifically, the control unit 201 can identify other power transmission coils that interfere with the power transmission using the first power transmission coil.

[0117] The control unit 201 pre-identifies other coils (second power transmission coils) that interfere with the power transmission from the first power transmission coil or other coils (third power transmission coils) that do not interfere with the power transmission from the first power transmission coil, and stores identification information for indicating the identified power transmission coils in the memory 207. The control unit 201 selects a third power transmission coil that is determined not to interfere with the first power transmission coil when the first power transmission coil is selected, and performs control of power transmission.

[0118] Hereinafter, Figure 5 will be described with reference to Figure 5 is a schematic illustration of Figure 4 a configuration example of the NFC antennas 602a and 602b (see alternating long and short dashed lines) with respect to the plurality of power transmission coils illustrated in (C) of

[0119] An example will be described in which a first region and a second region corresponding to a first power transmission coil group and a second power transmission coil group are provided as regions where TX can perform power transmission using a plurality of power transmission coils. It is assumed that the first power transmission circuit 203 can be connected to the power transmission coils 400, 401, 402, 409, 410, and 411.

[0120] Therefore, the first power transmission circuit 203 can transmit power to the power receiving device 101 placed on the area 601a indicated by the dotted line. It is assumed that the second power transmission circuit 205 can be connected to the power transmission coils 403, 404, 405, 406, 407, and 408. Therefore, the second power transmission circuit 205 can transmit power to the power receiving device 101 placed on the area 601b indicated by the dotted line.

[0121] TX can transmit power to at most one RX in each of the areas 601a or 601b. That is, the power transmission device 100 can transmit power to a total of two power receiving devices simultaneously.

[0122] In the WPC standard, the areas corresponding to the areas 601a and 601b are called active areas. This area is defined as the part through which a sufficiently high magnetic flux can pass when TX supplies power to RX.

[0123] In the present embodiment, according to the definition in the WPC standard, the areas 601a and 601b where power can be transmitted are called power transmissible areas or power transmission areas. As indicated by the alternating long and short dotted lines, the NFC antennas are arranged in the power transmission coils and the power transmission areas.

[0124] In a top view, the NFC antenna 602a is arranged to surround the area 601a corresponding to the first power transmission area, and the NFC antenna 602b is arranged to surround the area 601b corresponding to the second power transmission area.

[0125] In the present embodiment, when viewed in a direction perpendicular to the plane including the power transmission coils, the areas 601a and 601b overlap each other. The NFC antennas 602a and 602b are arranged in areas corresponding to different power transmission coil groups except for the overlapping part of the power transmission areas.

[0126] Therefore, NFC tags independent of each power transmission area can be detected, and appropriate control can be performed when an NFC tag is detected. A control method associated with the detection of NFC tags will be described later.

[0127] The following will refer to Figure 6 and Figure 7 to describe the processing flow performed by TX. Figure 6 is a flowchart exemplifying an example of the processing flow performed by TX. This processing flow is realized, for example, by causing the control unit 201 of TX to execute a program read from the memory 207.

[0128] Part of the following processing flow can be implemented by hardware. For example, in such a case, the hardware can use a predetermined compiler to automatically generate a dedicated circuit using a gate array circuit such as an FPGA from a program for implementing the processing steps.

[0129] This processing flow is performed when the TX is powered on, when a start instruction for a non-contact charging application is input by the user of the TX, or when the TX is connected to a commercial power supply and supplied with power therefrom.

[0130] In Figure 6 S501, the TX performs NFC tag detection processing. This processing will be described later. Then, in S502, the TX performs the processing specified in the ping phase of the WPC standard and waits for an object to be placed on the TX.

[0131] In the ping phase, the TX repeatedly and intermittently transmits an AP based on the WPC standard and performs processing for detecting an object within the power transmission range. At this time, the TX can sequentially transmit the AP from each power transmission coil, but the present disclosure is not limited thereto. For example, the TX can simultaneously transmit the AP from multiple power transmission coil groups that do not interfere with each other.

