Power supply device that supplies power to power receiving device in contactless manner, method of controlling power supply device, and storage medium

A power supply device includes a first communication antenna, a second communication antenna, a power supply antenna for power supply to a power receiving device, a communication control unit to control sharing processing via the first communication antenna and establishment processing of establishing the communication via the second communication antenna with the power receiving device with information shared by the sharing processing, a power supply control unit to control authentication processing for the power supply to the power receiving device and power supply processing of performing the power supply to the power receiving device authenticated by the authentication processing, and a control unit configured to control the sharing processing and the authentication processing to be performed alternately, wherein, in a case where the power supply processing starts before completion of the establishment processing, the power supply stops and the sharing processing is performed again.

BACKGROUND

Field

The present disclosure relates to a power supply device that supplies power to a power receiving device in a contactless manner.

Description of the Related Art

In recent years, there has been known a power supply system including a power supply device that outputs power in a contactless manner without connection with a connector and a power receiving device that charges a secondary battery with the power output from the power supply device. The power supply system forms a power supply path when the devices come within a predetermined distance to each other.

There has been known a technique of facilitating establishment of higher-speed communication in contactless close proximity wireless communication that forms a communication path in a similar manner that devices come close to each other (Japanese Patent Laid-Open No. 2014-131108).

Based on an idea that the proximity between devices enables for processing for power supply and close proximity wireless communication, from the conventional techniques described above, consideration is made in that higher-speed wireless communication is performed with power supply received. In this case, the power in power supply has influence on the close proximity wireless communication, and thus it is likely that correct communication cannot be performed. As a result, it may be difficult to establish the higher-speed wireless communication.

SUMMARY

A power supply device configured to supply power to a power receiving device in a contactless manner includes a first communication antenna for communication with the power receiving device, a second communication antenna for communication with the power receiving device, a power supply antenna for power supply to the power receiving device, a communication control unit configured to control sharing processing of sharing a communication parameter with the power receiving device via the first communication antenna and establishment processing of establishing the communication via the second communication antenna with the power receiving device with information shared by the sharing processing, a power supply control unit configured to control authentication processing for the power supply to the power receiving device via the power supply antenna and power supply processing of performing the power supply via the power supply antenna to the power receiving device authenticated by the authentication processing; and a control unit configured to control the sharing processing and the authentication processing to be performed alternately, wherein, in a case where the power supply processing starts before completion of the establishment processing of establishing the communication via the second communication antenna, the power supply stops and the sharing processing is performed again.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments will be described in detail below with reference to the drawings.

A first embodiment will be described in detail below with reference to the drawings. A power supply system according to the first embodiment includes a power supply device100and a power receiving device200, as illustrated inFIG. 1. In the contactless power supply system according to the first embodiment, in a case where the distance between the power supply device100and the power receiving device200is within a predetermined range, the power supply device100performs power supply to the power receiving device200in a contactless manner through a power supply antenna104. Based on information superimposed on the power output through the power supply antenna104, the power supply device100authenticates whether the power receiving device200is a contactless power-supply compliant device.

The power receiving device200charges a secondary battery208attached to the power receiving device200with the power received from the power supply device100through a power receiving antenna204.

In a case where the distance between the power supply device100and the power receiving device200is within the predetermined range, the power supply device100performs first communication processing with the power receiving device200through a first communication antenna106. Then, the power supply device100performs second communication with the power receiving device200through a second communication antenna107.

In a case where the distance between the power supply device100and the power receiving device200exceeds the predetermined range, the power supply device100cannot perform the power supply to the power receiving device200. Note that the predetermined range enables the authentication to be performed between the power supply device100and the power receiving device200.

FIG. 2is a block diagram of the contactless power supply system including the power supply device100and the power receiving device200.

First, the power supply device100will be described.

As illustrated inFIG. 2, the power supply device100includes a power supply unit101, a first communication unit102, a second communication unit103, the power supply antenna104, a control unit105, the first communication antenna106, and the second communication antenna107.

