Power receiving apparatus, control method of power receiving apparatus, and storage medium

A power receiving apparatus includes a power receiving unit configured to wirelessly receive power from a power transmission apparatus, a communication unit configured to perform communication based on a standard of Near Field Communication (NFC), a detection unit configured to detect the power transmission apparatus, and a control unit configured to control the communication unit not to perform the communication based on the standard of NFC based on detection of the power transmission apparatus by the detection unit, wherein the power receiving unit receives power after the control unit controls the communication unit not to perform communication based on the standard of NFC.

BACKGROUND

Field of the Disclosure

The present disclosure relates to a power receiving apparatus, a control method of a power receiving apparatus, and a storage medium.

Description of the Related Art

In recent years, the technological development of wireless power transmission systems such as a wireless charging system has been widely conducted. Japanese Patent Application Laid-Open No. 2016-007116 discusses a power transmission apparatus and a power receiving apparatus that are compliant with a standard (hereinafter, referred to as a “WPC standard”) stipulated by a Wireless Power Consortium (WPC), which is a group for developing standards of wireless charging.

A Near Field Communication (NFC) method is one type of a wireless communication method. In addition, a standard (specification) stipulated by the NFC forum defines a card emulation mode in which a battery-driven NFC module emulates an NFC tag or an NFC card (hereinafter, collectively referred to as an “NFC tag”). Moreover, the NFC forum also defines a reader/writer mode for reading an NFC tag and a peer-to-peer mode for directly exchanging messages between NFC devices. Among power receiving apparatuses such as smartphones that are compliant with the WPC standard, some power receiving apparatuses include an NFC module operating in these modes, and perform communication based on the standard of NFC.

An NFC tag does not include a battery and is driven using energy of electromagnetic wave transmitted from a communication partner in communication. If the above-described power transmission apparatus wirelessly transmits high power to this NFC tag, an antenna element included in the NFC tag can possibly be damaged. It can be considered that, for avoiding such a situation, the power transmission apparatus restricts power transmission when the power transmission apparatus detects an object performing communication based on the standard of NFC. Nevertheless, in such a configuration, the following issues are generated. More specifically, when the power transmission apparatus detects an object performing communication based on the standard of NFC, the power transmission apparatus is considered to restrict power transmission irrespective of whether the object is an NFC tag or a power receiving apparatus performing communication based on the standard of NFC. Thus, if power transmission to a power receiving apparatus performing communication based on the standard of NFC is restricted, the amount of received power may be insufficient.

SUMMARY

Some embodiments are directed to enabling a power receiving apparatus that performs communication based on a standard of NFC to appropriately receive power.

According an aspect of some embodiments, a power receiving apparatus includes a power receiving unit configured to wirelessly receive power from a power transmission apparatus, a communication unit configured to perform communication based on a standard of Near Field Communication (NFC), a detection unit configured to detect the power transmission apparatus, and a control unit configured to control the communication unit not to perform the communication based on the standard of NFC based on detection of the power transmission apparatus by the detection unit, wherein the power receiving unit receives power after the control unit controls the communication unit not to perform communication based on the standard of NFC.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. The following exemplary embodiments are mere examples and are not intended to limit the scope of all embodiments to the configurations and methods described in the exemplary embodiments.

Hereinafter, a first exemplary embodiment will be described.FIG. 1illustrates a configuration example of a wireless charging system (wireless power transmission system) according to the present exemplary embodiment. The system includes a power receiving apparatus101and a power transmission apparatus102. Hereinafter, a power receiving apparatus will be referred to as an RX and a power transmission apparatus will be referred to as a TX. The RX101and the TX102are compliant with a Wireless Power Consortium (WPC) standard. The RX101receives power from the TX102and enables a battery to be charged. The TX102is an electronic device that wirelessly transmits power to the RX101placed on a charging stand of the TX102. Hereinafter, the description will be given using an example case where the RX101is placed on the charging stand. Nevertheless, when the TX102transmits power to the RX101, the RX101only needs to exist within a power transmittable range (operating volume) of the TX102and may not need to be placed on the charging stand.

The RX101and the TX102can include a function of executing an application other than wireless charging. As an example, the RX101is a smartphone and the TX102is an accessory device for charging the smartphone. The RX101and the TX102may be storage devices, such as hard disc devices or memory devices, or may be an information processing apparatus, such as a personal computer (PC). Alternatively, the RX101and the TX102may be imaging apparatuses (camera, video camera, etc.), for example. The RX101and the TX102may be image input apparatuses, such as scanners, or may be image output apparatuses, such as printers, copiers, or projectors. Also, the TX102may be a smartphone. In this case, the RX101may be another smartphone, or may be a wireless earphone. Then, the RX101may be an automobile. Furthermore, the TX102may be a charger which is set on a console or the like in an automobile.

The RX101is equipped with a Near Field Communication (hereinafter, referred to as “NFC”) function, and can read an NFC tag or perform electronic money payment, for example, using the function. The TX102is also equipped with the NFC function for reading an NFC tag. The TX102can detect an NFC tag by performing communication based on a standard of NFC. Furthermore, the TX102can stop or restrict power transmission processing based on the detection result to protect an NFC tag.

The system performs wireless power transmission using an electromagnetic induction method for wireless charging, based on the WPC standard. For example, the RX101and the TX102perform wireless power transmission for wireless charging that is based on the WPC standard, between a power receiving antenna of the RX101and a power transmission antenna of the TX102. In addition, a wireless power transmission method applied to the system is not limited to a method defined by the WPC standard, and may be an electromagnetic induction method, a magnetic field resonance method, an electric field resonance method, a microwave method, or a method using a laser. In the present exemplary embodiment, wireless power transmission is used for wireless charging, but wireless power transmission may be performed for purposes other than wireless charging.

