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

Abstract

To detect removal of a power reception device even during a period of stopping power transmission in a power transmission device that has received an EPT packet designating a period of stopping power transmission.SOLUTION: A power transmission device 100 controls a power transmission coil 105 to transmit a check signal for checking presence of a power reception device 200 during a period in which power transmission is stopped based on reception of an EPT packet including information on a period in which power transmission is stopped from the power reception device 200 by a communication unit 104. The power transmission device detects at least one of voltage and current applied to the power transmission coil 105 when the check signal is transmitted by a detection unit 108, and determines whether or not there is an RX200 that transmits the EPT packet based on detection results.SELECTED DRAWING: Figure 6

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 technology]

[0002] In recent years, technological development of wireless power transmission systems such as contactless charging systems has been widely carried out. Patent Document 1 discloses a power transmitting device and a power receiving device that comply with a standard (hereinafter referred to as the "WPC standard") established by the Wireless Power Consortium (WPC), a standardization organization for contactless charging. Patent Document 1 also discloses that when the power receiving device detects an abnormality, it transmits a signal indicating the stop of power transmission. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-165761 A Summary of the Invention [Problem to be solved by the invention]

[0004] It is conceivable to designate a power transmission suspension period using this signal indicating the suspension of power transmission. Specifically, it is conceivable to include information designating the power transmission suspension period in the signal indicating the suspension of power transmission. When the power transmission device receives a signal indicating the suspension of power transmission including information designating the power transmission suspension period, the power transmission device will stop power transmission during the power transmission suspension period. Therefore, it is conceivable that the transmission of a signal for detecting an object will also be stopped. In this case, even if the power receiving device on the power transmission device is removed during the power transmission suspension period, the removal of the power receiving device cannot be detected until the period has elapsed, and it is conceivable that it will take time to detect the removal.

[0005] In view of the above problems, the present invention , send In an electrical device, object The purpose of this method is to detect the removal of [Means for solving the problem]

[0006] A power transmission device according to one aspect of the present invention is a power transmission device that wirelessly transmits power, and includes a transmission unit that transmits a signal and a detection unit that performs processing to detect an object, and the transmission unit , No. After signal 1 is sent To If a body is detected, a second signal is transmitted to activate the power receiving device, and after the second signal is transmitted, To confirm the presence of an object transmit a third signal, and the detection means performs a process of detecting an object based on parameters acquired when no object is present and parameters acquired after the third signal is transmitted; when an object is detected after the third signal is transmitted, the transmitting means transmits the third signal again without transmitting the second signal; After the third signal is transmitted, To The body is not detected It became transmit the first signal when The transmitting means transmits the second signal when an object is no longer detected after the third signal is transmitted and when an object is detected after the first signal is transmitted. do. Effect of the Invention

[0007] In the present invention , send In an electrical device, object The removal of the signal can be detected. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a power transmission device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing a configuration example of a power receiving device according to the present embodiment; [Diagram 3] FIG. 1 is a diagram showing an example of a wireless power transmission system according to an embodiment of the present invention; [Figure 4] FIG. 13 is a diagram showing an example of a sequence in the case where the power receiving device is not removed in the present embodiment; [Diagram 5] FIG. 13 is a diagram showing an example of a sequence when a power receiving device is removed and a new power receiving device is placed in the present embodiment; [Figure 6] FIG. 1 is a diagram showing an example of a flowchart of processing performed by a power transmitting device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] FIG. 3 shows a configuration example of a contactless charging system (wireless power transmission system) according to this embodiment. This system includes a power transmitting device and a power receiving device. Hereinafter, the power transmitting device may be called TX, and the power receiving device may be called RX. TX100 is an electronic device that wirelessly transmits power to RX200 placed on its own charging stand. RX200 is an electronic device that receives power wirelessly transmitted from TX100 and charges its built-in battery. Below, a case where RX200 is placed on the charging stand will be described as an example. However, when TX100 transmits power to RX200, RX200 does not need to be placed on the charging stand as long as it is within the power transmission range of TX100.

[0011] The TX100 receives power from a commercial power source via an AC connector 301, and the power is supplied to a power supply unit 102. The RX200 receives power from a power transmitting coil 105 of the TX100 via a power receiving coil 205 of the RX200 itself. The power received by the RX200 is charged into a battery (not shown). The power transmitting coil 105 and the power receiving coil 205 are a type of antenna. In the following description, a coil is used as an example, but an antenna having a shape other than a coil may be used instead of the power transmitting coil 105 and the power receiving coil 205.

