Power transmission device, method executed by power transmission device, and program

Abstract

A power transmission device 100 performs authentication processing with a power reception device 200 by using an electronic certificate. The power transmission device 100 controls power transmission to the power reception device 200 on the basis of a cause of authentication failure.

Description

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

[0001] The present disclosure relates to the technology of wireless power transmission.

[0002] One contactless charging standard is a standard (hereinafter referred to as the "WPC standard") established by the standardization organization Wireless Power Consortium (WPC). Patent Document 1 discloses a power transmitting device and a power receiving device that comply with the WPC standard. Patent Document 2 discloses an authentication method between a power transmitting device and a power receiving device for contactless charging. The power transmitting device disclosed in Patent Document 2 transmits challenge data to the power receiving device. The power receiving device performs authentication calculations on the challenge data to create response data and transmits it to the power transmitting device. The power transmitting device executes an authentication protocol by comparing the response data received from the power receiving device. This enables highly secure authentication processing. Patent Document 3 discloses a wireless power transmission system that performs bidirectional authentication. The power transmitting device and the power receiving device mutually verify the authenticity of electronic certificates and can determine the values ​​of transmitted and received power based on the verification results.

[0003] JP 2016-007116 A JP 2010-104097 A JP 2022-043259 A

[0004] However, if mutual authentication between a power transmitting device and a power receiving device is unsuccessful, a countermeasure is required. In this case, conventional techniques have not considered what kind of power transmission control is appropriate. In particular, no technique has been disclosed for performing detailed power transmission control in response to an authentication error that occurs when a power transmitting device acts as an initiator to authenticate a power receiving device. The present disclosure determines control content according to the result of authentication performed by a power transmitting device on a power receiving device, and performs power transmission control.

[0005] A power transmission device according to an embodiment of the present disclosure includes a power transmission means for wirelessly transmitting power to a power receiving device and an authentication means for performing authentication processing between the power receiving device and the power transmission means using an electronic certificate, and if the authentication is not successful, the power transmission means controls the power transmission based on the cause.

[0006] According to the present disclosure, it is possible to determine the control content according to the result of authentication performed by the power transmitting device on the power receiving device and perform power transmission control.

[0007] 1 is a block diagram showing an example of the configuration of a contactless charging system. FIG. 2 is a block diagram showing an example of the configuration of a power transmission device. FIG. 3 is a block diagram showing an example of the configuration of a power receiving device. FIG. 4 is a diagram showing an example of the operation sequence of a contactless charging system. FIG. 5 is a flowchart of a setting process of GP (Guaranteed Power). FIG. 6 is a diagram showing an example of the relationship between an authentication result and a GP setting value. FIG. 7 is a flowchart explaining the process up to power transmission in a power transmission device. FIG. 8 is a sequence diagram showing an example of communication between a power transmission device and a power receiving device. FIG. 9 is a flowchart explaining the process up to power transmission in a power receiving device. FIG. 10 is a diagram showing an example of the configuration of a packet. FIG. 11 is a flowchart showing another example of the process up to power transmission in a power receiving device. FIG. 12 is a flowchart showing another example of the process up to power transmission in a power transmission device.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. First, system configurations and modifications related to embodiments of the present disclosure will be described. This disclosure will show an example of a wireless charging system (contactless charging system) to which a wireless power transmission system is applied. While the present disclosure will describe a case in which contactless charging conforming to the WPC standard is performed between a power transmitting device and a power receiving device, the present disclosure is not limited thereto, and contactless charging may be performed based on other standards.

[0009] 1 shows an example of the configuration of a wireless power transmission system, which is composed of a power transmitting device 100 and a power receiving device 200. For simplicity of notation, the power transmitting device 100 may be referred to as TX and the power receiving device 200 may be referred to as RX below. Detailed configurations of TX and RX will be described later with reference to FIGS. 2 and 3.

[0010] The power transmitting device 100 (TX) is connected to an AC adapter 301 using a USB cable 300, and power is supplied via a wire (hereinafter referred to as "wired power supply"). The AC adapter 301 converts power from a commercial power source supplied via a power plug 302 into a voltage suitable for the TX and supplies it to the TX. The TX supplies power wirelessly to the power receiving device 200 (RX) (hereinafter referred to as "wireless power supply"). The RX receives the power wirelessly transmitted from the TX and charges, for example, a battery inside the RX.

[0011] The configuration in FIG. 1 is an example, and other configurations may be used. Below, an example configuration capable of performing authentication regarding wired power supply will be described, but the present disclosure is not limited to this, and can also be applied to a configuration in which authentication regarding wired power supply is not performed. Furthermore, the USB Power-Delivery standard is shown as an example of a standard related to wired power supply. It is assumed that authentication is performed based on the authentication standard supported by this standard.

[0012] Furthermore, the system configuration shown in Fig. 1 having one TX and one RX is one example. For example, there are the following configurations: - A configuration in which multiple TXs receive wired power supply and each TX transmits power to a single common RX; - A configuration in which multiple TXs receive wired power supply and each TX transmits power to a separate RX; - A configuration in which one TX receives wired power supply and transmits power to multiple RXs.

[0013] An example configuration of a power transmitting device 100 (TX) will be described with reference to FIG. 2 . FIG. 2 is a block diagram showing an example configuration of the TX. For example, the TX has functions defined in version 1.2.2 of the WPC standard (hereinafter referred to as "WPC standard v1.2.2"). The TX has a power supply capability of outputting a maximum of 15 watts of power to a charging unit of an RX that complies with the WPC standard. The TX includes a control unit 101, a power supply unit 102, a power transmitting unit 103, a communication unit 104, a power transmitting coil 105, a display unit 106, a memory 107, a first authentication unit 108, and a second authentication unit 109.

[0014] The control unit 101 includes one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and controls the entire TX. That is, the control unit 101 controls the operation of each unit (102 to 109). The control unit 101 may also include an application-specific integrated circuit (ASIC) or an FPGA (Field Programmable Gate Array). The control unit 101 determines the power transmission control content based on the result of WPT authentication (described later) and the result of USB authentication for the wired power supply unit (such as the AC adapter 301 and the USB cable 300). For example, the maximum allowable power value during power transmission is set based on the control content determined by the control unit 101.

[0015] The power supply unit 102 receives power for the operation of the TX from the AC adapter 301 via the USB cable 300, and supplies power for the operation of at least the control unit 101 and the power transmission unit 103. The power supply unit 102 has a configuration capable of supporting authentication of wired power supply devices and power supply. To receive power supply via the USB cable 300, the power supply unit 102 can support the USB Power-Delivery standard and the Authentication standard, which authenticates connected USB devices. Note that the TX may receive power supply in accordance with a standard other than the USB Power-Delivery standard, or may be configured to perform authentication in accordance with a standard other than the Authentication standard. Furthermore, the power supply unit 102 or the first authentication unit 108 may be configured to support multiple standards. For example, the power supply unit 102 or the first authentication unit 108 can determine the standard to be used based on which terminal of the TX is used, in accordance with the connection form with the power supply source.

[0016] The power transmitting unit 103 generates an AC voltage and an AC current when transmitting power to the RX via the power transmitting coil 105. For example, the power transmitting unit 103 can convert a DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration. In this case, the power transmitting unit 103 has a plurality of FETs (Field Effect Transistors) that form a bridge circuit and a gate driver that controls the ON / OFF of the FETs.

[0017] The communication unit 104 performs control communication with the RX (communication unit 204 in FIG. 3) regarding control of contactless charging based on the WPC standard. The communication unit 104 can perform so-called in-band communication, in which the AC voltage or AC current generated by the power transmission unit 103 is modulated and a signal of information to be transmitted to the RX is superimposed on the radio wave of wireless power transmission. However, this is not limited to this. The communication unit 104 may also perform communication with the RX via so-called out-of-band communication. Examples of out-of-band communication include communication using NFC, RFID, Wi-Fi (registered trademark), Bluetooth (registered trademark) Low Energy, etc. Here, out-of-band communication refers to communication performed without superimposing a signal on the radio wave of wireless power transmission. At least a portion of the frequency band used in out-of-band communication is not included in the frequency band for power transmission. Furthermore, the frequency band used in out-of-band communication and the frequency band for power transmission do not need to overlap at all.

