Power transmission device, communication method, and program

Abstract

To provide a technique for realizing suitable cooperative operation between a power receiving device and a power transmitting device in a wireless power transmission system, when a reader / writer is mounted on the power receiving device.SOLUTION: A power receiving device (102) for wirelessly receiving power from a power transmitting device (100) includes a first communication unit (204) for communicating with the power transmitting device, a second control unit (210) for detecting other devices capable of performing short-range wireless communication, and a first control unit (201) for controlling whether or not to execute detection by the second control unit. The first control unit controls to execute detection by the second control unit when it is determined that the transmitting device does not have a detection function and when the detection state of the other device by the second control unit is not fixed, and controls not to execute detection by the second control unit when the detection state is fixed. The first communication unit transmits a signal according to the detection result of the second control unit to the power transmitting device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power transmission device, a communication method, and a program. [Background technology]

[0002] Technological development of wireless power transmission systems is currently underway. The WPC, a standardization organization for contactless charging standards, has established standards for power transmitters and receivers that make up wireless power transmission systems (hereafter referred to as the WPC standards). WPC stands for Wireless Power Consortium. Meanwhile, the NFC standard is known as a standard for short-range wireless communication. NFC stands for Near Field Communication.

[0003] In the NFC standard, polling refers to transmitting a carrier wave and modulating the carrier wave to send a message to detect the device with which to communicate. Polling is sent by a device that has the functionality of an NFC-standard reader / writer. An NFC tag is a device that has the functionality to receive polling sent by a reader / writer and respond to this polling by applying load modulation to the carrier wave transmitted by the reader / writer.

[0004] Patent Document 1 describes a configuration in which a power receiving device that has an NFC tag function and conforms to the WPC standard transmits a response to polling performed by a power transmitting device that has a reader / writer function conforming to the NFC standard and conforms to the WPC standard. Patent Document 1 also describes that the wireless power is limited when the power transmitting device performs NFC communication in order to avoid problems in NFC communication caused by interference between wireless power and NFC communication (polling and response). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2014-093818 Summary of the Invention [Problem to be solved by the invention]

[0006] When wireless power transmission is performed while an NFC tag is in close proximity to a power transmitting device, the NFC tag may be damaged by the transmitted power output from the power transmitting device. As disclosed in Patent Document 1, if the power transmitting device has a reader / writer function, the power transmitting device can detect the presence of an NFC tag by polling and limit the transmitted power, thereby preventing damage to the NFC tag. Similarly, if the power receiving device has a reader / writer function, wireless power transmission can be appropriately controlled depending on the presence or absence of an NFC tag, even if the power transmitting device does not have a reader / writer function. However, to date, no proposal has been made regarding cooperative operation between the power receiving device and the power transmitting device to prevent damage to the NFC tag when the power receiving device has a reader / writer function.

[0007] The present invention provides a technique for realizing suitable cooperative operation between a power receiving device and a power transmitting device in a wireless power transmission system when a reader / writer is mounted in the power receiving device. [Means for solving the problem]

[0008] A power transmission device according to one aspect of the present invention comprises: A power transmission means for wirelessly transmitting power; A detection means for detecting an NFC tag that performs near field communication (NFC) by polling the NFC; a receiving means for receiving a request for information on the power transmitting device from a power receiving device capable of detecting an NFC tag by NFC polling; a transmitting means for transmitting, to the power receiving device, information indicating whether the power transmitting device supports an NFC tag detection process, information indicating whether the power transmitting device has executed an NFC tag detection process, and information indicating a result of the NFC tag detection process, after receiving the request; send The means is the power receiving device Send a Ping to launch . [Effects of the Invention]

[0009] According to the present invention, when a reader / writer is mounted in the power receiving device, a suitable cooperative operation between the power receiving device and the power transmitting device in a wireless power transmission system is realized. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2A is a diagram showing an example of a system configuration according to an embodiment, and FIG. 2B is a block diagram showing an example of a configuration of a power receiving device according to an embodiment. [Figure 2] FIG. 1 is a block diagram showing an example of the configuration of a power transmitting device according to an embodiment. [Figure 3] 10 is a flowchart showing an operation of a control unit of the power receiving device. [Figure 4] 1 is a conceptual diagram of NFC-related communication between a first control unit and a second control unit. [Figure 5] 10 is a flowchart showing an operation of a control unit of the power transmitting device. [Figure 6] FIG. 3 is an operation sequence diagram of the wireless charging system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] FIG. 1(a) is a diagram illustrating an example of the configuration of a wireless power transmission system according to an embodiment. A WPC-compliant power receiving device 102 is mounted on a WPC-compliant power transmitting device 100. 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 further have the functions described 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 power received from the power transmitting device 100 to a load (e.g., a rechargeable battery) connected to the power transmitting device 100. When an NFC tag 101 is in proximity to the power transmitting device 100, it can be affected by the wireless power transmitted by the power transmitting device 100.

[0013] 1B is a block diagram showing an example of the configuration of a power receiving device 102 according to an embodiment. The power receiving device 102 is equipped with an NFC reader / writer. Note that, in this embodiment, the power transmitting device 100 and the power receiving device 102 are described as complying with the WPC standard, but are not limited thereto and may comply with other wireless power transmission standards.

