Power transmission device, communication method, and storage medium

Abstract

The present invention relates to a power transmission device, a communication method, and a storage medium. The power transmission device includes: a power transmission unit that wirelessly transmits power; a detection unit that performs a detection process by polling NFC, the detection process detecting an NFC tag for performing near-field communication NFC; a reception unit that receives a request for information about the power transmission device from a power reception device; and a transmission unit that, after receiving the request, transmits a signal to the power reception device, the signal including information indicating whether the detection process has been performed by the power transmission device and information indicating the result of the detection process.

Description

[0001] This application is a divisional application of the patent application with the filing date of February 28, 2020, application number 202080031104.2 (international application number PCT / JP2020 / 008408), and invention title "Power receiving device, power transmitting device, method, and wireless power transmission system". Technical Field

[0002] The present invention relates to a power receiving device, a power transmitting device, a control method thereof, and a wireless power transmission system. Background Art

[0003] The technical development of wireless power transmission systems has been widely carried out. As a standard for power transmitting devices and power receiving devices that form a wireless power transmission system, a standard defined by WPC (hereinafter referred to as the WPC standard) is provided. WPC is a standardization organization for non-contact charging standards. Note that WPC is an abbreviation for Wireless Power Consortium. On the other hand, as a standard for short-range wireless communication, the NFC standard is known. NFC is an abbreviation for Near Field Communication.

[0004] In the NFC standard, sending a carrier wave and modulating the carrier wave to send a message for detecting a communication partner device is called polling. Polling is sent by a device having a reader / writer function conforming to the NFC standard. A device having the following function is called an NFC tag: receiving the polling sent by the reader / writer and responding to the polling by load modulating the carrier wave sent by the reader / writer.

[0005] Patent Document 1 describes an arrangement in which a power receiving device conforming to the WPC standard and having an NFC tag function sends a response to polling performed by a power transmitting device conforming to the WPC standard and having a reader / writer function conforming to the NFC standard. To avoid NFC communication failures caused by interference between wireless power and NFC communication, Patent Document 1 restricts wireless power when the power transmitting device performs NFC communication (polling and response).

[0006] Citation List

[0007] Patent Document

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2014-093818 Summary of the Invention

[0009] Technical Problem

[0010] When wireless power transmission is performed while an NFC tag is close to a power transmission device, the NFC tag may be damaged by the transmitted power output from the power transmission device. If the power transmission device has the reader / writer function in Patent Document 1, damage to the NFC tag can be avoided when the power transmission device detects the presence of the NFC tag by polling and limits the power to be transmitted. Similarly, if the power receiving device has the reader / writer function, even if the power transmission device does not have the reader / writer function, wireless power transmission can be appropriately controlled according to the presence or absence of the NFC tag. However, no cooperative operation between the power receiving device and the power transmission device has been proposed to avoid damaging the NFC tag when the reader / writer function is implemented in the power receiving device.

[0011] The present invention provides the following technology, which is related to the cooperative operation between a power receiving device and a power transmission device in a wireless power transmission system when a reader / writer is implemented in the power receiving device.

[0012] Solution to the problem

[0013] A power receiving device according to an aspect of the present invention has the following arrangement. That is, there is provided a power receiving device for wirelessly receiving power from a power transmission device, the power receiving device including:

[0014] a communication unit configured to communicate with the power transmission device;

[0015] a detection unit configured to detect another device capable of performing short-range wireless communication;

[0016] a determination unit configured to determine whether the power transmission device has a detection function for detecting another device capable of performing short-range wireless communication; and

[0017] a control unit configured to control whether to perform the detection by the detection unit,

[0018] wherein, if the determination unit determines that the power transmission device does not have the detection function, the control unit controls to: perform the detection by the detection unit when the detection state of the other device by the detection unit is not determined, and not perform the detection by the detection unit when the detection state of the detection unit is determined, and the communication unit transmits a signal corresponding to the detection result of the detection unit to the power transmission device.

[0019] Advantageous effects of the invention

[0020] According to the present invention, a preferred cooperative operation between the power receiving device and the power transmission device in a wireless power transmission system is achieved when a reader / writer is implemented in the power receiving device.

[0021] Other features and advantages of the present invention will become apparent from the following description in conjunction with the accompanying drawings. Note that the same reference numerals denote the same or similar components throughout the drawings. Description of the Drawings

[0022] The drawings included in and forming a part of this specification illustrate embodiments of the present invention and, together with the description, are used to explain the principles of the present invention.

[0023] Figure 1A Figure 1A is a diagram showing an example of the system configuration according to an embodiment;

[0024] Figure 1B Figure 1B is a block diagram showing an example of the arrangement of the power receiving device according to an embodiment;

[0025] Figure 2 Figure 2 is a block diagram showing an example of the arrangement of the power transmitting device according to an embodiment;

[0026] Figure 3 Figure 3 is a flowchart showing the operations performed by the control unit of the power receiving device;

[0027] Figure 4 Figure 4 is a conceptual diagram of the communication regarding NFC between the first control unit and the second control unit;

[0028] Figure 5 Figure 5 is a flowchart showing the operations performed by the control unit of the power transmitting device; and

[0029] Figure 6 Figure 6 is a sequence diagram of the operation of the wireless charging system according to an embodiment. Detailed Description of the Embodiments

[0030] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that the following embodiments are not intended to limit the scope of the invention. In the embodiments, multiple features are described, but the invention does not require all of these features, and multiple such features can be appropriately combined. In addition, in the drawings, the same reference numerals are given to the same or similar configurations, and their redundant descriptions are omitted.

