Power transmission apparatus, method of power transmission apparatus, and storage medium

Abstract

The invention relates to a power transmission apparatus, a method of the power transmission apparatus, and a storage medium. The power transmitting device includes: a power transmitting section for transmitting ping to wake up the power receiving device; a receiving section for receiving, from a power receiving device, identification information and a request for information on the power transmitting device; a detection unit that performs a detection process for detecting an NFC tag that performs NFC by polling of near field communication (NFC); and a transmission unit that, when the detection process has not been executed, transmits the request to a power receiving device after receiving the request. Information indicating that the detection process is supported by the power transmission device, information indicating that the power transmission device has not executed the detection process, and information indicating that an NFC tag is not detected.

Description

[0001] This application is a divisional application of an invention patent application with an application date of February 28, 2020, application number 202080031104.2 (international application number PCT / JP2020 / 008408), and invention name “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 and a control method thereof, and a wireless power transmitting system. Background Art

[0003] Technical development of wireless power transmission systems has been widely carried out. As a standard for a power transmission device and a power receiving device forming a wireless power transmission system, a standard defined by WPC (hereinafter referred to as the WPC standard) is provided, which is a standardization organization for contactless charging standards. Note that WPC is an abbreviation of 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 message for detecting a communication partner device by sending a carrier wave and modulating the carrier wave is called polling. Polling is sent by a device having a reader / writer function that complies with the NFC standard. A device having the following function: receiving a polling sent by a reader / writer and responding to the polling by load modulating the carrier wave sent by the reader / writer is called an NFC tag.

[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. In order to avoid NFC communication failure caused when wireless power and NFC communication interfere with each other, Patent document 1 limits wireless power when the power transmitting device performs NFC communication (polling and response).

[0006] Reference List

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-093818 Summary of the invention

[0009] Technical issues

[0010] When wireless power transmission is performed while an NFC tag is close to a power transmitting device, the NFC tag may be damaged by the transmission power output from the power transmitting device. If the power transmitting device has a reader / writer function in Patent Document 1, damage to the NFC tag can be avoided when the power transmitting device detects the presence of an NFC tag by polling and limits the power to be transmitted. Similarly, if the power receiving device has a reader / writer function, even if the power transmitting device does not have a reader / writer function, wireless power transmission can be appropriately controlled according to the presence / absence of an NFC tag. However, a cooperative operation between a power receiving device and a power transmitting device for avoiding damage to an NFC tag when a reader / writer function is implemented in a power receiving device has not yet been proposed.

[0011] The present invention provides a technology associated with cooperative operation between a power receiving device and a power transmitting device in a wireless power transmission system when a reader / writer is implemented in the power receiving device.

[0012] Solutions to the problem

[0013] A power receiving device according to one 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 transmitting device, the power receiving device comprising:

[0014] a communication unit for communicating with the power transmission device;

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

[0016] a determination section for determining whether the power transmitting device has a detection function for detecting another device capable of short-range wireless communication; and

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

[0018] Among them, if the determination unit determines that the power transmitting device does not have a detection function, the control unit controls so that: when the detection unit has not determined the detection state of another device, the detection by the detection unit is performed, and when the detection state of the detection unit is determined, the detection by the detection unit is not performed, and the communication unit sends a signal corresponding to the detection result of the detection unit to the power transmitting device.

[0019] Advantageous Effects of the Invention

[0020] According to the present invention, a preferable cooperative operation between a power receiving device and a power transmitting 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.Please note that the same reference numerals throughout the drawings represent the same or similar components. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

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

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

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

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

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

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

[0029] [ Figure 6 ] Figure 6 is a sequence diagram of the operation of the wireless charging system according to the embodiment. DETAILED DESCRIPTION

[0030] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Please note that the following embodiments are not intended to limit the scope of the invention. A plurality of features are described in the embodiments, but the invention requiring all of these features is not limited, and a plurality of such features may be appropriately combined. In addition, in the accompanying drawings, the same reference numerals are assigned to the same or similar configurations, and their redundant description is omitted.

