Power transmission device, control method performed by the power transmission device, and program

Abstract

The purpose is to detect the removal of a power receiving device even during the period when power transmission is suspended, in a power transmission device that has received an EPT packet specifying the period during which power transmission will be suspended. [Solution] Based on the fact that the power transmission device 100 has received an EPT packet containing information about the period during which power transmission will be stopped from the power receiving device 200 via the communication unit 104, the power transmission coil 105 controls to transmit a confirmation signal to confirm the presence of the power receiving device 200 during the period during which power transmission will be stopped. The detection unit 108 detects at least one of the voltage and current applied to the power transmission coil 105 when the confirmation signal is transmitted, and based on the detection result, determines whether or not the RX200 that sent the EPT packet exists.

Description

Technical Field

[0001] The present invention relates to a power transmission device, a control method executed by the power transmission device, and a program.

Background Art

[0002] In recent years, technical development of wireless power transmission systems such as non-contact charging systems has been widely carried out. Patent Document 1 discloses a power transmission device and a power reception device compliant with a standard (hereinafter referred to as the "WPC standard") established by the non-contact charging standardization organization Wireless Power Consortium (WPC). Patent Document 1 also discloses that when the power reception device detects an abnormality, a signal indicating power transmission stop is transmitted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is conceivable to specify a power transmission stop period using this signal indicating power transmission stop. Specifically, it is conceivable to include information specifying the power transmission stop period in the signal indicating power transmission stop. When the power transmission device receives a signal indicating power transmission stop including information specifying the power transmission stop period, the power transmission device stops power transmission during that power transmission stop period. For this reason, it is considered that the transmission of a signal for detecting an object is also not performed. In this case, even if the power reception device on the power transmission device is removed during the power transmission stop period, it is considered that the removal of the power reception device cannot be detected until the period elapses, and it takes time to detect the removal.

[0005] In view of the above issues, the present invention aims to detect the removal of a power receiving device even during the period in which power transmission is stopped, in a power transmission device that has received a signal indicating a power transmission stop specifying a period in which power transmission is stopped. [Means for solving the problem]

[0006] A power transmission device according to one aspect of the present invention comprises an antenna for wirelessly transmitting power to a power receiving device, receiving means for receiving a signal from the power receiving device, detection means for detecting at least one of the voltage and current of the antenna, and control means for controlling the antenna, wherein the control means controls the antenna to transmit a confirmation signal to confirm the existence of a power receiving device that transmitted the signal indicating the power transmission stop, based on the reception of a signal indicating the power transmission stop from the power receiving device including information on the period during which power transmission will be stopped, the detection means detects at least one of the voltage and current of the antenna when the confirmation signal is transmitted, and the control means determines whether or not a power receiving device that transmitted the signal indicating the power transmission stop exists, based on the detection result by the detection means. [Effects of the Invention]

[0007] In the present invention, a power transmission device that receives a signal indicating a power transmission suspension specifying a period for which power transmission will be stopped can detect the removal of a power receiving device even during the period when power transmission is suspended. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the configuration of the power transmission device in this embodiment. [Figure 2] This figure shows an example of the configuration of the power receiving device in this embodiment. [Figure 3] A diagram showing an example of a wireless power transmission system in this embodiment. [Figure 4] This figure shows an example of the sequence when the power receiving device is not removed in this embodiment. [Figure 5] This figure shows an example of the sequence when the power receiving device is removed and a new power receiving device is installed in this embodiment. [Figure 6] This figure shows an example of a flowchart of the processing of the power transmission device in this embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are merely examples for illustrating the technical concept of the present invention, and the present invention is not intended to be limited to the configurations and methods described in the embodiments.

[0010] Figure 3 shows an example of the configuration of a contactless charging system (wireless power transmission system) according to this embodiment. This system consists of a power transmission device and a power receiving device. Hereinafter, the power transmission device may be referred to as TX and the power receiving device as RX. TX100 is an electronic device that wirelessly transmits power to RX200 placed on its charging base. RX200 is an electronic device that receives power wirelessly from TX100 and charges its built-in battery. Hereinafter, the explanation will be given using the case where RX200 is placed on the charging base as an example. However, for TX100 to transmit power to RX200, RX200 does not need to be placed on the charging base as long as it is within the power transmission range of TX100.

[0011] TX100 receives power from a commercial power source via AC connector 301, and this power is supplied to the power supply unit 102. RX200 receives power from the power transmission coil 105 of TX100 via its own power receiving coil 205. The power received by RX200 is used to charge a battery (not shown). Note that the power transmission coil 105 and power receiving coil 205 are types of antennas. In the following explanation, coils will be used as an example, but an antenna with a non-coil shape may be used instead of the power transmission coil 105 and power receiving coil 205.

[0012] The TX100 and RX200 may have the functionality to perform applications other than contactless charging. One example of the RX200 is a smartphone, and one example of the TX100 is an accessory device for charging that smartphone. The TX100 and RX200 may be storage devices such as hard disk drives or memory devices, or information processing devices such as personal computers (PCs). Furthermore, the TX100 and RX200 may be image input devices such as imaging devices (cameras, video cameras, etc.) or scanners, or image output devices such as printers, copiers, or projectors. Also, the TX100 may be a smartphone. In this case, the RX200 may be another smartphone or wireless earphones. The RX200 may also be an automobile. Furthermore, the TX100 may be a charger installed in the console of an automobile.