[0132] In this case, the TX can sequentially transmit the AP for each combination of multiple power transmission coil groups that do not interfere with each other. When an object within the power transmission range has been detected, the TX transmits a DP based on the WPC standard. The DP can be transmitted using the power transmission coil that has detected the placed object by transmitting the AP. After S502, the processing flow proceeds to S503.

[0133] In S503, the TX determines whether an RX is placed thereon. This determination is made by determining whether a predetermined response to the DP has been received. When a response to the DP has been received, the TX determines that the detected object is an RX and the RX has been placed on the TX, and then the processing flow proceeds to S504. When a predetermined response to the DP has not been received, the TX determines that the detected object is not an RX and the RX has not been placed on the TX, and then the processing flow proceeds to S501.

[0134] In S504, the TX stores the identifier of the power transmission coil that has transmitted the DP in the memory. This identifier includes identification information for identifying the power transmission coil in the corresponding power transmission coil group. Here, the TX can use this identifier to identify the power transmission area based on the pre-stored configuration relationship between the power transmission coil and the power transmission area. Then, the processing flow proceeds to S505.

[0135] In S505, TX obtains identification information and capability information from RX through communication in the configuration phase specified in the WPC standard. The identification information of RX includes a manufacturer code and a basic device ID. The capability information of RX includes the following information.

[0136] · Information for identifying the corresponding version of the WPC standard

[0137] · The maximum power value, which is a value for identifying the maximum power that can be supplied from RX to a load

[0138] · Information for indicating whether a negotiation function based on the WPC standard is provided

[0139] This information is an example, and the identification information and capability information of RX can be replaced with other information or can additionally include other information. For example, the identification information can be any other identification information for identifying the identity of RX, such as a wireless power ID, etc. TX can use a method other than communication in the configuration phase based on the WPC standard to obtain the identification information and capability information of RX. Then, the processing flow proceeds to S506.

[0140] In S506, TX performs a negotiation process with RX through communication in the negotiation phase specified in the WPC standard and determines the GP value. Alternatively, in S506, a process for determining the GP value is performed using a method other than communication in the negotiation phase based on the WPC standard.

[0141] Alternatively, for example, in the case where information indicating that RX does not correspond to the negotiation phase has been obtained in S505, TX determines the GP value as a predetermined value without performing communication in the negotiation phase. The predetermined value is, for example, a value predefined in the WPC standard. Then, the processing flow proceeds to S507.

[0142] In S507, TX transitions to the calibration phase based on the WPC standard and calculates a reference value (threshold) of power loss based on the received power value of RX. In the calibration phase, TX derives the relationship between the received power value and the transmitted power value in a state where there is no foreign object.

[0143] TX uses the predetermined received power value obtained from RX based on the WPC standard to derive data indicating the power loss between TX and RX in a state where there is no foreign object. For example, the predetermined received power value includes the received power value in a light load state and the received power value in a connected load state.

[0144] In the foreign object detection process based on the power loss method, the power loss between the TX and the RX during power transmission is calculated based on the received power value of the RX relative to the transmitted power value according to the derived relationship. This power loss is compared with a threshold value, and when the power loss is equal to or greater than the threshold value, the TX determines that "a foreign object exists" or "the possibility of a foreign object existing is high". After S507, the processing flow proceeds to S508.

[0145] In S508, the TX starts power transmission to the RX. The power transmission is carried out through the processing in the power transfer stage. The present disclosure is not limited to this, and power transmission can be carried out using methods other than the WPC standard. Subsequently, in S509, the TX performs NFC tag detection processing, and the processing flow proceeds to S510.

[0146] The NFC tag detection processing can be periodically performed in parallel with the power transmission. In S510, the TX determines whether to stop the power transmission. When it is determined that the power transmission is to be stopped, the TX ends the processing flow and returns the processing flow to the initial state. When it is determined that the power transmission is not to be stopped, the processing flow proceeds to S508, and the TX continues the power transmission.

[0147] When an End Power Transfer (EPT) packet based on the WPC standard has been received from the RX, the TX ends the processing flow at any stage based on the WPC standard.