[0031] Figure 1A: is a diagram showing an example of the construction of a wireless power transmission system according to an embodiment. A power receiving device 102 that complies with the WPC (Wireless Power Consortium) standard is placed on a power transmitting device 100 that complies with the WPC standard. The power receiving device 102 receives power wirelessly transmitted from the power transmitting device 100. The power transmitting device 100 and the power receiving device 102 of this embodiment comply with the WPC standard, and each has a function defined in the 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 (NearField Communication) tag 101 is close to the power transmitting device 100, it is affected by the wireless power transmitted by the power transmitting device 100.

[0032] Figure 1B 1 is a block diagram showing an example of the arrangement of the power receiving device 102 according to the 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 conform to the WPC standard. However, the present invention is not limited to this, and these devices may conform to 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 the 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 power to drive the first control unit 201.

[0034] The first communication unit 204 performs wireless communication with the power transmission device 100 under the control of the first control unit 201. In this 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 transmission device 100. The load modulation may 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 may perform load modulation in accordance with Low power consumption (hereinafter referred to as "BLE") standard communication. In addition, the first communication unit 204 can be used in accordance with the IEEE802.11 standard series such as or wireless LAN (e.g. ) communication method to communicate.

[0035] The 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. The NFC 202 is formed by an NFC coil and a circuit that complies with the NFC standard. The second control unit 210 for controlling the NFC 202 has a function of transmitting / receiving information related to the operation of the NFC 202 to / from the first control unit 201. The NFC 202 can detect another device (e.g., an NFC tag) having a function capable of communicating with the NFC 202. In addition, the second control unit 210 and the 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 the user of various information. The present embodiment assumes 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 may 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, 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 may be packaged and implemented as one component. In addition, the NFC 202 and the second control unit 210 are shown as separate units, but they may be packaged and implemented as one component. That is, the above-mentioned constituent elements are not limited in terms of the form of implementation, etc., as long as they can realize the function (described later).

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

[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 a FET (field effect transistor). The power transmission unit 303 includes a gate driver that controls ON / OFF of the FET. 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 applicable to 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 this 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 may perform a communication conforming to Low power consumption (hereinafter referred to as "BLE") standard communication. In addition, the third communication unit 304 can be used in accordance with the IEEE802.11 standard series such as or wireless LAN (e.g. ) communication method to communicate.

[0041] The memory 308 stores the calculation result 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 / receiving information related to the operation of the NFC 302 to / from the second control unit 210 of the power receiving device 102. The UI 306 is a user interface of the power transmitting device 100 and has a function of notifying the user of various information.

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

[0043] As described above, the power transmission device 100 and the power receiving device 102 each have an NFC reader / writer function. If the NFC tag 101 exists 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 operate in cooperation 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 reader / writer functions of the power transmitting device 100 and the power receiving device 102 perform polling at the same time, the polling interferes with each other, so the NFC tag 101 may not receive the polling correctly and cannot respond to the polling. In this case, even if the NFC tag 101 exists nearby, the power transmitting device 100 and the power receiving device 102 cannot detect it. As a result, even if the NFC tag 101 exists nearby, wireless power transmission between the power transmitting device 100 and the power receiving device 102 may start, thereby damaging the NFC tag 101. In order to solve this problem, it is important to detect the NFC tag 101 through a cooperative operation between the power transmitting device 100 and the power receiving device 102. More specifically, the power transmitting device 100 and the power receiving device 102 perform the following processing. Note that the reader / writer is an example of a detection function for detecting an NFC tag.

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

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

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

[0048] The above-mentioned coordinated operation of [1] to [3] can solve the problem that the polling of the power transmitting device 100 and the polling of the power receiving device 102 interfere with each other and make it impossible to correctly detect the NFC tag 101. Figure 3 The flowchart shown describes the individual coordinated operations of [1] to [3].