[0013] Furthermore, although one RX200 and TX100 are shown in this embodiment, the configuration can also be applied to multiple RX200s powered by one TX100 or by separate TX100s.

[0014] This system performs wireless power transmission using an electromagnetic induction method for contactless charging, based on the WPC standard. Specifically, the RX200 and TX100 perform wireless power transmission for contactless charging based on the WPC standard between the receiving coil 205 of the RX200 and the transmitting coil 105 of the TX100. The wireless power transmission method (contactless power transmission method) applied to this system is not limited to the method specified in the WPC standard, but may also be other methods such as electromagnetic induction, magnetic field resonance, field resonance, microwave, or laser. Furthermore, in this embodiment, wireless power transmission is used for contactless charging, but wireless power transmission may also be used for purposes other than contactless charging.

[0015] The WPC standard defines the amount of power guaranteed when the RX200 receives power from the TX100 by a value called Guaranteed Power (hereinafter referred to as "GP"). GP indicates the power value at which the output to the load (e.g., a charging circuit) of the RX200 is guaranteed, even if the relative positions of the RX200 and TX100 change and the power transmission efficiency between the receiving coil 205 and the transmitting coil 105 decreases. For example, if the GP is 5 watts, even if the relative positions of the receiving and transmitting coils change and the power transmission efficiency decreases, the TX100 will be controlled to transmit power in a way that allows it to output 5 watts to the load within the RX200.

[0016] In this embodiment, the RX200 and TX100 communicate for power transmission and reception control based on the WPC standard. The WPC standard defines multiple phases, including the Power Transfer phase in which power transmission is performed and the phase before actual power transmission takes place, and necessary power transmission and reception control communication is performed in each phase. The phase before power transmission includes the Selection phase, Ping phase, Identification and Configuration phase, Negotiation phase, and Calibration phase. Hereinafter, the Identification and Configuration phase will be referred to as the I&C phase.

[0017] In the Selection phase, TX100 intermittently transmits an Analog Ping to detect that an object is placed on the charging stand (for example, RX200, a conductor piece, etc. is placed on the charging stand). That is, the Analog Ping is a detection signal for detecting the presence of an object. TX100 transmits the Analog Ping by applying a voltage or current to the power transmission coil 105. And when an object is placed on the charging stand and when no object is placed, a change occurs in the voltage or current applied to the power transmission coil 105. Therefore, TX100 detects at least one of the voltage value and the current value applied to the power transmission coil 105 when transmitting the Analog Ping. And TX100 determines that an object is present when the detected voltage value is lower than the threshold value or the detected current value exceeds the threshold value, and transitions to the Ping phase.

[0018] In the Ping phase, TX100 transmits a Digital Ping with higher power than the Analog Ping. The power of the Digital Ping is sufficient for the control unit of RX200 placed on the charging stand to start. RX200 notifies TX100 of the magnitude of the received voltage. That is, RX200 transmits a Signal Strength packet (hereinafter referred to as "SS packet") to TX100. In this way, TX100 recognizes that the object detected in the Selection phase is RX200 by receiving the response from RX200 that has received its Digital Ping. When receiving the notification of the received voltage value, TX100 transitions to the I&C phase.

[0019] In the I&C phase, TX100 identifies RX200 and acquires device configuration information (capability information) from RX200. Therefore, RX200 transmits an ID Packet and a Configuration Packet to TX100. The ID Packet contains the identification information of RX200, and the Configuration Packet contains the device configuration information (capability information) of RX200. TX100 that has received the ID Packet and the Configuration Packet responds with an acknowledgment (ACK). Then, the I&C phase ends.

[0020] In the Negotiation phase, the value of GP is determined based on the value of GP required by RX200 and the power transmission capability of TX100, etc.

[0021] In the Calibration phase, based on the WPC standard, RX200 notifies TX100 of the received power value, and TX100 performs adjustments for efficient power transmission.

[0022] In the Power Transfer phase, control is performed for starting, continuing power transmission, and stopping power transmission due to errors or full charge, etc.

[0023] TX100 and RX200 perform communication for these power transmission and reception controls by superimposing a signal on the power transmission by using the same antenna (or coil) as the wireless power transmission based on the WPC standard (hereinafter referred to as "First Communication"). Note that the range in which the First Communication based on the WPC standard is possible between TX100 and RX200 is substantially the same as the power transmission range of TX100.

[0024] RX200 according to this embodiment may perform challenge-response type communication using an electronic certificate with TX100 to authenticate TX100. That is, TX100 and RX200 perform communication for device authentication. The device authentication may be performed before the above Negotiation phase. In this case, the result of the device authentication can be reflected in the Negotiation phase. Specifically, it is as follows.

[0025] The RX200 requires TX100s that have successfully undergone equipment certification to have a GP of 15 watts, and TX100s that have not succeeded in equipment certification to have a GP of 5 watts. Note that the GP is not limited to combinations other than 15 watts and 5 watts; any combination of values ​​is acceptable as long as the GP with a successfully certified TX100 is greater than the GP with a failed certification. In other words, the RX200 requires that power transmission and reception with a large GP only occur with TX100s that have successfully undergone equipment certification. By determining the GP based on the results of equipment certification in this way, it is possible to receive power with a large GP only from TX100s that have passed the prescribed tests stipulated in the WPC standard and are deemed capable of transmitting power with a large GP. Note that failure to perform equipment certification includes cases where the TX100 does not have the function to perform this equipment certification, or where it has the function but fails to perform the certification.