[0014] The first control unit 201 has, 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 predetermined programs. The power receiving unit 203 receives wireless power transmitted by the power transmitting device 100 via the power receiving coil 205. The power receiving unit 203 converts the AC voltage / current received by the power receiving coil 205 into a DC voltage / current and supplies it to the charging unit 209. The DC voltage / current output by the power receiving unit 203 is also used as a power source for driving the first control unit 201.

[0015] The first communication unit 204 wirelessly communicates with the power transmitting device 100 under the control of the first control unit 201. In this embodiment, the first communication unit 204 performs load modulation, superimposes a signal on the electromagnetic waves of the wireless power received via the power receiving coil 205, and transmits the signal to the power transmitting 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 communication in accordance with the Bluetooth (registered trademark) Low Energy (hereinafter referred to as "BLE") standard. Furthermore, the first communication unit 204 may perform communication using a communication method such as a wireless LAN (e.g., Wi-Fi (registered trademark)) of the IEEE802.11 standard series or ZigBee.

[0016] The NFC 202, which serves as the second communication unit and is an example of near-field wireless communication, is an NFC reader / writer and is controlled by a program installed in the second control unit 210. The NFC 202 is composed of a circuit conforming to the NFC standard and an NFC coil. The second control unit 210, which controls the NFC 202, has a function of transmitting and receiving information related to the operation of the NFC 202 to and from the first control unit 201. The NFC 202 can detect other devices (e.g., NFC tags) that have a function capable of communicating with the NFC 202. The second control unit 210 and the NFC 202 operate by receiving power from a battery 207.

[0017] The UI 206 is a user interface of the power receiving device 102 and has a function of notifying the user of various information. In this embodiment, the UI 206 is described as being controlled by the second control unit 210, but this is not limited to this. For example, the UI 206 may be controlled by the first control unit 201, or may be controlled by another control unit (not shown). The charging unit 209 supplies power supplied from the power receiving unit 203 to the battery 207 and controls charging of the battery 207.

[0018] 1(b), 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 may be packaged and implemented as a single component. Also, the NFC 202 and the second control unit 210 are shown as separate units, but they may be packaged and implemented as a single component. In other words, there are no restrictions on the form, etc., for implementing each of the above-described components as long as they can realize the functions described below.

[0019] 2 is a block diagram showing an example of the configuration of the power transmitting device 100 according to an embodiment. In FIG. 2, the third control unit 301 has one or more processors and controls the entire power transmitting device 100. An example of such a processor is a CPU that implements various functions by executing programs. The power supply unit 307 uses power from a battery or an external power source (e.g., a commercial power source) to supply power for operating at least the third control unit 301, the fourth control unit 309, and the power transmitting unit 303.

[0020] The power transmitting unit 303 generates an AC voltage / current to be transmitted to the power receiving device 102 via the power transmitting coil 305. Specifically, the power transmitting unit 303 converts the DC voltage supplied by the power supply unit 307 into an AC voltage using a half-bridge or full-bridge switching circuit that uses FETs (Field Effect Transistors). The power transmitting unit 303 includes a gate driver that controls the ON / OFF of the FETs. The power transmitting unit 303 is capable of supplying 15 watts of power to the charging unit 209 of the power receiving device 102, which complies with the WPC standard.

[0021] The third communication unit 304 wirelessly communicates 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, superimposes a signal on the electromagnetic waves of power wirelessly transmitted via the power transmitting coil 305, and transmits the signal to the power receiving device 102. Note that the third communication unit 304 may perform communication in accordance with the Bluetooth (registered trademark) Low Energy (hereinafter referred to as "BLE") standard. Alternatively, the third communication unit 304 may perform communication using a communication method such as a wireless LAN (e.g., Wi-Fi (registered trademark)) of the IEEE802.11 standard series or ZigBee.

[0022] 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 also has a function of transmitting and receiving information related to the operation of the NFC 302 to and from the second control unit 210 of the power receiving device 102. The UI 306 is a user interface included in the power transmitting device 100, and has a function of notifying the user of various information.

[0023] The operation of the wireless power transmission system of this embodiment having the above configuration will be described below.

[0024] As described above, both the power transmitting device 100 and the power receiving device 102 have an NFC reader / writer function. When an NFC tag 101 is present near the power transmitting device 100 and the power receiving device 102, the NFC tag 101 is affected by wireless power transmission based on the WPC standard. Therefore, the power transmitting device 100 and the power receiving device 102 cooperate to prevent the NFC tag 101 from being affected in this way. More specifically, the power transmitting device 100 and the power receiving device 102 detect the presence of the NFC tag 101 by polling before transmitting or receiving power wirelessly, and determine whether or not to perform wireless power transmission based on the detection result.