The power supply unit101transmits the power with a predetermined frequency for output in the contactless manner to the power supply antenna104. The power supply unit101includes an oscillator, a power amplifier, and a voltage adjusting circuit, and inputs an alternate current signal from the oscillator into the power amplifier supplied with a voltage adjusted by the voltage adjusting circuit to amplify the signal as power to be output. The predetermined frequency can be a variable value or a fixed value.

The power supply unit101can include an impedance converting circuit that adjusts output impedance, or can change the frequency or phase of the power to be output. The power supply unit101also receives the information superimposed on the output power by the power receiving device200to determine whether the power receiving device200is a device compliant with the power supply scheme of the power supply unit101. The power supply unit101can superimpose information on the power to be output to transmit the information to the power receiving device200. The power to be output from the power supply unit101includes at least first power with which the authentication is performed to the power receiving device200, and second power larger than the first power, with which state information is received from the power receiving device200. The first power to be output from the power supply unit101is sufficient for the operation of the power receiving device200. The power supply unit101also performs simplified communication with the control unit105.

For example, the simplified communication enables information indicating 0 or 1 to be transmitted between the power supply unit101and the control unit105connected through a dedicated control line. When receiving a power-supply start request signal from the control unit105, the power supply unit101outputs the power for power supply. The power output by the power supply unit101first includes the first power, and then autonomously switches to the second power in a case where it is determined, after the authentication of the power receiving device200, that the power receiving device200is a device compliant with the power supply scheme of the power supply device100. When it is determined, after the authentication, that the power receiving device200is a device compliant with the power supply scheme of the power supply device100, the power supply unit101transmits a signal indicating that the power supply is being performed to the control unit105and switches the power being output to the second power. In a case where information received from the power receiving device200indicates that power receiving is to be finished, the power supply unit101transmits a power-supply finish request signal to the control unit105. The communication between the power supply unit101and the control unit105can include serial communication in which multibit transmission or reception is performed. An example of the power supply scheme of the power supply unit101is the “Qi®” standard prescribed by wireless power consortium (WPC). In Qi®, the power to be output is modulated in frequency to have information and then is used for power supply control.

The first communication unit102transmits information from the control unit105to the first communication antenna106in a modulation scheme corresponding to a predetermined communication scheme to perform communication control of controlling the communication with the external power receiving device200. The first communication unit102demodulates a signal received through the first communication antenna106in a demodulation scheme corresponding to the predetermined communication scheme to transmit the signal to the control unit105. The first communication unit102converts information received from the control unit105into information supporting a protocol corresponding to the predetermined communication scheme to transmit the information to the first communication antenna106. The first communication unit102changes information supporting the predetermined protocol received from the power receiving device200to information necessary for the control unit105to transmit the information to the control unit105. The first communication unit102includes an impedance converting circuit for impedance matching with the first communication antenna106.

The predetermined communication scheme of the first communication unit102includes a short-range communication scheme, such as near field communication (NFC). The first communication unit102communicates with an electronic device compliant with the same communication scheme, in addition to the power receiving device200.

The second communication unit103transmits information from the control unit105in a modulation scheme corresponding to a predetermined communication scheme to the second communication antenna107to perform communication control of controlling the communication with the external power receiving device200. The second communication unit103demodulates a signal received through the second communication antenna107in a demodulation scheme corresponding to the predetermined communication scheme to transmit the signal to the control unit105. The second communication unit103converts information received from the control unit105into information supporting a protocol corresponding to the predetermined communication scheme to transmit the information to the second communication antenna107. The second communication unit103changes information supporting the predetermined protocol received from the power receiving device200to information necessary for the control unit105to transmit the information to the control unit105. The second communication unit103includes an impedance converting circuit for impedance matching with the second communication antenna107.