[0148] When an NFC tag has been detected as a result of the NFC tag detection processing in the RX, or when the battery is fully charged, an EPT packet is also sent from the RX to the TX, and thus the processing flow returns to the initial state. In this case, the processing flow returns to the NFC tag detection processing (S501), but it can also return to the processing in the ping stage (S502).

[0149] In Figure 6 the exemplified example, the NFC tag detection processing in the TX is performed after the processing in the ping stage (S502) and before the start of the power transmission processing (S508), but it can be performed in the processing at any stage.

[0150] The various processes for power transmission and the NFC tag detection processing can be carried out independently. For example, the NFC tag detection processing (S501) and the processing in the ping stage (S502) can be performed simultaneously. The TX can stay in the initial state until it is detected that the NFC tag has been removed.

[0151] The following will refer to Figure 7 to illustrate Figure 6 the processing of S501 and S509 in Figure 7It is a flowchart exemplifying an example of NFC tag detection processing. In S700, TX starts a processing loop and selects a target NFC antenna, and then in S701, TX detects the NFC tag.

[0152] The NFC tag detection processing can be performed for each tag type in the order of Type-A, Type-B, and Type-F using a reader / writer function based on the NFC standard, but the present disclosure is not limited thereto. For example, TX can sequentially detect NFC tags for each NFC tag type using the NFC antenna. After S701, the processing flow proceeds to S702.

[0153] In S702, TX determines whether an NFC tag has been detected using the selected NFC antenna. If an NFC tag has been detected (Yes in S702), the processing flow proceeds to S703. If no NFC tag has been detected (No in S702), the processing flow proceeds to S706.

[0154] In S703, TX determines whether power transmission to the power receiving device is in progress in the power transmission area where the NFC antenna used by the detected NFC tag is arranged. If it is determined that power transmission to the power receiving device is in progress in the power transmission area (Yes in S703), the processing flow proceeds to S704.

[0155] On the other hand, if it is determined that power transmission to the power receiving device is not in progress in the power transmission area (No in S703), the processing flow proceeds to S705. In S704, TX stops power transmission in the power transmission area.

[0156] For example, a process for stopping power transmission to the power receiving device using a predetermined power transmission coil is performed. In S705, TX stops transmitting the AP from the power transmission coil in the power transmission area. When the processing in S704 or S705 ends, the processing flow using the target NFC antenna ends, and the processing flow proceeds to S706.

[0157] In S706, TX performs the processing from S701 to S705 for all NFC antennas and determines whether the NFC tag detection processing has been completed. If it is determined that the NFC tag detection processing has been completed, TX ends this processing flow and returns the processing flow to the initial state.

[0158] If it is determined that the NFC tag detection processing has not been completed, the processing flow proceeds to S700, and TX selects the next target NFC antenna and continues this processing flow (performs the processing from S701 to S706).

[0159] The following will refer to Figure 8 to illustrate an example of the operation sequence of TX and RX.Figure 8 It is a sequence diagram that illustrates the operation sequence of TX in the left part and the operation sequence of RX in the right part. In the initial state, it is assumed that RX is not placed on TX.

[0160] TX sequentially transmits AP from each power transmission coil, and starts the power transmission process after detecting that RX has been placed on it. After that, it is assumed that an NFC tag is placed in a power transmission area other than the power transmission area where RX has been placed. In this case, the NFC tag is detected through the NFC tag detection process. Here, since the NFC antenna used by the NFC tag is arranged in a power transmission area other than the power transmission area where power transmission is in progress, TX does not stop power transmission.

[0161] In F801, TX starts the NFC tag detection process. This process corresponds to Figure 6 the process of S501 in Figure 7 TX sequentially detects the NFC tag in the NFC antennas 602a and 602b ( Figure 7 : S701). Since there is no NFC tag at this time point, the NFC tag is not detected in any NFC antenna (it is "No" in S702), and the NFC tag detection process ends.

[0162] Then, in F802, TX sequentially transmits AP from the power transmission coils 400, 401,... and waits until an object is placed on it. This corresponds to Figure 6 the process of S502 in Figure 6 In F803, RX is placed on TX. In F804, when TX has sequentially transmitted AP from the power transmission coils 400, 401,..., the AP changes. Therefore, in F805, TX detects that an object has been placed on the power transmission coil 401.