[0031] Figure 1A ​​​​​​​​​​​​​​It is a diagram showing an example of the configuration of a wireless power transmission system according to an embodiment. A power receiving device 102 compliant with the WPC (Wireless Power Consortium) standard is placed on a power transmitting device 100 compliant with the WPC standard. The power receiving device 102 receives the power wirelessly transmitted from the power transmitting device 100. The power transmitting device 100 and the power receiving device 102 of the present embodiment comply with the WPC standard and each have functions defined in WPC standard v1.2.3. The power transmitting device 100 can detect the power receiving device 102. The power receiving device 102 can supply the power received from the power transmitting device 100 to a load (e.g., a rechargeable battery) connected to itself. When an NFC (Near Field Communication) tag 101 approaches the power transmitting device 100, it is affected by the wireless power transmitted by the power transmitting device 100.

[0032] Figure 1B It is a block diagram showing an example of the arrangement of the power receiving device 102 according to an embodiment. The power receiving device 102 implements an NFC reader / writer. This embodiment assumes that the power transmitting device 100 and the power receiving device 102 comply with the WPC standard. However, the present invention is not limited thereto, and these devices may comply with another wireless power transmission standard.

[0033] The first control unit 201 includes, for example, one or more processors and controls the entire power receiving device 102. An example of a processor is a CPU (Central Processing Unit) that implements various functions by executing a predetermined program. The power receiving unit 203 receives the wireless power transmitted by the power transmitting device 100 via a power receiving coil 205. The power receiving unit 203 converts the AC voltage / AC current received by the power receiving coil 205 into a DC voltage / DC current and supplies it to the charging unit 209. In addition, the DC voltage / DC current output from the power receiving unit 203 is also used as the power for driving the first control unit 201.

[0034] The first communication unit 204 performs wireless communication with the power transmitting device 100 under the control of the first control unit 201. In the present embodiment, the first communication unit 204 performs load modulation to superimpose a signal on the electromagnetic wave of the wireless power received via the power receiving coil 205 and transmits the signal to the power transmitting device 100. The load modulation can be frequency modulation or amplitude modulation. The memory 208 stores the calculation results of the first control unit 201. Note that the first communication unit 204 can perform communication compliant with the low power consumption (hereinafter referred to as “BLE”) standard. In addition, the first communication unit 204 can be compliant with the IEEE802.11 standard series such as or a communication method of a wireless LAN (e.g., ) to perform communication.

[0035] NFC 202, which serves as the second communication unit and is an example of short - range wireless communication, is an NFC reader / writer and is controlled by a program implemented in the second control unit 210. NFC 202 is formed of an NFC coil and a circuit compliant with the NFC standard. The second control unit 210 for controlling NFC 202 has a function of transmitting to / receiving from the first control unit 201 information related to the operation of NFC 202. NFC 202 can detect another device (e.g., an NFC tag) having a function capable of communicating with NFC 202. In addition, the second control unit 210 and NFC 202 operate by receiving power supply from the battery 207.

[0036] The UI 206 is a user interface of the power receiving device 102 and has a function of notifying various information to the user. In this embodiment, it is assumed that the UI 206 is controlled by the second control unit 210, but the present invention is not limited thereto. For example, the UI 206 can be controlled by the first control unit 201 or another control unit (not shown). The charging unit 209 supplies the power supplied from the power receiving unit 203 to the battery 207, thereby controlling the charging of the battery 207.

[0037] Please note that Figure 1B The first communication unit 204, the power receiving unit 203, and the first control unit 201 are shown as separate units, but some or all of these units can be encapsulated and implemented as one component. In addition, NFC 202 and the second control unit 210 are shown as separate units, but they can be encapsulated and implemented as one component. That is, the above - mentioned respective constituent elements are not limited in terms of the form of implementation, etc., as long as they can achieve the functions (described later).

[0038] Figure 2 is a block diagram showing an example of the arrangement of the power transmitting device 100 according to an embodiment. Referring to Figure 2 , the third control unit 301 includes one or more processors and controls the entire power transmitting device 100. Examples of the processor are CPUs that implement various functions by executing programs. The power supply unit 307 uses power from a battery or an external power source (e.g., commercial power) to supply power used for operation by at least the third control unit 301, the fourth control unit 309, and the power transmitting unit 303.

[0039] The power transmission unit 303 generates an AC voltage / AC current to be transmitted to the power receiving device 102 via the power transmission coil 305. More specifically, the power transmission unit 303 converts the DC voltage supplied from the power supply unit 307 into an AC voltage by using a switching circuit having a half-bridge or full-bridge structure of FETs (field effect transistors). The power transmission unit 303 includes a gate driver that controls the ON / OFF of the FETs. The power transmission unit 303 has the ability to supply 15 watts of power to the charging unit 209 of the power receiving device 102 compliant with the WPC standard.

[0040] The third communication unit 304 performs wireless communication with the power receiving device 102 under the control of the third control unit 301. In the present embodiment, the third communication unit 304 performs load modulation to superimpose a signal on the electromagnetic wave of the power wirelessly transmitted via the power transmission coil 305 and transmits the signal to the power receiving device 102. Note that the third communication unit 304 can perform communication compliant with the low power consumption (hereinafter referred to as “BLE”) standard. In addition, the third communication unit 304 can communicate by a communication method compliant with the IEEE802.11 standard series such as or wireless LAN (e.g., ).