[0049] Figure 3 : is a flowchart showing the processing performed by the first control unit 201 of the power receiving device 102 . Figure 5 1 is a flowchart showing the processing performed by the third control unit 301 of the power transmission device 100. Figure 3 and Figure 5 The operation of the power receiving device 102 and the power transmitting device 100 according to this embodiment is described with reference to the flowchart of FIG. Figure 5 Steps S502 to S512 of FIG. 5 show part of the processing performed by the power transmission device 100 during the negotiation phase (processing until a "No" determination is made in step S512). First, [1] among the three cooperative operations described above will be described. [1] corresponds to the case where the power transmission device 100 does not include a reader / writer (in Figure 2 In this case, the power transmission device 100 does not include the NFC 302 nor the fourth control unit 309. In this case, the power transmission device 100 transmits in step S502 that it does not have a reader / writer function and does not have an execution Figure 5 Notification of the function of the 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 size of the digital ping is at least enough 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 size 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 send 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 version information of the WPC standard to which the first control unit 201 complies and an individual identification number of the first control unit 201. In addition, the first control unit 201 controls the first communication unit 204 to send a configuration packet to the power transmission device 100. The configuration packet is a packet defined by the WPC standard, and includes information about 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. 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. Upon receiving the ACK from the power transmission device 100, the first control unit 201 transitions to the negotiation phase. Upon sending 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 inquires the power transmitting device 100 whether the power transmitting device 100 has a reader / writer function (detection function) for detecting an NFC tag (step S402). For this inquiry, a general request packet (capability) among general request packets defined by the WPC standard and representing an inquiry to the power transmitting device can be used. The general request packet (capability) is a packet for inquiring about the capability information of the power transmitting device. Please note that the packets that can be used to inquire about the presence or absence of the NFC tag detection function are not limited to the above-mentioned packets. 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 transmitting device 100 sends a notification of a packet indicating whether the power transmitting device 100 has a reader / writer function (step S502). In this example, the power transmitting device 100 sends a notification that it does not have a reader / writer function. The first control unit 201 that performs the above determination processing in step S402 is an example of a component for communicating with the power transmitting device 100 using the first communication unit 204 and determining whether the power transmitting device 100 has a function of detecting an NFC tag (another device). Note that in this embodiment, as will be referred to later Figure 6 As described, the general request packet (capability) and the capability packet are used for the above-mentioned inquiry and response about 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 the NFC tag detection function (no NFC reader / writer) (step S402 is "No"), the processing proceeds to step S403. If the first control unit 201 therefore determines that the power transmission device 100 does not have the NFC tag detection function, the first control unit 201 inquires 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 referred to as status confirmation hereinafter.

[0056] Now refer to Figure 4 A response to the above-mentioned status confirmation from the second control unit 210 is described. Figure 4201 and 201. It is a table showing the communication content of the status confirmation related to 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 a 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 yet performed polling based on an 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 an instruction from the first control unit 201. In addition, bit 1 indicates whether an NFC tag has been detected as a result of performing the above-mentioned polling. If bit 1 is "0", this indicates that the second control unit 210 has not yet detected an NFC tag. If bit 1 is "1", this indicates that the second control unit 210 has detected an NFC tag.

[0057] It is assumed here that, as a response to the status confirmation, the first control unit 201 is notified of "00", which indicates that the second control unit 210 has not yet performed the polling process and has not yet detected the NFC tag, that is, the detection status of the NFC tag is not confirmed. Note that if bit 0 is "0", polling has not yet been performed, so regardless of the state of bit 1, it can be determined that the detection status of the NFC tag is not confirmed. When the first control unit 201 receives a response "00" to the status confirmation inquiry indicating that polling has not yet 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 step S405 and step 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 the NFC 202 is not determined, the first control unit 201 uses the second control unit 210 and the NFC 202 to perform NFC tag detection.