[0163] Then, in F806, TX transmits DP, and in F807, RX detects that RX has been placed on TX. On the other hand, TX detects that the placed object is RX based on the response to DP.

[0164] This corresponds to Figure 6 the case where the judgment result in Figure 6 S503 is affirmative ("Yes"), and the processing flow enters S504. In F808, TX stores the identifier of the power transmission coil 401 corresponding to the area where RX is placed in the memory 207 ( Figure 6 : S504). TX can judge that RX has been placed on the area 601a (power transmission area) based on the pre-stored configuration relationship between the power transmission coil and the power transmission area.

[0165] Subsequently, in F809, through the communication in the configuration stage, TX performs the process of obtaining the identification information and capability information from RX. This process corresponds toFigure 6 This corresponds to the process of S505 in []. In F810, TX and RX communicate during the negotiation phase.

[0166] This process corresponds to Figure 6 the process of S506 in []. For example, TX and RX negotiate through communication and determine the GP value to be 15 (watts). In F811, TX derives the relationship between the received power value and the transmitted power value in the state where there is no foreign object through communication during the calibration phase, and calculates the reference value of power loss. This process corresponds to Figure 6 the process of S507 in []. In F812, TX starts the process of transmitting power to RX. This process corresponds to Figure 6 the process of S508 in [].

[0167] After that, in F813, the NFC tag is placed on the area 601b (power transmission area) of TX. Area 601b is the area corresponding to the NFC antenna 602b. In F814, TX sequentially detects the NFC tag in the NFC antennas 602a and 602b. This process corresponds to Figure 6 the process of S509 in [].

[0168] In F815, the NFC tag in the NFC antenna 602b is detected. This corresponds to Figure 7 the case where the judgment result of S702 in [] is affirmative ("yes"). In F816, TX determines that the NFC tag is located in the area 601b corresponding to the NFC antenna 602b, and this area is different from the area 601a including the power transmission coil 401 that is transmitting power to RX.

[0169] This corresponds to Figure 7 the case where the judgment result of S703 in [] is negative ("no"), and TX continues to transmit power to RX. Then, in F817, TX stops transmitting the AP from the power transmission coil in the area 601b corresponding to the NFC antenna 602b where the NFC tag has been detected.

[0170] The power transmission device 100 according to the present embodiment has a structure in which a plurality of power transmission areas are provided and NFC antennas are provided for each power transmission area. After starting to transmit power to the power receiving device, the power transmission device 100 sequentially performs NFC tag detection processing on all the NFC antennas.

[0171] In the case of performing power transmission in the power transmission area corresponding to the area where the NFC antenna used for detecting the detected NFC tag is provided as a result of the NFC tag detection, control for restricting power transmission is performed, but the power transmission being performed in other power transmission areas is not restricted.

[0172] The control for restricting power transmission includes the control for stopping power transmission or the control for reducing the power transmission amount. Therefore, even when the NFC tag is placed on the power transmission device 100, power transmission can be continuously performed in a power transmission area where the possibility of breakage, heat generation, or interference with power transmission of the NFC tag is low.

[0173] Therefore, unnecessary stop or restriction of power transmission can be suppressed. When the power transmission area where the NFC antenna used for detecting the NFC tag is provided is a power transmission area other than the power transmission area where power transmission is currently being performed, control is performed to stop sending a ping (sending an AP) from the power transmission coil in this power transmission area.

[0174] Therefore, power transmission in a power transmission area where the possibility of breakage, heat generation, etc. of the NFC tag is high can be suppressed, and a wireless power transmission system with higher safety and higher efficiency can be realized.

[0175] In the present embodiment, a process for detecting the following device (electronic tag) is performed, and this device can communicate via a communication antenna (NFC antenna) provided in an area where power transmission using a power transmission coil can be performed. For example, when the power receiving device is placed on the power transmission device, the power transmission device stores information for indicating the area where the power receiving device has been detected using the power transmission coil.