[0025] Furthermore, if the reader / writers of the power transmitting device 100 and the power receiving device 102 simultaneously poll, the polling may interfere with each other, preventing the NFC tag 101 from correctly receiving the polling and making it unable to respond to the polling. In this case, the power transmitting device 100 and the power receiving device 102 cannot detect the NFC tag 101 even if it is nearby. As a result, wireless power transmission may begin between the power transmitting device 100 and the power receiving device 102 even if the NFC tag 101 is nearby, potentially damaging the NFC tag 101. To solve this problem, it is important that the power transmitting device 100 and the power receiving device 102 operate in cooperation to detect the NFC tag 101. Specifically, the power transmitting device 100 and the power receiving device 102 perform the following processes. The reader / writer is an example of a detection function for detecting an NFC tag.

[0026] [1] If the power transmitting device does not have a reader / writer, the power receiving device 102 activates the reader / writer to detect the NFC tag. [2] If the power transmitting device has a reader / writer but is not performing polling processing, the power receiving device 102 performs polling processing. [3] If the power transmitting device has a reader / writer and has already executed the polling process, the power receiving device 102 does not execute the polling process. The above cooperative operations [1] to [3] can solve the problem that the polling of the power transmitting device 100 and the power receiving device 102 interferes with each other and the NFC tag 101 cannot be correctly detected. Each of the cooperative operations [1] to [3] will be described below with reference to the flowchart in FIG.

[0027] FIG. 3 is a flowchart showing processing by the first control unit 201 of the power receiving device 102. FIG. 5 is a flowchart showing processing by the third control unit 301 of the power transmitting device 100. The operations of the power receiving device 102 and the power transmitting device 100 according to this embodiment will be described using the flowcharts of FIGS. 3 and 5. Note that S502 to S512 in FIG. 5 show part of the processing executed by the power transmitting device 100 during the negotiation phase (the processing up until NO is determined in S512). First, of the three cooperative operations described above, [1] will be described. [1] is a case where the power transmitting device 100 does not have a reader / writer (in FIG. 2, the power transmitting device 100 does not have the NFC 302 or the fourth control unit 309). In this case, the power transmitting device 100 notifies in S502 that it does not have a reader / writer function, and does not have the function to execute the processing of S503 to S505 in FIG. 5.

[0028] The power transmitting device 100 transmits a Digital Ping defined in the WPC standard (S501). When the power receiving device 102 receives the Digital Ping from the power transmitting device 100, the first control unit 201 is activated (S401). Here, the magnitude of the power of the Digital Ping is at least sufficient to activate the first control unit 201 of the power receiving device 102 located near the power transmitting coil 305.

[0029] The first control unit 201, which has been activated by the Digital Ping, controls the first communication unit 204 to transmit a Signal Strength Packet, which indicates the strength of the received Digital Ping, to the power transmitting device 100. The Signal Strength Packet is a packet defined in the WPC standard, and is transmitted to the power transmitting device 100 via the power receiving coil 205.

[0030] 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 transmitting 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 conforms, an individual identification number of the first control unit 201, and the like. Furthermore, the first control unit 201 controls the first communication unit 204 to transmit a configuration packet to the power transmitting 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.

[0031] The first control unit 201 receives an ACK from the third control unit 301 of the power transmitting device 100 as a response to the Configuration Packet. Here, the ACK is a signal defined in the WPC standard, and indicates that the power transmitting device 100 has correctly received the information included in the Configuration Packet and has accepted its contents. When the first control unit 201 receives the ACK from the power transmitting device 100, it transitions to the Negotiation phase. When the third control unit 301 transmits the ACK, it transitions to the Negotiation phase. In the Negotiation phase, negotiations regarding wireless power transmission are carried out between the power receiving device 102 and the power transmitting device 100.

[0032] Next, in the negotiation phase, the first control unit 201 inquires of the power transmitting device 100 whether the power transmitting device 100 has a reader / writer function (detection function) for detecting an NFC tag (S402). For this inquiry, a General Request Packet (Capability) from among General Request Packets defined in the WPC standard and indicating an inquiry to a power transmitting device can be used. The General Request Packet (Capability) is a packet for inquiring about capability information of the power transmitting device. Note that packets that can be used for the inquiry about the presence or absence of an NFC tag detection function are not limited to the above-mentioned packets. For example, among packets defined in the WPC standard, a Reserved Packet or a Proprietary Packet, whose packet type is not defined, may be defined and used as an inquiry about the presence or absence of an NFC tag detection function. Alternatively, among Specific Requests and General Requests defined in the WPC standard, a Reserved Packet or a Proprietary Packet, whose packet type is not defined, may be used.

[0033] In response to the inquiry from the power receiving device 102, the third control unit 301 of the power transmitting device 100 notifies the power receiving device 102 of a packet indicating whether or not the power transmitting device 100 has a reader / writer function (S502). Here, the notification indicates that the power receiving device 102 does not have a reader / writer function. The first control unit 201 that executes the determination process of S402 as described above is an example of a configuration for communicating with the power transmitting device 100 using the first communication unit 204 and determining whether or not the power transmitting device 100 has a function for detecting an NFC tag (another device). Note that, as will be described later with reference to FIG. 6, in this embodiment, a General Request Packet (Capability) and a Capability packet are used for the inquiry and response regarding the function. If the first control unit 201 receives a response from the power transmitting device 100 indicating that the power transmitting device 100 does not have an NFC tag detection function (does not have an NFC reader / writer) (NO in S402), the process proceeds to S403. In this way, when the first control unit 201 determines that the power transmitting device 100 does not have the function of detecting an NFC tag, it inquires of the second control unit 210 whether or not an NFC tag has been detected and the result of the detection (S403). Hereinafter, such an inquiry is referred to as a status check.