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

[0059] Note that in this embodiment, an EPT packet containing an information element indicating a temporary pause is represented as EPT (pause). In addition, the predetermined time from suspending power transmission to restarting 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 polling instruction from the first control unit 201.

[0060] Upon receiving EPT (pause), the power transmitting device 100 temporarily stops sending digital ping (steps S508 and S509). This can prevent the influence of digital ping on the polling performed by the power transmitting device 100 and its response. Please note that the temporary pause period (the above-mentioned predetermined time) can be preset in the power transmitting device 100, or information for specifying the predetermined time can be included in EPT (pause). If the information for specifying the predetermined time is included in EPT (pause), the power transmitting device 100 stops sending digital ping for the predetermined time specified by EPT (pause). When the digital ping is detected to be stopped, the second control unit 210 causes NFC 202 to start sending polling, thereby performing polling processing (step S408). The second control unit 210 stores the NFC tag detection result obtained by the polling process. Afterwards, if the power receiving device 102 receives the transmission of the digital ping from the power transmitting device 100, it sends a signal to the power transmitting device 100 according to the NFC tag detection result. More specifically, if the power receiving device 102 detects the NFC tag, it transmits an EPT (NFC) packet obtained by storing an information element indicating that an NFC tag has been detected in the EPT packet to the power transmitting device 100. In addition, if no NFC tag is detected, a signal strength packet or the like is transmitted.

[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 to this. For example, it is possible to request that the maximum value of the transmitted power be limited to a predetermined value or less. In this case, the maximum value of the transmitted power is determined within a range that does not affect the polling. In addition, in this request, the power receiving device 102 can notify the power transmitting device of the maximum value of the transmitted power.

[0062] Assume that as a result of polling, a response from the NFC tag 101 is received 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 passed, the first control unit 201 is reactivated by receiving a digital ping from the power transmission device 100 again (step S401), and the above-mentioned steps S402 to S405 are performed. 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 (has determined the detection status of the NFC tag). 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, which 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 limit the transmission of the digital ping ("Yes" in steps S404, S405, and S409 and 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 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 to this. For example, it is possible to request that the maximum value of the transmitted power be limited to a predetermined value or less. In this case, the maximum value of the power to be transmitted is determined within the range of not damaging the NFC tag. In addition, in the request, the power receiving device 102 can 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). Upon receiving the EPT, the power transmission device 100 stops wireless power transmission. The state in which the first control unit 201 cannot receive a response to the status confirmation from the second control unit 210 occurs in the following occasions: for example, when the second control unit 210 stops its operation due to no remaining battery. In this case, the power receiving device 102 cannot confirm the presence / 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 with respect to step S411, the power transmission device 100 may be requested to limit the maximum value of the transmitted power to a predetermined value or less, rather than completely stopping the power transmission. This allows less power to be transmitted to such an extent that the NFC tag is not damaged, so that the battery 207 can be charged by this power.

[0065] Since the power receiving device 102 operates as described above, if the power transmitting 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 NFC tag detection has been performed and the result thereof is stored in the second control unit 210 powered by the battery 207. Therefore, the preferred control is implemented as follows.

[0066] If NFC-related information is stored in a volatile memory (not shown) in the first control unit 201, when the digital ping is stopped by the sending of EPT (pause), the first control unit 201 and the volatile memory are reset unnecessarily. As a result, in the status confirmation after reactivation (step S403), 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" which is a reset state. This problem is solved by storing the NFC-related information in the second control unit 210 which is powered by the battery 207 and is not reset due to the stop of the digital ping. Note that when the first control unit 201 refers to the stored NFC-related information (the detection status of the NFC tag by the reader / writer), the second control unit 210 deletes the NFC-related information. This point will be referred to later. Figure 6 Give a description.