[0176] When the antenna of the detected device is an antenna provided in the area corresponding to the stored information, the power transmission device performs control for restricting power transmission. This control is the control for stopping power transmission or the control for reducing the power transmission amount.

[0177] According to the present embodiment, a technique can be provided for appropriately detecting a predetermined device and enabling power transmission control in a power transmission device including a plurality of power transmission coils for performing wireless power transmission and a communication antenna.

[0178] [Modification Example of the First Embodiment]

[0179] The difference between the modification example and the first embodiment in which one NFC antenna is provided for each power transmission area of the TX lies in the configuration of the NFC antenna. For example, the modification example adopts a structure in which two or more than two NFC antennas are provided for each power transmission area.

[0180] There are a structure in which one NFC antenna is provided for each power transmission coil, and a structure in which one NFC antenna is provided for each group of a plurality of adjacent power transmission coils that are simultaneously used for power transmission to the power receiving device.

[0181] There is the following structure: For each area including the target power transmission coil and the power transmission coils that interfere with the target power transmission coil, two or more than two NFC antennas are provided. Alternatively, there is the following structure: In the area including the power transmission coils shared by each power transmission area, NFC antennas other than the NFC antennas provided in each power transmission area are provided.

[0182] Therefore, when the NFC tag is placed on the TX, the TX can determine whether power transmission is to be stopped for each smaller area or determine whether the power transmission power is to be reduced. Therefore, power transmission can be continuously performed with a higher probability.

[0183] [Second Embodiment]

[0184] The second embodiment of the present disclosure will be described below. In this embodiment, an example of a power transmission device including only the first power transmission circuit 203 and the first communication unit 204 as the power transmission circuit and the communication unit will be described.

[0185] The description of the details that are the same as those in the first embodiment in this embodiment will be omitted, and the differences will be mainly described. This omission of description also applies to the embodiments or modified examples to be described later.

[0186] The following will refer to Figure 9 to describe an example of the configuration of the power transmission coil and the NFC antenna according to this embodiment. It is assumed that the first power transmission circuit 203 according to this embodiment can be connected to all the power transmission coils 400 to 411.

[0187] When viewed in the direction perpendicular to the plane including the power transmission coil, Figure 9 the area 901 indicated by the dotted line in is the area including the power transmission coils 400 to 411 and corresponds to the power transmission area. Therefore, the first power transmission circuit 203 can perform power transmission to the power receiving device 101 placed in the area 901. The area 901 can be used to perform power transmission to at most one power receiving device. That is, the TX can perform power transmission to a total of one power receiving device.

[0188] In Figure 9 in the power transmission coil and the power transmission area, the NFC antennas are schematically indicated by alternating long and short dotted lines. The NFC antenna 902a is arranged to surround the power transmission ranges of the power transmission coils 400, 401, 402, 409, 410, and 411 in the area 901.

[0189] The NFC antenna 902b is arranged to surround the energizable ranges of the power transmission coils 403, 404, 405, 406, 407, and 408 in the area 901. Two or more NFC antennas may be arranged in the same power transmission area. Therefore, independent NFC tag detections can be performed in two or more ranges into which the power transmission area is divided, and in the case where an NFC tag is detected, the TX can perform appropriate control.

[0190] The following will refer to Figure 6 and Figure 10 to describe the processes of S501 and S509 performed by the TX in the present embodiment. The processes of S502 to S508 and S510 are the same as those in the first embodiment, and thus the description thereof will be omitted. Figure 10 is a flowchart exemplifying the flow of the NFC tag detection process. In S1000, the TX selects a target NFC antenna, and then the process flow proceeds to S1001.

[0191] In S1001, the TX determines whether the power transmission coil that is currently performing power transmission is included in the area corresponding to the NFC antenna. If it is determined that the power transmission coil that is currently performing power transmission is included in the area (Yes in S1001), the process flow proceeds to S1002. If it is determined that the power transmission coil that is currently performing power transmission is not included in the area (No in S1001), the process flow proceeds to S1004.