[0012] The TX100 and the RX200 may have a function of executing an application other than contactless charging. An example of the RX200 is a smartphone, and an example of the TX100 is an accessory device for charging the smartphone. The TX100 and the RX200 may be storage devices such as a hard disk device or a memory device, or may be information processing devices such as a personal computer (PC). The TX100 and the RX200 may be image input devices such as an imaging device (camera, video camera, etc.) or a scanner, or may be image output devices such as a printer, a copier, or a projector. The TX100 may be a smartphone. In this case, the RX200 may be another smartphone or a wireless earphone. The RX200 may be an automobile. The TX100 may be a charger installed in a console or the like in the automobile.

[0013] Furthermore, in this embodiment, one RX 200 and one TX 100 are shown, but the present invention can also be applied to a configuration in which a plurality of RX 200 transmit power from one TX 100 or from separate TX 100s.

[0014] This system performs wireless power transmission using an electromagnetic induction method for contactless charging based on the WPC standard. That is, RX200 and TX100 perform wireless power transmission for contactless charging based on the WPC standard between the receiving coil 205 of RX200 and the transmitting coil 105 of TX100. Note that the wireless power transmission method (contactless power transmission method) applied to this system is not limited to the method defined by the WPC standard, and may be a method using other electromagnetic induction method, magnetic field resonance method, electric field resonance method, microwave method, laser method, etc. Also, in this embodiment, wireless power transmission is used for contactless charging, but wireless power transmission may be performed for purposes other than contactless charging.

[0015] In the WPC standard, the magnitude of power guaranteed when the RX200 receives power from the TX100 is stipulated by a value called Guaranteed Power (hereinafter referred to as "GP"). GP indicates a power value that is guaranteed to be output to a load of the RX200 (e.g., a charging circuit, etc.) even if the positional relationship between the RX200 and the TX100 fluctuates and the power transmission efficiency between the receiving coil 205 and the transmitting coil 105 decreases. For example, when the GP is 5 watts, the TX100 transmits power by controlling so as to output 5 watts to the load in the RX200, even if the positional relationship between the receiving coil and the transmitting coil fluctuates and the power transmission efficiency decreases.

[0016] The RX200 and TX100 according to this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard specifies a number of phases, including a power transfer phase in which power transmission is performed and a phase before actual power transmission, and communication for necessary power transmission and reception control is performed in each phase. Phases before power transmission include a selection phase, a ping phase, an identification and configuration phase, a negotiation phase, and a calibration phase. In the following, the identification and configuration phase is referred to as an I&C phase.

[0017] In the Selection phase, the TX100 intermittently transmits Analog Pings to detect that an object has been placed on the charging stand (for example, that the RX200 or a conductor piece has been placed on the charging stand). In other words, the Analog Ping is a detection signal for detecting the presence of an object. The TX100 transmits Analog Pings by applying a voltage or current to the power transmitting coil 105. The voltage or current applied to the power transmitting coil 105 changes when an object is placed on the charging stand and when no object is placed on the charging stand. Therefore, the TX100 detects at least one of the voltage value and the current value applied to the power transmitting coil 105 when transmitting Analog Pings. The TX100 determines that an object is present when the detected voltage value is below a threshold value or the detected current value exceeds a threshold value, and transitions to the Ping phase.

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

[0019] In the I&C phase, the TX100 identifies the RX200 and obtains device configuration information (capability information) from the RX200. To do this, the RX200 transmits an ID packet and a configuration packet to the TX100. The ID packet contains the identification information of the RX200, and the configuration packet contains the device configuration information (capability information) of the RX200. Upon receiving the ID packet and configuration packet, the TX100 responds with an acknowledgement (ACK). Then the I&C phase ends.

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

[0021] In the calibration phase, based on the WPC standard, the RX200 notifies the TX100 of the received power value, and the TX100 makes adjustments to transmit power efficiently.

[0022] In the power transfer phase, control is performed for starting and continuing power transmission, as well as stopping power transmission due to an error or full charge.

[0023] The TX100 and the RX200 perform communication for controlling the power transmission and reception by superimposing a signal on the transmitted power using the same antenna (or coil) as that for 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 the TX100 and the RX200 is almost the same as the power transmission range of the TX100.

[0024] The RX200 according to this embodiment may perform challenge-response type communication using a digital certificate with the TX100 to perform device authentication of the TX100. That is, the TX100 and the RX200 perform communication for device authentication. Device authentication may be performed before the above-mentioned negotiation phase. In this case, the result of device authentication can be reflected in the negotiation phase. More specifically, this is as follows.