[0067] The same effect can be obtained even if the NFC-related information is stored in another component that is not reset by the cessation of the digital ping. 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 transmitting device 100 can store NFC-related information. This is because the internal circuit of the power transmitting device 100 is powered by the power supply unit 307 and is therefore not reset even if the digital ping stops. In this case, during the negotiation phase, the power transmitting device 100 can notify the power receiving device 102 of the NFC-related information.

[0068] Next, we will refer to Figure 3 and Figure 5 The flowchart of [2] describes one of the three coordinated operations described above. This operation is an operation when the power transmission device 100 has a function of detecting an NFC tag but does not perform polling processing.

[0069] If, as a 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 processing proceeds to step S412. If the power transmission device 100 includes a reader / writer, the power receiving device 102 can be controlled not to perform polling, but by switching the operation according to the detection state of the NFC tag in the power transmission device 100, the present embodiment achieves a more preferred collaborative operation. 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 inquiring the power transmission device 100 for NFC-related information during the negotiation phase and receiving a response thereto from the power transmission device 100. To this end, the method for requesting and communicating with the power transmission device 100 is described in detail below. Figure 4 A packet of information corresponding to bit 0 and bit 1 shown (a packet for inquiring about NFC-related information) is transmitted to the power transmission device 100 .

[0070] As a packet for inquiring NFC-related information, for example, among the packets defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined may be defined. Alternatively, among the general request and the specific request defined by the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined may be used.

[0071] Upon receiving the inquiry about NFC-related information, the third control unit 301 of the power transmission device 100 performs status confirmation by inquiring the fourth control unit 309 whether NFC tag detection has been performed and the result of the detection process (steps S503 and S504). Figure 4 The power transmission device 100 receives information of the detection state described in the embodiment, and transmits a packet including the information to the power transmission device 100 using the third communication unit 304 as a response to the inquiry about the NFC-related information (step S505).

[0072] Assume that the response from the power transmitting device 100 is information ("00") indicating that polling has not been performed and the NFC tag has not been detected ("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 the above-mentioned steps S407 and subsequent steps, 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 transmitting 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 can perform the processing in step S403 and subsequent steps.

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

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

[0075] Then, refer to Figure 3 The flowchart of describes [3] among the above three coordinated operations. This operation is an operation when the power transmission device 100 includes a reader / writer and the polling process has been performed in the power transmission device 100.

[0076] Assume that the response from the power transmission device 100 to the inquiry about the NFC-related information transmitted by the first control unit 201 is information indicating that polling has been performed and an NFC tag has not been detected ( Figure 4 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 process. Figure 3 The processing shown is performed, thereby performing wireless power transmission from the power transmitting device 100 to the power receiving device 102.

[0077] Assume that the response from the power transmission device 100 is information indicating that polling has been performed and an NFC tag has been detected ( Figure 4 In this case, the first control unit 201 determines to confirm that there is an NFC tag near the power transmission device 100, sends EPT (NFC) to the power transmission device 100, and ends the process (steps S412, S413, and S410). In this case, the power transmission from the power transmission device 100 is stopped, and the wireless power transmission from the power transmission device 100 to the power receiving device 102 is not performed.

[0078] Note that the above has been described an arrangement in which the first control unit 201 transmits EPT (NFC) in response to detection of an NFC tag to stop power transmission by the power transmission device 100, but the present invention is not limited thereto. For example, an arrangement may be adopted in which a packet for requesting less power to be transmitted to such an extent that the NFC tag is not damaged is transmitted to the power transmission device 100 instead of transmitting EPT (NFC), and the battery 207 is charged with the power.

[0079] Next, we will refer to Figure 6 An operation sequence of wireless power transmission performed by the power receiving device 102 and the power transmitting device 100 operating as described above according to the present embodiment is described. Figure 6 is a sequence diagram of the operation of the wireless charging system according to the embodiment. Figure 6 The operation sequence in case [1] among the above three types of collaborative operations is illustrated.