[0018] The display unit 106 displays predetermined information so that the user can check it. For example, the predetermined information is information indicating the status of the TX or information indicating the status of the contactless charging system including devices such as the TX, the RX, the USB cable 300, and the AC adapter 301. The display unit 106 may be configured with an LED (Light Emitted Diode). However, the display unit 106 is not limited to this, and may be configured to include a speaker, a vibration generating circuit, a display, etc. instead of or in addition to the LED. The memory 107 stores information indicating the overall status and each component of the TX and the contactless charging system.

[0019] The first authentication unit 108 performs authentication on the power supply unit 102, and the USB cable 300 and AC adapter 301 connected to the power supply unit 102. The first authentication unit 108 can perform authentication in accordance with the USB Authentication standard. However, the first authentication unit 108 is not limited to this example, and other standards that support authentication, such as the Quick Charge standard by Qualcomm, may also be used.

[0020] The second authentication unit 109 performs authentication between the TX and the RX through communication performed by the communication unit 104. The authentication performed by the second authentication unit 109 is called Wireless Power Transfer (hereinafter referred to as WPT) authentication. The second authentication unit 109 has a first part used when the TX performs WPT authentication on the RX, and a second part used when receiving WPT authentication from the RX. The first part and the second part may be configured separately, or the first and second parts may be configured as an integrated unit.

[0021] In FIG. 2 , the control unit 101, power supply unit 102, power transmission unit 103, communication unit 104, memory 107, first authentication unit 108, and second authentication unit 109 are illustrated as separate block elements, but any multiple block elements may be implemented on the same chip. For example, the power supply unit 102 compatible with USB Power-Delivery and the first authentication unit 108 compatible with the USB Authentication standard may be implemented on the same chip as a USB-related chip. In this case, the TX is configured such that the control unit 101 and the USB-related chip are connected via GPIO (General Purpose Input / Output) or serial communication. Furthermore, any multiple block elements among the second authentication unit 109, control unit 101, memory 107, power transmission unit 103, and communication unit 104 may be implemented on the same chip. Alternatively, one block element shown in FIG. 2 may be divided into a plurality of block elements or may be implemented by a plurality of chips.

[0022] An example configuration of the power receiving device 200 (RX) will be described with reference to Fig. 3 . Fig. 3 is a block diagram showing an example configuration of the RX. Like the TX, the RX complies with the WPC standard and further has functions defined in the WPC standard v1.2.2. For example, the RX includes a control unit 201, a display unit 202, a power receiving unit 203, a communication unit 204, a power receiving coil 205, a charging unit 206, a battery 207, an authentication unit 208, and a memory 209.

[0023] The control unit 201 includes one or more processors such as a CPU or MPU, an ASIC, an FPGA, or the like, and controls the entire RX. The control unit 201 controls the operation of each unit (202 to 209). The control unit 201 also determines the control content of power reception based on the result of authentication of the TX. For example, the control unit 201 sets the maximum value of power requested from the TX according to the determined control content.

[0024] The display unit 202 displays predetermined information so that the user can check it. For example, the predetermined information is information indicating the power supply status, the charging status of the RX, etc. The display unit 202 may include a speaker, a vibration generating circuit, a display, etc. in addition to or instead of the LED.

[0025] Power receiving unit 203 receives the power of the electromagnetic waves radiated from power transmitting coil 105 via power receiving coil 205. Power receiving unit 203 converts the AC voltage and AC current received into DC voltage and DC current used when control unit 201, charging unit 206, etc. operate. For example, power receiving unit 203 has the ability to output a maximum of 15 watts of power to charging unit 206.

[0026] The communication unit 204 performs control communication with the communication unit 104 of the TX regarding control of contactless charging based on the WPC standard. For example, this control communication is performed by load modulation. By varying the load on the RX, the state of power transmission between the TX and RX can be changed, and information can be transmitted by varying the current flowing through the transmitting coil 105. Note that the communication unit 204 can perform control communication by in-band communication such as load modulation, or out-band communication. The charging unit 206 charges the battery 207 based on the DC voltage and DC current from the power receiving unit 203.

[0027] The authentication unit 208 performs mutual authentication with the second authentication unit 109 of the TX through communication performed by the communication unit 204. The memory 209 stores information indicating the overall status and each component of the RX and the contactless charging system. A part of the memory 209 may be a secure element used when the TX authenticates the RX. A secure element is a general term for semiconductor components that have security capabilities that can withstand external analysis attacks, and includes a memory unit that can securely store data, an encryption logic circuit, etc.

[0028] In this disclosure, the fact that a TX or RX complies with the WPC standard including WPT authentication will be expressed as "complying with WPC standard version A." For example, WPC standard version A is standard v1.3, which is the successor to WPC standard v1.2.2, and includes at least the WPT authentication function.

[0029] 3, the power receiving unit 203, authentication unit 208, control unit 201, memory 209, communication unit 204, and charging unit 206 are shown as separate block elements, but any two or more of these block elements may be implemented on the same chip.Furthermore, one block element in FIG. 3 may be divided into multiple block elements or implemented by multiple chips.

[0030] In the contactless charging system, the TX performs the following authentications: - Authentication performed by the first authentication unit 108 with the AC adapter 301 and the USB cable 300 based on a first communication protocol (for example, USB authentication via the USB cable); - Authentication performed by the second authentication unit 109 mutually with the RX based on a second communication protocol that uses a medium (for example, the transmitting coil 105 and the receiving coil 205) different from that in the first communication protocol.

[0031] In the example of the present disclosure, the AC adapter 301, the USB cable 300, and the TX (power supply unit 102) are USB devices. The USB devices support USB authentication, and by successfully passing USB authentication, it can be confirmed that there is a low possibility of excessive heat generation, etc., even if the power specified by the USB authentication is supplied to those devices. For example, assume that the USB device passes USB authentication, and the specified power is supplied from the AC adapter 301 to the power supply unit 102 of the TX via the USB cable 300. In this case, there is a low possibility of excessive heat generation in the power supply unit 102, the USB cable 300, and the AC adapter 301.

[0032] On the other hand, if one or more of the power supply unit 102, the USB cable 300, and the AC adapter 301 do not support USB authentication, USB authentication will not be successful. In this case, if power specified in the USB authentication standard is supplied to the USB device, there is a possibility that excessive heat will be generated in either the device or the cable. Here, devices that do not support USB authentication include devices that support one of multiple versions of the USB standard that existed before the USB authentication standard was established. In this disclosure, USB devices that support one of multiple versions of the USB standard that existed before the USB authentication standard was established will be referred to as "legacy USB devices."

[0033] Furthermore, if one or more of the power supply unit 102, the USB cable 300, and the AC adapter 301 fail USB authentication and power specified by the USB authentication standard is supplied to the USB device, heat generation, etc. Here, cases where USB authentication fails include cases where the USB cable 300 or the AC adapter 301 nominally supports USB authentication, but the USB device does not actually support it.

[0034] Also, assume that the RX and TX are compliant with WPC Standard Version A and have mutually successfully completed WPT authentication. In this case, even if the TX transmits a predetermined power level specified by the standard to the RX, there is little likelihood of problems such as excessive heat generation occurring. On the other hand, assume that at least one of the RX and TX does not comply with WPC Standard Version A. In this case, when the TX transmits power specified by the standard to the RX, excessive heat generation or the like may occur in a device that does not comply with WPC Standard Version A. Devices that do not comply with WPC Standard Version A include devices that comply with any of multiple versions of the WPC Standard prior to WPC Standard Version A. In this disclosure, a TX or RX that complies with any of multiple versions of the WPC Standard prior to WPC Standard Version A will be referred to as a "legacy TX or RX."

[0035] Furthermore, WPT authentication between a TX and an RX may fail if the TX or RX nominally supports WPT authentication but does not actually support it. In this case, the TX and RX do not successfully complete WPT authentication, and excessive heat generation may occur if the TX transmits the power specified by the standard to the RX. Note that WPT authentication between devices that support WPT authentication is always successful.

[0036] In the system disclosed herein, if the USB cable 300 and AC adapter 301 are successfully USB-authenticated, and the RX and TX are also successfully WPT-authenticated with each other, it is determined that the specified power supply stipulated by the standard is possible. In this case, excessive heat generation and other issues are unlikely to occur, and the power receiving unit 203 of the RX can supply the specified power (e.g., 15 watts) to the load (charging unit 206). Also, consider a case where one or more of the power supply unit 102, USB cable 300, and AC adapter 301 of the TX are not successfully USB-authenticated, or the RX or TX are not successfully WPT-authenticated. In this case, there is a possibility that a problem may occur in supplying the specified power stipulated by the standard. If the power receiving unit 203 of the RX supplies 15 watts of power to the load, excessive heat generation and other issues may occur. In the following, in order to avoid such risks, if authentication is not successful, control is performed to limit the power supplied by the power receiving unit 203 to a power value (for example, 5 watts or less) smaller than a predetermined power (15 watts).

