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 transmitting device, a communication method, and a program. [Background technology]

[0002] Technological development of wireless power transmission systems is being widely conducted. Standards for power transmitting devices and power receiving devices that constitute wireless power transmission systems include standards established by WPC, a standardization organization for non-contact charging standards (hereinafter referred to as 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 a device with which to communicate. Polling is sent by a device that has the function of an NFC-standard reader / writer. An NFC tag is a device that has the function of receiving the polling sent by the reader / writer and responding 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 complies with the WPC standard transmits a response to polling performed by a power transmitting device that has a reader / writer function and complies with the NFC standard. Patent Document 1 limits the wireless power 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] JP 2014-093818 A 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 in Patent Document 1, if the power transmitting device has a reader / writer function, the power transmitting device detects the presence of an NFC tag by polling and limits the power to be transmitted, 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, no proposal has been made so far regarding the cooperative operation of 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 implemented in the power receiving device. [Means for solving the problem]

[0008] According to one aspect of the present invention, a power transmission device includes: A power transmitting 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 of the power transmitting device from a power receiving device capable of detecting an NFC tag by NFC polling; The power receiving device has a transmitting means for transmitting, after receiving the request, information indicating whether NFC tag detection processing is supported by the power transmitting device, information indicating whether NFC tag detection processing has been performed by the power transmitting device, and information indicating a result of the NFC tag detection processing to the power receiving device, and the receiving means receives identification information of the power receiving device. Effect 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 description 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 the embodiment. [Diagram 2] FIG. 1 is a block diagram showing an example of the configuration of a power transmitting device according to an embodiment. [Diagram 3] 5 is a flowchart showing an operation of a control unit of the power receiving device. [Figure 4] 4 is a conceptual diagram of NFC-related communication between a first control unit and a second control unit. [Diagram 5] 5 is a flowchart showing an operation of a control unit of the power transmitting device. [Figure 6] FIG. 4 is an operation sequence diagram of the wireless charging system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0012] FIG. 1(a) is a diagram showing an example of the configuration of a wireless power transmission system according to an embodiment. A power receiving device 102 conforming to the WPC standard is mounted on a power transmitting device 100 conforming to 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 conform to the WPC standard and further have functions described 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 power received from the power transmitting device 100 to a load (e.g., a rechargeable battery) connected to the power transmitting device 100. When the NFC tag 101 is in close 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 a configuration example 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 being compliant with the WPC standard, but are not limited thereto, and may be compliant 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. One example of a processor is a CPU (Central Processing Unit) that realizes various functions by executing a predetermined program. 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 / AC current received by the power receiving coil 205 into a DC voltage / DC current and supplies it to the charging unit 209. The DC voltage / DC 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 wave of the wireless power received via the power receiving coil 205, and transmits the signal to the power transmitting device 100. The load modulation may be frequency modulation or amplitude modulation. The memory 208 stores the calculation result of the first control unit 201. The first communication unit 204 may perform communication in accordance with the Bluetooth (registered trademark) Low Energy (hereinafter referred to as "BLE") standard. The first communication unit 204 may also perform communication by a communication method such as a wireless LAN (e.g., Wi-Fi (registered trademark)) of the IEEE802.11 standard series, ZigBee, etc.

[0016] The NFC 202, which is an example of short-distance wireless communication as the second communication unit, is an NFC reader / writer and is controlled by a program implemented 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 that 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 supply 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 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 them may be packaged and implemented as one component. Also, the NFC 202 and the second control unit 210 are shown as separate units, but they may be packaged and implemented as one component. In other words, there are no restrictions on the form or the like for realizing each of the above-mentioned configurations as long as they can realize the functions described below.

[0019] Fig. 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. One example of such a processor is a CPU that realizes various functions by executing a program. The power supply unit 307 supplies power for operating at least the third control unit 301, the fourth control unit 309, and the power transmitting unit 303 using power from a battery or an external power supply (e.g., a commercial power supply).

[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 a DC voltage supplied by the power supply unit 307 into an AC voltage by a switching circuit in a half-bridge or full-bridge configuration using a FET (Field Effect Transistor). The power transmitting unit 303 includes a gate driver that controls ON / OFF of the FET. The power transmitting unit 303 has a capacity to supply 15 watts of power to the charging unit 209 of the power receiving device 102 that 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 the power wirelessly transmitted via the power transmitting coil 305, and transmits the signal to the power receiving device 102. The third communication unit 304 may perform communication in compliance with the Bluetooth (registered trademark) Low Energy (hereinafter, referred to as "BLE") standard. The third communication unit 304 may also perform communication by a communication method such as a wireless LAN (e.g., Wi-Fi (registered trademark)) of the IEEE802.11 standard series, ZigBee, etc.