The predetermined communication scheme of the second communication unit103includes a long range communication scheme, such as a wireless local area network (LAN) standard or a Bluetooth® standard. The second communication unit103communicates with an electronic device compliant with the same communication scheme, in addition to the power receiving device200. In the present embodiment, a case where the second communication unit103uses a wireless LAN, will be described. In the present embodiment, in a case where the second communication unit103operates, a beacon is sent to form a wireless network. The power receiving device200accesses the wireless network to communicate with the power supply device100.

The long range communication to be performed by the second communication unit103is distant in wavelength. That is, because the communication to be performed by the second communication unit103(for example, 2.4 GHz) is sufficiently shorter in wavelength than the communication to be performed by the first communication unit102(for example, 13.56 MHz), the communication with the same power receiving device200is referred to as long range communication.

The power supply antenna104includes a loop-shaped coil, and generates a magnetic field for supplying the power receiving device200with the power generated by the power supply unit101in the contactless manner.

The control unit105includes a CPU and a memory that control digital data, and is connected to the power supply unit101, the first communication unit102, and the second communication unit103to control each unit. The control unit105transmits an operation request signal to the power supply unit101. When receiving the operation request signal from the control unit105, the power supply unit101autonomously outputs the first power to perform the authentication. When the authentication finishes, the power supply unit101outputs the second power to control the second power based on a signal received from the power receiving device200. When switching the power being output to the second power, the power supply unit101transmits the signal indicating that the power supply is being performed, to the control unit105. The control unit105identifies that the power receiving device200is located within the predetermined range, based on the signal indicating that the power supply is being performed/received from the power supply unit101.

The first communication antenna106includes a loop-shaped antenna, and is disposed near the power supply antenna104. The first communication antenna106generates a magnetic field for communication with a short-range external electronic device from power for communication from the first communication unit102.

The second communication antenna107includes a meander line antenna, and generates an electromagnetic wave from power for communication from the second communication unit103to communicate with the power receiving device200.

The power supply device100has been described above.

Next, the power receiving device200will be described.

As illustrated inFIG. 2, the power receiving device200includes a power receiving unit201, a first communication unit202, a second communication unit203, the power receiving antenna204, a control unit205, a first communication antenna206, a second communication antenna207, and the secondary battery208.

Based on the power received from the power supply device100through the power receiving antenna204, the power receiving unit201supplies the secondary battery208with the power to charge the secondary battery208. The power receiving unit201includes a rectifying smoothing circuit and a charging control circuit, and converts the alternate current power received through the power receiving antenna204into direct current power with the rectifying smoothing circuit to control the direct current power for a charging current and a charging voltage meeting the remaining capacity of the secondary battery208. The power receiving unit201can include an impedance converting circuit that adjusts input impedance. The power receiving unit201superimposes information onto the received power to transmit the information to the power supply device100. The information to be transmitted to the power supply device100indicates that the secondary battery208has been fully charged or the power receiving device200is compliant with the power supply scheme of the power supply device100.

The first communication unit202transmits information from the control unit205in a modulation scheme corresponding to the predetermined communication scheme to the first communication antenna206to communicate with the external power supply device100. The first communication unit202demodulates a signal received via the first communication antenna206in a demodulation scheme corresponding to the predetermined communication scheme to transmit the signal to the control unit205. The first communication unit202converts information received from the control unit205into the information supporting the protocol corresponding to the predetermined communication scheme to transmit the information to the first communication antenna206. The first communication unit202changes the information supporting the predetermined protocol received from the power supply device100to information necessary for the control unit205, to transmit the information to the control unit205. The first communication unit202includes an impedance converting circuit for impedance matching with the first communication antenna206.

The second communication unit203transmits information from the control unit205in a modulation scheme corresponding to the predetermined communication scheme to the second communication antenna207to communicate with the external power supply device100. The second communication unit203demodulates a signal received via the second communication antenna207in a demodulation scheme corresponding to the predetermined communication scheme to transmit the signal to the control unit205. The second communication unit203converts information received from the control unit205into the information supporting the protocol corresponding to the predetermined communication scheme to transmit the information to the second communication antenna207. The second communication unit203converts the information supporting the predetermined protocol received from the power supply device100into information necessary for the control unit205to transmit the information to the control unit205. The second communication unit203includes an impedance converting circuit for impedance matching with the second communication antenna207.