[0037] Next, an example of processing executed in the system of the present disclosure will be described. Fig. 4 is a sequence diagram showing an example of processing including USB authentication and WPT authentication. Fig. 5 is a flowchart showing an example of processing executed by the TX and RX. Fig. 5(A) shows an example of processing executed by the control unit 101 of the TX regarding setting of Guaranteed Power (hereinafter, referred to as "GP", and its value is referred to as the GP value). Fig. 5(B) shows an example of processing executed by the control unit 201 of the RX regarding setting of GP. Fig. 6 shows an example of a GP limit value used in Negotiation, which will be described later, depending on the results of USB authentication and WPT authentication. This limit value corresponds to the maximum value (upper limit) of the allowable GP.

[0038] First, we will explain the GP determined by negotiation between the TX and the RX. The GP value is the power value guaranteed by the TX with respect to the output power to the load of the RX, even if the positional relationship between the TX and the RX is shifted and the power transmission efficiency between the power transmitting coil 105 and the power receiving coil 205 decreases. The load in the RX is the target to which the power receiving unit 203 supplies power, and includes the charging unit 206 in FIG. 3 . For example, assume that the GP is 5 watts. Even if the positional relationship between the power transmitting coil 105 and the power receiving coil 205 is shifted and the power transmission efficiency between the two coils decreases, the TX controls the power transmitting unit 103 so that the power receiving unit 203 can output 5 watts of power. In the present disclosure, the GP is limited depending on the authentication result. For example, if authentication is unsuccessful or authentication is not supported, excessive heat generation due to the transmission of power specified by the standard can be suppressed.

[0039] Before describing Figures 4 and 5, the GP limit values ​​used in negotiation will be described with reference to Figure 6. Figure 6(A) is a table showing an example of GP limit values ​​in TX. Figure 6(B) is a table showing an example of GP limit values ​​in RX.

[0040] In FIG. 6A , columns 600, 601, and 602 indicate "USB authentication not supported," "USB authentication failed," and "USB authentication successful," respectively. "USB authentication not supported" means that any of the USB devices does not support USB authentication (however, devices that support USB authentication have been successfully authenticated). The USB devices are the power supply unit 102, USB cable 300, and AC adapter 301 of the TX. "USB authentication failed" means that any of the USB devices is at least nominally USB authentication-enabled, but USB authentication has failed. "USB authentication successful" means that USB authentication has been successful for all of the power supply unit 102, USB cable 300, and AC adapter 301 of the TX. Rows 603, 604, and 605 indicate "WPT authentication not supported," "WPT authentication failed," and "WPT authentication successful," respectively. "WPT authentication not supported" means that the RX does not support WPT authentication. "WPT authentication failed" means that the RX supports WPT authentication but the WPT authentication failed. "WPT authentication successful" means that the RX supports WPT authentication and the WPT authentication was successful.

[0041] In FIG. 6A , the numerical values ​​corresponding to each column and row are GP values ​​(unit: watts). This GP value is a power limit value. A column containing multiple numerical values, such as "0, 2.5, 5," indicates that one of three GP values ​​is pre-configured. This is also true for FIG. 6B . In the example of FIG. 6A , in the case of a device that does not support USB authentication (column 600), the GP value can be limited to 5 regardless of the WPT authentication results, thereby preventing excessive heat generation and other issues. Alternatively, in the case of a device that does not support USB authentication (column 600) and fails WPT authentication (row 604), the GP value can be limited to 0 (no power transmission) or 2.5 (less than 5 watts). In this case, the GP value is limited to a smaller value compared to a device that does not support WPT authentication (row 603). The reason for this is that, regarding the failure of WPT authentication, for example, there is a possibility that the RX nominally supports WPT authentication but does not support it properly, or that it is a device (such as a counterfeit) that does not meet the WPC standard. In order to prevent excessive heat generation, the GP value can be limited to 5. On the other hand, by limiting the GP value to a lower value (0 or 2.5) than that of a legacy RX that does not support WPT authentication but complies with the proper standard, it is possible to suppress or avoid power transmission to a counterfeit device that appears to support WPT authentication.

[0042] In the case of USB authentication failure (column 601) in FIG. 6A , regardless of the WPT authentication result, the GP value is limited to 5 or less. Compared to the case of USB authentication non-compliance (column 600), the GP value may be limited to a smaller value. For example, the GP value corresponding to row 603 or row 605, respectively, may be limited to 0 (no power transmission) or 2.5 (less than 5 watts). This is because, in the case of USB authentication failure, for example, the USB device being authenticated may be a counterfeit that nominally supports USB authentication but does not comply with the official standard. By limiting the GP value to a lower value (0 or 2.5) compared to a legacy USB device that does not support USB authentication but complies with the official standard, it is possible to suppress or prevent power supply from a counterfeit device that appears to support USB authentication.

[0043] In the case of successful USB authentication (column 602) in FIG. 6A , even if the RX supplies 15 watts to the load, there is little likelihood of excessive heat generation, etc., with respect to the TX's power supply unit 102, USB cable 300, and AC adapter 301. 15 watts corresponds to the maximum GP value that the TX can supply to the RX. The TX sets the GP based on the results of WPT authentication. For example, if WPT authentication is not supported (row 603), the TX limits the GP value to 5 for the reasons described above. Furthermore, if WPT authentication fails (row 604), the TX can limit the GP value to a smaller value (0 or 2.5). If both USB authentication (column 602) and WPT authentication (row 605) are successful, the TX determines that there is little likelihood of excessive heat generation, etc., occurring. The TX sets the GP upper limit to 15 watts, which is the maximum value of the TX's power transmission capacity and the RX's power receiving capacity. Alternatively, the RX may request 15 watts as GP from the TX, which is the maximum value of the TX's power transmission capability and the RX's power receiving capability.

[0044] In this disclosure, an example of USB authentication is shown, but if USB authentication is not performed, the data in column 602 in Fig. 6A may be used as a table of GP limit values. In this case, USB authentication is not performed, but the GP value is set using data that is stored assuming that USB authentication was successful.

[0045] Since no USB devices are connected to the power supply circuit of the RX, USB authentication is not performed. Therefore, the GP limit value is determined by the result of WPT authentication with the TX. In FIG. 6B, rows 613, 614, and 615 indicate "WPT authentication not supported," "WPT authentication failed," and "WPT authentication successful," respectively. Column 610 indicates the GP limit values ​​corresponding to rows 613 to 615. WPT authentication not supported (row 613) in FIG. 6B means that the TX does not support WPT authentication. In this case, for the same reason as in the case of the TX, the GP upper limit value is set to 5. WPT authentication failed (row 604) means that the TX supports WPT authentication but failed. In this case, the GP value is limited to 5 or a lower value (0 or 2.5). WPT authentication successful (row 605) means that the TX supports WPT authentication and WPT authentication was successful. In this case, the RX determines that there is no risk of excessive heat generation, and sets the maximum value (upper limit) of the GP to 15 watts, which is the maximum capacity of the TX and RX.

[0046] As described above, the TX determines the upper limit of GP that can be tolerated as a transmission power value in the negotiation phase based on the USB authentication result, the WPT authentication result, and the information shown in Fig. 6(A). The RX determines the maximum GP value to be requested from the TX in the negotiation phase based on the WPT authentication result and the information shown in Fig. 6(B). If both the USB authentication and the WPT authentication are successful, the transmission power according to the maximum capabilities of the TX and the RX can be determined in the negotiation phase.

[0047] Next, with reference to FIG. 4 , the processing flow from system startup to power transmission will be described. If the RX determines that at least one device to be authenticated in WPT authentication is incompatible or has failed authentication, it operates so as not to request a large amount of power as a GP value from the TX. The right side of FIG. 4 shows the operations of the power transmitting unit 103, control unit 101, and power supply unit 102 of the TX, while the left side shows the operations of the control unit 201 and power receiving unit 203 of the RX. At F400, an AC adapter 301 is connected to the power supply unit 102 via a USB cable 300. At F401, the control unit 101 of the TX performs USB authentication on the connected USB device. The control unit 101 activates the first authentication unit 108. The USB devices to be authenticated are the USB cable 300 and the AC adapter 301. The first authentication unit 108 determines whether the USB device is compatible with USB authentication.