In the WPC standard, the magnitude of power that can be guaranteed when the RX101receives power from the TX102is defined by a value of guaranteed power (hereinafter, referred to as “GP”). The value of GP indicates a value of power guaranteed to be output to a load in the RX101(e.g., charging circuit, etc.) even if a positional relationship between the RX101and the TX102varies and power transmission efficiency between the power receiving antenna and the power transmission antenna declines, for example. When the value of GP indicates 5 watts, for example, the TX102performs power transmission while controlling power such that power of 5 watts can be output to the load in the RX101even if a positional relationship between the power receiving antenna and the power transmission antenna varies and power transmission efficiency declines.

The RX101and the TX102according to the present exemplary embodiment perform communication for power transmission and reception control that is based on the WPC standard. The WPC standard defines a plurality of phases including a Power Transfer Phase in which power transfer is executed, and phases preceding actual power transfer, and communication for power transmission and reception control required in each phase is performed. The phases preceding power transfer include a Selection Phase, a Ping Phase, an Identification and Configuration Phase, a Negotiation Phase, and a Calibration Phase. Hereinafter, the Identification and Configuration Phase will be referred to as an I&C Phase.

In the Selection Phase, the TX102intermittently transmits an Analog Ping, and detects that an object is placed on the charging stand of the TX102(e.g., the RX101or a conductor strip is placed on the charging stand). The TX102detects at least either one of a voltage value and a current value of the power transmission antenna that are obtainable when the Analog Ping is transmitted, determines that an object exists if the voltage value falls below a certain threshold or if the current value exceeds a certain threshold, and shifts to the Ping Phase.

In the Ping Phase, the TX102transmits a Digital Ping having larger power than the Analog Ping. The Digital Ping has power large enough for activating a control unit of the RX101placed on a charging stand. The RX101notifies the magnitude of received voltage to the TX102. In this manner, by receiving a response from the RX101that has received the Digital Ping, the TX102recognizes that the object detected in the Selection Phase is the RX101. If the TX102receives the notification of a received voltage value, the TX102shifts to the I&C Phase.

In the I&C Phase, the TX102identifies the RX101and acquires device configuration information (capability information) from the RX101. Thus, the RX101transmits an ID Packet and a Configuration Packet to the TX102. The ID Packet includes identification information of the RX101and the Configuration Packet includes device configuration information (capability information) of the RX101. The TX102that has received the ID Packet and the Configuration Packet returns an acknowledge (ACK) as a response. Then, the I&C Phase is ended.

In the Negotiation Phase, a value of GP is determined based on a value of GP required by the RX101or power transmission capability of the TX102.

In the Calibration Phase, the RX101notifies a received power value to the TX102and the TX102performs adjustment for efficiently transmitting power, based on the WPC standard.

In the Power Transfer Phase, control for a start or continuation of power transmission and for a stop of power transmission caused due to an error or full charge is performed.

For the above-described power transmission and reception control, the TX102and the RX101perform communication (hereinafter, referred to as “first communication”) for superimposing a signal on electromagnetic waves transmitted from an antenna, using the same antenna (coil) as that for wireless power transmission, based on the WPC standard. A range in which the first communication that is based on the WPC standard can be performed between the TX102and the RX101is substantially similar to a power transmissible range in which the TX102can transmit power.

To perform the above-described power transmission and reception control, the TX102and the RX101may perform communication (hereinafter, referred to as “second communication”) using an antenna and a frequency that are different from those for wireless power transmission. For example, a frequency band of electromagnetic waves used in the second communication is higher than a frequency band of electromagnetic waves used in the first communication. In this case, by using the second communication, it is possible to perform higher-speed communication than that performed in the case of using the first communication.

Examples of the second communication include a communication method that is compliant with a Bluetooth 0 Low Energy (hereinafter, referred to as “BLE”) standard. In this case, the TX102operates as a Peripheral in the BLE standard and the RX101operates as a Central in the BLE standard, but these roles according to the BLE standard may be reversed. In addition, the second communication may be performed in compliance with another communication method, such as a wireless local area network (LAN) (e.g., Wi-Fi®) of the IEEE802.11 standard series or ZigBee. When the TX102can perform the second communication and the RX101exists in the power transmissible range, the RX101and the TX102can exchange information by the second communication.

Subsequently, configurations of the power receiving apparatus101(the RX101) and the power transmission apparatus102(the TX102) according to the present exemplary embodiment will be described. The configurations to be described below are mere examples, and a part (or all depending on the case) of the configurations to be described may be omitted or substituted with another configuration having another similar function, or yet another configuration may be added to the configurations to be described. Furthermore, one block to be described below may be divided into a plurality of blocks or a plurality of blocks may be merged into one block.

FIG. 2is a functional block diagram illustrating a configuration example of the RX101according to the present exemplary embodiment. The following description will be given using a smartphone as an example of the RX101, but the RX101according to the present exemplary embodiment is not limited to this.

The RX101includes a control unit201, a power source unit202, a power receiving antenna203, a smartphone function processing unit204, a WPC communication unit205, a storage unit206, a power receiving unit207, a charging unit208, a battery209, and an NFC unit210. In addition, a plurality of functional blocks illustrated inFIG. 2may be implemented as one hardware module.

The control unit201controls the entire smartphone (i.e., the RX101) by executing a control program stored in the storage unit206, for example. In other words, the control unit201controls each functional unit illustrated inFIG. 2. Furthermore, the control unit201may perform control for executing an application other than wireless power transmission. As an example, the control unit201includes one or more processors, such as a central processing unit (CPU) or a microprocessor unit (MPU). In addition, the entire smartphone may be controlled by cooperation with an operating system (OS) executed by the control unit201.

In addition, the control unit201may include hardware dedicated for specific processing, such as an application specific integrated circuit (ASIC). In addition, the control unit201may include an array circuit, such as a field programmable gate array (FPGA) compiled so as to execute predetermined processing. The control unit201causes the storage unit206to store information to be stored during the execution of various types of processing. In addition, the control unit201can measure time using a timer (not illustrated).

The power source unit202supplies power to each functional block in conjunction with the charging unit208and the battery209. The smartphone function processing unit204includes those functions normally included in a smartphone, such as a user interface (UI), a phone call unit, and an internet processing unit. The descriptions of these functions will be omitted.