The power receiving antenna204includes a loop-shaped coil, and receives the alternate current magnetic field from the power supply device100as the alternate current power.

The control unit205includes a CPU and a memory that control digital data, and is connected to the power receiving unit201, the first communication unit202, and the second communication unit203to control each unit. The CPU of the control unit205includes two CPUs, a CPU with large power consumption that performs high-speed processing, and a CPU with low power consumption that operates at low speed. The CPU that performs high-speed processing mainly operates to perform the second communication processing in communication with the second communication unit203.

The low-speed CPU mainly performs the first communication processing and power receiving operation in communication with the power receiving unit201and the first communication unit202.

The first communication antenna206includes a loop-shaped antenna, and is disposed near the power receiving antenna204. The first communication antenna206receives the magnetic field with the information superimposed output from the power supply device100.

The second communication antenna207including a meander line antenna receives the electromagnetic wave output from the power supply device100.

In the present embodiment, the power supply device100transmits the power to the power receiving device200in the contactless manner, and the power receiving device200receives the power from the power supply device100in the contactless manner. “Contactless” can be also referred to as “wireless” or “noncontact”.

<Operation of Power Supply Device100>

FIG. 3is a flowchart of the operation of the power supply device100according to the present embodiment.

At S301, the control unit105first initializes a stored control value. Specifically, the control unit105controls the power supply unit101to set, at zero, the count of the number of transitions to power supply.

At S302, the control unit105controls the first communication unit102to transmit via the first communication antenna106a polling signal for verifying whether an opposed device (i.e., the power receiving device200) is located within the predetermined range. In a case where it is verified that the power receiving device200is located within the predetermined range, the control unit105performs the first communication processing to transmit a request signal for transmission of information indicating whether the power receiving device200is compliant with the second communication processing. When determining that the power receiving device200is compliant with the second communication processing, the power supply device100transmits a communication parameter as unique information regarding the second communication of the power supply device100to the power receiving device200. This arrangement enables the unique information regarding the second communication to be shared between the power supply device100and the power receiving device200. The processing at the present step is an exemplary sharing processing. The unique information regarding the second communication includes a service set identifier (SSID) and a password to be used for the wireless LAN.

At S303, the control unit105verifies whether a response signal has been received from the other device via the first communication antenna106and the first communication unit102. In a case where the response signal has been received, the power receiving device200is considered to be within the communication range, and then the processing proceeds to S311. In a case where the response signal has not been received, the power receiving device200accessible in communication is considered not to be within the communication range, and the processing proceeds to S304.

At S304, the control unit105transmits the operation request signal to the power supply unit101, and then the power supply unit101outputs the first power for authentication into the predetermined range via the power supply antenna104.

At S305, the control unit105continues transmitting the operation request signal to the power supply unit101to perform authentication processing. Specifically, the power supply unit101determines whether the power receiving device200compliant with the power supply scheme of the power supply device100is located within the predetermined range based on the signal received via the power supply antenna104. When receiving, from the power receiving device200, the signal indicating that the power receiving device200is compliant with the power supply scheme of the power supply device100, the power supply unit101determines that the power receiving device200is located within the predetermined range. The authentication processing is then completed. The power receiving device200is determined to be supplied with the power, and additionally the signal indicating that the power supply is being performed is transmitted to the control unit105. Then, the processing proceeds to S306. In a case where the control unit105has not received the signal indicating that the power supply is being performed from the power supply unit101over a certain period, the control unit105determined that the power receiving device200compliant with the power supply scheme of the power supply device100is not located within the predetermined range. Then, the processing returns to S302. In this case, the control unit105stops transmitting the operation request signal to the power supply unit101.

At S306, the control unit105continues transmitting the operation request signal to the power supply unit101because the control unit105has received the signal, from the power supply unit101at S305, indicating that the power receiving device200is located. After the completion of the authentication processing, the power supply unit101autonomously switches the power being output to the second power. This arrangement starts power supply processing. The power supply processing is performed in parallel to the processing at and after S308until the power supply processing stops at S315.