[0192] In S1002, the TX detects the NFC tag. Then, in S1003, the TX determines whether the NFC tag has been detected. If the NFC tag has been detected (Yes in S1003), the process flow proceeds to S1005. On the other hand, if the NFC tag has not been detected (No in S1003), the process flow proceeds to S1006.

[0193] In S1004, the TX stops transmitting the AP from the power transmission coil existing in the area corresponding to the target NFC antenna, and ends the process flow for the target NFC antenna. In S1005, the TX stops the power transmission process, and the TX ends the process flow for the target NFC antenna. After S1004 or S1005, the process flow proceeds to S1006.

[0194] In S1006, the TX performs the processes of S1001 to S1005 for all the NFC antennas, and determines whether the NFC tag detection process has been completed.

[0195] When TX determines that the NFC tag detection process has been completed, the processing flow ends and returns to the initial state. When it is determined that the NFC tag detection process is not completed, the processing flow proceeds to S1000, and TX selects the next target NFC antenna and continues the processing flow (performs the processing of S1001 to S1006).

[0196] The following will refer to Figure 11 to describe the operation sequences of TX and RX according to this embodiment. In the state where RX is not placed on TX, TX sequentially transmits AP from each power transmission coil.

[0197] When the placement of RX is detected, TX starts the power transmission process. After that, the NFC tag is placed in the area of the NFC antenna provided in the following area, which does not include the power transmission coil that is currently transmitting power to RX.

[0198] In this case, TX does not use this NFC antenna to detect the NFC tag, so the power transmission does not stop. Except for Figure 8 the reference numerals of the NFC antennas in, the operations of F1101 to F1112 are the same as those of F801 to F812, so their descriptions will be omitted.

[0199] In F1113, the NFC tag is placed in the range corresponding to NFC antenna 902b in TX. In F1114, since the power transmission coil 401 that is currently transmitting power exists in the area corresponding to NFC antenna 902a, TX uses only NFC antenna 902a to detect the NFC tag.

[0200] This process corresponds to Figure 10 the process of S1002 in. In F1115, TX continues the power transmission process to RX. On the other hand, TX stops transmitting AP from the power transmission coil in the area corresponding to NFC antenna 902b. This process corresponds to Figure 10 the process of S1004 in.

[0201] In this embodiment, a structure is adopted in which two or more NFC antennas having a smaller size than the power transmission area of the power transmission device are provided in one power transmission area of the power transmission device. After the power transmission to the power receiving device has started, the power transmission device uses only the NFC antenna corresponding to the area including the power transmission coil that is currently transmitting power to detect the NFC tag.

[0202] Therefore, even when the NFC tag is placed on the power transmission device, power transmission can be continuously performed in an area where the possibility of damage, heat generation, or interference with power transmission of the NFC tag is low. Therefore, unnecessary stops or restrictions of power transmission can be suppressed.

[0203] The power transmission device stops transmitting the AP from the power transmission coil outside the area of the specific NFC antenna corresponding to the area including the power transmission coil that is currently performing power transmission. Therefore, unnecessary power transmission can be suppressed, and a wireless power transmission system with higher safety and higher efficiency can be achieved.

[0204] [Modification Example of the Second Embodiment]

[0205] Regarding the multiple NFC antennas in the power transmission device (TX), there is a first method of arranging the NFC antennas to overlap each other and a second method of arranging the NFC antennas not to overlap each other. In the present disclosure, either the first method or the second method can be performed.

[0206] Alternatively, the first method can be performed in a part of the NFC antenna group, and the second method can be performed in other parts of the NFC antenna group. For example, the following structure can be adopted as a modification example.

[0207] · A structure in which one NFC antenna is provided for each power transmission coil

[0208] · A structure in which one NFC antenna is provided for each group of multiple adjacent power transmission coils that are simultaneously used for power transmission to the RX

[0209] · A structure in which one NFC antenna is provided for each area including the target power transmission coil and the power transmission coil that interferes with the target power transmission coil

[0210] According to the modification example, since it is possible to set whether to perform NFC tag detection for each smaller area, it is possible to suppress unnecessary stops or restrictions of power transmission with a higher probability.