[0034] Here, the response from the second control unit 210 in the above-mentioned status confirmation will be described with reference to FIG. 4. FIG. 4 is a diagram showing the content of communication between the first control unit 201 and the second control unit 210 for status confirmation regarding NFC tag detection. The response to the status confirmation inquiry consists of two bits. Bit 0 indicates whether polling has been performed. Polling here refers to polling performed via the 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 in response to 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. Furthermore, 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 detected an NFC tag. If Bit 1 is "1," this indicates that the second control unit 210 has detected an NFC tag.

[0035] Here, it is assumed that the second control unit 210 notifies the first control unit 201 of “00” as a response to the status check, indicating that the polling process has not been performed and that the NFC tag has not been detected, i.e., the detection state of the NFC tag is undetermined. Note that if bit 0 is “0,” polling has not been performed, and therefore it may be determined that the detection state of the NFC tag is undetermined regardless of the state of bit 1. When the first control unit 201 receives a response “00” from the second control unit 210 in response to the status check inquiry, indicating that polling has not been performed (the detection state of the NFC tag is undetermined), the first control unit 201 instructs the second control unit 210 to perform polling (YES in S404, NO in S405, S406). As described above, when it is determined that the power transmitting device 100 does not have the function of detecting an NFC tag and the detection state of the NFC tag by the NFC 202 is undetermined, the first control unit 201 performs NFC tag detection using the second control unit 210 and the NFC 202.

[0036] At this time, when detecting an NFC tag using the NFC 202, the first control unit 201 requests the power transmitting device 100, via communication using the first communication unit 204, to limit power transmission by the power transmitting device 100 for a predetermined time. For example, in order to prevent polling from being affected by Digital Ping, the first control unit 201 temporarily suspends power transmission by Digital Ping and transmits data to the power transmitting device 100 requesting that it be resumed after a predetermined time (S407). The request for temporary suspension of power transmission can be made using an End Power Transmission (EPT) packet, which requests the suspension of power transmission and is defined in the WPC standard. The first control unit 201 transmits an EPT to the power transmitting device 100, to which an information element indicating the temporary suspension of power transmission has been added.

[0037] In this embodiment, an EPT packet including an information element indicating a temporary suspension is referred to as EPT (suspended). The predetermined time from suspension to resumption of power transmission is set to be longer than the time required for the second control unit 210 to receive a polling instruction from the first control unit 201, transmit a polling signal using the NFC 202, and receive a response to the polling signal.

[0038] Upon receiving the EPT (interrupted), the power transmitting device 100 temporarily suspends the transmission of Digital Ping (S508, S509). This prevents the polling performed by the power transmitting device 100 and the response thereto from being affected by the Digital Ping. The period for the temporary suspension (the above-mentioned predetermined time) may be set in advance in the power transmitting device 100, or information specifying the predetermined time may be included in the EPT (interrupted). When information specifying the predetermined time is included in the EPT (interrupted), the power transmitting device 100 suspends the transmission of Digital Ping for the predetermined time specified by the EPT (interrupted). When the second control unit 210 detects that the Digital Ping has been suspended, it causes the NFC 202 to start transmitting polling and executes polling processing (S408). The second control unit 210 stores the detection result of the NFC tag obtained by this polling processing. After that, when the power receiving device 102 receives power transmitted by Digital Ping from the power transmitting device 100, it transmits a signal according to the detection result of the NFC tag to the power transmitting device 100. Specifically, when the power receiving device 102 detects an NFC tag, it transmits an EPT (NFC) packet, in which an information element indicating that an NFC tag has been detected, to the power transmitting device 100. When the power receiving device 102 does not detect an NFC tag, it transmits a Signal Strength Packet or the like.

[0039] In the above description, power transmission by the power transmitting device 100 is stopped when the NFC tag 101 is detected (when polling is performed), but this is not limited to this. For example, a request may be made 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 that does not affect polling. In addition, in this request, the maximum value of the transmitted power may be notified from the power receiving device 102 to the power transmitting device.

[0040] Here, it is assumed 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 holds information indicating this detection state (referred to as NFC-related information). After the aforementioned predetermined time has elapsed, the first control unit 201 restarts (S401) in response to a Digital Ping received again from the power transmitting device 100, and executes the above-described steps S402 to S405. In S405, the first control unit 201 checks the state regarding NFC tag detection with the second control unit 210, and determines whether the second control unit 210 has executed polling (whether the detection state of the NFC tag has been determined). The second control unit 210 has detected the NFC tag in response to the polling instruction from the first control unit 201, and therefore transmits “11” to the first control unit 201, indicating that polling has been executed (bit 0 is “1”) and that the NFC tag has been detected (bit 1 is “1”).