At S307, the control unit105increments and stores the number of transitions into second information indicating the number of transitions to power supply because the control unit105has received, from the power supply unit101, the signal indicating that the power supply is being performed.

At S308, when the control unit105determines that the second communication has started from first information indicating that the second communication has started, the processing proceeds to S309. Otherwise, the processing proceeds to S314. The first information indicating whether the second communication processing has started is stored at S312after the performance of the first communication processing at S302.

At S309, the control unit105performs secondary-battery remaining-capacity handling processing. The secondary-battery remaining-capacity handling processing is intended for handling a case where the remaining capacity of the secondary battery208decreases to a predetermined value due to the performance of the second communication processing while the power receiving device200is receiving the power. The details thereof are described below with reference toFIG. 4.

At S310, when receiving a signal indicating that the power receiving has finished from the power receiving device200, the power supply unit101transmits the power-supply finish request signal to the control unit105. When receiving the power-supply finish request signal from the power supply unit101, the control unit105stops transmitting the operation request signal to the power supply unit101and finishes the power supply to finish the present processing of the power supply device100. The power receiving device200transmits the signal indicating that the power receiving has finished in a case where the secondary battery208has been fully charged or an abnormality has been detected in a charging operation.

At S311, the control unit105determines whether the power supply device100is already in communication through the second communication unit103. In a case where it is determined that the power supply device100is out of communication, the processing proceeds to S312. In a case where it is determined that the power supply device100is in communication, the processing proceeds to S313.

At S312, the control unit105performs establishment processing for establishing the second communication. For example, the establishment processing includes security authentication processing for starting communication compliant with a wireless LAN communication standard. The communication link between the power supply device100and the power receiving device200is established with the SSID used at S302. For example, information to be used in the second communication processing, includes image information with a large information amount. The power supply device100receives the information from the power receiving device200. The control unit105of the power supply device100requests the power receiving device200to transmit the image information as the second communication processing. Note that the wireless LAN communication that has started at S312continues operating in parallel to the processing at and after S312. After that, the processing proceeds to S304.

At S313, the control unit105verifies whether the communication partner in the second communication processing is identical to that in the first communication processing. The verification is performed such that the power supply device100receives the unique ID information regarding the power receiving device200at S303and similarly receives the unique ID information regarding the power receiving device200in the second communication. In a case where the power supply device100is already in communication with the identical partner, the processing proceeds to S304without performance of the processing at S312anew. In a case where the partner in the communication is not identical to that in the first communication, the processing returns to S302.

At S314, the control unit105determines whether the number of transitions to power supply that is the second information at S307has reached a predetermined number. In a case where the control unit105determines the second information has reached the predetermined number, the processing proceeds to S309for the secondary-battery remaining-capacity handling processing. When the control unit105determines the second information has not reached the predetermined number, the processing proceeds to S315. The counting of the number of transitions to power supply at S307is intended for handling a case where the second communication cannot be performed because the remaining capacity of the secondary battery208of the power receiving device200is empty. The power receiving device200is supplied with the second power from the power supply device100at S306, but a one-time power supply is not necessarily sufficient power for the power receiving device200to perform the second communication processing. Thus, the power supply is repeated several times (for example, five times), so that the power receiving device200can acquire sufficient power. The counting of the number of transitions to power supply at S307is also intended for handling a case where the power receiving device200includes a device not compliant with the first communication processing or the second communication processing. When the control unit105determines at S314that the repetition of power supply has been made to the predetermined number, the processing does not return to S302. Thus, a time during which no power supply is being performed is avoided so that a time necessary for the secondary battery208of the power receiving device200to be fully charged can be reduced.