The WPC communication unit205performs the above-described communication for power reception control that is based on the WPC standard, with a communication unit included in the TX102. The WPC communication unit205acquires information transmitted from the TX102by demodulating electromagnetic waves input from the power receiving antenna203, and performs the first communication with the TX102by superimposing, on electromagnetic waves, information to be transmitted to the TX102by performing load modulation on the electromagnetic waves. In other words, the first communication performed by the WPC communication unit205is performed by superimposition of a signal related to information to be transmitted to the TX102on electromagnetic waves transmitted from the power transmission antenna of the TX102. The WPC communication unit205may communicate with the TX102using the second communication in place of the first communication, or may communicate with the TX102using both of the first communication and the second communication. In addition, when the WPC communication unit205performs the second communication, the RX101includes an antenna different from the power receiving antenna203. During the power reception, the WPC communication unit205performs the above-described communication for power reception control that is based on the WPC standard, with the communication unit included in the TX102.

The storage unit206stores a control program and also stores states of the RX101and the TX102, for example.

The power receiving unit207acquires power generated in the power receiving antenna203. Specifically, the power receiving unit207acquires alternating-current power (alternating-current voltage and alternating current) generated in the power receiving antenna203by electromagnetic induction caused by electromagnetic waves emitted from the power transmission antenna of the TX102. Then, the power receiving unit207converts the alternating-current power into direct-current power or alternating-current power with a predetermined frequency, and outputs power to the charging unit208that performs processing for charging the battery209. In other words, the power receiving unit207supplies power to a load in the RX101. The above-described value of GP indicates an amount of power guaranteed to be output from the power receiving unit207. The power receiving unit207has the capability to supply power for the charging unit208to charge the battery209and supply power for outputting power of 15 watts to the charging unit208.

The NFC unit210performs communication processing with another communication device using the NFC function. The NFC unit210operates in modes that are compliant with a specification stipulated by the NFC forum, for example. The above-described modes include, for example, a card emulation mode substituted for a role as a noncontact IC card, a reader/writer mode for reading an NFC tag, and a peer-to-peer mode (P2P) mode for NFC devices directly exchanging messages. For example, electronic money payment is executable by the card emulation mode. The NFC unit210includes an antenna (not illustrated), different from the power receiving antenna203, for performing near field communication.

FIG. 3is a functional block diagram illustrating a configuration example of the TX102according to the present exemplary embodiment. As an example, the TX102includes a control unit301, a power source unit302, a power transmission antenna303, a WPC communication unit304, a storage unit305, a power transmission unit306, and an NFC unit307. InFIG. 3, the control unit301, the power source unit302, the power transmission unit306, the WPC communication unit304, the storage unit305, and the NFC unit307are described as separate units, but a plurality of arbitrary functional blocks among these units may be mounted on the same chip.

The control unit301controls the entire power transmission apparatus by executing a control program stored in the storage unit305, for example. In other words, the control unit301controls each functional unit illustrated inFIG. 3. The control unit301further performs control related to the control of power transmission in the TX102. The control unit301may perform control for executing an application other than wireless power transmission. The control unit301includes one or more processors, such as a CPU(s) or a MPU(s). In addition, the control unit301may include hardware dedicated for specific processing, such as an ASIC, or an array circuit, such as an FPGA, compiled so as to execute predetermined processing. The control unit301causes the storage unit305to store information to be stored during the execution of various types of processing. In addition, the control unit301can measure a time using a timer (not illustrated).

The power source unit302supplies power to each functional block. The power source unit302is a commercial power source or a battery, for example. Power supplied from the commercial power source is stored in the battery.

The WPC communication unit304performs the above-described control communication that is based on the WPC standard, with the RX101. The WPC communication unit304performs the first communication by modulating electromagnetic waves output from the power transmission antenna303and transferring information to the RX101. In addition, the WPC communication unit304acquires information transmitted by the RX101by demodulating the electromagnetic waves output from the power transmission antenna303and modulated by the RX101. In other words, the first communication performed by the WPC communication unit304is performed by superimposition of the information on the electromagnetic waves transmitted from the power transmission antenna303. In addition, the WPC communication unit304may communicate with the RX101using the second communication in place of the first communication, or may communicate with the RX101using both of the first communication and the second communication. In addition, when the WPC communication unit304performs the second communication, the TX102includes an antenna different from the power transmission antenna303. During the power transmission, the WPC communication unit304performs the above-described control communication that is based on the WPC standard, with the WPC communication unit205included in the RX101.

The storage unit305stores a control program and also stores states of the TX102and the RX101.

The power transmission unit306converts direct-current power or alternating-current power input from the power source unit302into alternating-current frequency power in a frequency band used for wireless power transmission, and the power transmission unit306generates electromagnetic waves for causing the RX101to receive power by inputting the alternating-current frequency power to the power transmission antenna303. For example, the power transmission unit306converts direct-current voltage supplied from the power source unit302into alternating-current voltage, using a switching circuit having a half-bridge or full-bridge configuration that uses a field-effect transistor (FET). In this case, the power transmission unit306includes a gate driver that controls the ON/OFF of the FET.

By adjusting either one or both of voltage (power transmission voltage) and current (power transmission current) to be input to the power transmission antenna303, the power transmission unit306controls the intensity of electromagnetic waves to be output. If power transmission voltage or power transmission current is increased, the intensity of electromagnetic waves gets higher, and if power transmission voltage or power transmission current is decreased, the intensity of electromagnetic waves gets lower. In addition, based on an instruction from the control unit301, the power transmission unit306performs output control of alternating-current frequency power so as to start or stop power transmission from the power transmission antenna303. In addition, the power transmission unit306has the capability to supply power for outputting power of 15 watts to the charging unit208of the RX101that is compliant with the WPC standard.