[0026] However, device authentication may be performed after the Negotiation phase. For example, device authentication may be performed during the Power Transfer phase. In this case, in order to reflect the results of device authentication in the GP, the process should proceed to the ReNegotiation phase, the GP should be determined again, and then the process should proceed back to the Power Transfer phase. Alternatively, device authentication may be performed in parallel with phases preceding the Power Transfer phase, such as the Selection phase.

[0027] Furthermore, communication for device authentication may be performed using a first communication method that uses the same antenna (or coil) as wireless power transmission, or it may be performed using a communication method that uses a different antenna (or coil) and frequency than wireless power transmission (hereinafter referred to as "second communication"). Here, it is assumed that the second communication method is capable of higher speed than the first communication method. Specifically, the electromagnetic waves used in the second communication method shall have a higher frequency band than the electromagnetic waves used in the first communication method.

[0028] As an example of the second communication, in this embodiment, a communication method compliant with the Bluetooth® Low Energy (hereinafter referred to as "BLE") standard will be used. Furthermore, TX100 will operate as the Peripheral of BLE, and RX200 will operate as the Central of BLE, but these BLE roles may be reversed. In addition, the second communication may be performed by other communication methods such as wireless LAN (e.g., Wi-Fi®), ZigBee, NFC (Near Field Communication), etc., which are part of the IEEE 802.11 standard series.

[0029] (Device configuration) Next, the configurations of the power transmission device (TX100) and power receiving device (RX200) according to this embodiment will be described. Note that the configuration described below is merely an example, and some (or in some cases all) of the described configuration may be replaced or omitted by other configurations that perform similar functions, and further configurations may be added to the described configuration. Furthermore, one block shown in the following description may be divided into multiple blocks, or multiple blocks may be integrated into one block.

[0030] Figure 1 shows an example configuration of TX100 in this embodiment. TX100 includes a control unit 101, a power supply unit 102, a power transmission unit 103, a communication unit 104, a power transmission coil 105, a notification unit 106, a memory 107, a detection unit 108, a timer 109, and a temperature sensor 110. In addition, TX100 may include an authentication unit for performing device authentication.

[0031] The following example shows the communication unit 104 performing first communication using the power transmission coil 105, but it is not limited to this. In other words, the TX100 may have a communication antenna used when performing the second communication described above, and may perform second communication. Furthermore, the communication performed by the communication unit 104 may include communication for power transmission and reception control, and may also include communication for equipment authentication.

[0032] The control unit 101 controls the entire TX by executing a control program stored, for example, in the memory 107. That is, the control unit 101 controls the various parts shown in Figure 1. The control unit 101 may also perform control for applications other than wireless power transmission. The control unit 101 is composed of one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit 101 may also be composed of hardware dedicated to specific processing, such as an Application Specific Integrated Circuit (ASIC). Furthermore, the control unit 101 may be composed of array circuits, such as a Field Programmable Gate Array, that have been compiled to execute predetermined processing. The control unit 101 stores information that should be stored while various processing is being executed in the memory 107. The control unit 101 can also measure time using a timer 109.

[0033] The power supply unit 102 supplies power to the entire TX100, enabling control of the TX100 by the control unit 101, as well as power transmission and communication. The power supply unit 102 converts power supplied from outside the TX100, for example from the commercial power supply, to the required voltage and supplies power to the entire TX100. Alternatively, the power supply unit 102 may be a battery. Power supplied from the commercial power supply is stored in the battery.

[0034] The power transmission unit 103 converts the DC or AC power input from the power supply unit 102 into AC frequency power in the frequency band used for wireless power transmission, and inputs this AC frequency power to the power transmission coil 105 to generate electromagnetic waves for the RX200 to receive power. The frequency of the AC power generated by the power transmission unit 103 is, for example, several hundred kHz (e.g., 110kHz to 205kHz). This frequency is different from the communication frequency (2.4GHz) used in the second communication, such as BLE. Based on instructions from the control unit 101, the power transmission unit 103 inputs the AC frequency power to the power transmission coil 105 so that it outputs electromagnetic waves for transmitting power to the RX200. The power transmission unit 103 also controls the intensity of the output electromagnetic waves by adjusting the voltage (transmission voltage) or current (transmission current), or both, input to the power transmission coil 105. Increasing the transmission voltage or transmission current increases the intensity of electromagnetic waves, while decreasing the transmission voltage or transmission current decreases the intensity of electromagnetic waves. Furthermore, the transmission unit 103 controls the output of AC frequency power so that power transmission from the transmission coil 105 is started or stopped based on instructions from the control unit 101.

[0035] Specifically, the power transmission unit 103 converts the voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration that utilizes FETs. The power transmission unit 103 also includes a gate driver that controls the ON / OFF state of the FETs.