[0025] The RX200 requests the TX100 for which the equipment authentication has been successful to set the GP to 15 watts, and requests the TX100 for which the equipment authentication has not been successful to set the GP to 5 watts. The GP is not limited to combinations other than 15 watts and 5 watts, and any combination of values ​​may be used as long as the GP with the TX100 for which the equipment authentication has been successful is greater than the GP when the equipment authentication has not been successful. In other words, the RX200 requests that power transmission and reception be performed at a larger GP only with the TX100 for which the equipment authentication has been successful. In this way, by determining the GP based on the result of the equipment authentication, it is possible to receive power at a larger GP only from the TX100 that has passed a predetermined test defined in the WPC standard and is recognized as being capable of transmitting power at a larger GP. Cases where the equipment authentication is not successful include cases where the TX100 does not have the function to perform this equipment authentication, or cases where the TX100 has the function to perform equipment authentication but fails.

[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 result of device authentication in the GP, the system may transition to the ReNegotiation phase, re-determine the GP, and then transition to the Power Transfer phase again. Device authentication may also be performed in parallel with a phase prior to the Power Transfer phase, such as the Selection phase.

[0027] Furthermore, the communication for device authentication may be performed as a first communication using the same antenna (or coil) as the wireless power transmission, or may be performed as a communication (hereinafter referred to as "second communication") using an antenna (or coil) and frequency different from those used for the wireless power transmission. Here, the second communication is capable of faster communication 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.

[0028] In this embodiment, the second communication is performed using a communication method conforming to the Bluetooth (registered trademark) Low Energy (hereinafter, referred to as "BLE") standard as an example. Although the TX100 operates in the role of a BLE peripheral and the RX200 operates in the role of a BLE central, these BLE roles may be reversed. The second communication may be performed using other communication methods such as wireless LAN (e.g., Wi-Fi (registered trademark)) of the IEEE802.11 standard series, ZigBee, and NFC (Near Field Communication).

[0029] (Device configuration) Next, the configuration of the power transmitting device (TX100) and the power receiving device (RX200) according to this embodiment will be described. Note that the configuration described below is merely an example, and a part (or in some cases, the whole) of the configuration described may be replaced with another configuration performing a similar function or may be omitted, and further configuration may be added to the configuration described. Furthermore, one block shown in the following description may be divided into multiple blocks, or multiple blocks may be integrated into one block.

[0030] 1 is a diagram showing an example of the configuration of the TX 100 in this embodiment. The TX 100 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 to the above, the TX 100 may include an authentication unit that performs device authentication.

[0031] In the following, an example in which the communication unit 104 performs the first communication using the power transmission coil 105 will be described, but the present invention is not limited to this. That is, the TX 100 may have a communication antenna used when performing the second communication described above, and may perform the second communication. The communication performed by the communication unit 104 may include communication for power transmission and reception control, and may further include communication for device authentication.

[0032] The control unit 101 controls the entire TX by executing a control program stored in the memory 107, for example. That is, the control unit 101 controls each unit shown in FIG. 1. The control unit 101 may also perform control for executing applications other than wireless power transmission. The control unit 101 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The control unit 101 may be configured with hardware dedicated to a specific process, such as an application specific integrated circuit (ASIC). The control unit 101 may also be configured with an array circuit, such as a field programmable gate array, compiled to execute a specific process. The control unit 101 stores information to be stored during execution of various processes in the memory 107. The control unit 101 may also measure time using a timer 109.

[0033] The power supply unit 102 supplies the entire TX 100 with power required for the control of the TX 100 by the control unit 101 and for power transmission and communication. The power supply unit 102 converts power supplied from an external source, such as a commercial power source, to a required voltage and supplies power to the entire TX 100. The power supply unit 102 may also be a battery. The battery stores power supplied from the commercial power source.