The NFC unit307performs communication processing with another communication device using the NFC function. The NFC unit307can detect the existence of an NFC device. The NFC device includes both of an NFC tag and a device having an activated NFC function. In the NFC device detection performed by the NFC unit307, it is difficult to distinguish between an NFC tag and a device having an activated NFC function. Thus, if an NFC device is detected by the NFC unit307, because the NFC device might be an NFC tag, the control unit301restricts power transmission by controlling the power transmission unit306to stop power transmission or reduce power to be transmitted. The NFC unit307includes an antenna (not illustrated), different from the power transmission antenna303, for performing communication related to the standard of NFC.

FIG. 4is a diagram illustrating an operation sequence of a wireless charging system. In the present exemplary embodiment, a user uses electronic money payment and the NFC function of the RX101is activated.

First of all, the user of the RX101brings the RX101closer to the power transmission apparatus102to charge the RX101. Specifically, the user places the RX101on the TX102.

In S401, the TX102always performs NFC device detection processing for preventing damages to an NFC tag. In other words, by the detection processing, it is possible to detect the existence of a device having an activated NFC function in addition to an NFC tag. The processing is periodically executed by timer control. Thus, if the RX101having the activated NFC function is brought closer to the TX102, in S402, the TX102detects that an NFC device exists nearby. In the detection processing, the TX102transmits carrier waves. If the NFC device makes a response upon receipt of the carrier waves, the TX102detects the existence of the NFC device. The TX102executes the processing as polling processing. The detection processing may be irregularly executed.

In the processing related to the power transmission and reception, first of all, the TX102performs object detection processing and detection processing of the RX101. Specifically, in S403, the TX102repeatedly and intermittently transmits an Analog Ping of the WPC standard via the power transmission antenna303. Then, the TX102detects a voltage value or a current value of the power transmission antenna303at the time of transmission of the Analog Ping, and determines that an object exists near the power transmission antenna303, if the voltage value falls below a certain threshold or if the current value exceeds a certain threshold. The TX102then shifts to the Ping Phase.

In the Ping Phase, in S404, the TX102transmits a Digital Ping having larger power than the Analog Ping. The Digital Ping has power large enough for activating at least the control unit201of the RX101that exists near the power transmission antenna303.

If the control unit201of the RX101is activated by the power (Digital Ping) received via the power receiving antenna203, then in S405, the control unit201recognizes that the TX102exists nearby. Then, if the RX101is detected by the TX102as an NFC device, then in S406, the control unit201deactivates the NFC function of the RX101to prevent power transmission from being restricted.

For deactivating the NFC function, it is considered to return no response in the NFC device detection processing performed by the TX102in S401, or to stop power supply to the NFC unit210from the power source unit202. In addition, a message for requesting the user to deactivate the NFC function may be displayed on the UI included in the smartphone function processing unit204, and the NFC function may be deactivated in accordance with an instruction from the user. For charging processing, the RX101executes processing of preventing the user from activating the NFC function via the UI. This is because, unless the foregoing processing is performed, the user can activate the NFC function during charging. As a result, the TX102detects a device having an activated NFC function and restricts power transmission. If power to be supplied from the TX102is restricted, charging of the RX101may fail or a charging time may become longer. To avoid such a situation, UI display for preventing the NFC function from being activated may be presented during charging via the smartphone function processing unit204.

If the RX101detects the Digital Ping, then in S407, the RX101notifies a Signal Strength Packet (received voltage value) to the TX102. Then, the RX101shifts to the I&C Phase. The notification of the Signal Strength Packet is communicated via the WPC communication unit205and the WPC communication unit304. If the TX102receives the notification of the Signal Strength Packet, the TX102shifts to the I&C Phase.

In the I&C Phase, in S408, the RX101transmits an Identification (ID) Packet to the TX102. The ID Packet includes, in addition to a manufacturer code and a basic device ID which serve as identification information unique to the RX101, an information element that can identify the version of the WPC standard that the RX101is compliant with. In S409, the RX101further transmits a Configuration Packet to the TX102. The Configuration Packet includes the following information as capability information of the RX101. More specifically, the capability information includes a maximum power value that is a value for identifying the maximum power that can be supplied by the RX101to the load, and information indicating whether a negotiation function of the WPC standard is included.

If the TX102receives these packets, the TX102checks whether the RX101includes the negotiation function. If the RX101includes the negotiation function, then in S410, the TX102transmits an ACK. Then, the TX102shifts to the Negotiation Phase. If the RX101receives the ACK in S410, the RX101shifts to the Negotiation Phase.

In the Negotiation Phase, the TX102and the RX101perform negotiation for determining the above-described GP. Specifically, the RX101notifies a candidate value of GP using a Specific Request Packet. The TX102accepts or refuses the notification. In this example, because the RX101has the capability to output power of 15 watts to the charging unit208, in S411, the RX101notifies the maximum power of 15 watts as a candidate value of GP. The RX101waits for reception of a positive acknowledge (ACK) or a negative acknowledge (NACK) from the TX102.

Since the transmission of high output power can possibly damage an NFC tag, the TX102has a threshold of a power value at which an NFC tag is not damaged. In this example, the threshold value is defined to be 6 watts, but the threshold value is not limited to this. In S402, the TX102that has received the Specific Request Packet detects the existence of an NFC device using the NFC unit307. However, because it is difficult to determine whether the detected NFC device is an NFC tag or a device having an activated NFC function, the TX102determines that the power transmission of 15 watts can possibly damage an NFC tag if the detected NFC device is an NFC tag. Thus, in S412, the TX102transmits an NACK in response to the notification of the Specific Request Packet indicating the power value is equal to or larger than the threshold.

If the RX101does not receive an ACK but receives a NACK, the RX101determines that the TX102has not detected that the NFC function of the RX101has been deactivated. Thus, in S415, the RX101notifies again 15 watts as the value of GP.

On the other hand, if the above-described periodical NFC tag detection processing is executed in S413, then in S414, the TX102detects that no NFC device exists near the TX102. In other words, the detection in this means that the deactivation of the NFC function of the RX101is detected. Thus, because the TX102can accept the maximum power of 15 watts as a value of GP, in S416, the TX102returns an ACK in response to a re-request for power transmission of 15 watts which is made by the RX101in S415. Then, reception of power of 15 watts is determined.