[0048] The first authentication unit 108 performs USB authentication for all USB devices, and if all USB authentications are successful, it determines that the USB authentication is "successful." Furthermore, if any USB authentications are unsuccessful, the first authentication unit 108 determines that the USB authentication is "incompatible" or "failed." The first authentication unit 108 determines that the USB authentication is "failed" if there is even one device that is compatible with USB authentication but has failed authentication. Furthermore, the first authentication unit 108 determines that the USB authentication is "incompatible" if all devices that have failed USB authentication are devices that do not support USB authentication. The first authentication unit 108 may also determine that the USB authentication is "failed" or "incompatible" based on the attributes of the devices that have failed authentication. For example, if there is a device that has failed authentication, the first authentication unit 108 can identify the attributes of the device and make a determination based on the attributes.

[0049] For example, a case will be described in which USB authentication of the AC adapter 301 is successful, but the USB cable 300 does not support USB authentication. In this case, the first authentication unit 108 determines that the USB authentication is "not supported." Furthermore, if USB authentication of the AC adapter 301 is successful, but the USB cable 300 supports USB authentication but fails, the first authentication unit 108 determines that the USB authentication is "failed." Furthermore, if USB authentication of both the AC adapter 301 and the USB cable 300 is successful, the first authentication unit 108 determines that the USB authentication is "successful." The control unit 101 performs a process of storing information on the USB authentication result in the memory 107.

[0050] In F402 of FIG. 4, the control unit 101 determines the power supply specifications for the voltage and current supplied from the AC adapter 301 based on the sequence of the USB-Power Delivery standard. The power supply voltage of the power supply unit 102 is determined by the internal configuration of the TX, so the current value is determined in this case. For example, the power supply voltage is set to 15 V, and the output current of the power supply unit 102 is set to a maximum of 3 A. When reducing the current value, the control unit 101 of the TX determines the amount of reduction in the current value based on the information shown in FIG. 6A. For example, based on the data for USB authentication non-compliance (column 600), the maximum allowable GP value during power transmission is determined to be 5 watts in the negotiation phase of the WPC standard. The control unit 101 determines the current value taking into account power loss within the TX. For example, when the positional relationship between the transmitting coil 105 and the receiving coil 205 changes and the inter-coil efficiency becomes the lowest, the system efficiency is set to 50% when the RX outputs a GP of 5 W (watts). In this case, the power supplied from the power supply unit 102 to the power transmission unit 103 and the control unit 101 is 10 W (5 W × 2). When the power supply voltage is 15 V, the output current is 10 W / 15 V ≈ 0.67 A. In the present disclosure, if a USB device does not support USB authentication, the GP value is limited to 5. Therefore, the current value that the power supply unit 102 should determine by negotiation with the AC adapter 301 based on the sequence of the USB-Power Delivery standard may be approximately 0.67 A. Based on this current value, the control unit 101 of the TX determines the power supply specifications with the AC adapter 301. On the other hand, if USB authentication is successful, the power supply specifications are determined to be 2.0 A (15 W × 2 / 15 V) so as to accommodate a GP value of 15 watts, which is the maximum capacity of the TX and RX.

[0051] 4, the control unit 101 of the TX starts up the power transmitting unit 103. For example, a so-called power-on reset is performed in which power is applied from the power supply unit 102 to one or more of the control unit 101, the power transmitting unit 103, and the communication unit 104. Alternatively, the first authentication unit 108 may input a LOW signal (approximately 0 V) ​​to one or more of the control unit 101, the power transmitting unit 103, and the communication unit 104 of the TX to reset one of these functional units. In this case, after the power supply specifications have been determined and the GP value has been set, the first authentication unit 108 releases the reset by transmitting a HI signal (3.3 V, etc.) to the relevant component.

[0052] When the power transmitting unit 103 is activated, the TX starts operation in accordance with the WPC standard. In this disclosure, in addition to the phase in accordance with the WPC standard, an authentication phase is defined as a phase in which WPT authentication is performed. In the authentication phase, the TX and RX perform authentication based on WPT authentication. If the TX and RX support the authentication phase, the TX and RX execute the selection phase process. Then, the TX transitions to the ping phase and the identification & configuration phase (hereinafter referred to as the "I&C phase"), and then transitions to the authentication phase. After the authentication phase, processing of each phase is executed in the order of a negotiation phase, a calibration phase, and a power transfer phase (hereinafter referred to as a "PT phase").

[0053] In the Selection phase of F404 in FIG. 4 , the power transmitting unit 103 transmits an Analog Ping (hereinafter referred to as AP) via the power transmitting coil 105. The AP is a signal having a small amount of power for detecting an object present near the power transmitting coil 105. The TX detects the voltage value or current value of the power transmitting coil 105 during AP power transmission, and determines that an object is present when the detected voltage value is below a threshold value or when the detected current value exceeds a threshold value. When the phase transitions to the Ping phase of F405, the TX transmits a Digital Ping (hereinafter referred to as DP). The power of the DP is greater than the power of the AP and is sufficient to activate the control unit 201 of the RX present near the power transmitting coil 105. When the control unit 201 of the RX is activated by the DP that has received power via the receiving coil 205, it notifies the TX of the magnitude of the received voltage in F406 and transitions to the I&C phase. On the other hand, when the TX receives a notification of the received voltage value from the RX, it transitions to the I&C phase.

[0054] In the I&C phase, the RX transmits an Identification Packet (ID Packet) to the TX in F407, and transmits a Configuration Packet to the TX in F408. The TX responds with an acknowledgement (ACK) to the Configuration Packet transmitted by the RX. When the I&C phase ends, the TX and RX can transmit data to each other. Next, the process transitions to the Authentication phase.

[0055] In F409 of Fig. 4, power transmission and reception for WPT authentication is performed between the power transmitting unit 103 of the TX and the power receiving unit 203 of the RX. The second authentication unit 109 of the TX and the authentication unit 208 of the RX perform WPT authentication processing with each other in the authentication phase. The authentication target of the TX is the RX as a power receiving device in the contactless charging system. The authentication target of the RX is the TX as a power transmitting device in the contactless charging system. Details of the authentication phase will be described later.

[0056] The control unit 101 of the TX stores information on the WPT authentication result in the memory 107. The control unit 201 of the RX stores information on the WPT authentication result in the memory 209. In F410a, the control unit 101 of the TX determines the maximum value of GP to be used in the negotiation phase based on the information on the USB authentication result and the WPT authentication result stored in the memory 107 and the information shown in Fig. 6(A). Meanwhile, in F410b, the control unit 201 of the RX determines the maximum value of GP to be used in the negotiation phase based on the information on the WPT authentication result stored in the memory 209 and the information shown in Fig. 6(B).

[0057] Thereafter, in F411, the control unit 101 of the TX and the control unit 201 of the RX negotiate in the negotiation phase to determine the GP. Based on the authentication results of the first authentication unit 108 (USB authentication), the second authentication unit 109 (WPT authentication) of the TX, and the authentication unit 208 (WPT authentication) of the RX, negotiation of the transmission power is performed. Through this negotiation, the transmission power is set to a value equal to or less than the power allowed by the limited GP value (F410a, F410b). For example, if the RX "succeeds in WPT authentication" (row 615 in FIG. 6B), the GP is allowed up to 15 watts. On the other hand, if the RX "fails in WPT authentication" (row 614 in FIG. 6B), the GP is limited to 5 watts or less. In the negotiation phase, the control unit 201 of the RX requests the GP from the TX.

[0058] Furthermore, in the case of "USB authentication successful" (FIG. 6A: column 602) and "WPT authentication successful" (FIG. 6A: row 605) in the TX, GP is allowed up to 15 watts. On the other hand, in the case of "USB authentication not supported" (FIG. 6A: column 600), GP is limited to 5 watts or less. In the negotiation phase, if the control unit 201 of the RX requests a GP of more than 5 watts, the control unit 101 of the TX sends a negative response NAK to the request. On the other hand, if the RX requests a GP of less than the limit, the control unit 101 of the TX sends an acknowledgement (ACK) as a positive response.

[0059] As described above, the maximum GP value is determined based on the USB authentication result and the mutual WPT authentication result between the TX and RX. If any of the multiple authentications fails, the GP value is limited, thereby preventing excessive heat generation and the like. Furthermore, the control unit 101 of the TX can set the GP value to the maximum capacity of the power transmitting unit 103 only if all authentications are successful. Note that if USB authentication is not performed, the maximum GP value is determined based on the mutual WPT authentication result between the TX and RX. In this case, the result of the WPT authentication by the TX to the RX is considered to be "USB authentication successful" (column 602 in Figure 6A), and the GP is limited as necessary.