[0034] The power transmitting unit 103 converts the DC or AC power input from the power supply unit 102 into AC frequency power in a frequency band used for wireless power transmission, and inputs the AC frequency power to the power transmitting coil 105 to generate electromagnetic waves for receiving power at the RX200. The frequency of the AC power generated by the power transmitting unit 103 is, for example, about several hundred kHz (for example, 110 kHz to 205 kHz). This frequency is different from, for example, a BLE communication frequency (2.4 GHz) used in the second communication. The power transmitting unit 103 inputs the AC frequency power to the power transmitting coil 105 based on an instruction from the control unit 101 so that the power transmitting coil 105 outputs electromagnetic waves for transmitting power to the RX200. The power transmitting unit 103 also controls the intensity of the electromagnetic waves to be output by adjusting the voltage (power transmitting voltage) or current (power transmitting current) input to the power transmitting coil 105, or both. Increasing the transmission voltage or the transmission current increases the intensity of the electromagnetic waves, and decreasing the transmission voltage or the transmission current decreases the intensity of the electromagnetic waves. In addition, the power transmitting unit 103 performs output control of the AC frequency power based on an instruction from the control unit 101 so that power transmission from the power transmitting coil 105 is started or stopped.

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

[0036] The communication unit 104 performs control communication based on the WPC standard with the RX200 as described above. The communication unit 104 modulates the electromagnetic waves output from the power transmitting 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 transmitting coil 105 and modulated in the RX200 to acquire information transmitted by the RX200. That is, the first communication performed by the communication unit 104 is superimposed on the electromagnetic waves transmitted from the power transmitting coil 105.

[0037] Furthermore, the communication unit 104 may perform the 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 in the second communication are in a higher frequency band than the electromagnetic waves used in the first communication. The communication unit 104 may have a modulation / demodulation circuit and a communication protocol processing function required for performing communication conforming to the BLE standard, for example.

[0038] The communication unit 104 may perform communication for device authentication with the RX 200. The communication for device authentication may be a second communication that is a faster communication than the first communication.

[0039] The communication unit 104 receives a signal (End Power transfer packet, hereinafter referred to as "EPT packet") indicating the stop of power transmission from the RX200. This EPT packet may include information indicating the reason for requesting the stop of power transmission, or may include information indicating the power transmission stop period and the power transmission start time. The reasons for requesting the stop of power transmission may include when the temperature of the RX200 exceeds the upper limit, when charging is completed, when negotiation has failed, or when a request is made to detect 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. The notification unit 106 notifies the user of, for example, information indicating the charging state of the TX 100 or the state related to power transmission of the wireless power transmission system. The notification unit 106 includes, for example, a display, an LED, a speaker, a vibration generating circuit, and other notification devices. The notification unit 106 may have any configuration as long as the user can understand whether or not power is being transmitted. For example, the notification unit 106 may be an LED that lights up green when power is not being transmitted and lights up red when power is being transmitted. The notification unit 106 may also be an LED that lights up when power is being transmitted and blinks when power is not being transmitted. The notification unit 106 may also notify the user by emitting light when power is being transmitted and by making a sound when power is not being transmitted.

[0041] The memory 107 stores various information such as information indicating the state of each unit or the entire state of the wireless power transmission system, control programs, etc. The memory 107 may store information obtained by a functional unit other than the control unit 101.

[0042] The detection unit 108 detects at least one of the voltage value and the current value of the power transmitting coil 105. Specifically, the detection unit 108 detects the voltage value and / or the current value of the power transmitting coil 105 when an Analog Ping is transmitted in the Selection phase. The detection unit 108 also detects the voltage value and / or the current value of the power transmitting coil 105 when a signal for confirming the presence of the RX200, which will be described later, is transmitted. Based on the detection result by the detection unit 108, that is, the detection value, the control unit 101 can detect that an object has been placed on the charging stand or that an object has been removed.

[0043] The timer 109 measures time using, for example, a count-up timer that measures the elapsed time from the time of activation, a count-down timer that counts down from a set time, etc. After the communication unit 104 receives an EPT packet indicating a power transmission stop from the RX200, if the EPT packet contains information indicating a power transmission stop period, the timer 109 sets the period and starts counting down.

[0044] The temperature sensor 110 measures the temperature of the TX 100. 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 upper limit of the temperature stored in the memory 107 with the temperature measured by the temperature sensor 110, and when the temperature measured by the temperature sensor 110 exceeds the upper limit, the control unit 101 controls the power transmission unit 103 to stop the power transmission. Note that the temperature of the TX 100 may rise when transmitting a large amount of power continuously for a long period of time or when transmitting power in a high-temperature environment such as the inside of a car under the blazing sun during the day.

[0045] In FIG. 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 units, but any multiple of these units may be implemented within the same chip.

[0046] 2 is a diagram showing an example of the configuration of the RX 200 in this embodiment. The RX 200 has 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 to the above, the RX 200 may have an authentication unit that performs device authentication.