After the reception of power of 15 watts is determined, in S417, the TX102and the RX101shift to the Calibration Phase. In the Calibration Phase, the TX102determines a parameter required for a foreign substance detection function of detecting that an object other than the RX101exists near a power transmission antenna303, which will not be described in detail.

After that, in S418, the TX102and the RX101shift to the Power Transfer Phase, and the RX101starts charging of the battery209. During the charging, the TX102and the RX101continuously perform control communication that is based on the WPC standard, via the WPC communication unit205and the WPC communication unit304.

If the RX101ends the charging, in S419, the RX101transmits an End Power Transfer Packet to the TX102. The TX102that has received the packet stops power supply to the RX101.

If the RX101ends the charging, then in S420, the RX101activates the NFC function of the RX101and brings an application that uses the NFC function into an effective state.

As described above, the RX101according to the present exemplary embodiment deactivates the NFC function of the RX101by detecting the existence of the TX102. The RX101accordingly can receive appropriate power from a power transmission apparatus equipped with an NFC tag detection function, and the impairment of user-friendliness can be prevented.

In the present exemplary embodiment, if both of the RX101and an NFC tag are placed on the charging stand of the TX102, the NFC tag is detected by the NFC tag detection processing of the TX102. The power transmission is thus restricted so as not to damage the NFC tag. Even if an NFC tag is attached to the RX101, a similar effect can be obtained.

A method in which an RX detects the existence of a TX is not limited to the method in which a Digital Ping is received by a WPC communication unit. For example, a mechanical switch provided on the RX may be turned ON by a trigger provided on a charging surface of a charging stand of the TX when the RX is placed thereon. The RX may detect the TX by detecting a specific physical amount (e.g., current or voltage of the RX101).

(Flow of Processing of Power Receiving Apparatus)

Next, an operation procedure of the RX101and the TX102according to the present exemplary embodiment will be described with reference toFIGS. 5A and 5B(hereinafter collectively referred to asFIG. 5).

FIG. 5is a flowchart illustrating an example of a flow of processing executed by the RX101. The processing can be implemented by the control unit201of the RX101executing a program read from the storage unit206, for example. At least part of the following procedure may be implemented by hardware. The hardware in this case can be implemented, for example, by automatically generating a dedicated communication circuit that uses a gate array circuit, such as an FPGA, from a program for implementing each processing operation, using a predetermined compiler. The processing can be executed if the power of the RX101is turned on, if the RX101is activated by power supply from the battery209or the TX102, or if the user of the RX101inputs a start instruction of a wireless charging application. In addition, the processing may be started in response to another trigger.

First of all, in F501, the RX101determines whether a Digital Ping is received. If the RX101is activated by power (Digital Ping) received via the power receiving antenna203(YES in F501), then in F502, the control unit201of the RX101recognizes that the TX102exists nearby. In F503, the control unit201deactivates the NFC function of the RX101for preventing the RX101from being detected by the TX102as a device having an activated NFC function, and preventing power transmission from being restricted. A method of deactivating the NFC function is as described above.

If the RX101detects the Digital Ping, then in F504, the RX101notifies a Signal Strength Packet (received voltage value) to the TX102. Then, the RX101shifts to the I&C Phase. The notification of the Signal Strength Packet is communicated via the WPC communication unit205and the WPC communication unit304.

In the I&C Phase, in F505and F506, the RX101transmits an ID Packet and a Configuration Packet to the TX102.

In F507, the RX101determines whether an ACK is received. If the RX101receives an ACK from the TX102(YES in F507), the RX101shifts to the Negotiation Phase. If the RX101does not receive an ACK (NO in F507), the RX101determines that the TX102does not include the negotiation function. In F522, reception of power of 5 watts is determined.

In the Negotiation Phase, the TX102and the RX101negotiate to determine the above-described value of GP. Specifically, the RX101notifies a candidate value of GP using a Specific Request Packet. In this example, because the RX101has the capability to output power of 15 watts to the charging unit208, in F508, the RX101notifies the maximum power of 15 watts as a candidate value of GP. The RX101waits for reception of a positive acknowledge (ACK) or a negative acknowledge (NACK) from the TX102.

In F509, the RX101determines whether an ACK is received. If the RX101receives an ACK as a response of the TX102(YES in F509), the processing proceeds to F521. In F521, reception of power of 15 watts is determined. In F510, the RX101determines whether a NACK is received. If the RX101receives neither an ACK nor a NACK (NO in F509and NO in F510), it is determined that power cannot be received from the TX102, and the processing is ended. In this case, in F520, the RX101activates the NFC function of the RX101and brings an application that uses the NFC function into an effective state. Then, the RX101ends the processing.

If the RX101does not receive an ACK but receives an NACK (NO in F509and YES in F510), the RX101determines that the TX102has not detected the deactivation of the NFC function of the RX101. The processing proceeds to F511. In F511, the RX101determines whether a NACK is received a certain fixed number of times or more. If the RX101has not received an NACK the certain fixed number of times or more (NO in F511), then in F508, the RX101notifies again 15 watts as GP.

If the RX101has received a NACK the certain fixed number of times or more (YES in F511), the RX101determines that the TX102cannot transmit with a power of 15 watts for some reasons. In F512, the RX101requests power reception of 5 watts from the TX102as a candidate value of GP. In F513, the RX101determines whether an ACK is received from the TX102as a response to the request. If the RX101receives an ACK from the TX102as a response to the request (YES in F513), then in F514, reception of power of 5 watts is determined. If the RX101does not receive an ACK (NO in F513), it is determined that power cannot be received from the TX102, the processing is ended.

The specific reason why the TX102cannot transmit with a power of 15 watts is that an NFC tag is detected or a device having an activated NFC function exists. By receiving a NACK the certain fixed number of times or more after deactivating the NFC unit210of the RX101, the RX101can determine that the TX102has detected an NFC tag or a device having an activated NFC function. Then, in F514, a transmission of power of 5 watts, which is a power that does not affect an NFC tag, is determined.