[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 the 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 prior to wirelessly transmitting and receiving power, and determine whether or not to perform wireless power transmission depending on the detection result.

[0025] In addition, when the reader / writers of the power transmitting device 100 and the power receiving device 102 simultaneously poll, the polls may interfere with each other, and the NFC tag 101 may not be able to receive the polling correctly and may not be able to respond to the polling. In that case, the power transmitting device 100 and the power receiving device 102 may not be able to detect the NFC tag 101 even if it is nearby. As a result, even if the NFC tag 101 is nearby, wireless power transmission may start between the power transmitting device 100 and the power receiving device 102, and the NFC tag 101 may be damaged. In order to solve such a problem, it is important that the power transmitting device 100 and the power receiving device 102 work in cooperation to detect the NFC tag 101. Specifically, the power transmitting device 100 and the power receiving device 102 perform the following process. 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 operates 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 the 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 the process by the first control unit 201 of the power receiving device 102. FIG. 5 is a flowchart showing the process by the third control unit 301 of the power transmitting device 100. The operation of the power receiving device 102 and the power transmitting device 100 according to the present embodiment will be described with reference to the flowcharts of FIG. 3 and FIG. 5. Note that S502 to S512 in FIG. 5 show a part of the process executed by the power transmitting device 100 during the negotiation phase (the process until NO is determined in S512). First, [1] of the above-mentioned three cooperative operations 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 and 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 of executing the processes 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 started (S401). Here, the magnitude of the power of the Digital Ping is at least sufficient to start up the first control unit 201 of the power receiving device 102 present in the vicinity of the power transmitting coil 305.

[0029] The first control unit 201, which has been started by the Digital Ping, controls the first communication unit 204 to transmit a Signal Strength Packet indicating 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 complies, 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 regarding 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 the contents. When the first control unit 201 receives the ACK from the power transmitting device 100, the first control unit 201 transitions to a negotiation phase. When the third control unit 301 transmits the ACK, the third control unit 301 transitions to a negotiation phase. In the negotiation phase, negotiations regarding wireless power transmission are performed 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) of the General Request Packet, which is defined in the WPC standard and indicates an inquiry to the 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 the detection function of an NFC tag are not limited to the above-mentioned packets. For example, a Reserved Packet or a Proprietary Packet, which is not defined as a packet type, of the packets defined in the WPC standard may be defined and used as an inquiry about the presence or absence of the detection function of an NFC tag. Alternatively, a Reserved Packet or a Proprietary Packet, which is not defined as a packet type, of the Specific Request or General Request defined in the WPC standard 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, it is notified 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). In this embodiment, a General Request Packet (Capability) and a Capability packet are used for the inquiry and response regarding the above-mentioned function, which will be described later with reference to FIG. 6. When the first control unit 201 receives a response from the power transmitting device 100 indicating that the power transmitting device 100 does not have a function for detecting an NFC tag (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 a function for detecting an NFC tag, it inquires of the second control unit 210 as to 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 state confirmation will be described with reference to FIG. 4. FIG. 4 is a diagram showing the contents of communication for state confirmation regarding detection of an NFC tag between the first control unit 201 and the second control unit 210. The response to the inquiry for state confirmation is composed of two bits. Bit 0 indicates whether or not 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. When bit 0 is "0", it indicates that the second control unit 210 has not performed polling according to an instruction from the first control unit 201. When bit 0 is "1", it indicates that the second control unit 210 has performed polling according to an instruction from the first control unit 201. When bit 1 is "0", it indicates that the second control unit 210 has detected an NFC tag as a result of performing the above-mentioned polling. When bit 1 is "0", it indicates that the second control unit 210 has not detected an NFC tag. When bit 1 is "1", it 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 state confirmation, which indicates that the polling process has not been performed and that the NFC tag has not been detected, that is, the detection state of the NFC tag is undetermined. If bit0 is "0", polling has not been performed, so it may be determined that the detection state of the NFC tag is undetermined regardless of the state of bit1. When the first control unit 201 receives a response "00" from the second control unit 210 in response to the state confirmation inquiry, which indicates 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 a 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 detection of the NFC tag 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 to limit power transmission by the power transmitting device 100 for a predetermined time by communication using the first communication unit 204. For example, in order to prevent polling from being affected by Digital Ping, the first control unit 201 transmits data to the power transmitting device 100 requesting that the power transmission of Digital Ping be temporarily suspended and resumed after a predetermined time (S407). The request for the temporary suspension of power transmission can use an End Power Transmission (EPT) packet defined in the WPC standard for requesting the suspension of power transmission. The first control unit 201 transmits to the power transmitting device 100 an EPT to which an information element indicating the temporary suspension of power transmission is added.