[0060] Next, in F412 of Fig. 4, the TX and RX notify each other of the reason for restricting the GP. The control unit 101 of the TX notifies the control unit 201 of the RX of the reason for restricting the GP, and the control unit 201 acquires the authentication results by the first authentication unit 108 and the second authentication unit 109. The control unit 201 of the RX also notifies the control unit 101 of the TX of the reason for restricting the GP, and the control unit 101 acquires the authentication result by the authentication unit 208. The reason notification may be performed using a RESULT packet (see 820a and 820b in Fig. 8(D)) described later.

[0061] Here, an example of a notification process of the reason for restricting GP will be described. The control unit 101 of the TX stores information on the WPT authentication result and the USB authentication result related to the power supply unit 102 of the TX in a RESULT packet and transmits the packet to the control unit 201 of the RX. For example, the control unit 101 provides one bit in the RESULT packet to store information on the WPT authentication result. The one-bit information is "1" if the WPT authentication is successful and "0" if the WPT authentication is unsuccessful. The control unit 101 of the TX also provides one bit in the RESULT packet to store the USB authentication result between the AC adapter 301 and the USB cable 300. The one-bit information is "1" if all USB authentications are successful and "0" if any USB authentications are unsuccessful. The control unit 101 transmits the RESULT packet in which the authentication results are stored.

[0062] The USB authentication result sent from the TX to the RX is transmitted, for example, by a Power Transmitter Capability Packet of the WPC standard v1.2.2, as shown in FIG. 10B. In FIG. 10B, bits 6 and 7 (1100) of Bank 1, which are "Reserved," or bits 2 to 7 (1101) of Bank 2, can be used to transmit the USB authentication result. The TX stores information indicating one of the following in the corresponding area and transmits it: "Has the function to notify the USB authentication result," "USB authentication has been completed," or "USB authentication result."

[0063] Furthermore, the control unit 201 of the RX stores the result of the WPT authentication in a RESULT packet and transmits it to the control unit 101 of the TX. For example, the control unit 201 provides one bit in the RESULT packet to store the result of the WPT authentication. The one-bit information is "1" if the WPT authentication is successful, and "0" if the WPT authentication is unsuccessful.

[0064] Thereafter, in F413, the control unit 101 of the TX and the control unit 201 of the RX execute processing of the calibration phase between the power transmitting unit 103 and the power receiving unit 203. Next, in F414, a transition to the PT phase occurs. In the PT phase, power is transmitted from the TX to the RX. The RX supplies power to a load based on the power received from the TX. In F415b, the control unit 201 of the RX displays on the display unit 202 that power is being restricted based on the reason notification in F412. Also, in F415a, the control unit 101 of the TX displays on the display unit 106 that power is being restricted based on the reason notification in F412. For example, based on a bit indicating the USB authentication result or the WPT authentication result in the reason notification (RESULT packet, etc.), a message is displayed saying, "Slow charging is in progress because USB authentication was not successful (due to the USB device)." Alternatively, if the negotiation results in GP being determined to be 0 watts (power transmission not occurring), the message "USB authentication was not successful (caused by the USB device) and charging will not occur." is displayed. By viewing this information, the user can recognize that charging will take longer than if no power restrictions were imposed. The user can also replace the USB cable or USB adapter with a product that supports USB authentication. Information about the WPT authentication result may also be provided in the display content, which can achieve the same effect as described above.

[0065] Furthermore, if the result of the negotiation is that the transmission power is not limited, a message such as "High-speed charging in progress" is displayed. The cases where the transmission power is limited, where the transmission power is not limited, and where charging is not performed may be displayed with different LED colors or lighting patterns. Alternatively, a method may be used to notify the user with different sounds or vibrations in each case.

[0066] In the present disclosure, an example has been shown in which the TX is activated (F403) after USB authentication (F401). However, the present disclosure is not limited to this. Alternatively, the USB device and the wireless charging system may be activated simultaneously, and USB authentication and WPT authentication may be performed asynchronously. In this case, if it is determined that the transmission power is limited by USB authentication after the TX starts transmitting power, the transmission power of the wireless charging system is limited again through negotiation, thereby achieving the same effect as the example of the present disclosure. However, as in the present disclosure, a configuration in which the TX is activated for WPT authentication after determining whether to limit the transmission power through USB authentication can be expected to achieve even greater effects. By the time the TX determines the GP in the negotiation phase of F411, the USB authentication has already determined whether to limit the transmission power. Therefore, there is no need to perform the negotiation phase again, thereby simplifying the processing.

[0067] Next, referring to FIG. 5A, an example of processing executed by the control unit 101 of the TX regarding GP settings will be shown. Processing starts after the USB cable 300 and AC adapter 301 are connected to the power supply unit 102 of the TX. In S501, the control unit 101 of the TX executes USB authentication processing. The first authentication unit 108 executes USB authentication processing for all USB devices (USB cable 300 and AC adapter 301) that are the subject of authentication. In S502, the control unit 101 stores information indicating the USB authentication result in the memory 107. Next, in S503, the control unit 101 executes WPT authentication processing. Next, in S504, the control unit 101 stores information indicating the WPT authentication result in the memory 107. In S505, the control unit 101 executes WPT authentication processing. The maximum value of GP to be used in the negotiation phase is determined based on the information on the USB authentication result and the WPT authentication result stored in the memory 107 and the information shown in Fig. 6A. Then, the series of processes is terminated.

[0068] Next, referring to FIG. 5B, an example of processing executed by the control unit 201 of the RX regarding GP setting is shown. After processing starts, in S513, the control unit 201 executes WPT authentication processing. The authentication unit 208 of the RX performs WPT authentication processing in the authentication phase. The target of authentication for the RX is the TX as a power transmitting device in the contactless charging system. In S514, the control unit 201 stores information indicating the WPT authentication result in the memory 209. Next, in S515, the control unit 201 determines the maximum value of GP to be used in the negotiation phase based on the WPT authentication result stored in the memory 209 in S514 and the information shown in FIG. 6B. Then, the series of processing ends.

[0069] Next, the operation of WPT authentication and backward compatibility will be described. When transmitting higher power in accordance with the WPC standard, a provision for a WPT authentication function to avoid excessive heat generation, etc., may be added to the existing WPC standard. It is important that a TX with a WPT authentication function is not only compatible with an RX with a similar WPT authentication function, but also ensures backward compatibility with legacy RXs. It is also important that an RX with a WPT authentication function ensures backward compatibility with legacy TXs. Below, a method is described that considers backward compatibility by adding a WPT authentication function while complying with the legacy WPC standard.

[0070] FIG. 7 is a flowchart showing an example of processing by the TX control unit 101. FIG. 8 is a sequence diagram explaining backward compatibility by version A or legacy TX or RX. FIG. 9 is a flowchart showing an example of processing by the RX control unit 201. FIG. 10(A) shows the bit structure of a Configuration Packet according to the WPC standard. Areas for the Power Class and Maximum Power Value of Bank 0, a reserved area for Bank 1 (1000), a reserved area for Bank 2 (1001), a reserved area for Bank 4 (1002), etc. are provided. FIG. 10(B) shows the bit structure of a Power Transmitter Capability Packet according to the WPC standard v1.2.2. There are provided areas for the Power Class and Guaranteed Power Value of Bank 0, a reserved area (1100) of Bank 1, and a reserved area (1101) of Bank 2. The reserved areas (1100, 1101) can be used to transmit the USB authentication result.

[0071] In this disclosure, WPT authentication will be described as a challenge-response type authentication using a digital certificate, similar to USB authentication, but is not limited to this. TX acts as an initiator that transmits a challenge text to RX, and RX acts as a responder that encrypts the challenge text and transmits it to TX. Similarly, when RX acts as an initiator that transmits a challenge text to TX, TX acts as a responder that encrypts the challenge text and transmits it to RX. Here, the initiator is a device that performs WPT authentication, and the responder is a device that receives WPT authentication.

[0072] Before explaining the flow of each process, we will explain the categories of TX and RX based on the WPC standard v1.2.2. TX and RX are categorized as follows according to the size of GP: TX and RX with a maximum GP of 5W (watts): Basic Power Profile (hereinafter referred to as BPP). TX and RX with 5W < GP ≦ 15W: Extended Power Profile (hereinafter referred to as EPP).