After the RX101notifies again 15 watt as GP, if the RX101receives an ACK (YES in F509), then in F521, a reception of power of 15 watts is determined.

After the reception of power of 15 watts is determined, then in F515, the RX101shifts to the Calibration Phase. In F516, the RX101shifts to the Power Transfer Phase, and in F517, the RX101starts charging of the battery209.

In F518, the RX101determines whether the charging is completed. If the RX101ends the charging (YES in F518), then in F519, the RX101transmits an End Power Transfer Packet to the TX102. If the RX101ends the charging, in F520, the RX101activates the NFC function of the RX101and brings an application that uses the NFC function into an effective state.

(Flow of Power Transmission Processing of Power Transmission Apparatus)

Next, an operation procedure of power transmission processing of the TX102according to the present exemplary embodiment will be described with reference toFIG. 8.

FIG. 8is a flowchart illustrating an example of a flow of processing executed by the TX102. The processing can be implemented by the control unit301of the TX102executing a program read from the storage unit305, for example. At least part of the following procedure may be implemented by hardware. The hardware in this case can be implemented, for example, by automatically generating a dedicated communication circuit that uses a gate array circuit, such as an FPGA, from a program for implementing each processing operation, using a predetermined compiler. The processing can be executed if power of the TX102is turned on, if the user of the TX102inputs a start instruction of a wireless charging application, or if the TX102is connected to a commercial power source and supplied with power. In addition, the processing may be started in response to another trigger.

In the power transmission processing, first of all, in F801, the TX102performs object detection processing. In F802, the TX102performs detection processing for detecting the RX101. Specifically, the TX102repeatedly and intermittently transmits an Analog Ping of the WPC standard via the power transmission antenna303. Then, the TX102detects a voltage value or a current value of the power transmission antenna303that is obtainable when the Analog Ping is transmitted, and determines that an object exists near the power transmission antenna303, if the voltage value falls below a certain threshold or if the current value exceeds a certain threshold. The TX102accordingly shifts to the Ping Phase. In the Ping Phase, the TX102transmits a Digital Ping having larger power than the Analog Ping. The Digital Ping has power large enough for activating at least the control unit201of the RX101that exists near the power transmission antenna303.

If the TX102receives the notification of the Signal Strength Packet from the RX101, the TX102shifts to the I&C Phase.

In the I&C Phase, in F803and F804, the TX102receives an ID Packet and a Configuration Packet from the RX101. If the TX102receives these packets, then in F805, the TX102checks whether the RX101includes the negotiation function. If the RX101includes the negotiation function (YES in F805), the processing proceeds to F806. In F806, the TX102transmits an ACK. Then, the TX102shifts to the Negotiation Phase.

On the other hand, if the TX102determines that the RX101does not include the negotiation function (NO in F805), then in F819, transmission of a power of 5 watts is determined.

In the Negotiation Phase, the TX102and the RX101negotiate to determine the above-described value of GP. The TX102waits for transmission of a Specific Request Packet or a General Packet from the RX101.

In F807, the TX102determines whether a General Packet is received. If the TX102does not receive a General Packet (NO in F807) but receives a Specific Request Packet, the processing proceeds to F809. In F809, the TX102determines whether power required by the Packet is equal to or larger than a threshold. Since the transmission of high output power can possibly damage an NFC tag, the TX102has a threshold of a power value at which an NFC tag is not damaged. In this example, the threshold is defined to be 5 watts.

If the power required by the RX101is smaller than the threshold (NO in F809), then in F820, the TX102that has received the Specific Request Packet transmits an ACK to the RX101. In F821, transmission of the required power (5 watts in this case) is determined.

On the other hand, if the power required by the RX101is equal to or larger than the threshold (YES in F809), then in F810, the TX102determines whether an NFC device is detected. For the determination, the TX102inquires of the NFC unit307. Since the NFC unit307detects an NFC device (YES in F810), the TX102determines that transmission of power of 15 watts can possibly damage an NFC tag. Thus, in F818, the TX102transmits a NACK in response to the notification of the Specific Request Packet indicating the required power equal to or larger than the threshold. Then, the TX102waits again for transmission of a Specific Request Packet or a General Packet from the RX101.

Meanwhile, if the above-described NFC device detection processing is periodically executed, the TX102stops detecting an NFC device near the TX102(NO in F810). The TX102thus can accept the maximum power of 15 watts as a value of GP. In F811, the TX102accordingly transmits an ACK in response to a re-request for transmission of power of 15 watts from the RX101. Then, in F812, power transmission of 15 watt is determined.

After the required power or the power transmission of 15 watts is determined, in F813, the TX102shifts to the Calibration Phase. After that, in F814, the TX102shifts to the Power Transfer Phase.

In F815, the TX102determines whether an End Power Transfer Packet is received from the RX101. If the TX102receives an End Power Transfer Packet from the RX101(YES in F815), then in F817, the TX102stops power transfer to the RX101.

In the present exemplary embodiment described above, the description has been given using an example case where the NFC function is activated in the RX101. The present exemplary embodiment is, however, not limited to this. For example, even if the NFC function is deactivated in the RX101, a similar effect can be obtained by controlling the RX101so as to ban the activation of the NFC function when the existence of the TX102is detected. The control may be performed by a method in which the user disables the activation of an NFC function using a UI, or may be performed by a method of disabling operations on the RX101, for example.

In addition, in place of the processing in F511ofFIG. 5, the RX101may perform processing for measuring a time from when an ACK is received in F507, and comparing the measured time and a threshold, for example. In this case, if the measured time is equal to or smaller than the threshold, the processing in F508may be performed again, and if the measured time exceeds the threshold, the processing may proceed to the processing in F512and subsequent operations.

In addition, the description has been given using an example in which the NFC device detection processing (S401) is performed by the TX102prior to the transmission of the Analog Ping (S403), but the present exemplary embodiment is not limited to this. For example, the NFC device detection processing (S401) may be performed after the transmission of the Analog Ping or the transmission of the Digital Ping (S404).