[0037] In this embodiment, an EPT packet including an information element indicating a temporary interruption is expressed as EPT (interruption). The predetermined time from the interruption of power transmission to the resumption 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] The power transmitting device 100 that has received the EPT (interrupted) temporarily stops the transmission of the Digital Ping (S508, S509). This makes it possible to prevent 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 interruption (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 stops the transmission of the Digital Ping for the predetermined time specified by the EPT (interrupted). When the second control unit 210 detects that the Digital Ping has been stopped, it causes the NFC 202 to start transmitting the polling, and executes the polling process (S408). The second control unit 210 stores the detection result of the NFC tag by this polling process. After that, when the power receiving device 102 receives a Digital Ping from the power transmitting device 100, the power receiving device 102 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, the power receiving device 102 transmits an EPT (NFC) packet in which an information element indicating that an NFC tag has been detected is stored in the EPT packet to the power transmitting device 100. When an NFC tag is not detected, the power receiving device 102 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 the above. For example, a request may be made to limit the maximum value of the transmission power to a predetermined value or less. In this case, the maximum value of the transmission power is determined within a range that does not affect polling. In addition, in this request, the maximum value of the transmission 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 the 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). When the above-mentioned predetermined time has elapsed, the first control unit 201 restarts (S401) by the Digital Ping received again from the power transmitting device 100, and executes the above-mentioned S402 to S405. In S405, the first control unit 201 checks the state regarding the detection of the NFC tag with the second control unit 210, and judges whether or not the second control unit 210 has performed the polling (whether or not the detection state of the NFC tag has been determined). Since the second control unit 210 has detected the NFC tag in response to the polling instruction from the first control unit 201, it transmits "11" to the first control unit 201, indicating that the polling has been performed (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 the NFC tag has been detected, and therefore requests the power transmitting device 100 to limit the power transmission of the Digital Ping (S404, S405, YES in S409, S410). Specifically, the power receiving device 102 transmits an EPT(NFC) packet, in which an information element indicating that the NFC tag has been detected is stored, to the power transmitting device 100. The third control unit 301 of the power transmitting device 100 that has received the EPT(NFC) stops wireless power transmission (S510, S511). Note that, in the above description, the power transmitting device 100 has stopped power transmission by the EPT(NFC) packet, but this is not limited thereto. For example, it may be requested that the maximum value of the transmission 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, in the request, the maximum value of the transmission power may be notified from the power receiving device 102 to the power transmitting device.

[0042] On the other hand, when no response to the state confirmation is 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 state confirmation from the second control unit 210 may occur, for example, when the second control unit 210 stops operating because the battery is exhausted. In such a case, the power receiving device 102 cannot confirm the presence or absence of an NFC tag. Therefore, in order to more reliably avoid the possibility that the NFC tag is present in the vicinity of the power transmitting device 100 and is damaged by power transmission, the first control unit 201 stops power transmission by the power transmitting device 100. Note that, regarding S411, instead of completely stopping power transmission, the power transmitting device 100 may be requested to limit the maximum value of the transmission power to a predetermined value or less. In this way, a small amount of power that does not damage the NFC tag is transmitted, 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 is stored in a volatile memory (not shown) inside the first control unit 201, the first control unit 201 and the volatile memory are reset when Digital Ping is stopped by sending EPT (interrupt). As a result, in the state check after restart (S403), the determination should be based on "11" indicating that polling processing has been completed and an NFC tag has been detected, but the determination is based on "00" in the reset state. 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 by the stop of Digital Ping. Note that the second control unit 210 erases the NFC-related information held by the first control unit 201 (detection state of the NFC tag by the reader / writer). This point will be described later with reference to FIG. 6.

[0045] The same effect can be obtained even if the NFC-related information is stored by another configuration that is not reset by the stop of Digital Ping. For example, the NFC-related information may be implemented so as 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. The power transmitting device 100 may also 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 if 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, the above-mentioned three cooperative operations will be described with reference to the flowcharts of Fig. 3 and Fig. 5. This operation is performed when the power transmitting device 100 has a function of detecting an NFC tag but is not performing a polling process.