[0041] The memory 308 stores the calculation results of the third control unit 301. The NFC 302 is an NFC reader / writer. The fourth control unit 309 controls the NFC 302. The fourth control unit 309 has a function of transmitting to / receiving from the second control unit 210 of the power receiving device 102 information related to the operation of the NFC 302. The UI 306 is a user interface of the power transmission device 100 and has a function of notifying various information to the user.

[0042] The operation of the wireless power transmission system having the above arrangement according to the present embodiment will be described below.

[0043] As described above, each of the power transmission device 100 and the power receiving device 102 has an NFC reader / writer function. If the NFC tag 101 is present near the power transmission device 100 and the power receiving device 102, the NFC tag 101 is affected by the wireless power transmission based on the WPC standard. Therefore, the power transmission device 100 and the power receiving device 102 perform cooperative operations so that the NFC tag 101 is not affected by the wireless power transmission. More specifically, the power transmission device 100 and the power receiving device 102 detect the presence of the NFC tag 101 by polling before wireless power transmission / reception and decide whether wireless power transmission can be performed based on the detection result.

[0044] In addition, if the polling of the reader / writer functions of the power transmission device 100 and the power reception device 102 is performed simultaneously, the polling interferes with each other. Therefore, the NFC tag 101 may not be able to receive the polling correctly and may not respond to the polling. In this case, even if the NFC tag 101 is present nearby, the power transmission device 100 and the power reception device 102 may not be able to detect it. As a result, even if the NFC tag 101 is present nearby, wireless power transmission between the power transmission device 100 and the power reception device 102 may start, thereby damaging the NFC tag 101. To solve this problem, it is important to detect the NFC tag 101 through cooperative operations between the power transmission device 100 and the power reception device 102. More specifically, the power transmission device 100 and the power reception device 102 perform the following processing. Note that the reader / writer is an example of a detection function for detecting the NFC tag.

[0045] [1] If the power transmission device does not include a reader / writer, the power reception device 102 operates its reader / writer to detect the NFC tag.

[0046] [2] If the power transmission device includes a reader / writer but has not yet performed the polling process, the power reception device 102 performs the polling process.

[0047] [3] If the power transmission device includes a reader / writer and has already performed the polling process, the power reception device 102 does not perform the polling process.

[0048] The cooperative operations of [1] to [3] above can solve the problem that the polling of the power transmission device 100 and the polling of the power reception device 102 interfere with each other and the NFC tag 101 cannot be detected correctly. The respective cooperative operations of [1] to [3] will be described below with reference to Figure 3 the flowcharts shown.

[0049] Figure 3 is a flowchart showing the processing performed by the first control unit 201 of the power reception device 102. Figure 5 is a flowchart showing the processing performed by the third control unit 301 of the power transmission device 100. The operations of the power reception device 102 and the power transmission device 100 according to the present embodiment will be described with reference to Figure 3 and Figure 5 the flowcharts. Note that Figure 5 Steps S502 to S512 ofFigure 2 in which the power transmission device 100 includes neither the NFC 302 nor the fourth control unit 309). In this case, the power transmission device 100 transmits, in step S502, a notification that it does not have a reader / writer function and does not have a function of performing the Figure 5 processing in steps S503 to S505).

[0050] The power transmission device 100 transmits a digital ping defined by the WPC standard (step S501). When the power receiving device 102 receives the digital ping from the power transmission device 100, the first control unit 201 is activated (step S401). At this time, the power magnitude of the digital ping is at least sufficient to activate the first control unit 201 of the power receiving device 102 present near the power transmission coil 305.

[0051] The first control unit 201 activated by the digital ping controls the first communication unit 204 to transmit a signal strength packet indicating the magnitude of the received digital ping to the power transmission device 100. The signal strength packet is a packet defined by the WPC standard and is transmitted to the power transmission device 100 via the power receiving coil 205.

[0052] Next, the first control unit 201 controls the first communication unit 204 to transmit an ID packet including its own identification information to the power transmission device 100. The ID packet is a packet defined by the WPC standard and includes the version information of the WPC standard that the first control unit 201 conforms to and the individual identification number of the first control unit 201. In addition, the first control unit 201 controls the first communication unit 204 to transmit a configuration packet to the power transmission device 100. The configuration packet is a packet defined by the WPC standard and includes information about the functions supported by the first control unit 201.

[0053] In response to the configuration packet, the first control unit 201 receives an ACK from the third control unit 301 of the power transmission device 100. The ACK is a signal defined by the WPC standard and indicates that the power transmission device 100 has correctly received the information included in the configuration packet and confirmed the content of the information. When receiving the ACK from the power transmission device 100, the first control unit 201 transitions to the negotiation phase. When transmitting the ACK, the third control unit 301 transitions to the negotiation phase. In the negotiation phase, negotiation regarding wireless power transmission is performed between the power receiving device 102 and the power transmission device 100.

[0054] Next, in the negotiation phase, the first control unit 201 asks the power transmission device 100 whether the power transmission device 100 has a reader / writer function (detection function) for detecting NFC tags (step S402). For this inquiry, a general request packet (capability) among the general request packets defined by the WPC standard and representing an inquiry to the power transmission device can be used. The general request packet (capability) is a packet for inquiring about the capability information of the power transmission device. Note that the packet that can be used to inquire about the presence or absence of the NFC tag detection function is not limited to the above packet. For example, among the packets defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined can be defined as an inquiry about the presence or absence of the NFC tag detection function and used. Alternatively, among the specific requests and general requests defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined can be used.