[0041] The first control unit 201 is notified by the second control unit 210 that an NFC tag has been detected, and therefore requests the power transmitting device 100 to limit the power transmission of the Digital Ping (YES in S404, S405, S409, S410). Specifically, the power receiving device 102 transmits to the power transmitting device 100 an EPT(NFC) packet, the EPT packet including an information element indicating that an NFC tag has been detected. The third control unit 301 of the power transmitting device 100 that has received the EPT(NFC) packet stops wireless power transmission (S510, S511). Note that, although the EPT(NFC) packet has stopped power transmission by the power transmitting device 100 in the above example, the present invention is not limited to this. For example, the first control unit 201 may 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 damage the NFC tag. In addition, the power receiving device 102 may notify the power transmitting device of the maximum value of the transmitted power in the request.

[0042] On the other hand, if a response to the status check is not received from the second control unit 210 (NO in S404), the first control unit 201 transmits an EPT to the power transmitting device 100 (S411). The power transmitting device 100 that has received the EPT stops wireless power transmission. A situation in which the first control unit 201 cannot receive a response to the status check from the second control unit 210 may occur, for example, when the second control unit 210 has stopped operating because the battery is out of charge. In such a case, the power receiving device 102 cannot confirm the presence or absence of an NFC tag. Therefore, to more reliably prevent an NFC tag located near the power transmitting device 100 from being damaged by power transmission, the first control unit 201 stops power transmission by the power transmitting device 100. Note that, in S411, instead of completely stopping power transmission, the first control unit 201 may request the power transmitting device 100 to limit the maximum value of the transmitted power to a predetermined value or less. In this way, a small amount of power is transmitted that does not damage the NFC tag, and the battery 207 can be charged with that power.

[0043] As described above, when the power transmitting device 100 does not have a reader / writer, the power receiving device 102 operates the reader / writer to detect an NFC tag. Furthermore, in this embodiment, the second control unit 210, which receives power from the battery 207, stores NFC-related information indicating whether or not NFC tag detection has been performed and the result of the detection. Therefore, the following preferable control is realized.

[0044] If the NFC-related information were stored in a volatile memory (not shown) inside the first control unit 201, the first control unit 201 and the volatile memory would be reset when Digital Ping was stopped by the transmission of EPT (interrupt). As a result, in the status check after restart (S403), the determination would be based on "00" indicating the reset state, rather than "11," which indicates that polling processing has been completed and an NFC tag has been detected. This problem is solved by storing the NFC-related information in the second control unit 210, which receives power from the battery 207 and is not reset when Digital Ping is stopped. Note that the second control unit 210 erases the NFC-related information it holds (the state of NFC tag detection by the reader / writer) when the first control unit 201 references the NFC-related information. This point will be described later with reference to FIG. 6.

[0045] Furthermore, the same effect can be obtained even if the NFC-related information is stored in another configuration that is not reset when Digital Ping is stopped. For example, the NFC-related information may be implemented to be stored in a non-volatile memory (not shown). Such a non-volatile memory may be implemented inside the first control unit 201 or may be connected to the first control unit 201. Alternatively, the power transmitting device 100 may store the NFC-related information. This is because the internal circuit of the power transmitting device 100 receives power supply from the power supply unit 307, and therefore the state is not reset even when Digital Ping is stopped. In this case, the NFC-related information may be notified from the power transmitting device 100 to the power receiving device 102 in the negotiation phase.

[0046] Next, of the three cooperative operations described above, [2] will be described with reference to the flowcharts of Figures 3 and 5. This operation is performed when the power transmitting device 100 has a function for detecting an NFC tag but is not performing polling processing.

[0047] When the first control unit 201 receives a response to the General Request Packet (Capability) indicating that the power transmitting device 100 has a reader / writer (YES in S402), the process proceeds to S412. If the power transmitting device 100 has a reader / writer, the power receiving device 102 may be controlled not to perform polling. However, in this embodiment, more suitable cooperative operation is achieved by switching the operation depending on the detection state of the NFC tag in the power transmitting device 100. First, when the first control unit 201 determines that the power transmitting device 100 has a reader / writer, the first control unit 201 determines whether polling has been performed in the power transmitting device 100 (S412). This determination can be made by inquiring about NFC-related information to the power transmitting device 100 in the negotiation phase and receiving the response from the power transmitting device 100. To this end, the first control unit 201 transmits to the power transmitting device 100 a packet requesting information corresponding to bit 0 and bit 1 shown in FIG. 4 (a packet inquiring about NFC-related information).

[0048] As a packet for inquiring about NFC-related information, for example, a reserved packet or a proprietary packet, which is defined in the WPC standard and has no defined packet type, can be defined. Also, a reserved packet or a proprietary packet, which is defined in the WPC standard and has no defined packet type, can be used.

[0049] The third control unit 301 of the power transmitting device 100, which has received the inquiry about the NFC-related information, checks the state by inquiring of the fourth control unit 309 about whether NFC tag detection has been performed and the result of the detection (S503, S504). The third control unit 301 receives information indicating the detection state described in Fig. 4 from the fourth control unit 309, and transmits a packet including this information to the power receiving device 102 using the third communication unit 304 as a response to the inquiry about the NFC-related information (S505).