[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. When the power transmitting device 100 has a reader / writer, the power receiving device 102 may be controlled not to execute polling. In this embodiment, however, the operation is switched according to the detection state of the NFC tag in the power transmitting device 100, thereby realizing a more suitable cooperative operation. 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 executed in the power transmitting device 100 (S412). This determination can be realized 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. For this purpose, a packet requesting information corresponding to bit 0 and bit 1 shown in FIG. 4 (a packet inquiring about NFC-related information) is transmitted to the power transmitting device 100.

[0048] As a packet for inquiring about NFC-related information, for example, a reserved packet or a proprietary packet whose packet type is not defined among packets defined in the WPC standard can be defined. Also, a reserved packet or a proprietary packet whose packet type is not defined among general requests or specific requests defined in the WPC standard may be used.

[0049] The third control unit 301 of the power transmitting device 100 that has received the inquiry about the NFC-related information checks the state by inquiring of the fourth control unit 309 about whether or not 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 above-mentioned processing from S407 onwards, the second control unit 210 detects the 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. When NO in S412, the first control unit 201 may perform 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 for detecting an NFC tag (i.e., perform polling). Here, among packets defined in the WPC standard, a reserved packet or a proprietary packet in which the packet type is not defined may be defined as a packet indicating the intention of the first control unit 201 to perform an NFC detection process. For example, among General Request and Specific Request defined in the WPC standard, a reserved packet or a proprietary packet in which the packet type is not defined may be used.

[0052] When the power transmitting device 100 receives a packet indicating an intention to perform an NFC detection process from the power receiving device 102, the power transmitting device 100 may not perform a polling process for a predetermined time (S505, S507). This makes it possible to more reliably prevent interference between the polling 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 required 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, the operation [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 a polling process in the power transmitting device 100.

[0054] Assume that the response from the power transmitting device 100 to the inquiry about the NFC-related information sent by the first control unit 201 is information indicating that polling is being performed and that 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 in the vicinity of the power transmitting device 100, and ends 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 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 in the vicinity of 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 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 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 the embodiment. Fig. 6 illustrates an operation sequence for the case [1] of the above three cooperative operations.

[0058] When the power transmitting unit 303 of the power transmitting device 100 is started, it starts the Selection phase and transmits an Analog Ping via the power transmitting coil 305 (600). The Analog Ping is a signal of minute power 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 higher than the Analog Ping (601).

[0059] When the first control unit 201 receives the Digital Ping, it 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 an NFC tag (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 an NFC tag 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 performs a state check 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 the state check, the second control unit 210 resets (deletes) the detection state of the NFC tag (NFC-related information) that is held (610).

[0061] When "00" is received from the second control unit 210 as a result of the state check, the first control unit 201 issues a polling instruction to the second control unit 210 (611). When an ACK for 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 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 state (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 an 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 the NFC-related information (620). Specifically, after transmitting the detection status "11" to the first control unit 201, the second control unit 210 resets the detection status to "00". This is because the second control unit 210 needs to transmit information in response to the polling (614) performed immediately after the most recent polling instruction (611) from the first control unit 201 (that is, the most recent NFC-related information) to the first control unit 201 as a response (619).

[0064] If the stored NFC-related information is not cleared and the state of the polling executed immediately before is stored, the following problems may occur. For example, assume that when the state check (608) is received, the fact that no NFC tag was detected by the previously executed polling (i.e., state "10") is stored. When "10" is transmitted as the response (609) from the second control unit 210, the first control unit 201 does not issue a polling instruction (YES in S405, NO in S409) based on the flowchart of FIG. 3. In this case, if an NFC tag exists when the state check (608) is requested, a problem occurs in which the NFC tag cannot be detected. Such a problem can be avoided by clearing the stored state (setting it to "00") when the second control unit 210 responds to the request for state check from the first control unit 201. That is, the second control unit 210 stores the result of the detection executed in response to the first control unit 201's decision to execute detection of the NFC tag 101 as the detection state 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] In addition, 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). Since 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 assume that immediately after transmitting 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 the vicinity at the time of polling, the NFC-related status is "10" (as a result of the polling process, the NFC tag is not detected). After that, it is assumed that the power receiving device 102 is placed on another power transmitting device, and an NFC tag is present in the vicinity of 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 that the first control unit 201 receives from the second control unit 210 indicates a detection status ("10"), so that polling is not performed and it is determined that there is no NFC tag. In this case, the second control unit 210 should notify the first control unit 201 of the NFC-related status as "00", but in reality, the status "10" is stored, and a status mismatch occurs.