[0055] In response to the above inquiry from the power receiving device 102, the third control unit 301 of the power transmission device 100 sends a notification of a packet indicating whether the power transmission device 100 has a reader / writer function (step S502). In this example, the power transmission device 100 sends a notification that it does not have a reader / writer function. The first control unit 201 that performs the above determination process in step S402 is an example of a component that communicates with the power transmission device 100 using the first communication unit 204 and determines whether the power transmission device 100 has a function of detecting NFC tags (another device). Note that in this embodiment, as will be described later with reference to Figure 6 the general request packet (capability) and the capability packet are used for the above-mentioned inquiry and response regarding the function. If the first control unit 201 receives a response from the power transmission device 100 indicating that the power transmission device 100 does not have an NFC tag detection function (no NFC reader / writer) (step S402 is "no"), the process proceeds to step S403. If the first control unit 201 thus determines that the power transmission device 100 does not have an NFC tag detection function, the first control unit 201 asks the second control unit 210 whether NFC tag detection has been performed and about the result of the detection process (step S403). This inquiry will be hereinafter referred to as status confirmation.

[0056] Now, reference will be made to Figure 4 the response to the above status confirmation from the second control unit 210. Figure 4This is a table showing the communication content related to the status confirmation regarding the detection of the NFC tag between the first control unit 201 and the second control unit 210. The response to the status confirmation inquiry is formed by 2 bits. Bit 0 indicates whether polling has been performed. In this example, polling is the polling performed via NFC 202 and an NFC coil (not shown) based on a polling instruction from the first control unit 201. If bit 0 is "0", this indicates that the second control unit 210 has not performed polling based on the instruction from the first control unit 201. If bit 0 is "1", this indicates that the second control unit 210 has performed polling in response to the instruction from the first control unit 201. In addition, bit 1 indicates whether the NFC tag has been detected as a result of performing the above polling. If bit 1 is "0", this indicates that the second control unit 210 has not detected the NFC tag. If bit 1 is "1", this indicates that the second control unit 210 has detected the NFC tag.

[0057] Here, it is assumed that, as a response to the status confirmation, the first control unit 201 is notified of "00", which means that the second control unit 210 has not performed the polling process and has not detected the NFC tag, that is, the detection status of the NFC tag has not been confirmed. Note that if bit 0 is "0", polling has not been performed, so regardless of the status of bit 1, it can be determined that the detection status of the NFC tag has not been confirmed. When the first control unit 201 receives the response "00" to the status confirmation inquiry indicating that polling has not been performed from the second control unit 210, the first control unit 201 instructs the second control unit 210 to perform polling ("Yes" in step S404, "No" in steps S405 and S406). As described above, if it is determined that the power transmission device 100 does not have the function of detecting the NFC tag and the detection status of the NFC tag detected by NFC 202 is not determined, the first control unit 201 uses the second control unit 210 and NFC 202 to perform NFC tag detection.

[0058] At this time, when using NFC 202 to perform NFC tag detection, the first control unit 201 restricts the power transmission of the power transmission device 100 for a predetermined time by sending a communication request using the first communication unit 204. For example, the first control unit 201 temporarily suspends the sending of digital pings so that polling is not affected by digital pings, and after the predetermined time, sends data for requesting the restart of power transmission to the power transmission device 100 (step S407). For the temporary suspension request of power transmission, an End Power Transmission (EPT) packet defined by the WPC standard for requesting the stop of power transmission can be used. The first control unit 201 sends an EPT to the power transmission device 100 with an information element added indicating the temporary suspension of power transmission.

[0059] Note that, in this embodiment, the EPT packet including the information element indicating a temporary pause is represented as EPT (pause). Further, the predetermined time from the pause power transmission to the restart power transmission is at least longer than the time taken to send a poll using NFC 202 and receive a response thereto after the second control unit 210 receives a poll instruction from the first control unit 201.

[0060] Upon receiving EPT (pause), the power transmission device 100 temporarily stops sending digital pings (steps S508 and S509). This can prevent the influence of the digital pings on the poll of the power transmission device 100 and its response. Note that the temporary pause period (the above-mentioned predetermined time) can be preset in the power transmission device 100, or information for specifying the predetermined time can be included in the EPT (pause). If the information for specifying the predetermined time is included in the EPT (pause), the power transmission device 100 stops sending digital pings for the predetermined time specified by the EPT (pause). When the stop of digital pings is detected, the second control unit 210 causes NFC 202 to start sending a poll, thereby performing a polling process (step S408). The second control unit 210 stores the NFC tag detection result obtained through the polling process. Thereafter, if the power receiving device 102 receives the sending of digital pings from the power transmission device 100, it sends a signal to the power transmission device 100 according to the NFC tag detection result. More specifically, if the power receiving device 102 detects the NFC tag, it sends an EPT (NFC) packet obtained by storing the information element indicating that the NFC tag has been detected in the EPT packet to the power transmission device 100. Further, if the NFC tag is not detected, a signal strength packet or the like is sent.