[0073] Furthermore, the WPC standard v1.2.2 adds a negotiation function between TX and RX for GP, and EPP TX and RX have the negotiation function. BPP TX and RX are further categorized into those that support the negotiation function and those that do not.

[0074] The TX can determine whether the RX has the negotiation function by the Configuration Packet (see FIG. 10(A)). The packet stores the setting information of the RX, and the negotiation function can be determined by the value of the Neg bit (Bank 4, bit 7). Specifically, this is as follows: - If the Neg bit is "1", the RX has the negotiation function. - If the Neg bit is "0", the RX does not have the negotiation function. In this disclosure, unless otherwise specified, it is assumed that the legacy TX and RX have the negotiation function and that the negotiation process is performed in the negotiation phase.

[0075] It is important that TX and RX conforming to WPC Standard Version A that are WPT certified are backward compatible with legacy RX and TX conforming to WPC Standard v1.2.2, respectively. A TX (or RX) conforming to WPC Standard Version A is required to operate without conflict with an RX (or TX) conforming to a WPC Standard earlier than Version A.

[0076] 7 to 9 , an example will be described in which a TX and RX compliant with WPC Standard Version A have backward compatibility with WPC Standard v1.2.2. Assume a case where the TX and RX are compliant with the legacy EPP of WPC Standard v1.2.2. In this case, the state transitions of the TX and RX are in the order of Selection phase, Ping phase, I&C phase, Negotiation phase, Calibration phase, and PT phase. Assume also a case where the legacy TX or RX is a BPP device without a negotiation function. In this case, the state transitions of the TX and RX are in the order of Selection phase, Ping phase, I&C phase, and PT phase.

[0077] Assume that both TX and RX support the authentication phase. In this case, the state transitions between TX and RX are in the order of Selection phase, Ping phase, I&C phase, and Authentication phase. After the Authentication phase, the state transitions are in the order of Negotiation phase, Calibration phase, and PT phase.

[0078] The authentication phase is executed, for example, before the negotiation phase. The reason for this is that the GP value is changed depending on the result of WPT authentication, as described with reference to FIG. 6 . Assume that the TX and RX determine a GP through negotiation in the negotiation phase and then transition to the authentication phase. The already determined GP may be reset depending on the result of the authentication phase. That is, after the GP is determined, depending on the result of WPT authentication, it may become necessary to lower the GP to avoid or suppress excessive heat generation, etc. If the GP is reset (changed), the processing procedure (protocol) until transitioning to the PT phase may become complicated, and the processing time may increase. In response to this, the authentication phase is executed prior to the negotiation phase. This allows the GP to be determined in the negotiation phase on the basis of the GP restricted in the authentication phase. By restricting the GP in the authentication phase prior to the negotiation phase in this way, GP resetting does not occur before transitioning to the PT phase, so that transition to the PT phase can be made quickly.

[0079] In v1.3 of the WPC standard, when the GP set in the capability information of the TX in the authentication phase is to be distinguished from the GP in other phases, the GP is referred to as Negotiable Load Power (hereinafter referred to as NLP). The NLP is the maximum value of GP that can be negotiated between the TX and the RX in the negotiation phase after the authentication phase.

[0080] 7, 8A, and 9, a processing example in accordance with the WPC standard v1.2.2 when both the TX and RX support legacy EPP will be described. In the following, it is assumed that USB authentication between the TX and the USB cable 300 and the AC adapter 301 is successful. In this processing example, only the portions of the flowcharts in FIGS. 7 and 9 related to legacy EPP are executed. That is, since the processing of S703 to S708b in FIG. 7 does not exist in the legacy TX, the processing of S701, S702, S704, and S709 to S713 will be described. Furthermore, since the processing of S903 to S907b and S908 in FIG. 9 does not exist in the legacy RX, the processing of S901, S902, and S909 to S912 will be described. Note that FIG. 8A only shows the sequence after the I&C phase, which is related to backward compatibility.

[0081] In S701 of FIG. 7, the TX and RX perform the Selection phase and Ping phase processes, and then transition to the I&C phase. In S702, the TX receives an Identification Packet (ID Packet) and a Configuration Packet from the RX. Arrow 800 in FIG. 8A indicates that the legacy RX transmits an ID Packet to the legacy TX. The ID Packet stores information indicating the version of the supported WPC standard (v1.2.2 in this case) in addition to the individual identification information of the device itself. Arrow 801 in FIG. 8A indicates that the legacy RX transmits a Configuration Packet of the WPC standard v1.2.2 to the legacy TX. The packet contains the following information: Maximum Power Value, which is the maximum power value that the RX can supply to the load. Neg bit information, which is a bit indicating whether or not the device has a negotiation function.

[0082] The legacy TX does not execute the process of S703, and proceeds to the process of S704 corresponding to the negative determination result (No) of S703. In S704, the TX determines whether the RX has the negotiation function. If the TX determines that the RX has the negotiation function (Yes in S704), the TX proceeds to the process of S713. If the TX determines that the RX does not have the negotiation function (No in S704), the TX proceeds to the process of S712.

[0083] In S713, the TX transmits an ACK in response to the Configuration Packet from the RX. Arrow 802 in FIG. 8A indicates that the legacy TX transmits an ACK to the legacy RX. After S713, the process proceeds to S709, where the process transitions to the Negotiation phase. Next, in S710, the TX determines a GP, and then transitions to the Calibration phase in S711. In the Calibration phase, the TX adjusts the power transmitted to the RX by the TX based on the correlation between the value measured inside the TX and the value of the received power measured inside the RX. Next, in S712, the process transitions to the PT phase.

[0084] If the determination result in S704 is NO, that is, if the RX is a BPP that does not support the Negotiation function (the value of the Neg bit is 0), the process proceeds to S712. In this case, the TX transitions to the PT phase without sending an ACK to the RX. Also, if the TX itself is a BPP and does not support the Negotiation function, the TX transitions to the PT phase without sending an ACK to the RX. In this case, the GP is limited to 5 watts. After S712, the TX ends the series of processes.

[0085] On the other hand, in S901 of Fig. 9, RX transmits an ID packet to TX (Fig. 8(A): 800). Next, RX transmits a configuration packet to TX (Fig. 8(A): 801). The configuration packet of WPC standard v1.2.2 includes information on the neg bit. RX sets the neg bit to "1". "1" indicates that the device has a negotiation function. After S901, the process proceeds to S902.

[0086] In S902, the RX determines whether or not it has received an ACK (802 in FIG. 8A) in response to the Configuration Packet from the TX. If the RX has received an ACK (Yes in S902), it determines that the TX supports the Negotiation function. As described above, the process of S908 is not executed, so the process proceeds from S902 to S909, and the RX transitions to the Negotiation phase. The RX transmits a Specific Request packet to the TX, requesting the power required by its own device (for example, 15 watts). The arrow 803 in FIG. 8A indicates that the RX transmits a "Specific Request (15W)" to the TX. This packet is a Specific Request packet that includes information indicating that the RX is requesting 15 watts from the TX as a GP.

[0087] On the other hand, in S902, it is assumed that the RX conforming to the WPC standard v1.2.2 does not receive an ACK within a predetermined time from the time of transmission of the Configuration Packet (No in S902). For example, the predetermined time is 15 ms (milliseconds). In this case, as described above, the process of S903 is not executed, and the process proceeds to S911, where the RX determines that the TX is a BPP that does not have the negotiation function. Next, the RX transitions to the PT phase in S912, and then ends the series of processes.

[0088] When the TX receives a Specific Request (15 W) from the RX, as indicated by the arrow 803 in FIG. 8A, it compares the power transmission capability of its own device with the requested power (15 watts). If the TX determines that it can transmit power at the power requested by the RX, it transmits an acknowledgement (ACK) to the RX. If the TX determines that it cannot transmit power at the power requested by the RX, it transmits a negative acknowledgement (NAK) to the RX. The arrow 804 in FIG. 8A indicates that the TX determines that it can transmit 15 watts, determines the GP to be 15 watts (FIG. 7: S710), and transmits an ACK to the RX.

[0089] The TX transitions to the calibration phase (FIG. 7: S711). When the RX receives an ACK from the TX in response to the specific request sent to the TX, the process proceeds from S909 to S910. In S910, a state transition to the calibration phase is performed. After the calibration process, the process proceeds to S912, a state transition to the PT phase is performed, and wireless power transmission from the TX to the RX begins.