[0036] The communication unit 104 performs control communication with the RX200 based on the WPC standard as described above. The communication unit 104 modulates the electromagnetic waves output from the power transmission coil 105 and transmits information to the RX200 to perform the first communication. The communication unit 104 also demodulates the electromagnetic waves output from the power transmission coil 105 and modulated in the RX200 to obtain the information transmitted by the RX200. In other words, the first communication performed by the communication unit 104 is superimposed on the electromagnetic waves sent from the power transmission coil 105.

[0037] Furthermore, the communication unit 104 may perform a second communication using a communication antenna (not shown). As described above, the second communication is faster than the first communication. Specifically, the electromagnetic waves used for the second communication are in a higher frequency band than the electromagnetic waves used for the first communication. The communication unit 104 may have modulation / demodulation circuits and communication protocol processing functions necessary for performing communication compliant with standards such as BLE.

[0038] The communication unit 104 may communicate with the RX200 for device authentication. The communication for device authentication may be a second communication which is faster than the first communication.

[0039] The communication unit 104 receives a signal from the RX200 indicating the termination of power transmission (End Power Transfer packet, hereinafter referred to as "EPT packet"). This EPT packet may contain information indicating the reason for requesting the termination of power transmission, as well as information indicating the duration of the power transmission termination and the start time of power transmission. Reasons for requesting the termination of power transmission may include the RX200's temperature exceeding the upper limit, the completion of charging, the failure of negotiation, or the detection of an object other than the power receiving device (hereinafter referred to as "foreign object").

[0040] The notification unit 106 notifies the user of information by any method, such as visual, auditory, or tactile. For example, the notification unit 106 notifies the user of information such as the charging status of the TX100 or the status of power transmission of the wireless power transmission system. The notification unit 106 is composed of, for example, a display, LEDs, a speaker, a vibration generating circuit, and other notification devices. The notification unit 106 can have any configuration as long as the user can understand whether power is being supplied or not. For example, the notification unit 106 may be an LED that lights up green when power is not being supplied and lights up red when power is being supplied. Alternatively, the notification unit 106 may be an LED that lights up when power is being supplied and blinks when power is not being supplied. Furthermore, the notification unit 106 may notify by emitting light when power is being supplied and by emitting sound when power is not being supplied.

[0041] Memory 107 stores various information, such as information representing the status of each part and the entire wireless power transmission system, as well as control programs. Memory 107 may also store information obtained by a different functional unit than the control unit 101.

[0042] The detection unit 108 detects at least one of the voltage value and / or current value of the power transmission coil 105. Specifically, the detection unit 108 detects the voltage value and / or current value of the power transmission coil 105 when Analog Ping is transmitted during the Selection phase. The detection unit 108 also detects the voltage value and / or current value of the power transmission coil 105 when a signal is transmitted to confirm the presence of the RX200, which will be described later. Based on the detection results from the detection unit 108, i.e., the detected values, the control unit 101 can detect whether an object has been placed on the charging base or whether an object has been removed.

[0043] Timer 109 performs timing using, for example, a count-up timer that measures the elapsed time since activation, or a count-down timer that counts down from a set time. In addition, after the communication unit 104 receives an EPT packet indicating power outage from RX200, if the EPT packet contains information indicating the power outage period, Timer 109 sets that period and starts counting down.

[0044] The temperature sensor 110 measures the temperature of the TX100. Based on the temperature measured by the temperature sensor 110, the control unit 101 determines whether or not to transmit power. For example, the control unit 101 compares the temperature measured by the temperature sensor 110 with the upper limit of the temperature stored in the memory 107, and if the temperature measured by the temperature sensor 110 exceeds the upper limit, it controls the power transmission unit 103 to stop power transmission. Note that the temperature of the TX100 may rise if a large amount of power is transmitted continuously for a long period of time, or if power is transmitted in a high-temperature environment such as inside a car in direct sunlight during the day.

[0045] In Figure 1, the control unit 101, power supply unit 102, power transmission unit 103, communication unit 104, memory 107, and timer 109 are shown as separate components, but any multiple of these components may be implemented on the same chip.

[0046] Figure 2 shows an example configuration of the RX200 in this embodiment. The RX200 includes a control unit 201, a charging unit 202, a battery 203, a power receiving unit 204, a power receiving coil 205, a communication unit 206, a memory 207, a notification unit 208, and a temperature sensor 209. In addition, the RX200 may have an authentication unit for performing device authentication.

[0047] The control unit 201 controls the entire RX200 by executing a control program stored in, for example, memory 207. That is, the control unit 201 controls each part shown in Figure 2. The control unit 201 may also perform control related to power reception control, including communication for device authentication in the RX200. Furthermore, the control unit 201 may perform control for executing applications other than wireless power transmission. The control unit 201 is configured to include one or more processors, such as a CPU or MPU. The control unit 201 may also be configured to include hardware dedicated to specific processing, such as application-specific integrated circuits (ASICs). The control unit 201 may also be configured to include array circuits such as FPGAs compiled to execute predetermined processing. The control unit 201 stores information that should be stored while various processing is being executed in memory 207.

[0048] The charging unit 202 charges the battery 203 using power supplied from the power receiving unit 204, which will be described later.

[0049] The battery 203 supplies power necessary for controlling various parts of the RX200 by the control unit 201, as well as power reception and communication. The battery 203 also stores power received via the power receiving coil 205 by the charging unit 202.