At S315, the control unit105waits for a predetermined time until a certain amount of power is supplied to the power receiving device200, and then stops transmitting the operation request signal to the power supply unit101. The processing returns to S302and then the first communication processing is re-performed. After that, the processing at S302to S314is repeated. That is, the first communication processing at S302and the authentication processing at S304are alternately repeated.

As described above, the power supply device100according to the first embodiment stores, at S312, the information indicating whether the second communication processing has started. This arrangement enables the processing to return to the first communication processing at S302in a case where the second communication processing has not started, without enabling only the power supply operation to continue even when the authentication for power supply has correctly finished at S305. Thus, the second communication processing is enabled with the power supply retained.

The flow of the secondary-battery remaining-capacity handling processing at S309ofFIG. 3will be described with reference toFIG. 4.

The flow of the secondary-battery remaining-capacity handling processing is intended for handling a case where the remaining capacity of the secondary battery208decreases to the predetermined value due to the performance of the second communication processing while the power receiving device200is receiving the power. That is, for example, a case where the power supply efficiency is low and the power receiving device200cannot receive sufficient power because the power receiving device200is within the predetermined range from the power supply device100but is located in the vicinity on the boundary of the range. In a power supply system in which the positional relationship in which the power supply efficiency is always favorable is acquired in power supply because of the physical shapes of the power supply device100and the power receiving device200, the control unit105can skip the present processing to proceed to S310.

At S401, the control unit105determines whether the second communication processing started at S311has finished. When determining that the second communication has finished, the control unit105finishes the present secondary-battery remaining-capacity handling processing in order to perform only the power supply. When the control unit105determines that the second communication has not finished, the processing proceeds to S402.

At S402, the control unit105communicates with the power receiving device200in the second communication to determine whether the remaining capacity of the secondary battery208of the power receiving device200is the predetermined value or less. In a case where the remaining capacity of the secondary battery208of the power receiving device200is the predetermined value or less, the processing proceeds to S403in order to suspend the second communication processing. Otherwise, the processing proceeds to S406.

Because of the determination at S402that the remaining capacity of the secondary battery208is the predetermined value or less, the control unit105suspends, at S403, the second communication processing to enable the power receiving device200to efficiently charge the secondary battery208with the received power.

At S404, the control unit105waits for a predetermined time until the secondary battery208is sufficiently charged. The predetermined time can be a fixed time, such as 15 minutes, or a maximum time during which the link of the second communication processing can be retained.

At S405, the control unit105resumes the second communication processing after the predetermined time at S404, and the processing returns to S402.

At S406, the control unit105waits for a predetermined time because of the determination, at S402, that the remaining capacity of the secondary battery208is not the predetermined value or less, and then the processing returns to S401. The reason for the wait for the predetermined time is that the remaining capacity of the secondary battery208does not vary rapidly.

As described above, the present processing controls the second communication processing to prevent the secondary battery208from being empty, even in a case where the power receiving device200cannot receive sufficient power and the remaining capacity decreases while the power is being received.

In a power supply system in which the positional relationship in which the power supply efficiency is always favorable is acquired in power supply because of the physical shapes of the power supply device100and the power receiving device200, the control unit105of the power supply device100can skip the present processing to proceed to S310.

<Operation of Power Receiving Device200>

FIG. 5is a flowchart of the operation of the power receiving device200according to the present embodiment.

At S501, the control unit205waits until the first communication unit202receives power for the first communication processing or the power receiving unit201receives the first power from the power supply device100. When the power for the first communication is received, the processing proceeds to S509. When the first power is received, the processing proceeds to S502.

Because the power receiving device200is in low-power-consumption operation at S501, the control unit205of the power receiving device200can operate with the power output from the power supply device100even when the secondary battery208is empty.

At S502, it is determined whether the power receiving unit201has received an authentication request signal for power supply from the power supply device100. In a case where the authentication request is received, the processing proceeds to S503. In a case where the power receiving unit201has not received the first power after a certain time with no receipt of the authentication request signal, a signal to be transmitted to the control unit205stops, and the control unit205returns the processing to S501.