[0050] Assume that the response from the power transmitting device 100 is information (“00”) indicating that polling is not being performed and that an NFC tag has not been detected (NO in S412). In this case, the first control unit 201 instructs the second control unit 210 to perform polling (S406). Then, by the processing from S407 onwards described above, the second control unit 210 detects an NFC tag without interfering with Digital Ping. Note that although the configuration has been described in which the power receiving device 102 immediately performs polling when the power transmitting device 100 is not performing polling (NO in S412), the present invention is not limited to this. If NO in S412, the first control unit 201 may perform the processing from S403 onwards.

[0051] Furthermore, following the inquiry about the NFC-related information, the first control unit 201 may transmit to the power transmitting device 100 a packet indicating that the first control unit 201 will perform processing to detect an NFC tag (i.e., perform polling). Here, among packets defined in 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 to perform the NFC detection processing. For example, among General Requests and Specific Requests defined in the WPC standard, a reserved packet or a proprietary packet whose packet type is not defined may be used.

[0052] When the power transmitting device 100 receives a packet indicating an intention to perform the NFC detection process from the power receiving device 102, the power transmitting device 100 may refrain from performing the polling process for a predetermined time (S505, S507). This more reliably prevents interference between the pollings transmitted by the NFC 302 of the power transmitting device 100 and the NFC 202 of the power receiving device 102. Here, the predetermined time is set to be at least longer than the time it takes for the second control unit 210 to receive a polling instruction, transmit a polling signal, and receive a response thereto.

[0053] Next, of the three cooperative operations, [3] will be described with reference to the flowchart in Fig. 3. This operation is performed when the power transmitting device 100 has a reader / writer and has already executed polling processing in the power transmitting device 100.

[0054] Assume that the response from the power transmitting device 100 to the inquiry about NFC-related information sent by the first control unit 201 is information indicating that polling is being performed and no NFC tag has been detected ("10" in FIG. 5) (YES in S412, NO in S413). In this case, the first control unit 201 determines that no NFC tag is present near the power transmitting device 100, terminates the process shown in FIG. 3, and wireless power transmission from the power transmitting device 100 to the power receiving device 102 is performed.

[0055] Also, assume that the response from the power transmitting device 100 is information indicating that polling is being performed and that an NFC tag has been detected ("11" in FIG. 4). In this case, the first control unit 201 confirms that an NFC tag is present near the power transmitting device 100, transmits an EPT(NFC) to the power transmitting device 100, and ends this process. In this case, power transmission from the power transmitting device 100 is stopped, and wireless power transmission from the power transmitting device 100 to the power receiving device 102 is not executed.

[0056] In the above description, the first control unit 201 transmits EPT(NFC) in response to the detection of an NFC tag and stops power transmission by the power transmitting device 100, but the present invention is not limited to this. For example, instead of EPT(NFC), a packet requesting the transmission of small power that does not damage the NFC tag may be transmitted to the power transmitting device 100, and the battery 207 may be charged with the power.

[0057] Next, an operation sequence of wireless power transmission by the power receiving device 102 and the power transmitting device 100 of this embodiment, which operate as described above, will be described with reference to Fig. 6. Fig. 6 is an operation sequence diagram of the wireless charging system according to this embodiment. Fig. 6 illustrates an operation sequence for case [1] of the three cooperative operations described above.

[0058] When the power transmitting unit 303 of the power transmitting device 100 is activated, it starts the Selection phase and transmits an Analog Ping via the power transmitting coil 305 (600). The Analog Ping is a minute power signal for detecting an object present near the power transmitting coil 305. The power transmitting device 100 detects the voltage value or current value of the power transmitting coil 305 when transmitting the Analog Ping, and if the voltage is below a certain threshold or the current value exceeds a certain threshold, it determines that an object is present and transitions to the Ping phase. In the Ping phase, the power transmitting device 100 transmits a Digital Ping with a power greater than that of the Analog Ping (601).

[0059] Upon receiving the Digital Ping, the first control unit 201 transmits a Signal Strength Packet, an ID Packet, and a Configuration Packet to the power transmitting device 100 (602, 603, 604). When the power transmitting device 100 transmits an ACK in response to the Configuration Packet and the power receiving device 102 receives this (605), the power transmitting device 100 and the power receiving device 102 transition to a Negotiation phase. In the Negotiation phase, the first control unit 201 transmits a General Request (Capability) to the power transmitting device 100 inquiring whether or not the power transmitting device 100 has a function for detecting NFC tags (606). The first control unit 201 receives a Capability including information indicating whether or not the power transmitting device 100 has a function for detecting NFC tags from the power transmitting device 100 (607).

[0060] Here, it is assumed that the power transmitting device 100 does not have a reader / writer function (does not have a function to detect an NFC tag). In this case, the first control unit 201 checks the status regarding the detection of an NFC tag with the second control unit 210 (608). In Fig. 6, "00" indicating that the polling process has not been executed and that an NFC tag has not been detected is received from the second control unit 210 (609). After responding to the request for status check, the second control unit 210 resets (deletes) the held NFC tag detection status (NFC-related information) (610).