[0050] In the receiving coil 205, an induced electromotive force is generated by electromagnetic waves radiated from the transmitting coil 105 of TX100, and the receiving unit 204 acquires the power generated in the receiving coil 205. The receiving unit 204 acquires the AC power generated by electromagnetic induction in the receiving coil 205. The receiving unit 204 then converts the AC power to DC or AC power of a predetermined frequency and outputs the power to the charging unit 202, which performs processing for charging the battery 203. The above-mentioned GP is the power that is guaranteed to be output from the receiving unit 204.

[0051] The communication unit 206 performs control communication with the TX100 based on the WPC standard as described above. The communication unit 206 demodulates the electromagnetic wave input from the receiving coil 205 to obtain the information transmitted from the TX100, and performs first communication with the TX100 by load modulating the electromagnetic wave and superimposing the information to be transmitted to the TX100 onto the electromagnetic wave. In other words, the first communication performed by the communication unit 206 is performed by superimposing it onto the electromagnetic wave sent from the transmitting coil 105 of the TX100.

[0052] Furthermore, the communication unit 206 may perform a second communication using a communication antenna (not shown). As described above, the second communication is faster than the first communication. Specifically, the electromagnetic waves used for the second communication have a higher frequency band than the electromagnetic waves used for the first communication. The communication unit 206 may have, for example, modulation / demodulation circuits and communication protocol processing functions necessary for performing communication compliant with the BLE standard.

[0053] The communication unit 206 may communicate with the TX100 for device authentication. The communication for device authentication may be a second communication which is faster than the first communication.

[0054] The communication unit 206 transmits an EPT packet to the TX100 indicating a power outage. This EPT packet may contain information indicating the reason for requesting a power outage, or information indicating the duration of the power outage. Reasons for requesting a power outage may include the RX200's temperature exceeding the upper limit, charging being completed, negotiation failing, or the detection of an object other than the power receiving device (hereinafter referred to as "foreign object").

[0055] As described above, memory 207 stores various information such as identification information and device configuration information, as well as control programs. Note that memory 207 may also store information obtained by a different functional unit than the control unit 101.

[0056] The notification unit 208 notifies the user of information by any method, such as visual, auditory, or tactile. For example, the notification unit 208 notifies the user of the charging status of the RX200 or the status of power transmission of the wireless power transmission system. The notification unit 208 is composed of, for example, a display, LED, speaker, vibration generating circuit, or other notification devices. The notification unit 106 can be configured in any way that allows the user to understand whether power is being transmitted or not. For example, the notification unit 208 may be an LED that lights up green when power is not being received and lights up red when power is being received. Alternatively, the notification unit 208 may be an LED that lights up when power is being received and blinks when power is not being received. Furthermore, the notification unit 208 may notify by light when power is being received and by sound when power is not being received.

[0057] The temperature sensor 209 measures the temperature of the RX200. Based on the temperature measured by the temperature sensor 209, the control unit 201 decides whether or not to send an EPT packet. For example, the control unit 201 compares the temperature measured by the temperature sensor 209 with the upper limit of the temperature stored in the memory 207, and if the temperature measured by the temperature sensor 209 exceeds the upper limit, it controls the communication unit 206 to send an EPT packet. Note that the temperature of the RX200 may rise due to factors such as receiving a large amount of power for a long period of time, or receiving power in a high-temperature environment such as inside a car in direct sunlight during the day.

[0058] In Figure 2, the control unit 201, charging unit 202, power receiving unit 204, communication unit 206, and memory 207 are shown as separate components, but any number of these may be implemented on the same chip.

[0059] (Process flow) In this embodiment, when TX100 receives an EPT packet containing information specifying the power outage period, TX100 sends a signal (hereinafter referred to as the "confirmation signal") to confirm the presence of RX200. This allows TX100 to detect early if RX200 has been removed, and then return to the Selection phase more quickly.

[0060] Here, we will explain examples of the processing flow performed by TX100 and RX200 using Figures 4 and 5. Figure 4 shows the processing sequence between the power transmission unit and the power receiving unit during a power outage, when the power receiving unit is not removed. On the other hand, Figure 5 shows the processing sequence between the power transmission unit and the power receiving unit during a power outage, when the power receiving unit is removed and a new power receiving unit is installed.

[0061] First, using Figure 4, we will explain the process between the power transmission unit (TX) and the power receiving unit (RX) during a power outage, assuming there is no replacement of the power receiving unit. Note that the sequence in Figure 4 starts with the power transmission unit (TX) and the power receiving unit (RX) in the Power Transfer phase. In other words, the power transmission unit (TX) and the power receiving unit (RX) have already gone through the Selection phase, Ping phase, I&C phase, Negotiation phase, and Calibration phase.

[0062] In S401, RX200 transmits an EPT packet containing information specifying the period for which power transmission will be stopped. Here, the specified period is 10 seconds, but is not limited to this. The EPT packet is transmitted when the temperature of RX200 exceeds the upper limit, as described above. However, RX200 may also transmit an EPT packet if it detects an abnormality other than temperature. For example, RX200 may transmit an EPT packet if it determines that there is a possibility that a foreign object such as an NFC tag is placed on the charging cradle. Also, if TX100 detects an abnormality in TX100, it may transmit a signal to RX200 to transmit an EPT packet. Based on the receipt of this signal, RX200 may transmit an EPT packet. An example of detecting an abnormality in TX100 is when the temperature measured by the temperature sensor 110 exceeds the upper limit.