Since the authentication signal from the power supply device100was received at S502, the power receiving unit201modulates, at S503, the first power from the power supply unit101to transmit a response signal to the power supply device100. During this time, the power receiving unit201can transmit a signal indicating that a response has been made to the authentication to the control unit205. In a case where the power receiving unit201does not transmit to the control unit205the signal indicating that a response has been made to the authentication, the control unit205enables the processing to proceed to S504due to the elapse of the predetermined time.

At S504, the power receiving unit201receives the second power for power supply from the power supply device100to perform charge processing to the secondary battery208. The power receiving unit201transmits a signal indicating that charging is being performed to the control unit205.

At S505, the control unit205determines whether the second communication has started. In a case where the second communication has not started, the processing returns to S501. Separately from the control unit205, the power receiving unit201continues charging the secondary battery208while the second power is being received from the power supply device100. When the second communication processing has not started, the power supply device100stops the power supply at S315and then the processing goes back to S302. Thus, the power receiving device200does not receive the power.

At S506, the control unit205determines whether the second communication processing is to be finished. When the control unit205determines that the second communication processing is to be finished, the processing proceeds to S507since the remaining capacity of the secondary battery208is not considered. When the control unit205determines that the second communication processing is not to be finished, the processing proceeds to S512since the remaining capacity of the secondary battery208is considered.

At S507, the control unit205controls the second communication unit203to finish the second communication processing with the power supply device100.

At S508, based on the signal from the power receiving unit201indicating that charging is being performed, the control unit205determines whether the charging has finished. When the charge processing finishes, the control unit205finishes the present processing of the power receiving device200. Before the power receiving unit201stops the transmission of the signal indicating that charging is being performed and notifies the control unit205of the finish of the charging, the power receiving unit201transmits a signal indicating a power receiving finish to the power supply device100. The notification of the power receiving finish is issued in a case where the secondary battery208is fully charged or a usual state occurs as a charging state.

At S509, the control unit205starts the first communication processing because the first communication unit202has received the power for the first communication processing at S501.

At8510, the control unit205controls the first communication unit202to determine whether the first communication processing has finished. The unique information regarding the second communication is received from the power supply device100in the first communication processing.

At S511, the control unit205waits for receipt from the power supply device100of a start request signal for the second communication processing via the second communication unit203. Upon receipt, the processing proceeds to S512.

At S512, the control unit205starts the second communication processing. In the second communication processing, information including a large information amount, such as the image information retained by the power receiving device200, is transmitted to the power supply device100. Thus, the power receiving device200power consumption is large (for example, 1 W) during the second communication processing.

Because of the determination at S506that the second communication processing has not finished, the control unit205detects the remaining capacity of the secondary battery208at S513. In a case where the remaining capacity of the secondary battery208is the predetermined value (for example, one tenth of the fully charged state) or less, the processing proceeds to S514. When the control unit205determines that, the remaining capacity of the secondary battery208is not the predetermined value or less, the processing returns to S506.

Because of the determination at S513that the remaining capacity of the secondary battery208is the predetermined value or less, the control unit205transmits, at S514, a signal indicating that the remaining capacity of the secondary battery208is empty to the power supply device100via the second communication unit203.

Because the remaining capacity of the secondary battery208is the predetermined value or less and it is necessary to suppress the power consumption, the control unit205requests, at S515, the second communication unit203to suspend the second communication. Then, the processing returns to S511to wait for resumption of the second communication processing.

As described above, the power receiving device200performs the operation processing as illustrated inFIG. 5so that the power supply device100according to the first embodiment of the present disclosure can perform the second communication processing during the power supply.

The power supply device100according to the present disclosure is not limited to the power supply device100described in the present embodiment. The power receiving device200according to the present disclosure is not limited to the power receiving device200described in the present embodiment. For example, the power supply device100and the power receiving device200can be realized by a system including a plurality of devices.

Other Embodiments

This application claims the benefit of Japanese Patent Application No. 2017-183512, filed Sep. 25, 2017, which is hereby incorporated by reference herein in its entirety.