[0211] [Other Modification Examples]

[0212] The modification examples of the first embodiment and the second embodiment will be described below. In the case where an NFC tag has been detected using the NFC antenna corresponding to the area including the power transmission coil that is currently performing power transmission, the TX according to the modification example does not stop the power transmission process but restricts the power transmission.

[0213] For example, the TX performs control or setting for changing the power transmission power value to a sufficiently small value (equal to or less than 5 watts). The TX determines whether to restrict the power transmission based on the result of the NFC tag detection and the detection result based on any state detection method other than the NFC tag detection (which includes the foreign object detection method).

[0214] Examples of the state detection method include a state detection method based on the quality factor (Q value, Q factor) associated with the power transmission coil, a state detection method based on the difference between the power transmission power value and the power reception power value, and a state detection method based on an index indicating the attenuation of the radio wave for power transmission.

[0215] Alternatively, the example may also include a state detection method based on an index indicating the electromagnetic coupling state between the power transmission coil for TX and the power reception coil for RX, a state detection method based on the temperature of TX or RX, and a state detection method based on the current flowing in the power transmission coil or the power reception coil.

[0216] The restrictions on power transmission include a decrease in the power transmission of TX, a decrease in the power reception of RX, or a change in the power transmission value or the power reception value within a predetermined range based on the negotiation between TX and RX.

[0217] In the first embodiment and the second embodiment, TX sequentially performs NFC tag detection processing for each NFC antenna. In a modified example, a plurality of NFC antennas that can be controlled simultaneously are used to perform NFC tag detection processing in parallel.

[0218] Therefore, in the case where the NFC tag is placed on TX, the NFC tag can be detected in a shorter period of time, and a wireless power transmission system with higher security and higher efficiency can be realized.

[0219] In the first embodiment and the second embodiment, TX periodically performs NFC tag detection processing. In a modified example, TX performs NFC tag detection processing using a trigger different from the trigger in the embodiment.

[0220] For example, TX monitors the change in the impedance value in the NFC antenna, and performs NFC tag detection processing when the change is greater than a threshold value. Therefore, unnecessary tag detection processing can be suppressed in a situation where the possibility of placing an NFC tag is low, and a wireless power transmission system with higher security and higher efficiency can be realized.

[0221] In the first embodiment and the second embodiment, when no NFC tag is detected as a result of the NFC tag detection processing, TX continues to perform power transmission to RX. In a modified example, when no NFC tag is detected, TX performs any of the above state detection methods (including the foreign object detection method).

[0222] For example, TX determines whether there is a state abnormality (whether there is a foreign object) or the possibility thereof (the probability of the presence of a foreign object), and determines whether to continue power transmission to RX. Foreign objects that are not detected in the NFC tag detection processing can be detected in a shorter period of time, and a wireless power transmission system with higher security and higher efficiency can be realized.

[0223] In the embodiment, wireless communication specified in the NFC standard is used to detect the electronic tag. The present disclosure is not limited to this example, and non-contact / short-range radio communication such as radio frequency identifier (RFID) etc. can be used.

[0224] In this case, an NFC tag can be replaced with an IC tag, an IC card, an RF tag, an RF card, or the like. An electronic tag is an example of a device that can communicate with a TX via a predetermined antenna, and embodiments of the present disclosure can be applied to various electronic devices that can wirelessly communicate with a TX.

[0225] [Other Embodiments]

[0226] The present disclosure can also be implemented by the following process: providing a program for implementing one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device reading and executing the program. The present disclosure can also be implemented by a circuit (e.g., an ASIC) for implementing one or more functions.

[0227] The present disclosure includes, for example, using at least one processor or circuit to implement the functions of the above-described embodiments. Distributed processing can be performed using two or more processors.

[0228] [Cross - Reference to Related Applications]

[0229] Claims the priority of Japanese Patent Application No. 2022 - 200184 filed on December 15, 2022. The content of the Japanese patent application is incorporated herein by reference.