[0061] When "00" is received from the second control unit 210 as a result of the status check, the first control unit 201 issues a polling instruction to the second control unit 210 (611). When an ACK in response to the polling instruction is received from the second control unit 210 (612), the first control unit 201 transmits an EPT (interrupt) to the power transmitting device 100 (613). When the power transmitting device 100 temporarily interrupts the transmission of Digital Ping power in response to the EPT (interrupt), the second control unit 210 performs a polling process (614). Here, when a response is received from the NFC tag (615), the second control unit 210 updates and holds the detection status (NFC-related information) of the NFC tag (616).

[0062] Thereafter, the first control unit 201 receives a Digital Ping from the power transmitting device 100 again and restarts (617), and again checks the status with the second control unit 210 (618). At this stage, the second control unit 210 performs a polling process and holds NFC-related information indicating that an NFC tag has been detected, so it transmits "11" (FIG. 4) to the first control unit 201 as a response to the status check (619). After the second control unit 210 responds with the status check, it clears (deletes) the held NFC-related information (620). Having received "11" as the NFC tag detection status, the first control unit 201 transmits EPT(NFC) to the power transmitting device 100 to stop power transmission by the power transmitting device 100 (621).

[0063] As described above, after the second control unit 210 has responded to the status check, that is, in response to being referred to by the first control unit 201, the second control unit 210 clears (620) the NFC-related information. Specifically, after transmitting the detection status "11" to the first control unit 201, the second control unit 210 resets the detection status to "00." The reason for this is that the second control unit 210 needs to transmit, as a response (619), to the first control unit 201, information (that is, the latest NFC-related information) in response to the polling (614) performed immediately after the latest polling instruction (611) from the first control unit 201.

[0064] If the stored NFC-related information is not cleared and the status of the most recently executed polling is retained, the following problem may occur. For example, assume that, at the time when the status check (608) is received, the stored information indicates that no NFC tag was detected in the previous polling (i.e., the status "10"). If "10" is sent as the response (609) from the second control unit 210, the first control unit 201 will not issue a polling instruction (YES in S405, NO in S409) based on the flowchart in FIG. 3. In this case, if an NFC tag is present at the time when the status check (608) is requested, a problem occurs in which the NFC tag cannot be detected. This problem can be avoided by the second control unit 210 clearing the stored status (setting it to "00") when responding to the status check request from the first control unit 201. That is, the second control unit 210 retains the result of the detection performed in response to the first control unit 201's decision to detect the NFC tag 101 as the detection status in a storage unit (e.g., non-volatile memory). When the first control unit 201 refers to the detection state stored in the storage unit, the second control unit 210 operates to delete the detection state from the storage unit.

[0065] Furthermore, while Digital Ping is stopped by EPT (interrupt) (613), the power receiving device 102 may be moved from the power transmitting device 100 to another power transmitting device (not shown). Because the first control unit 201 is stopped while Digital Ping is stopped, the first control unit 201 cannot detect such a replacement.

[0066] Let us consider a case where, immediately after transmitting an EPT (interrupt), the power receiving device 102 is removed from the power transmitting device 100 by the user and polling is performed before the power receiving device 102 is placed on another power transmitting device. In this case, since there is no NFC tag in proximity at the time of polling, the NFC-related status is "10" (as a result of the polling process, no NFC tag is detected). After that, assume that the power receiving device 102 is placed on another power transmitting device, and an NFC tag is present in proximity to the other power transmitting device. In this case, when the power receiving device placed on the other power transmitting device resumes operation, the NFC-related information received by the first control unit 201 from the second control unit 210 indicates a detected status ("10"). Therefore, polling is not performed and it is determined that no NFC tag is present. In this case, the second control unit 210 should notify the first control unit 201 that the NFC-related status is "00," but the second control unit 210 actually stores the status "10," resulting in a status mismatch.

[0067] Therefore, when the first control unit 201 of the power receiving device 102 acquires the identification information of the power transmitting device 100 and executes detection of an NFC tag by the NFC 202, the first control unit 201 checks whether the identification information acquired before and after the execution matches. If the two do not match, the first control unit 201 erases the detection state held in the second control unit 210.

[0068] For example, the first control unit 201 inquires about the identification information of the power transmitting device 100 every time it receives a Digital Ping and starts up. Specifically, it transmits a packet inquiring about the identification information of the power transmitting device, among General Request Packets defined in the WPC standard, and receives the identification information of the power transmitting device. An example of such a packet is a General Request Packet (Power Transmitter Identification). The first control unit 201 compares the identification information previously acquired from the power transmitting device with the identification information currently acquired, and if the identification information does not match, it instructs the second control unit 210 to clear the NFC-related information. In this way, it is possible to compare the identification information of the power transmitting device before and after transmitting the EPT (interrupt) (before and after the NFC tag detection operation), thereby eliminating the above-mentioned problem.