[0063] When the TX100 receives the aforementioned EPT packet in the communication unit 104, it stops power transmission from the power transmission unit 103, sets the timer 109 to 10 seconds, and starts the countdown.

[0064] In S402, the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to transmit a confirmation signal one second after the countdown begins. Here, the power of the confirmation signal is the same as the power of the Analog Ping transmitted in the Selection phase described above.

[0065] TX100 detects at least one of the voltage and current values ​​applied to the power transmission coil 105 when transmitting a confirmation signal. This is done to detect the removal of RX200 by utilizing the fact that a change occurs in the voltage or current applied to the power transmission coil 105 when RX200 is placed on the charging base compared to when RX200 is removed. TX100 determines that RX200 is placed on the charging base because the difference between its detected value and the detected value when an object, i.e., RX200, was detected in the Selection phase (hereinafter referred to as the "reference detected value") is within a predetermined range. This is because the power of the confirmation signal is equivalent to the power of Analog Ping. The reference detected value is stored in memory 107. Furthermore, Analog Ping does not necessarily have to be sent 1 second after the countdown begins. For example, the timing of sending Analog Ping may be set by the user.

[0066] While we won't go into detail here, for example, if the EPT packet contains information indicating a request for foreign object detection, the TX100 will perform foreign object detection using a known method.

[0067] In S403, the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to transmit a confirmation signal two seconds after the countdown begins. TX100 detects at least one of the voltage value and current value applied to the power transmission coil 105 when transmitting the confirmation signal. TX100 then determines that the RX200 is placed on the charging base because the difference between the detected value and the reference detected value is within a predetermined range.

[0068] Similarly, a confirmation signal is transmitted every second. The interval between transmissions of the confirmation signal may be shorter or longer than one second. The interval between transmissions of the confirmation signal may be set by the user. The confirmation signal may also be transmitted periodically or aperiodicly.

[0069] In S404, the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to transmit a confirmation signal 10 seconds after the countdown begins. TX100 detects at least one of the voltage value and current value applied to the power transmission coil 105 when transmitting the confirmation signal. TX100 then determines that the RX200 is placed on the charging base because the difference between the detected value and the reference detected value is within a predetermined range.

[0070] In S405, after it is determined that the RX200 is placed on the charging cradle, the control unit 101 of the TX100 controls the power transmission unit 103 to send a Digital Ping.

[0071] In S406, RX200 sends an SS packet in response to the Digital Ping. Subsequently, TX100 and RX200 go through the Ping phase, I&C phase, Negotiation phase, and Calibration phase again, and then proceed to the Power Transfer phase.

[0072] In addition, in S406, the RX200 can also send an EPT packet instead of an SS packet. If this EPT packet contains information specifying the period for which power transmission will be suspended, the process returns to S402. If the EPT packet does not contain information specifying the period for which power transmission will be suspended, the process proceeds to the Selection phase.

[0073] Figure 5 illustrates the process between the power transmission unit (TX) and the power receiving unit (RX) during a power outage when a power receiving unit is removed and a new power receiving unit is installed. Specifically, after RX200 is removed, RX500 is installed on the charging base of TX100. RX500 is a power receiving unit with the same configuration as RX200 described above. Detailed explanations of points similar to those in Figure 4 are omitted. Also, in the sequence in Figure 5, as in Figure 4, the power transmission unit (TX) and power receiving unit (RX) begin in the Power Transfer phase.

[0074] In S501, similar to S401, RX200 transmits an EPT packet containing information specifying the period for which power transmission will be stopped. When TX100 receives the aforementioned EPT packet in the communication unit 104, it stops power transmission from the power transmission unit 103, sets the timer 109 to 10 seconds, and starts the countdown.

[0075] In S502, similar to S402, the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to transmit a confirmation signal one second after the countdown begins. TX100 detects at least one of the voltage value and current value of the power transmission coil 105 applied when transmitting the confirmation signal. TX100 then determines that the RX200 is placed on the charging base because the difference between the detected value and the reference detected value is within a predetermined range.

[0076] This section describes the case where RX200 is removed after S502 and before the next confirmation signal is transmitted.

[0077] In S503, the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to transmit a confirmation signal two seconds after the countdown begins. TX100 detects at least one of the voltage value and current value applied to the power transmission coil 105 when transmitting the confirmation signal. However, since RX200 has been removed, the detected value detected by TX100 changes. Specifically, the difference between this detected value and the reference detected value exceeds a predetermined range. As a result, TX100 determines that RX200 is not placed on the charging base, forcibly stops the timer 109, and terminates the countdown operation. The transmission of the confirmation signal is then stopped.

[0078] In S504, TX100 returns to the Selection phase, and the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to send an Analog Ping. Then, TX100 detects at least one of the voltage value and current value applied to the power transmission coil 105 when sending the Analog Ping. TX100 determines that no object is placed on the charging base because the difference between the detected value and the detected value when no object is placed on the base is within a predetermined range.

[0079] This section describes the case where the RX500 is placed on the TX100 charging cradle after S504 and before the next Analog Ping is sent.