[0047] The control unit 201 controls the entire RX200 by executing a control program stored in the memory 207, for example. That is, the control unit 201 controls each unit shown in FIG. 2. The control unit 201 may also control power reception control including communication for device authentication in the RX200. Furthermore, the control unit 201 may control execution of applications other than wireless power transmission. The control unit 201 includes one or more processors, such as a CPU or an MPU. The control unit 201 may be configured with hardware dedicated to a specific process, such as an application specific integrated circuit (ASIC). The control unit 201 may also be configured with an array circuit, such as an FPGA, compiled to execute a specific process. The control unit 201 stores information to be stored during execution of various processes in the memory 207.

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

[0049] The battery 203 supplies power required for the control of each part of the RX 200 by the control unit 201, and for power reception and communication. The battery 203 also stores the power received by the charging unit 202 via the power receiving coil 205.

[0050] In the power receiving coil 205, an induced electromotive force is generated by the electromagnetic waves radiated from the power transmitting coil 105 of the TX 100, and the power receiving unit 204 acquires the power generated in the power receiving coil 205. The power receiving unit 204 acquires AC power generated by electromagnetic induction in the power receiving coil 205. Then, the power receiving unit 204 converts the AC power into DC power or AC power of a predetermined frequency, and outputs the power to the charging unit 202 that performs processing to charge the battery 203. The above-mentioned GP is power that is guaranteed to be output from the power receiving unit 204.

[0051] The communication unit 206 performs control communication based on the WPC standard with the TX100 as described above. The communication unit 206 demodulates the electromagnetic waves input from the power receiving coil 205 to obtain information transmitted from the TX100, and performs the first communication with the TX100 by superimposing the information to be transmitted to the TX100 on the electromagnetic waves through load modulation of the electromagnetic waves. That is, the first communication performed by the communication unit 206 is performed by being superimposed on the electromagnetic waves transmitted from the power transmitting coil 105 of the TX100.

[0052] Furthermore, the communication unit 206 may perform the 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 in the second communication are in a higher frequency band than the electromagnetic waves used in the first communication. The communication unit 206 may have a modulation / demodulation circuit and a communication protocol processing function required for performing communication conforming to the BLE standard, for example.

[0053] The communication unit 206 may perform communication for device authentication with the TX 100. The communication for device authentication may be a second communication that is a faster communication than the first communication.

[0054] The communication unit 206 transmits an EPT packet indicating the stop of power transmission to the TX100. This EPT packet may include information indicating the reason for requesting the stop of power transmission, or may include information indicating the period during which power transmission is stopped. The reasons for requesting the stop of power transmission may include the case where the temperature of the RX200 exceeds an upper limit, the case where charging is completed, the case where negotiation has failed, or the case where detection of an object other than the power receiving device (hereinafter referred to as a "foreign object") is requested.

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

[0056] The notification unit 208 notifies the user of information by any method such as visual, auditory, or tactile. The notification unit 208 notifies the user of, for example, the charging state of the RX200 and the state related to power transmission of the wireless power transmission system. The notification unit 208 includes, for example, a display, an LED, a speaker, a vibration generating circuit, and other notification devices. The notification unit 106 may have any configuration as long as the user can understand the presence or absence of power transmission. 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. The notification unit 208 may also be an LED that lights up when power is being received and blinks when power is not being received. The notification unit 208 may also notify the user by emitting light when power is being received and by making a 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 to transmit an EPT packet. For example, the control unit 201 compares the upper limit of the temperature stored in the memory 207 with the temperature measured by the temperature sensor 209, and if the temperature measured by the temperature sensor 209 exceeds the upper limit, the control unit 201 controls the communication unit 206 to transmit the EPT packet. Note that the temperature of the RX200 may rise when it receives large power continuously for a long period of time, or when it receives power in a high-temperature environment such as the inside of a car under the blazing sun during the day.

[0058] In FIG. 2, the control unit 201, the charging unit 202, the power receiving unit 204, the communication unit 206, and the memory 207 are illustrated as separate units, but any two or more of these may be implemented on the same chip.

[0059] (Processing flow) In this embodiment, when the TX100 receives an EPT packet including information specifying a power transmission suspension period, the TX100 sends a signal to confirm the presence of the RX200 (hereinafter, referred to as a "confirmation signal"). This allows the TX100 to detect the removal of the RX200 early on. Then, the TX100 can quickly return to the Selection phase.