[0069] For example, assume that before the power receiving device 102 transmits the EPT (interrupted) (613), it is placed on the power transmitting device 100 with identification information "aa," and is replaced by another power transmitting device (with identification information "bb") while the Digital Ping is interrupted. In this case, the identification information of the power transmitting device before and after the EPT (interrupted) (after the first control unit 201 is restarted) does not match (aa ≠ bb), and therefore the NFC status is cleared to "00." As a result, the first control unit 201 receives "00" as the response (619) to the status check (619), and becomes able to detect the NFC tag placed on another power transmitting device.

[0070] On the other hand, if the NFC tag was placed on the power transmitting device with identification information "aa" before sending the EPT (interrupted) (613) and is still placed on the same power transmitting device (identification information "aa") after the Digital Ping is interrupted, the identification information before and after the EPT (interrupted) matches, so the NFC-related information is not cleared. Therefore, the first control unit 201 receives the NFC-related information (619) updated after the polling (614), making it possible to correctly detect the presence or absence of an NFC tag placed on the power transmitting device.

[0071] In the present embodiment, the NFC reader / writer is used only for detecting an NFC tag, but the present invention is not limited to this. For example, in a product (e.g., a smartphone) (not shown) in which the power receiving device 102 is implemented, the reader / writer may be used for another application (other than for detecting an NFC tag).

[0072] Note that if the NFC reader / writer is used with another application and the above-described NFC-related information is stored, the following problem may occur. That is, if another application uses the reader / writer to communicate with an 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 it transmits a response to the status check. Therefore, if the power transmitting device 100 and the power receiving device 102 come 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 check (403). As a result, the first control unit 201 transmits EPT(NFC) to the power transmitting device 100, and the battery 207 of the power receiving device 102 cannot be charged even if there is no NFC tag close to the power transmitting device 100.

[0073] Therefore, the second control unit 210 stores, as the NFC-related status, the detection result obtained by polling immediately after receiving a polling instruction for controlling wireless power transmission from the first control unit 201, and does not store the NFC-related status otherwise. By doing so, even if the reader / writer is operated by another application, the second control unit 210 does not update the NFC-related information, thereby solving the above problem.

[0074] <Other embodiments> In the above-described wireless power transmission system, the wireless power transmission method is not particularly limited. For example, the wireless power transmission method can be a magnetic resonance method, which transmits power by coupling through magnetic field resonance between a resonator (resonant element) of a power transmitting device and a resonator (resonant element) of a power receiving device. In addition, a power transmission method using an electromagnetic induction method, an electric field resonance method, a microwave method, a laser method, etc. can be used.

[0075] The power transmitting device and the power receiving device may be, for example, an image input device such as an imaging device (such as a camera or a video camera) or a scanner, or an image output device such as a printer, a copier, a projector, etc. The power transmitting device and the power receiving device may 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.

[0076] The flowchart shown in FIG. 3 starts when the first control unit 201 is powered on. The process shown in FIG. 3 is realized by the first control unit 201 executing a program stored in the memory of the power receiving device 102. The process shown in FIG. 5 is realized by the third control unit 301 executing a program stored in the memory of the power transmitting device 100. At least a part of the processes shown in the flowcharts of FIG. 3 and FIG. 5 may be realized by hardware. When realized by hardware, for example, a predetermined compiler may be used to automatically generate a dedicated circuit on an FPGA from a program for realizing each step. FPGA is an abbreviation for Field Programmable GATE Array. A GATE Array circuit may be formed in the same manner as an FPGA and realized as hardware.

[0077] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0078] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0079] 102: power receiving device, 201: first control unit, 202: NFC, 203: power receiving unit, 204: first communication unit, 205: power receiving coil, 206: UI, 207: battery, 208: memory, 209: charging unit, 210: second control unit

Claims

1. A power transmission device, A power transmission means for wirelessly transmitting power; a detection means for detecting an NFC tag that performs near field communication (NFC) by polling the NFC; a receiving means for receiving a request for information on the power transmitting device from a power receiving device capable of detecting an NFC tag by NFC polling; a transmitting means for transmitting, to the power receiving device, information indicating whether the power transmitting device supports an NFC tag detection process, information indicating whether the power transmitting device has executed an NFC tag detection process, and information indicating a result of the NFC tag detection process, after receiving the request; The power transmitting device is characterized in that the transmitting means transmits a Ping to activate the power receiving device.

2. The power transmitting device according to claim 1, characterized in that information indicating whether the power transmitting device supports NFC tag detection processing, information indicating whether the power transmitting device has performed NFC tag detection processing, and information indicating the results of the NFC tag detection processing are transmitted during a negotiation phase in which negotiations regarding wireless power transmission are conducted.

3. A communication method performed by a power transmission device that wirelessly transmits power, a detection step of detecting an NFC tag that performs near field communication (NFC) by polling the NFC; a receiving step of receiving a request for information on the power transmitting device from a power receiving device that can detect an NFC tag by NFC polling; a transmitting step of transmitting, to the power receiving device, information indicating whether the power transmitting device supports an NFC tag detection process, information indicating whether the power transmitting device has executed an NFC tag detection process, and information indicating a result of the NFC tag detection process, after receiving the request; a transmitting step of transmitting a ping to activate the power receiving device.

4. A program for causing a computer to execute the communication method according to any one of claims 3 to 5.

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