In the present exemplary embodiment, the description has been given using NFC as an example, but communication is not limited to this. For example, even in a case where the RX101includes a communication function of emulating a tag that performs communication other than NFC and can be damaged by the transmission of high power, the present exemplary embodiment can be applied.

Hereinafter, a second exemplary embodiment will be described. In the first exemplary embodiment, the description has been given of a configuration in which transmission of power of 15 watts is re-requested even if the RX101receives a NACK as a response of the TX102to a power transmission request of 15 watts. In this case, it can possibly take time until the charging is started. In the present exemplary embodiment, a configuration of shortening a time until a charging start will be described.

Since the configurations of a wireless charging system, a power receiving apparatus, and a power transmission apparatus according to the present exemplary embodiment are similar to those in the first exemplary embodiment, the description will be omitted. Hereinafter, an operation procedure of an RX101and a TX102according to the present exemplary embodiment will be described with reference toFIGS. 6 to 8.FIG. 6is a diagram illustrating an operation sequence of the wireless charging system according to the present exemplary embodiment.FIG. 7, consisting ofFIGS. 7A and 7B, is a flowchart illustrating an example of a flow of processing executed by the RX101according to the present exemplary embodiment.FIG. 8is a flowchart illustrating an example of a flow of power transmission processing executed by the TX102according to the present exemplary embodiment.

Since processing in S601to S612inFIG. 6is similar to the processing in S401to S412ofFIG. 4, the description will be omitted. In the processing executed by the RX101, since processing in F701to in F710ofFIG. 7is similar to the processing in F501to F510ofFIG. 5, the description will be omitted.

If the TX102refuses transmission of power of 15 watts in S612and F818(NO in F709), then in S613, the RX101transmits a General Packet (Capability), and in F711, the RX101checks the power that the TX102can transmit.

If the TX102receives a General Packet (YES in F807), then in S614and F808, the TX102returns an ACK as a response to the RX101because an NFC device is detected and the TX102sets 5 watts as the maximum power that can be transmitted. In response to the result, in S615and F712, the RX101requests 5 watts from the TX102as a value of GP. Then, in S616and F820, the TX102transmits an ACK.

In F713, the RX101determines whether the above-described ACK is received. The RX101receives the ACK (YES in F713), then in F714and F812, a power reception (power transmission) of 5 watts is determined. If the negotiation of GP is ended, then in S617, F715, and F813, the TX102and the RX101shift to the Calibration Phase.

After that, in S618, F716, and F814, the TX102and the RX101shift to the Power Transfer Phase. In F717, the RX101starts charging of the battery209.

Meanwhile, if the NFC device detection processing is periodically executed in S619, in S620, the TX102detects that no NFC device exists near the TX102(NO in F810). In other words, the deactivation of the NFC function of the RX101is detected.

In F718, the RX101determines whether the charging is completed. If the charging is not completed (NO in F718), then in F719, the RX101determines whether a power of 15 watts has been received. If a power of 15 watts has not been received (NO in F719), the RX101expects that a result obtained by the NFC device detection processing of the TX102has been updated, and in S621and F720, the RX101transmits a Re-Negotiation Request to receive larger power.

In F816, the TX102determines whether the Re-Negotiation Request is received. If the TX102receives the request (YES in F816), in S622and F806, the TX102transmits an ACK to the RX101.

Then, the RX101and the TX102shift to a Re-Negotiation Phase. In the Re-Negotiation Phase, the TX102and the RX101perform re-negotiation of GP. In this case, since the RX101has the capability to supply power for outputting a power of 15 watts to the charging unit208, in S623and F708, the RX101notifies again the maximum power of 15 watts as a candidate value of GP.

On the other hand, by the periodical NFC device detection processing (S619), in S620and F810, the TX102detects that no NFC device exists near the TX102(No in F810). Thus, the TX102that has received the Re-Negotiation Request and the Specific Request Packet can accept the maximum power of 15 watts as a value of GP. In other words, in S624and F811, the TX102transmits an ACK in response to the re-request of power transmission of 15 watts from the RX101(YES in F709). Then, in S626and S627, the RX101and the TX102shift to the Calibration Phase and the Power Transfer Phase.

Because processing performed in S628, S629, F721, and F722after the completion of charging (YES in F718) is similar to the processing performed in S419, S420, F519, and F520in the first exemplary embodiment, the description will be omitted.

As described above, the RX101according to the present exemplary embodiment deactivates the NFC function of the RX101by detecting the existence of the TX102. Thus, appropriate power can be received from the TX102equipped with an NFC device detection function, and the impairment of user-friendliness can be prevented. In addition, if the first power transmission request of 15 watts is refused, the RX101checks the maximum power that can be transmitted by the TX102, and performs negotiation using the checked maximum power. With this configuration, it is possible to shorten a time until charging is started, as compared with the first exemplary embodiment. Then, by shifting to the Re-Negotiation Phase after the start of charging, it is possible to shorten a charging time as compared with a case where the phase does not shift to the Re-Negotiation Phase.

Hereinafter, a third exemplary embodiment will be described. In the present exemplary embodiment, unlike the above-described exemplary embodiments, the description will be given of a method in which an RX101confirms that a TX102enters a state of detecting no NFC device, and the RX101makes a power transmission request of 15 watts. Specifically, in the present exemplary embodiment, the RX101transmits a signal for inquiring of the TX102whether an NFC device is detected. The packet will be referred to as an NFC_Status_Request Packet in the present exemplary embodiment.

As a response to the packet, the TX102transmits at least a result (response signal) of NFC device detection processing to the RX101. Specifically, the TX102transmits an ACK if an NFC device is detected, and transmits a NACK if no NFC device is detected.