[0090] As described above, the TX in accordance with the WPC standard v1.2.2 determines whether the RX is an EPP or BPP with a negotiation function, or a BPP without a negotiation function, based on the information in the Neg bit. If the RX is an EPP or BPP with a negotiation function, the TX transitions to the negotiation phase and starts transmitting power after negotiating the transmission power. On the other hand, if the RX is a BPP without a negotiation function, the TX transitions to the PT phase without transitioning to the negotiation phase, and transmits power to the RX at a relatively low power. Also, assume that the RX in accordance with the WPC standard v1.2.2 receives an ACK within a predetermined time from the time of transmitting the Configuration Packet. In this case, the state transitions to the Negotiation phase, but if the RX does not receive an ACK within a predetermined time, it transitions to the PT phase. The above operation ensures compatibility between the TX and RX that have the Negotiation function and the TX and RX that do not have the Negotiation function in the WPC standard v1.2.2.

[0091] Next, with reference to Figures 6(A), 7, 8(B), and 10(A), a processing example will be described in which the TX supports version A and the RX is legacy. In the following, it is assumed that the TX has successfully performed USB authentication of the USB cable 300 and the AC adapter 301. Note that the following explanations are all about backward compatibility with the WPC standard, and therefore the technology described below can be applied even if the TX does not have the first authentication unit 108.

[0092] Before describing the flow of each process, the Auth bit in the Configuration Packet will be defined. Fig. 10A shows the configuration of the Configuration Packet of the WPC standard v1.2.2. Note that descriptions of parts that are not relevant to the description of this disclosure will be omitted.

[0093] The Configuration Packet shown in FIG. 10A has multiple reserved areas. There is a reserved area 1000 from bit 0 to bit 7 of Bank 1, a reserved area 1001 from bit 4 to bit 6 of Bank 2, and a reserved area 1002 from bit 0 to bit 2 of Bank 4. In the present disclosure, the Auth bit is placed in bit 6 of Bank 2, but this is not limited to this example, and the Auth bit may be placed in another reserved area. Note that in the WPC standard v1.2.2, the bit value of all reserved areas is "0". The RX stores "1" in the Auth bit if its own device supports WPT authentication, and stores "0" in the Auth bit if it does not support WPT authentication. The location where the Auth bit value is stored is the location of the Reserved bit. Therefore, even an RX that complies with an older generation standard and does not recognize that the Auth bit value is stored at this location can store the value "0" at this location.

[0094] When the process proceeds from S702 to S703 in FIG. 7 , the TX acquires the value of the Auth bit of the Configuration Packet and determines whether the RX supports WPT authentication. In the legacy RX, since the value of the Auth bit is "0", the TX determines that the RX does not support WPT authentication (No in S703) and proceeds to the process of S704. In S704, the TX determines whether the RX has a negotiation function. If it is determined that the RX has the negotiation function (Yes in S704), the process proceeds to the process of S713. In S713, the TX transmits an ACK in response to the Configuration Packet and transitions to the negotiation phase in S709. An arrow 802 in Fig. 8B indicates that the TX transmits an ACK to the RX. An arrow 803 in Fig. 8B indicates that the RX transmits a Specific Request (15W) to the TX. When the TX receives a request for 15 watts as GP from the RX, it transmits a negative acknowledgement (NAK) to the RX, as indicated by an arrow 805, rejecting the request. This is because the RX does not support WPT authentication, and the TX determines that it should not transmit 15 watts in order to suppress or prevent excessive heat generation in the RX.

[0095] If the request is rejected by NAK, the RX sends a General Request defined in the WPC standard v1.2.2 to know the GP value that the TX can set. In this disclosure, a message requesting a Transmitter Capability Packet among General Requests is referred to as a General Request (capability). An arrow 806 in FIG. 8B indicates that the RX sends the request to the TX. The TX receives the General Request (capability). The TX stores information indicating 5 watts in the Guaranteed Power Value of the Power Transmitter Capability Packet and transmits it to the RX. The Transmitter Capability Packet contains information about the maximum GP value that can be tolerated in negotiation and is a packet defined in the WPC standard v1.2.2. Arrow 807 in FIG. 8B indicates that the TX transmits the packet to the RX. This value of 5 watts is determined based on the information shown in FIG. 6A as the maximum GP value that can be tolerated during power transmission. In other words, this value corresponds to WPT authentication non-compliance (row 603) and USB authentication success (column 602).

[0096] If the RX does not have the negotiation function (No in S704 in FIG. 7), the TX transitions to the PT phase in S712 without transmitting an ACK. In this case, the GP is limited to 5 watts. Also, since the RX is legacy, if the RX has the negotiation function (Yes in S704 in FIG. 7), the processes from S709 to S711 are performed in the same way as when the TX and RX are legacy.

[0097] As described above, by using the Auth bit defined in FIG. 10A, a TX that complies with WPC standard version A can operate without inconsistency with a legacy RX that complies with a WPC standard earlier than version A.

[0098] Next, with reference to Figures 6, 7, 8D, and 9, a case where both the TX and RX are version A will be described. This is the case where both the TX and RX support WPT authentication processing. In the following, it is assumed that the TX has successfully performed USB authentication with the USB cable 300 and AC adapter 301. First, the operation of the TX and RX of version A that support WPT authentication will be described.

[0099] In S901 of Fig. 9, the version A RX transmits a configuration packet with "1" stored in the Auth Bit to the TX. Arrow 801 in Fig. 8D indicates that the RX transmits the packet to the TX. Meanwhile, in S703 of Fig. 7, the version A TX acquires the value of the Auth Bit of the configuration packet. If the TX determines that the RX supports WPT authentication (Yes in S703), it proceeds to the processing of S705.

[0100] In S705 of Fig. 7, the TX transmits a predetermined acknowledgement (hereinafter referred to as ACK(auth)) to the RX. The ACK(auth) is distinguishable from a normal ACK and is an acknowledgement for the Configuration Packet consisting of a different bit pattern, and is a packet indicating that the TX supports WPT authentication. The arrow 802a in Fig. 8(D) indicates that the TX transmits the ACK(auth) to the RX.

[0101] After transmitting ACK (auth), TX transitions to the authentication phase in S706. On the other hand, if RX determines in S902 of FIG. 9 that ACK has not been received (No in S902), it proceeds to processing in S903. In S903, RX determines whether or not ACK (auth) has been received instead of ACK. If RX determines that ACK (auth) has been received (Yes in S903), it proceeds to processing in S904.

[0102] In S904, RX determines that TX supports WPT authentication. Then, in S905, RX transitions to the authentication phase. Arrows 814a to 820a and 814b to 820b in FIG. 8D show examples of WPT authentication. In S706 in FIG. 7, TX transitions to the authentication phase, and in S707a, TX sends a GET_DIGEST packet to RX. The GET_DIGEST packet is a packet requesting information about the digital certificate held by RX. Arrow 814a in FIG. 8D indicates that TX sends the packet to RX.

[0103] After S905 in Fig. 9, RX executes the processes of S906a, S907a, S906b, and S907b. In S906a, RX receives a GET_DIGEST packet and is authenticated by TX. Arrow 815a in Fig. 8D indicates that RX sends a DIGEST packet in response to the GET_DIGEST packet. DIGEST is information about the digital certificate held by RX. Next, as indicated by arrow 816a, TX sends a GET_CETTIFICATE packet to RX requesting detailed information about the digital certificate. As indicated by arrow 817a, RX sends a CERTIFICATE packet in response to the GET_CETTIFICATE packet.

[0104] Next, as shown by arrow 818a, TX sends a CHALLENGE message including the challenge text to RX. Arrow 819a indicates that RX sends a RESPONSE in which the challenge text is encrypted to TX. If the validity of the RESPONSE is confirmed, TX sends a RESULT (success) to RX in S708a of Fig. 7. Arrow 820a in Fig. 8(D) indicates that TX sends a RESULT (success) to RX.

[0105] In S907a of Fig. 9, RX receives RESULT (success). The information in RESULT (success) means that the WPT authentication was successful as a result of the RESPONSE. If the result of the RESPONSE is that the authentication failed, TX sends RESULT (fail) indicating that the authentication failed to RX. In S906b of Fig. 9, RX sends a GET_DIGEST packet to TX. Arrow 814b in Fig. 8(D) indicates that RX sends a GET_DIGEST packet to TX.

[0106] In S707b of Fig. 7, TX receives a GET_DIGEST packet and is authenticated by RX. This GET_DIGEST packet is a packet requesting information about the digital certificate owned by TX. Arrow 815b in Fig. 8(D) indicates that TX sends DIGEST to RX in response to the GET_DIGEST packet. This DIGEST is information about the digital certificate owned by TX.