[0061] Note that, in the above example, the power transmission of the power transmission device 100 is stopped when the NFC tag 101 is detected (polling is performed), but the present invention is not limited thereto. For example, it may be requested to limit the maximum value of the transmitted power to a predetermined value or less. In this case, the maximum value of the transmitted power is determined within a range not affecting the polling. Further, in this request, the power receiving device 102 may notify the power transmission device of the maximum value of the transmitted power.

[0062] Assume that as a result of polling, a response is received from the NFC tag 101 and the second control unit 210 detects the NFC tag. The second control unit 210 stores information indicating the detection status (NFC-related information). If the above-mentioned predetermined time has elapsed, the first control unit 201 is reactivated by the digital ping received again from the power transmission device 100 (step S401), and the above-mentioned steps S402 to S405 are executed. In step S405, the first control unit 201 performs a status confirmation related to the detection of the NFC tag with the second control unit 210, and determines whether the second control unit 210 has performed polling (the detection status of the NFC tag has been determined). Since the second control unit 210 has detected the NFC tag in response to the polling instruction of the first control unit 201, the second control unit 210 sends "11" to the first control unit 201, where "11" indicates that polling has been performed (bit 0 is "1") and the NFC tag has been detected (bit 1 is "1").

[0063] Since the second control unit 210 notifies the first control unit 201 that the NFC tag has been detected, the first control unit 201 requests the power transmission device 100 to restrict the transmission of the digital ping (steps S404, S405, and S409 and "Yes" in step S410). More specifically, the power receiving device 102 sends an EPT(NFC) packet to the power transmission device 100, which is obtained by storing an information element indicating that the NFC tag has been detected in the EPT packet. Upon receiving the EPT(NFC), the third control unit 301 of the power transmission device 100 stops the wireless power transmission (steps S510 and S511). Note that in the above example, the EPT(NFC) packet is used to stop the power transmission of the power transmission device 100, but the present invention is not limited thereto. For example, it may be requested to limit the maximum value of the transmitted power to a predetermined value or less. In this case, the maximum value of the power to be transmitted is determined within the range that does not damage the NFC tag. In addition, in this request, the power receiving device 102 may notify the power transmission device of the maximum value of the transmitted power.

[0064] On the other hand, if a response to the status confirmation is not received from the second control unit 210 (No in step S404), the first control unit 201 sends an EPT to the power transmission device 100 (step S411). When the EPT is received, the power transmission device 100 stops wireless power transmission. The state where the first control unit 201 cannot receive a response to the status confirmation from the second control unit 210 may occur in the following situations: for example, when the second control unit 210 stops its operation due to no remaining battery power. In this case, the power receiving device 102 cannot confirm the presence or absence of the NFC tag. Therefore, in order to more reliably avoid the possibility that the NFC tag exists near the power transmission device 100 and is damaged by power transmission, the first control unit 201 stops the power transmission of the power transmission device 100. Note that regarding step S411, instead of completely stopping the power transmission, the power transmission device 100 may be requested to limit the maximum value of the transmitted power to a predetermined value or less. This allows less power to be transmitted to such an extent that the NFC tag is not damaged, and thus the battery 207 can be charged with this power.

[0065] Since the power receiving device 102 operates as described above, if the power transmission device 100 does not have a reader / writer, the power receiving device 102 can detect the NFC tag by operating its reader / writer. In addition, in the present embodiment, NFC-related information indicating whether the NFC tag detection has been performed and its result is stored in the second control unit 210 powered by the battery 207. Therefore, the preferred control is implemented as follows.

[0066] If the NFC-related information is stored in the volatile memory (not shown) of the first control unit 201, when the digital ping stops due to the transmission of the EPT (pause), the first control unit 201 and the volatile memory are unnecessarily reset. As a result, in the status confirmation (step S403) after reactivation, it should be determined based on "11" indicating that the polling process has been performed and the NFC tag has been detected, but it is determined based on "00" as the reset state. This problem is solved by storing the NFC-related information in the second control unit 210 powered by the battery 207 and not reset by the stop of the digital ping. Note that when the first control unit 201 refers to the stored NFC-related information (the detection state of the NFC tag by the reader / writer), the second control unit 210 deletes the NFC-related information. This will be described later with reference to Figure 6 described below.

[0067] Even if the NFC-related information is stored in another component that is not reset due to the stop of the digital ping, the same effect can be obtained. For example, the NFC-related information can be stored in a non-volatile memory (not shown). The non-volatile memory can be implemented in the first control unit 201 or connected to the first control unit 201. Alternatively, the power transmission device 100 can store the NFC-related information. This is because the internal circuit of the power transmission device 100 is powered by the power supply unit 307, so it is not reset even if the digital ping stops. In this case, during the negotiation phase, the power transmission device 100 can notify the power reception device 102 of the NFC-related information.

[0068] Next, [2] in the above three cooperative operations will be described with reference to Figure 3 and Figure 5 's flowchart. This operation is the operation when the power transmission device 100 has the function of detecting the NFC tag but does not perform the polling process.

[0069] If, in response to the general request packet (capability), the first control unit 201 receives a response indicating that the power transmission device 100 includes a reader / writer ("Yes" in step S402), the process proceeds to step S412. If the power transmission device 100 includes a reader / writer, the power reception device 102 can be controlled not to perform polling, but in this embodiment, a more preferable cooperative operation is achieved by switching the operation according to the detection state of the NFC tag in the power transmission device 100. First, if the first control unit 201 determines that the power transmission device 100 includes a reader / writer, it determines whether the power transmission device 100 has performed polling (step S412). This determination process can be achieved by asking the power transmission device 100 for NFC-related information during the negotiation phase and receiving a response thereto from the power transmission device 100. For this purpose, a packet for requesting information corresponding to bits 0 and 1 shown in Figure 4 (a packet for asking about NFC-related information) is sent to the power transmission device 100.