[0060] Here, an example of the flow of processing executed by TX100 and RX200 will be described with reference to Figs. 4 and 5. Fig. 4 shows a sequence of processing between a power transmitting device and a power receiving device during power transmission suspension when the power receiving device is not removed. Meanwhile, Fig. 5 shows a sequence of processing between a power transmitting device and a power receiving device during power transmission suspension when the power receiving device is removed and a new power receiving device is installed.

[0061] First, the process between the power transmitting device (TX) and the power receiving device (RX) during power transmission stop when the power receiving device is not replaced will be described with reference to Fig. 4. The sequence in Fig. 4 starts from a state in which the power transmitting device (TX) and the power receiving device (RX) are in the Power Transfer phase. In other words, the power transmitting device (TX) and the power receiving device (RX) have already passed through the Selection phase, Ping phase, I&C phase, Negotiation phase, and Calibration phase.

[0062] In S401, the RX200 transmits an EPT packet including information specifying a period for stopping power transmission. Here, the specified period is 10 seconds, but is not limited to this. The EPT packet is transmitted when the temperature of the RX200 exceeds an upper limit value, as described above. However, the RX200 can transmit an EPT packet even when it detects an abnormality other than temperature. For example, the RX200 may transmit an EPT packet when it determines that a foreign object such as an NFC tag may be placed on the charging stand. Furthermore, when the TX100 detects an abnormality in the TX100, the TX100 may transmit a signal to the RX200 to transmit an EPT packet. Based on the reception of this signal, the RX200 may transmit an EPT packet. An example of a case where an abnormality in the TX100 is detected is when the temperature measured by the temperature sensor 110 exceeds an upper limit value.

[0063] When the TX 100 receives the above-mentioned EPT packet at the communication unit 104, it stops power transmission from the power transmission unit 103, sets the timer 109 to 10 seconds, and starts a countdown.

[0064] In S402, one second after the start of the countdown, the control unit 101 of the TX 100 controls the power transmitting unit 103 and the power transmitting coil 105 to transmit a confirmation signal. Here, the power of the confirmation signal is the same as the power of the Analog Ping transmitted in the above-mentioned Selection phase.

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

[0066] Although details will not be described here, for example, if the EPT packet contains information indicating a request for foreign object detection, the TX 100 performs foreign object detection using a known method.

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

[0068] Thereafter, the confirmation signal is transmitted every second in the same manner. The transmission interval of the confirmation signal may be shorter or longer than one second. The transmission interval of the confirmation signal may be set by the user. The confirmation signal may be transmitted periodically or non-periodically.

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

[0070] After it is determined in S405 that the RX200 is placed on the charging stand, the control unit 101 of the TX100 controls the power transmitting unit 103 to transmit a Digital Ping.

[0071] In S406, the RX200 transmits an SS packet in response to the Digital Ping. After that, the TX100 and the RX200 go through the above-mentioned Ping phase, I&C phase, Negotiation phase, and Calibration phase again, and then transition to the Power Transfer phase.

[0072] In addition, in S406, the RX200 can also transmit an EPT packet instead of an SS packet. If the EPT packet contains information specifying the period during which power transmission is stopped, the process returns to S402. If the EPT packet does not contain information specifying the period during which power transmission is stopped, the process proceeds to the Selection phase.

[0073] Fig. 5 explains the processing between the power transmitting device (TX) and the power receiving device (RX) during power transmission stop when the power receiving device is removed and a new power receiving device is placed. Specifically, after the RX200 is removed, the RX500 is placed on the charging stand of the TX100. The RX500 is a power receiving device having the same configuration as the RX200 described above. Note that detailed explanations of the same points as in Fig. 4 will be omitted. Also, the sequence in Fig. 5 starts with the power transmitting device (TX) and the power receiving device (RX) in the Power Transfer phase, as in Fig. 4.

[0074] In S501, similarly to S401, the RX200 transmits an EPT packet including information designating a period for which power transmission is to be stopped. When the TX100 receives the above-mentioned EPT packet at the communication unit 104, the TX100 stops power transmission from the power transmission unit 103, sets the timer 109 to 10 seconds, and starts a countdown.

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

[0076] A case will be described where RX200 is removed after S502 and before the next confirmation signal is transmitted.

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

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

[0079] A case will be described where the RX500 is placed on the charging base of the TX100 after S504 and before the next Analog Ping is sent.

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

[0081] Next, in S506, the TX 100 transmits a Digital Ping.

[0082] In S507, the RX500 transmits an SS packet in response to the Digital Ping. After that, the TX100 and the RX500 go through the above-mentioned Ping phase, I&C phase, Negotiation phase, and Calibration phase again, and then transition to the Power Transfer phase.