[0080] In S505, the control unit 101 of TX100 controls the power transmission unit 103 and the power transmission coil 105 to send an Analog Ping. The TX100 then detects at least one of the voltage value and current value applied to the power transmission coil 105 when sending the Analog Ping. The TX100 determines that an object has been placed on the charging base because the difference between the detected value and the detected value when no object is placed on it exceeds a predetermined range.

[0081] Next, in S506, TX100 sends a Digital Ping.

[0082] In S507, RX500 sends an SS packet in response to the Digital Ping. Subsequently, TX100 and RX500 go through the Ping phase, I&C phase, Negotiation phase, and Calibration phase again, and then proceed to the Power Transfer phase.

[0083] Thus, when the TX100 receives an EPT packet specifying a period for power transmission to be stopped, it activates a timer and sends a confirmation signal to verify the presence of the RX200. This allows for early detection of when the presence of the RX200 can no longer be confirmed, i.e., when the RX200 has been removed.

[0084] Furthermore, even while the timer is running, if the TX100 stops detecting objects, the timer is forcibly terminated and the system transitions to the normal Selection phase. This allows the power transmission control sequence to start earlier for the newly placed power receiving device (RX500) if the power receiving device is replaced during the power outage period specified in the EPT packet, thus shortening the time until power transmission can begin.

[0085] (Flowchart showing the processing of power transmission equipment) The following describes the processes that the TX100 executes upon receiving an EPT packet. Figure 6 is a flowchart of these processes.

[0086] In S600, the control unit 101 of TX100 determines whether or not it has received an EPT packet from the communication unit 104. If the communication unit 104 has received an EPT packet (Yes in S600), the process proceeds to S601. If the communication unit 104 has not received an EPT packet, the process remains in the Power Transfer phase and the determination in S600 is made.

[0087] In S601, when the control unit 101 of TX100 determines that it has received an EPT packet at the communication unit 104, it controls the power transmission unit 103 and the power transmission coil 105 to stop power transmission.

[0088] In S602, the control unit 101 sets the timer 109 based on the power outage period specified in the EPT packet, and starts the operation of the timer 109, i.e., the countdown.

[0089] In S603, the control unit 101 controls the power transmission unit 103 and the power transmission coil 105 at predetermined intervals to transmit a confirmation signal.

[0090] In S604, the control unit 101 determines whether or not an object is placed on the charging base of the TX100. Specifically, it does so as follows: First, the control unit 101 detects at least one of the voltage value and current value of the power transmission coil 105. Next, it compares this detected value with a reference detected value stored in the memory 107. If the difference is within a predetermined range (Yes in S604), it determines that the RX200 is still in place and proceeds to S605. On the other hand, if the difference between the detected value and the reference detected value exceeds a predetermined range (No in S604), it determines that the RX200 has been removed and proceeds to S607.

[0091] In S605, the control unit 101 determines whether the power outage period has elapsed using the timer 109. If the power outage period has not elapsed (No in S605), the process returns to S603. On the other hand, if the power outage period has elapsed (Yes in S605), the process proceeds to S606.

[0092] In S607, the control unit 101 forcibly terminates the operation of the timer 109, which is performing a countdown.

[0093] In S608, the control unit 101 controls the power transmission unit 103 to transmit Analog Ping at predetermined transmission intervals.

[0094] In S609, the control unit 101 determines whether or not an object has been placed on the charging base of the TX100. Specifically, it does so as follows: First, the control unit 101 detects at least one of the voltage value and current value of the power transmission coil 105. Next, it compares this detected value with the detected value stored in the memory 107 for the state when no object is placed. If the difference exceeds a predetermined range (Yes in S609), it determines that an object has been placed and proceeds to S606. On the other hand, if the difference is within a predetermined range (No in S609), it determines that no object has been placed and returns to S608.

[0095] In S606, the control unit 101 controls the power transmission unit 103 to send a Digital Ping. Subsequently, upon receiving an SS packet transmitted from RX200 or RX500, the system proceeds to the I&C phase in S610.

[0096] Subsequently, the process moves to the I&C phase (S610), the Negotiation phase (S611), the Calibration phase (S612), and the Power Transfer phase (S613). The Power Transfer phase then ends, for example, when the RX200 or RX500 battery is fully charged. Note that the I&C, Negotiation, Calibration, and Power Transfer phases are performed as described above, and their details are omitted here.

[0097] <Other Embodiments> (Regarding confirmation signals) The above explanation used an example where the power of the confirmation signal is the same as the power of the Analog Ping, but this is not limited to this. The power of the confirmation signal may be less than or greater than the power of the Analog Ping. Furthermore, the power of the confirmation signal may be equivalent to the power of the Digital Ping. Note that the power of the confirmation signal is less than the power used in the Power Transfer phase. In other words, the power of the confirmation signal is less than the power transmitted from the TX100 to charge the battery 203 based on the power received by the RX200.

[0098] If the power used for verification transmission is equivalent to that used for Analog Ping or Digital Ping, the power settings can be simplified.

[0099] In the embodiment described above, the transmission interval of the confirmation signal may be the same as or different from the transmission interval of Analog Ping in the Selection phase. For example, the time interval between S502 and S503 in Figure 5 may be the same as or different from the time interval between S503 and S504 or S504 and S505.