[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 a small power for detecting an object present near the power transmission coil 305. The power transmission device 100 detects a voltage value or a 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 a given threshold, the power transmission device 100 determines that the object exists and transitions to the ping phase. In the ping phase, the power transmission device 100 transmits a digital ping (601) with a power greater than that of the analog ping.

[0081] Upon receiving the digital ping, the first control unit 201 sends a signal strength packet, an ID packet, and a configuration packet to the power transmission device 100 (602, 603, and 604). 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) to the power transmission device 100 for inquiring whether the power transmission device 100 has an NFC tag detection function (606). The first control unit 201 receives a capability including information indicating whether the power transmission device 100 has an NFC tag detection function from the power transmission device 100 (607).

[0082] It is assumed here that the power transmission device 100 does not have a reader / writer function (does not have a function of detecting an NFC tag). In this case, the first control unit 201 performs a status confirmation regarding NFC tag detection for the second control unit 210 (608). Figure 6 , "00" indicating that the polling process has not been performed and the NFC tag has not been detected is received from the second control unit 210 (609). The second control unit 210 responds to the status confirmation request and then resets (deletes) the stored detection status of the NFC tag (NFC related information) (610).

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

[0084] After that, the first control unit 201 is reactivated by receiving a digital ping from the power transmission device 100 again (617), and the status confirmation of the second control unit 210 is re-performed (618). Since the second control unit 210 stores NFC-related information indicating that the polling process has been performed 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). Upon 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 to the first control unit 201 as a response (619) information (that is, the latest NFC-related information) to the polling (614) immediately after the latest polling instruction (611) of the first control unit 201.

[0086] If the stored NFC-related information is not cleared and the status of the polling performed immediately before is stored, the following failure is considered to occur. For example, it is assumed that when the status confirmation (608) is received, information indicating that the polling performed in the past has not detected an 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 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 when the status confirmation (608) is requested, a failure that the NFC tag cannot be detected occurs. This failure can be avoided by clearing (setting "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 the result of the detection performed in response to the decision of the first control unit 201 to perform the NFC tag 101 detection as the detection status in the storage unit (e.g., non-volatile memory). 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 by EPT (pause) (613), the power receiving device 102 may 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 movement.

[0088] The following case will be considered, in which, immediately after sending EPT (pause), polling is performed 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 when polling is performed, the state about NFC is "10" (as a result of performing the polling process, the NFC tag has not been detected). It is assumed that the power receiving device 102 is subsequently 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 state ("10"), so the first control unit 201 does not poll 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 state "00" about NFC, but the state "10" is actually stored, and a state 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 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 are performed match each other. If the multiple pieces of information do not match each other, the first control unit 201 deletes the detection state 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 inquires about the identification information of the power transmitting device 100. More specifically, in the general request packet defined by the WPC standard, a packet for inquiring about the identification information of the power transmitting device is sent, and the identification information of the power transmitting device is received. The packet is, for example, a general request packet (power transmitter identification). The first control unit 201 compares the identification information obtained last time with the identification information obtained this time. If the multiple identification information does not match, an instruction to clear the NFC related information is issued to the second control unit 210. As described above, multiple identification information of the power transmitting device before and after sending EPT (pause) (before and after the NFC tag detection operation) can be compared to solve the above-mentioned fault.

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

[0092] On the other hand, if the power receiving device is placed on the power transmitting device having identification information "aa" before EPT (pause) (613), and is placed on the same power transmitting device (identification information "aa") after the digital ping is paused, the multiple identification information before and after EPT (pause) match each other, and therefore, the NFC-related information is not cleared. Therefore, since the first control unit 201 receives the update information (619) about NFC after polling (614), it is possible to correctly detect the presence / absence of the NFC tag placed on the power transmitting device.

[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 (e.g., a smartphone) that implements the power receiving device 102, the reader / writer may be used for another application (for an application other than NFC tag detection).