[0083] In this way, when the TX100 receives an EPT packet specifying the period for which power transmission is to be stopped, it operates the timer and transmits a confirmation signal to confirm the presence of the RX200. This makes it possible to quickly detect when the presence of the RX200 can no longer be confirmed, that is, when the RX200 has been removed.

[0084] Furthermore, even if the timer is running, if the TX100 no longer detects an object, the timer is forcibly terminated and the system transitions to the normal Selection phase. This allows the control sequence for power transmission to be started quickly for the newly placed power receiving device (RX500) on the charging stand, shortening the time until power transmission starts, if the power receiving device is replaced during the power transmission stop period specified in the EPT packet.

[0085] (Flowchart showing processing of power transmitting device) The process that the TX 100 executes upon receiving an EPT packet will be described below. Figure 6 is a flowchart of that process.

[0086] In S600, the control unit 101 of the TX 100 judges whether or not an EPT packet has been received by 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 performs the judgment in S600.

[0087] In S601, when the control unit 101 of the TX 100 determines that the communication unit 104 has received an EPT packet, it controls the power transmitting unit 103 and the power transmitting coil 105 to stop power transmission.

[0088] In S602, the control unit 101 sets the timer 109 based on the power transmission suspension period specified in the EPT packet, and starts the operation of the timer 109, that is, starts counting down.

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

[0090] In S604, the control unit 101 judges whether or not an object is placed on the charging stand of the TX100. Specifically, the control unit 101 performs the following: First, the control unit 101 detects at least one of the voltage value and the current value of the power transmitting coil 105. Next, the control unit 101 compares this detection value with a reference detection value stored in the memory 107, and if the difference is within a predetermined range (Yes in S604), it is judged that the RX200 is still placed there, and the process proceeds to S605. On the other hand, if the difference between the detection value and the reference detection value exceeds the predetermined range (No in S604), it is judged that the RX200 has been removed, and the process proceeds to S607.

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

[0092] In S607, the control unit 101 forcibly ends the operation of the timer 109 which is counting down.

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

[0094] In S609, the control unit 101 judges whether or not an object has been placed on the charging stand of the TX 100. Specifically, the control unit 101 performs the following: First, the control unit 101 detects at least one of the voltage value and the current value of the power transmitting coil 105. Next, the control unit 101 compares this detected value with the detected value stored in the memory 107 when no object is placed, and if the difference exceeds a predetermined range (Yes in S609), it is judged that an object has been placed, and the process proceeds to S606. On the other hand, if the difference is within the predetermined range (No in S609), it is judged that no object has been placed, and the process returns to S608.

[0095] In S606, the control unit 101 controls the power transmitting unit 103 to transmit a Digital Ping. After that, when an SS packet transmitted from RX200 or RX500 is received, the process proceeds to the I&C phase in S610.

[0096] Thereafter, the process proceeds to an I&C phase of S610, a Negotiation phase of S611, a Calibration phase of S612, and a Power Transfer phase of S613. Thereafter, the Power Transfer phase ends when, for example, charging of the battery of the RX200 or RX500 is completed. Note that the I&C phase, Negotiation phase, Calibration phase, and Power Transfer phase only need to carry out the processes described above, and therefore descriptions thereof will be omitted here.

[0097] <Other embodiments> (Regarding confirmation signals) Although the above-mentioned power of the confirmation signal is described using an example in which it is the same as the power of the Analog Ping, this is not limited thereto. The power of the confirmation signal may be smaller than the power of the Analog Ping, or may be larger than the power of the Analog Ping. Also, the power of the confirmation signal may be equal to the power of the Digital Ping. Note that the power of the confirmation signal is smaller than the power in the Power Transfer phase. In other words, the power of the confirmation signal is smaller than the power transmitted from the TX100 to charge the battery 203 based on the power received by the RX200.

[0098] If the power of the confirmation transmission is equivalent to that of Analog Ping or Digital Ping, the power setting can be simplified.

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

[0100] If the transmission interval of the Analog Ping in the Selection phase is made shorter than the transmission interval of the confirmation signal, when the power receiving device is replaced as shown in FIG. 5, it is possible to quickly detect a new power receiving device (RX500).

[0101] If the transmission interval of the confirmation signal is made shorter than the transmission interval of the Analog Ping in the selection phase, removal of the power receiving device can be detected quickly, and the transition to the selection phase can be made quickly.