[0070] As a packet for asking about NFC-related information, for example, among the packets defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is undefined can be defined. Alternatively, among the general requests and specific requests defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is undefined can be used.

[0071] When receiving an inquiry about NFC-related information, the third control unit 301 of the power transmission device 100 confirms the status by asking the fourth control unit 309 whether NFC tag detection has been performed and the result of the detection process (steps S503 and S504). The third control unit 301 receives from the fourth control unit 309 a representation referring toFigure 4 information on the detected state, and in response to an inquiry about NFC-related information, sends a packet including this information to the power transmission device 100 using the third communication unit 304 (step S505).

[0072] Assume that the response from the power transmission device 100 is information indicating that polling has not been performed and no NFC tag has been detected ("00") ( "No" in step S412). In this case, the first control unit 201 instructs the second control unit 210 to perform polling (step S406). Then, in steps S407 and subsequent steps described above, the second control unit 210 detects the NFC tag without interfering with the digital ping. Note that the arrangement in which the power receiving device 102 immediately performs polling if the power transmission device 100 has not performed polling ( "No" in step S412) has been explained, but the present invention is not limited to this. If it is determined to be "No" in step S412, the first control unit 201 may perform the processing in steps S403 and subsequent steps.

[0073] In addition, after an inquiry about NFC-related information, the first control unit 201 may send a packet indicating that the first control unit 201 performs processing for detecting an NFC tag (i.e., polling) to the power transmission device. Among the packets defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined can be defined as a packet indicating the intention of the own device to perform NFC detection processing. For example, among the general request and specific request defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined can be used.

[0074] If the power transmission device 100 receives a packet indicating the intention to perform NFC detection processing from the power receiving device 102, it may not perform polling processing within a predetermined time ( "Yes" in steps S506 and S507). This can more reliably avoid the situation where the polling sent by the NFC 302 of the power transmission device 100 interferes with the polling sent by the NFC 202 of the power receiving device 102. Here, it is assumed that the predetermined time is at least longer than the time taken to send polling and receive its response after the second control unit 210 receives the polling instruction.

[0075] Subsequently, [3] among the above three cooperative operations will be described with reference to Figure 3 the flowchart. This operation is the operation when the power transmission device 100 includes a reader / writer and polling processing has been performed in the power transmission device 100.

[0076] Assume that the response to the inquiry about NFC-related information sent by the first control unit 201 from the power transmission device 100 is information indicating that polling has been performed and no NFC tag has been detected ( Figure 4 "10" in Figure 3 )(Yes in step S412 and No in step S413). In this case, the first control unit 201 determines to confirm that there is no NFC tag near the power transmission device 100 and ends the

[0077] processing shown in Figure 4

[0078]

[0079] Figure 6 Figure 6 Next, reference will be made to Figure 6 to describe the operation sequence of wireless power transmission performed by the power receiving device 102 and the power transmission device 100 operating as described above according to this embodiment. Figure 6 is a sequence diagram of the operation of the wireless charging system according to the embodiment. Figure 6 illustrates the operation sequence in case [1] of the above three collaborations.

[0080] After activation, the power transmission unit 303 of the power transmission device 100 starts the selection phase and transmits an analog ping (600) via the power transmission coil 305. The analog ping is a signal of small power used to detect an object present near the power transmission coil 305. The power transmission device 100 detects the voltage value or current value of the power transmission coil 305 when transmitting the analog ping. If the voltage is lower than a given threshold or the current value exceeds the given threshold, the power transmission device 100 determines that an object is present and transitions to the ping phase. In the ping phase, the power transmission device 100 transmits a digital ping (601) with power greater than that of the analog ping.

[0081] When receiving the digital ping, the first control unit 201 sends a signal strength packet, an ID packet, and a configuration packet (602, 603, and 604) to the power transmission device 100. If the power transmission device 100 sends an ACK to the configuration packet and the power receiving device 102 receives the ACK (605), the power transmission device 100 and the power receiving device 102 transition to the negotiation phase. In the negotiation phase, the first control unit 201 sends a general request (capability) for asking whether the power transmission device 100 has an NFC tag detection function to the power transmission device 100 (606). The first control unit 201 receives a capability from the power transmission device 100 including information indicating whether the power transmission device 100 has an NFC tag detection function (607).

[0082] Here, it is assumed that the power transmission device 100 does not have a reader / writer function (does not have a function of detecting NFC tags). In this case, the first control unit 201 performs a status confirmation regarding NFC tag detection for the second control unit 210 (608). Refer to Figure 6 , and receives "00" indicating that the polling process has not been executed and no NFC tag has been detected from the second control unit 210 (609). The second control unit 210 responds to the status confirmation request and then resets (deletes) the detected status of the stored NFC tag (NFC-related information) (610).

[0083] When receiving "00" from the second control unit 210 through status confirmation, the first control unit 201 issues a polling instruction (611) to the second control unit 210. When receiving an ACK (612) for the polling instruction from the second control unit 210, the first control unit 201 sends EPT (pause) (613) to the power transmission device 100. If the power transmission device 100 temporarily suspends the transmission of digital pings in response to EPT (pause), the second control unit 210 performs a polling process (614). When receiving a response from the NFC tag (615), the second control unit 210 updates the detection status (NFC-related information) of the NFC tag and stores it (616).