Hereinafter, an operation procedure of the RX101and the TX102according to the present exemplary embodiment will be described with reference toFIGS. 9 to 11.FIG. 9is a diagram illustrating an operation sequence of a wireless charging system according to the present exemplary embodiment.FIG. 10, consisting ofFIGS. 10A and 10B, is a flowchart illustrating an example of a flow of processing executed by the RX101according to the present exemplary embodiment.FIG. 11is a flowchart illustrating an example of a flow of power transmission processing executed by the TX102according to the present exemplary embodiment. Since processing in S901to S910and S917to S922ofFIG. 9is the same as the processing in S401to S410and S415to S420ofFIG. 4, the description will be omitted. Similarly, since processing in F1001to F1007, F1013to F1020, and F1023ofFIG. 10is the same as the processing in F501to F507, F513to F520, and F522ofFIG. 5, the description will be omitted. Since processing in F1101to F1108and F1112to F1119ofFIG. 11is the same as the processing in F801to F808and F812to F819ofFIG. 8, the description will be also omitted.

In S910, the RX101receives an ACK in response to the transmitted Configuration Packet (YES in F1007), and shifts to the Negotiation Phase. In S911and F1008, the RX101transmits an NFC_Status_Request to the TX102. If the RX101does not receive an ACK from the TX102as a response signal to the request (NO in F1009) and receives a NACK in S912(YES in F1010), the following processing is performed. More specifically, until the RX101receives a NACK a predetermined number of times (N times) (NO in F1011), in F1008, the RX101transmits an NFC_Status_Request to the TX102.

After that, if the TX102receives an NFC_Status_Request (YES in F1109), and if no NFC device is detected in S914(NO in F1110) as a result of the NFC device detection processing (S913), the following processing is performed. More specifically, in S916and F1111, the TX102transmits an ACK to the RX101as a response signal of the NFC_Status_Request.

If the RX101receives an ACK from the TX102in S916(YES in F1009), the RX101determines that the TX102detects no NFC device. Then, in S917and F1021, the RX101transmits a Specific Request (15 watts) to the TX102. If the RX101receives an ACK from the TX102as a response to the request in S918, then in F1022, the reception of the maximum power of 15 watts is determined.

If the TX102does not receive an NFC_Status_Request (NO in F11109), the processing equivalent to the processing in F809and subsequent ofFIG. 8is performed. Specifically, in F1120, the TX102determines whether required power is equal to or larger than a threshold. Then, if the required power is equal to or larger than the threshold (YES in F1120), then in F1110, the TX102determines whether an NFC device is detected. On the other hand, if the required power is smaller than the threshold (NO in F1120), then in F121, the TX102transmits an ACK to the RX101. Then, in F1122, the transmission of required power (5 watts in this case) is determined.

As described above, the RX101according to the present exemplary embodiment determines that the TX102enters a state of detecting no NFC device, based on the response to the NFC_Status_Request. With this configuration, in accordance with the response to NFC_Status_Request, a Specific Request (15 watt) can be transmitted at an appropriate timing and the Specific Request can be permitted. In other words, the TX102can also perform high-output power transmission processing with respect to the RX101equipped with an NFC unit operating in the card emulation mode.

The response to the NFC_Status_Request needs not be an ACK or a NACK. Specifically, the response may include at least an NFC tag detection bit, and may indicate that the TX102detects an NFC tag (or a device having an activated NFC function), if the NFC tag detection bit is 1. The response may indicate that the TX102does not detect an NFC tag (or a device having an activated NFC function), if the NFC tag detection bit is 0.

A packet in a General Request defined in the WPC standard v1.2.3 may be used for the NFC_Status_Request. For example, in the General Request, a Reserved Packet or a Proprietary Packet of which Packet type is undefined may be defined as an NFC_Status_Request.

A packet in a Specific Request defined in the WPC standard v1.2.3 may be used for the NFC_Status_Request. For example, in the Specific Request, a Reserved Packet or a Proprietary Packet of which Packet type is undefined may be defined as an NFC_Status_Request.

In addition, the NFC_Status_Request needs not be a Specific Request or a General Request as long as the packet is defined in the WPC standard v1.2.3.

Further, the NFC_Status_Request may be a packet that can be transmitted by the RX101in the Negotiation Phase or subsequent phases. Specifically, the NFC_Status_Request may be a packet that can be transmitted in the Negotiation Phase, the Power Transfer Phase, the Calibration Phase, or the Re-Negotiation Phase. Thus, if the TX102receives the packet in, for example, the Ping Phase or the Identification & Configuration phase that is not included in these phases, power transmission or control communication for power transmission may be stopped. Specifically, if the TX102receives not a Signal Strength Packet but an NFC_Status_Request in S907, the TX102stops power transmission or control communication for power transmission. Similarly, if the TX102receives an NFC_Status_Request in any of S907to S909, the TX102stops power transmission or control communication for power transmission. With this configuration, if a packet of an NFC_Status_Request is received in a phase other than a predetermined phase, it is possible to detect a malfunction of the RX101and stop power transmission or control communication for power transmission.

Other Exemplary Embodiments

Some embodiments can also be implemented by processing of supplying a program for implementing one or more functions of the above-described exemplary embodiments, to a system or an apparatus via a network or a storage medium, and reading and executing the program by one or more processors in a computer of the system or the apparatus. In addition, some embodiments can also be implemented by a circuit (e.g., ASIC) that implements one or more functions.

In addition, at least part of the processing illustrated in the flowchart inFIG. 5, 7, 8, 10, or11may be implemented by hardware. In the case of implementing the processing by hardware, for example, with use of a predetermined compiler, the processing can be implemented by automatically generating a dedicated communication circuit on an FPGA from a program for implementing each processing. In addition, similarly to an FPGA, a gate array circuit may be formed and implemented as hardware.

According to some embodiments, a power receiving apparatus that can execute communication based on a standard of NFC can appropriately receive power.

While the present disclosure has described exemplary embodiments, it is to be understood that various embodiments are not limited to the disclosed exemplary embodiments. Also, the scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims priority to Japanese Patent Application No. 2018-222507, which was filed on Nov. 28, 2018 and which is hereby incorporated by reference herein in its entirety.