[0100] If the transmission interval of Analog Ping in the Selection phase is shorter than the transmission interval of the confirmation signal, then, as shown in Figure 5, the detection of the new power receiving device (RX500) can be performed more quickly when the power receiving device is replaced.

[0101] By shortening the transmission interval of the confirmation signal, which is the same as the transmission interval of Analog Ping in the Selection phase, the removal of the power receiving device can be detected earlier, and the system can move to the Selection phase sooner.

[0102] (Regarding the determination of whether to remove the power receiving device) If the power of the confirmation signal differs from the power of Analog Ping, the following configuration can be used to detect the removal of the RX200. Specifically, first, when the TX100 sends the first confirmation signal (S402, S502), it detects at least one of the voltage value and current value of the power transmission coil 105 and stores this detected value in memory 107 as a reference detected value. Then, when sending the second and subsequent confirmation signals, it detects at least one of the voltage value and current value of the power transmission coil 105. Then, it compares this detected value with the above reference detected value, and if the difference exceeds a predetermined range, it is determined that the RX200 has been removed. On the other hand, if the difference is within the predetermined range, it is determined that the RX200 is placed on the charging base.

[0103] The reference detection value used as the criterion for determining whether the power receiving device has been removed may be either the voltage value or the current value of the power transmission coil 105 when no object is placed on it. The detection value at the time of transmission of the confirmation signal may be compared with this reference detection value, and if the difference exceeds a predetermined range, it may be determined that the RX200 is placed on the charging base; if it is within the predetermined range, it may be determined that the RX200 has been removed. In this case, the processing is the same as that for object detection using normal Analog Ping, so the processing content can be simplified.

[0104] (Detection of replacement of power receiving equipment) In the embodiment described above, an example was explained in which it is determined that RX200 has been removed and then that RX500 has been installed. However, if the replacement of the power receiving device is performed in a time shorter than the interval between the transmission of confirmation signals, there is a possibility that this replacement cannot be detected. To address this, first, when TX100 transmits the first confirmation signal (S402, S502), it detects at least one of the voltage value and current value of the power transmission coil 105 and stores this detected value in memory 107 as a reference detected value. Then, when transmitting the second and subsequent confirmation signals, it detects at least one of the voltage value and current value of the power transmission coil 105. Then, it compares this detected value with the above reference detected value, and if the difference exceeds a predetermined range, it is determined that RX200 has been replaced with RX500. In other words, in this case, the removal of RX200 and the installation of RX500 can be determined simultaneously.

[0105] Furthermore, it can also be implemented by supplying a program that implements one or more of the above-described functions to a system or device via a network or storage medium, and having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions.

[0106] Furthermore, at least a portion of the processes shown in the flowchart of Figure 6 may be implemented in hardware. If implemented in hardware, for example, a dedicated circuit can be automatically generated on an FPGA (Field Programmable Gate Array) from the program required to implement each process by using a predetermined compiler. Alternatively, a Gate Array circuit can be formed in a similar manner to an FPGA, and implemented as hardware. [Explanation of Symbols]

[0107] 100 Power transmission equipment 101 Control Unit 105 Power transmission coil 104 Communications Department 108 Detection unit 200 Power receiving equipment

Claims

1. A power transmission device for wirelessly transmitting power, A means for transmitting signals, It includes detection means that perform a process of detecting an object based on parameters acquired after the transmission of a signal, If an object is detected after the first signal has been transmitted, the transmitting means transmits a second signal to activate the power receiving device. The transmitting means transmits a third signal to confirm the presence of an object after the second signal has been transmitted. The detection means performs a process to detect an object based on the parameters obtained when no object is present after the transmission of the third signal and the parameters obtained after the transmission of the third signal. If an object is detected after the third signal has been transmitted, the transmitting means will transmit the third signal again without transmitting the second signal. The transmitting means transmits the first signal when no object is detected after the third signal has been transmitted. The transmitting means is a power transmission device that transmits the second signal if an object is no longer detected after the third signal has been transmitted and an object is detected after the first signal has been transmitted.

2. The power transmission device according to claim 1, wherein if the object detected after the first signal has been transmitted is a power receiving device, power is transmitted to the power receiving device.

3. The power transmission device according to claim 1, wherein the second signal is a Digital Ping as defined in the Wireless Power Consortium standard.

4. The power transmission device according to claim 1, wherein the first signal is an Analog Ping as defined in the Wireless Power Consortium standard.

5. A method performed by a power transmission device that transmits power wirelessly, The transmission process involves sending a signal, The system includes a detection step which performs an object detection process based on parameters acquired after the transmission of a signal, In the transmission process described above, a first signal is transmitted. In the detection step, after the first signal is transmitted, a process is performed to detect an object. If an object is detected after the first signal has been transmitted, a second signal is transmitted to activate the power receiving device. After the second signal is transmitted, a third signal is transmitted to confirm the presence of the object. After the third signal is transmitted, the system performs an object detection process based on the parameters obtained when no object is present and the parameters obtained after the third signal is transmitted. If an object is detected after the third signal has been transmitted, the third signal is transmitted again without transmitting the second signal. If the object is no longer detected after the third signal has been transmitted, the first signal is transmitted. A method to transmit the second signal if, after the third signal has been transmitted, the object is no longer detected, and after the first signal has been transmitted, the object is detected.

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