[0084] After that, the first control unit 201 is reactivated by receiving digital pings from the power transmission device 100 again (617), and the status confirmation of the second control unit 210 is re-executed (618). Since the second control unit 210 stores NFC-related information indicating that the polling process has been executed and the NFC tag has been detected at this stage, the second control unit 210 sends "11" ( Figure 4 ) as a response to the status confirmation (619). After sending the response to the status confirmation, the second control unit 210 clears (deletes) the stored NFC-related information (620). When receiving "11" as the detection status of the NFC tag, the first control unit 201 sends EPT (NFC) to the power transmission device 100 to stop the power transmission of the power transmission device 100 (621).

[0085] Note that, as described above, after the second control unit 210 sends a response to the status confirmation, that is, after the first control unit 201 refers to the NFC-related information, the NFC-related information is cleared (620). More specifically, after sending the detection status "11" to the first control unit 201, the second control unit 210 returns the detection status to "00". The reason for this is that the second control unit 210 needs to send information (i.e., the latest NFC-related information) of the polling (614) immediately after the latest polling instruction (611) of the first control unit 201 as a response (619).

[0086] If the stored NFC-related information is not cleared and the status of the immediately preceding polling is stored, the following failure is considered to occur. For example, assume that when receiving the status confirmation (608), information indicating that the polling performed in the past has not detected the NFC tag (i.e., status "10") is stored. If the second control unit 210 sends "10" as a response (609), the first control unit 201 is based on Figure 3The flowchart shown does not issue a polling instruction (Yes in step S405 and No in step S409). In this case, if the NFC tag exists at the time of the request status confirmation (608), a failure of not detecting the NFC tag occurs. This failure can be avoided by clearing (setting to "00") the stored status when the second control unit 210 responds to the status confirmation request from the first control unit 201. That is, the second control unit 210 stores, in a storage unit (e.g., a non-volatile memory), the result of the detection performed in response to the decision of the first control unit 201 to perform the detection of the NFC tag 101 as the detection status. If the first control unit 201 refers to the detection status stored in the storage unit, the second control unit 210 operates to delete the detection status from the storage unit.

[0087] When the digital ping stops (613) by the EPT (pause), the power receiving device 102 can move from the power transmitting device 100 to another power transmitting device (not shown). Since the first control unit 201 stops during the stop of the digital ping, the first control unit 201 cannot detect such a movement.

[0088] The following situation will be considered, in which polling is performed immediately after the EPT (pause) is sent and before the user removes the power receiving device 102 from the power transmitting device 100 and places it on another power transmitting device. In this case, since there is no NFC tag nearby at the time of polling, the status regarding NFC is "10" (as a result of performing the polling process, the NFC tag has not been detected). Assume that the power receiving device 102 is then placed on another power transmitting device and there is an NFC tag near the other power transmitting device. In this case, when the power receiving device placed on the other power transmitting device restarts its operation, the NFC-related information received from the second control unit 210 indicates the detection status ("10"), so the first control unit 201 does not perform polling and determines that there is no NFC tag. In this case, the second control unit 210 should notify the first control unit 201 of the status "00" regarding NFC, but actually stores the status "10", and a status mismatch occurs.

[0089] If the first control unit 201 of the power receiving device 102 obtains the identification information of the power transmitting device 100 and performs the detection of the NFC tag through the NFC 202, the first control unit 201 confirms whether the multiple pieces of identification information obtained before and after the detection execution match each other. If the multiple pieces of information do not match each other, the first control unit 201 deletes the detection status stored in the second control unit 210.

[0090] For example, whenever the first control unit 201 receives a digital ping and is activated, the first control unit 201 queries the identification information of the power transmission device 100. More specifically, among the general request packets defined by the WPC standard, a packet for querying the identification information of the power transmission device is sent, and the identification information of the power transmission device is received. This packet is, for example, a general request packet (power transmitter identification). The first control unit 201 compares the previously obtained identification information with the currently obtained identification information. If the multiple pieces of identification information do not match, an instruction to clear the NFC-related information is sent to the second control unit 210. As described above, multiple pieces of identification information of the power transmission device before and after sending EPT (pause) (before and after the NFC tag detection operation) can be compared, thus solving the above-mentioned failure.

[0091] For example, before the power receiving device 102 sends EPT (pause) (613), the power receiving device 102 is placed on the power transmission device 100 with the identification information "aa", and is moved to another power transmission device (identification information "bb") during the digital ping pause. In this case, the multiple pieces of identification information of the power transmission device before and after EPT (pause) (after the first control unit 201 is re-activated) do not match each other (aa≠bb), and the status regarding NFC is cleared to "00". As a result, the first control unit 201 obtains "00" as the response (619) to the status confirmation (618), and thus can detect the NFC tag placed on another power transmission device.

[0092] On the other hand, if the power receiving device is placed on the power transmission device with the identification information "aa" before EPT (pause) (613), and is placed on the same power transmission device (identification information "aa") after the digital ping pause, then the multiple pieces of identification information before and after EPT (pause) match each other. Therefore, the NFC-related information is not cleared. Thus, since the first control unit 201 receives the updated information (619) regarding NFC after polling (614), the presence or absence of the NFC tag placed on the power transmission device can be correctly detected.