Claims

1. A power transmission device, comprising: A power transmission component configured to perform power transmission using a plurality of power transmission coils; A first detection component configured to detect a power receiving device using the power transmission coils; A communication antenna disposed in an area where power transmission can be performed using the power transmission coils; A second detection component configured to detect a device capable of communication via the antenna; And A control component configured to control power transmission via the power transmission component using the power transmission coils used to detect the power receiving device, wherein, when power transmission to the power receiving device is being performed using the power transmission coils in an area where the antenna used by the second detection component to detect the device is disposed, the control component performs control to limit power transmission from the power transmission component.

2. The power transmission device according to claim 1, further comprising a storage component configured to store information indicating an area where the first detection component has detected the power receiving device. Among them, When the antenna used by the second detection component to detect the device is an antenna disposed in an area corresponding to the information stored in the storage component, the control component performs control to limit power transmission via the power transmission component.

3. The power transmission device according to claim 1, wherein, When viewed in a direction perpendicular to the plane including the power transmission coils, a first area where the antenna used by the second detection component to detect the device is disposed is an area including a second area where power transmission can be performed using the power transmission coils, and wherein, when power transmission from the power transmission coils to the power receiving device is not being performed in the second area, the control component performs control to stop detection by the first detection component using the power transmission coils in the second area.

4. The power transmission device according to claim 2, wherein, The control component does not perform processing for detecting the device using the antenna disposed in the area corresponding to the information stored in the storage component by the second detection component.

5. The power transmission device according to claim 1, further comprising a plurality of antennas, and Among them, When viewed in a direction perpendicular to the plane including the power transmission coils, each of the plurality of antennas is disposed in an area including an area where power transmission can be performed using a power transmission coil group including a plurality of power transmission coils.

6. The power transmission device according to claim 5, further comprising a first power transmission coil group and a second power transmission coil group, each of the first power transmission coil group and the second power transmission coil group including a plurality of power transmission coils. Among them, When viewed in a direction perpendicular to the plane including the power transmission coils, the first power transmission coil group and the second power transmission coil group overlap each other, a first antenna among the plurality of antennas is disposed in an area including an area corresponding to the first power transmission coil group, and a second antenna is disposed in an area including an area corresponding to the second power transmission coil group.

7. The power transmission device according to claim 1, further comprising: A power transmission coil group including a plurality of power transmission coils; And A plurality of antennas Among them, when viewed in a direction perpendicular to the plane including the power transmission coil, the plurality of power transmission coils overlap each other, and each of the plurality of antennas is arranged in a region including a part of the region where power transmission can be performed using the power transmission coil group.

8. The power transmission device according to claim 1, further comprising a plurality of antennas, and Among them, The second detection component uses the plurality of antennas to simultaneously detect the device.

9. The power transmission device according to claim 3, wherein, When power transmission to the power receiving device using the power transmission coil is not being performed in the second region, the control component performs control so that the power transmission component continues the process of power transmission using the power transmission coil in a region different from the second region.

10. The power transmission device according to claim 1, wherein, The device is an electronic tag based on a predetermined standard, and Among them, the second detection component uses the reader / writer function in the standard to detect the electronic tag.

11. A control method performed by a power transmission device, the power transmission device including a plurality of power transmission coils, the control method including: A step of using the power transmission coil to perform power transmission; A first detection step of using the power transmission coil to detect a power receiving device; A second detection step of detecting a device capable of communication via a communication antenna arranged in a region where power transmission can be performed using the power transmission coil; And A restriction step of restricting power transmission via the power transmission coil when power transmission to the power receiving device via the power transmission coil is being performed in a region where the antenna used to detect the device in the second detection step is arranged.

12. A storage medium for storing a computer program, the computer program causing a computer of a power transmission device including a plurality of power transmission coils to perform a method, the method including: A step of using the power transmission coil to perform power transmission; A first detection step of using the power transmission coil to detect a power receiving device; A second detection step of detecting a device capable of communication via a communication antenna arranged in a region where power transmission can be performed using the power transmission coil; And A restriction step of restricting power transmission via the power transmission coil when power transmission to the power receiving device via the power transmission coil is being performed in a region where the antenna used to detect the device in the second detection step is arranged.

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