[0067] Therefore, the first control unit 201 of the power receiving device 102 acquires the identification information of the power transmitting device 100, and when detecting an NFC tag by the NFC 202, checks whether the identification information acquired before and after the detection 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. Such a packet is, for example, 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 operation of detecting the NFC tag), and the above-mentioned problem is resolved.

[0069] For example, assume that before the power receiving device 102 transmits (613) an EPT (interrupted), the power receiving device 102 is placed on the power transmitting device 100 with identification information "aa", and is replaced by another power transmitting device (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), so 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 it becomes possible to detect the NFC tag placed on the other power transmitting device.

[0070] On the other hand, if the NFC tag was placed on the power transmitting device with the identification information "aa" before the EPT (interrupted) (613) was sent and is still placed on the same power transmitting device (with the 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), and it becomes 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 the application of detecting an NFC tag).

[0072] If the NFC-related information is stored when the NFC reader / writer is used in another application, the following problem may occur. That is, when the reader / writer is used in another application 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, when 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-associated state, the detection result 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-associated state otherwise. By doing so, even if the reader / writer is operated by another application, the second control unit 210 does not update the NFC-associated information, and the above problem can be solved.

[0074] <Other embodiments> In the above-mentioned wireless power transmission system, the wireless power transmission method is not particularly limited. For example, the wireless power transmission method may be a magnetic resonance method that transmits power by coupling due to magnetic 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. may 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 (camera, video camera, etc.) 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 device 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 is started 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 process shown in the flowcharts of FIG. 3 and FIG. 5 may be realized by hardware. When the process is realized by hardware, for example, a specific 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 a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0078] The invention is not limited to the above-described embodiments, and various modifications and variations are possible 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 transmitting means for wirelessly transmitting power; A detection unit that detects an NFC tag that performs near field communication (NFC) by polling the NFC; A receiving means for receiving a request for information of the power transmitting device from a power receiving device capable of detecting an NFC tag by NFC polling; a transmitting means for transmitting, after receiving the request, 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; The power transmitting device, wherein the receiving means receives identification information of the power receiving device.

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

3. The power transmitting device according to claim 1 or 2, characterized in that when the power transmitting device receives information indicating that NFC tag detection has not been performed by the power transmitting device, the information indicating whether NFC tag detection processing is supported by the power transmitting device, the information indicating whether NFC tag detection processing has been performed by the power transmitting device, and the information indicating the result of the NFC tag detection processing are transmitted to a power receiving device that detects NFC tags by NFC polling.

4. The power transmitting device according to any one of claims 1 to 3, characterized in that the information indicating whether the power transmitting device supports NFC tag detection processing, the information indicating whether the power transmitting device has performed NFC tag detection processing, and the information indicating the result of the NFC tag detection processing are transmitted to a power receiving device that transmits a request to limit the power to be transmitted when the power transmitting device receives information indicating that the power transmitting device has performed NFC tag detection and information indicating that the NFC tag has been detected.

5. 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 first receiving step of receiving a request for information of the power transmitting device from a power receiving device capable of detecting an NFC tag by NFC polling; a transmission step of transmitting, to the power receiving device, information indicating whether an NFC tag detection process is supported by the power transmitting device, information indicating whether an NFC tag detection process has been executed by the power transmitting device, and information indicating a result of the NFC tag detection process, after receiving the request; a second receiving step of receiving identification information of the power receiving device from the power receiving device.

6. The communication method described in claim 5, characterized in that the information indicating whether the power transmitting device supports NFC tag detection processing, the information indicating whether the power transmitting device has performed NFC tag detection processing, and the information indicating the result of the NFC tag detection processing are transmitted in a negotiation phase in which negotiations regarding wireless power transmission are performed.

7. The communication method according to claim 5 or 6, characterized in that the information indicating whether the power transmitting device supports NFC tag detection processing, the information indicating whether the power transmitting device has performed NFC tag detection processing, and the information indicating the result of the NFC tag detection processing are transmitted to a power receiving device that detects NFC tags by NFC polling when information indicating that the power transmitting device has not performed NFC tag detection is received.

8. The communication method according to any one of claims 5 to 7, characterized in that the information indicating whether the power transmitting device supports NFC tag detection processing, the information indicating whether the power transmitting device has performed NFC tag detection processing, and the information indicating the result of the NFC tag detection processing are transmitted to a power receiving device that transmits a request to limit the transmitted power when the power transmitting device receives information indicating that the power transmitting device has performed NFC tag detection and information indicating that the NFC tag has been detected.

9. A program for causing a computer to execute the communication method according to any one of claims 5 to 8.

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