[0093] This embodiment only illustrates the use of the NFC reader / writer for NFC tag detection, but the present invention is not limited thereto. For example, in a product (such as a smart phone) in which the power receiving device 102 is implemented, the reader / writer can be used for another application (for an application other than NFC tag detection).

[0094] Note that the following problems may occur if the above NFC-related information is stored when using the NFC reader / writer in another application. That is, if the reader / writer is used in another application to communicate with the NFC tag, the NFC-related information is updated to "11". As described above, the second control unit 210 does not clear the NFC-related information unless a response to the status confirmation is sent. Therefore, if the power transmission device 100 and the power reception device 102 are close to each other in this state, the first control unit 201 receives "11" as a response to the status confirmation (step S403) from the second control unit 210. As a result, the first control unit 201 unnecessarily sends EPT (NFC) to the power transmission device 100, and the battery 207 of the power reception device 102 cannot be charged even if there is no NFC tag near the power transmission device 100.

[0095] To solve this problem, the second control unit 210 stores the detection result obtained by polling immediately after receiving the polling instruction for controlling wireless power transmission from the first control unit 201 as the NFC-related status, otherwise it does not store the NFC-related status. Even if the reader / writer operates in another application, this can solve the above problem without the second control unit 210 updating the NFC-related information.

[0096] <Other embodiments>

[0097] In the above wireless power transmission system, the wireless power transmission method is not particularly limited. For example, as the wireless power transmission method, a magnetic resonance method can be used, which uses the coupling caused by the resonance of the magnetic field between the resonator (resonance element) of the power transmission device and the resonator (resonance element) of the power receiver to transmit power. Alternatively, a power transmission method using electromagnetic induction, electric field resonance, microwave, laser, etc. can be used.

[0098] In addition, both the power transmission device and the power reception device can be, for example, an image input device such as an image capturing device (camera, video camera, etc.) or a scanner, or an image output device such as a printer, a copier, or a projector. Further, both the power transmission device and the power reception device can be a storage device such as a hard disk drive or a memory device, or an information processing device such as a personal computer (PC) or a smartphone.

[0099] Figure 3 The shown flowchart starts when the first control unit 201 is powered on. Note that when the first control unit 201 executes the program stored in the memory of the power reception device 102, the Figure 3 shown processing is implemented. In addition, when the third control unit 301 executes the program stored in the memory of the power transmission device 100, theFigure 5 The processing shown Figure 3 and Figure 5 At least some of the processing shown in the flowchart of can be implemented by hardware. For example, if certain processing is implemented by hardware, dedicated circuits are automatically generated on an FPGA according to a program configured to implement each step using a pre-compiler. FPGA is an abbreviation for Field Programmable Gate Array. Alternatively, the processing can be implemented as hardware by forming a gate array circuit (such as an FPGA).

[0100] The present invention can be implemented by supplying a program that implements one or more functions of the above-described embodiments to a system or device via a network or a storage medium and causing one or more processors in a computer of the system or device to read and execute the program. The present invention can also be implemented by a circuit (e.g., an ASIC) for implementing one or more functions.

[0101] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, the following claims are made to inform the public of the scope of the present invention.

Claims

1. A power transmission device, comprising: A power transmission unit that wirelessly transmits power; A detection unit that performs a detection process by polling NFC, the detection process detecting an NFC tag for performing near field communication NFC; A receiving unit that receives identification information and a request for information about the power transmission device from a power receiving device; And A transmission unit that, after receiving the request and when the detection process has not been performed, transmits to the power receiving device information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not performed the detection process, and information indicating that no NFC tag has been detected.

2. The power transmission device according to claim 1, wherein, In a negotiation stage for negotiating wireless power transmission, information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not performed the detection process, and information indicating that no NFC tag has been detected are transmitted.

3. The power transmission device according to claim 1, wherein, When information indicating that the power transmission device has not performed the detection process is received, information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not performed the detection process, and information indicating that no NFC tag has been detected are transmitted to: a power receiving device that performs a detection process for detecting an NFC tag by polling NFC.

4. A communication method for a power transmission device that wirelessly transmits power, the communication method comprising: Performing a detection process by polling NFC, the detection process detecting an NFC tag for performing near field communication NFC; Receiving identification information from a power receiving device; Receiving a request for information about the power transmission device from the power receiving device; And After receiving the request and when the detection process has not been performed, transmitting to the power receiving device information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not performed the detection process, and information indicating that no NFC tag has been detected.

5. The communication method according to claim 4, wherein, In a negotiation stage for negotiating wireless power transmission, information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not performed the detection process, and information indicating that no NFC tag has been detected are transmitted.

6. The communication method according to claim 4, wherein, When information indicating that the power transmission device has not performed the detection process is received, information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not performed the detection process, and information indicating that no NFC tag has been detected are transmitted to: a power receiving device that performs a detection process for detecting an NFC tag by polling NFC.

7. A computer-readable storage medium that stores a program for causing a computer to execute a communication method for a power transmission device that wirelessly transmits power, the communication method comprising: Performing a detection process by polling NFC, the detection process detecting an NFC tag for performing near field communication NFC; Receiving identification information and a request for information about the power transmission device from a power receiving device; And After receiving the request and before the detection process is executed, send information indicating that the power transmission device supports the detection process, information indicating that the power transmission device has not executed the detection process, and information indicating that no NFC tag has been detected to the power receiving device.

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