[0102] (Determining whether a power receiving device has been removed) When the power of the confirmation signal is different from the power of the Analog Ping, the following configuration may be adopted to detect the removal of the RX200. That is, first, when the TX100 transmits the first confirmation signal (S402, S502), it detects at least one of the voltage value and the current value of the power transmitting coil 105, and stores the detected value in the memory 107 as a reference detection value. Then, it detects at least one of the voltage value and the current value of the power transmitting coil 105 when transmitting the second or subsequent confirmation signal. Then, it is possible to compare this detection value with the above-mentioned reference detection value, and if the difference exceeds a predetermined range, it is possible to determine that the RX200 has been removed. On the other hand, if the difference is within the predetermined range, it is possible to determine that the RX200 is placed on the charging stand.

[0103] The reference detection value that is the standard for determining whether the power receiving device has been removed may be either the voltage value or the current value of the power transmitting coil 105 when no object is placed on it. The detection value when the confirmation signal is transmitted is compared with this reference detection value, and if the difference between them exceeds a predetermined range, it is determined that the RX200 is placed on the charging stand, and if it is within the predetermined range, it is determined that the RX200 has been removed. In this case, since the process is the same as object detection using normal Analog Ping, the process contents can be simplified.

[0104] (Detection of replacement of power receiving device) In the above embodiment, an example has been described in which it is determined that the RX200 has been removed, and then it is determined that the RX500 has been placed. However, if the replacement of the power receiving device is performed in a time shorter than the transmission interval of the confirmation signal, there is a possibility that this replacement cannot be detected. For this reason, first, when the TX100 transmits the first confirmation signal (S402, S502), it detects at least one of the voltage value and the current value of the power transmitting coil 105, and stores the detected value in the memory 107 as a reference detection value. Then, it detects at least one of the voltage value and the current value of the power transmitting coil 105 when transmitting the second or subsequent confirmation signal. Then, it is sufficient to compare this detection value with the above-mentioned reference detection value, and determine that the RX200 has been replaced with the RX500 if the difference exceeds a predetermined range. That is, in this case, it is possible to simultaneously determine that the RX200 has been removed and that the RX500 has been placed.

[0105] The present invention can also be realized by supplying a program for implementing one or more of the above-described functions to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for implementing one or more of the functions.

[0106] At least a part of the processes shown in the flowchart of Fig. 6 may be realized by hardware. In the case of hardware realization, for example, a specific compiler may be used to automatically generate a dedicated circuit on an FPGA (Field Programmable Gate Array) from a program for realizing each process. Also, a gate array circuit may be formed in the same manner as the FPGA, and the process may be realized as hardware. [Explanation of symbols]

[0107] 100 Power transmission equipment 101 Control section 105 Transmission coil 104 Communications Department 108 Detection unit 200 Powered Device

Claims

1. A power transmitting device that wirelessly transmits power, A transmitting means for transmitting a signal; A detection means for performing a process of detecting an object, the transmitting means transmits a second signal to activate the power receiving device if an object is detected after the first signal is transmitted; the transmitting means transmits a third signal to confirm the presence of an object after the second signal is transmitted; the detection means performs a process of detecting an object based on a parameter acquired when no object is present after the third signal is transmitted and a parameter acquired after the third signal is transmitted; the transmitting means, when an object is detected after the third signal is transmitted, transmits the third signal again without transmitting the second signal; the transmitting means transmits the first signal when an object is no longer detected after the third signal is transmitted; The power transmitting device, wherein the transmitting means transmits the second signal when an object is no longer detected after the third signal is transmitted and when an object is detected after the first signal is transmitted.

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

3. The power transmitting device according to claim 1 , wherein the second signal is a Digital Ping defined by a standard of the Wireless Power Consortium.

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

5. A method performed by a power transmitting device that wirelessly transmits power, comprising: Transmitting a first signal; performing a process of detecting an object after the first signal is transmitted; If an object is detected after the first signal is transmitted, transmitting a second signal to wake up a power receiving device; transmitting a third signal after the second signal has been transmitted to confirm the presence of the object; After the third signal is transmitted, a process of detecting an object is performed based on the parameters acquired when no object is present and the parameters acquired after the third signal is transmitted; if an object is detected after the third signal is transmitted, transmitting the third signal again without transmitting the second signal; transmitting the first signal if the object is no longer detected after the third signal is transmitted; transmitting the second signal if an object is no longer detected after the third signal is transmitted and if an object is detected after the first signal is transmitted.

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