[0094] Please note that if the above-mentioned NFC-related information is stored when the NFC reader / writer is used in another application, the following problem may occur. 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 transmitting device 100 and the power receiving device 102 are close to each other in this state, the first control unit 201 receives "11" from the second control unit 210 as a response to the status confirmation (step S403). As a result, the first control unit 201 unnecessarily sends EPT (NFC) to the power transmitting device 100, and even if there is no NFC tag near the power transmitting device 100, the battery 207 of the power receiving device 102 cannot be charged.

[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 state, and otherwise does not store the NFC-related state. This can solve the above problem without the second control unit 210 updating the NFC-related information even if the reader / writer is operated in another application.

[0096] <Other embodiments>

[0097] In the above-mentioned wireless power transmission system, the wireless power transmission method is not particularly limited. For example, as a wireless power transmission method, a magnetic resonance method can be used, which uses 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 an electromagnetic induction method, an electric field resonance method, a microwave method, a laser, etc. can be used.

[0098] In addition, the power transmitting device and the power receiving device may each 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. In addition, the power transmitting device and the power receiving device may each 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 flowchart shown in FIG. 1 starts when the first control unit 201 is powered on. Note that when the first control unit 201 executes a program stored in the memory of the power receiving device 102, the power receiving device 102 is realized. Figure 3 In addition, when the third control unit 301 executes the program stored in the memory of the power transmission device 100, the Figure 5 Processing shown. Figure 3 and Figure 5 At least some of the processes shown in the flowchart of can be implemented by hardware. For example, if some of the processes are implemented by hardware, a dedicated circuit is automatically generated on an FPGA according to a program constructed to implement each step using a precompiler. FPGA is an abbreviation for field programmable gate array. Alternatively, the process can be implemented as hardware by forming a gate array circuit (such as FPGA).

[0100] The present invention can be implemented by supplying a program that implements one or more functions of the above-mentioned embodiments to a system or device via a network or 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., ASIC) for implementing one or more functions.

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

Claims

1. A power transmission device, comprising: a power transmitting unit configured to transmit a ping to wake up the power receiving device; a receiving section for receiving, from a power receiving device, identification information and a request for information about the power transmitting device; A detection unit configured to perform a detection process for detecting an NFC tag performing NFC (Near Field Communication) by NFC polling; as well as A sending unit is used to send to the power receiving device, after receiving the request, information indicating that the detection processing is supported by the power transmitting device, information indicating that the power transmitting device has not yet performed the detection processing, and information indicating that the NFC tag is not detected, when the detection processing has not yet been performed.

2. The power transmission device according to claim 1, wherein: When information indicating that the power transmitting device has not performed the detection processing is received, information indicating whether the detection processing is supported by the power transmitting device, information indicating whether the detection processing has been performed by the power transmitting device, and information indicating the result of the detection processing are sent to the power receiving device that performs the detection processing for detecting the NFC tag through NFC polling.

3. The power transmission device according to claim 1, wherein: When information indicating that the power sending device has performed the detection processing and information indicating that the NFC tag has been detected are received, information indicating whether the detection processing is supported by the power sending device, information indicating whether the detection processing has been performed by the power sending device, and information indicating the result of the detection processing are sent to the power receiving device that sends a request to stop power transmission.

4. A method for a power transmission device, the method comprising: Send a ping to wake up the power receiving device; A detection process for detecting an NFC tag performing NFC is performed through NFC (Near Field Communication) polling; receiving identification information from the power receiving device; receiving, from the power receiving device, a request for information regarding the power transmitting device; as well as When the detection processing has not yet been performed, after receiving the request, information indicating that the detection processing is supported by the power transmitting device, information indicating that the power transmitting device has not yet performed the detection processing, and information indicating that the NFC tag is not detected are sent to the power receiving device. 5 . A computer-readable storage medium storing a program for causing a computer to function as each section of the power transmission device defined in claim 1 .

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