[0107] Next, as shown by arrow 816b in Fig. 8(D), RX sends a GET_CETTIFICATE packet to TX requesting detailed information about the digital certificate. Arrow 817b indicates that TX sends a CERTIFICATE in response to the GET_CETTIFICATE packet. Next, as shown by arrow 818b in Fig. 8(D), RX sends a CHALLENGE message including a challenge text to TX. Arrow 819b indicates that TX sends a RESPONSE in which the challenge text is encrypted to RX. If the authenticity of the RESPONSE is confirmed, RX sends a RESULT (success) to TX in S907b in Fig. 9. An arrow 820b in Fig. 8D indicates that RX transmits a RESULT (success) to TX. In S708b in Fig. 7, TX receives the RESULT (success) from RX. Next, the process proceeds to S709.

[0108] After transmitting and receiving a RESULT (success) or RESULT (fail), the TX and RX transition to the negotiation phase (S709, S909). If the USB authentication and mutual WPT authentication are successful, the TX determines, based on the information shown in FIG. 6A, that 15 watts, which corresponds to successful WPT authentication (row 605) and successful USB authentication (column 602), is the maximum allowable GP value, and performs negotiation. Meanwhile, the RX determines, based on the information shown in FIG. 6B, that 15 watts, which corresponds to successful WPT authentication (row 615), is the maximum allowable GP value, and performs negotiation processing. Arrow 803 in FIG. 8D indicates that the RX requests 15 watts as the GP power value from the TX. The TX has determined the negotiated power value of the GP to be 15 watts. Arrow 804 indicates that the TX sends an ACK to the RX acknowledging the request from the RX.

[0109] If USB authentication or WPT authentication fails, the TX determines the maximum value of GP to be allowed in the negotiation phase based on the information shown in Fig. 6(A). If WPT authentication fails, the RX determines the maximum value of GP to be allowed in the negotiation phase based on the information shown in Fig. 6(B). Alternatively, if the TX receives RESULT(fail) from the RX, the TX may determine not to transmit power. If the RX receives RESULT(fail) from the TX, the RX may determine not to make a power transmission request.

[0110] The above-described configuration allows the control of power transmission or reception to be determined with higher accuracy, and also provides the effect of enhancing security. The TX of the present disclosure operates not only with an RX that complies with the WPC standard earlier than version A, but also with an RX that complies with version A.

[0111] In the authentication phase, an example has been shown in which TX first authenticates the authenticity of RX, and then RX authenticates the authenticity of TX, but the reverse order is also possible. If RX authenticates TX first and then TX authenticates RX, the order of the operations indicated by arrows 814a to 820a and 814b to 820b in Figure 8(D) is reversed. Also, in Figure 7, the processing of S707a and S708a is performed after the processing of S707b and S708b. Furthermore, in Figure 9, the processing of S906a and S907a is performed after the processing of S906b and S907b.

[0112] The order in which the TX and RX perform authentication can be either predetermined or not. In order to correctly perform authentication in the authentication phase, it is preferable that the initiator and responder perform the following processing after sending a GET_DIGEST packet. - The initiator should suspend or cancel the response even if it receives a GET_DIGEST packet from another device until it sends RESULT (success) or RESULT (fail) to the responder. - The responder should not send a GET_DIGEST packet until it receives RESULT (success) or RESULT (fail).

[0113] Here, a supplementary explanation will be given of the time interval between packets from the GET_DIGEST packet (FIG. 8(D): 814a, 814b) to the RESULT (success) (FIG. 8(D): 820a, 820b). Regarding the TX's response to the RX's packet, for example, in the negotiation phase of the WPC standard v1.2.2, the time from the end of the received packet to the beginning of the response packet to be sent is stipulated to be within 10 ms. In the authentication phase, the initiator needs to perform encryption and decryption processes to verify the validity of packets (DIGEST, CERTIFICATE, RESPONSE) related to the digital certificate sent by the responder. For this reason, responses take time in the authentication phase. Therefore, a longer response time is set in the authentication phase compared to the response times (Response times) specified in other phases. In the present disclosure, this response time is set to 50 ms. In FIG. 8(D), the response time is the time from DIGEST to GET_CERTIFICATE, from CERTIFICATE to CHALLENGE, and from RESPONSE to RESULT (success). By lengthening the response time, the control unit 101 of the TX does not need to operate at high speed, which reduces the power consumption of the control unit 101 and enables cost reduction by using a slower CPU.

[0114] The TX determines whether the RX supports WPT authentication based on the information (value) of the Auth bit in the Configuration Packet. Without being limited to this example, the TX can determine whether the RX supports WPT authentication based on the version information in the ID Packet. The TX can determine that the RX supports WPT authentication if the version information is version A (or a later version), and can determine that the RX does not support WPT authentication if the version information is earlier than version A.

[0115] Furthermore, if the TX receives a packet other than a predetermined packet from the RX during the Authentication phase, the power transmitting unit 103 may stop power transmission and transition to the Selection phase. By stopping power transmission when the TX receives a packet other than a predetermined packet due to a malfunction of the RX or the like, it is possible to prevent unexpected system operation. The predetermined packets are packets indicated by arrows 814a to 820a and arrows 814b to 820b in FIG. 8(D). That is, GET_DIGEST, DIGEST, GET_CERTIFICATE, CERTIFICATE, CHALLENGE, RESPONSE, and RESULT. Packets other than the predetermined packets are, for example, as follows: - Signal Strength Packet indicating the voltage value of the receiving voltage. - Control Error Packet requesting an increase or decrease in voltage value - Identification Packet (ID Packet) - Configuration Packet

[0116] Furthermore, the TX or RX may store the result of operating as an initiator (i.e., confirming the legitimacy of the responder) and the responder's identification information (device ID, manufacturer ID, certificate information, etc.) in non-volatile memory. Furthermore, the TX and RX may store only the identification information of the responder that failed authentication in non-volatile memory. The TX or RX may perform WPT authentication using the identification information of the responder that failed authentication, stored in non-volatile memory. For example, when the TX or RX performs authentication as an initiator, it is possible to determine the legitimacy of the device by comparing the identification number of the device to be authenticated with the identification number stored in non-volatile memory.

[0117] Next, with reference to Figures 6, 7, 8C, and 9, a case will be described where the TX is legacy and the RX supports version A. In the following, it is assumed that the TX has successfully performed USB authentication with the USB cable 300 and AC adapter 301. In S901 of Figure 9, the RX sends a Configuration Packet to notify the TX that the RX supports WPT authentication (801 in Figure 8C). However, since the TX is legacy, it ignores the Auth bit. Since the version A RX supports the negotiation function, the process proceeds from S704 to S713 in Figure 7 (Yes in S704). In S713, the TX sends an ACK, and then transitions to the negotiation phase in S709.

[0118] When the RX receives an ACK from the TX (FIG. 8C: 802), the process proceeds from S902 to S908 in FIG. 9 (Yes in S902). In S908, the RX determines that the TX does not support WPT authentication. This is because the RX itself supports WPT authentication, and if the TX supports WPT authentication, it will receive an ACK (auth) instead of an ACK. Next, in S909, the RX transitions to the Negotiation phase.

[0119] If the RX does not receive an ACK within 15 ms from the time of transmitting the Configuration Packet (No in S902) and does not receive an ACK (auth) either (No in S903), the process proceeds to S911. After determining in S911 that the TX is a BPP and does not support the Negotiation function, the RX transitions to the PT phase in S912.

[0120] The RX negotiates the GP in the Negotiation phase, but based on the information described in FIG. 6B, it determines that 15 watts should not be used to receive power in order to avoid risks such as excessive heat generation. The RX then decides to negotiate 5 watts as the GP. 5 watts corresponds to the power level corresponding to the WPT authentication not being supported (row 603) and the USB authentication being successful (column 602). As shown by arrow 809 in FIG. 8C, the RX transmits a Specific Request (5 W) to the TX. Arrow 804 indicates that the RX receives the ACK transmitted by the TX. After the Negotiation phase in S909 is completed, the RX transitions to the Calibration phase in S910. After the RX performs the processing required for calibration, the RX transitions to the PT phase in S912.

[0121] As described above, an RX that complies with WPC standard version A can operate without inconsistency with a TX that complies with a WPC standard earlier than version A.

[0122] In the wireless charging system disclosed herein, authentication is performed between the power supply device (AC adapter 301), which is a power supply source, and the power transmitting device using the USB protocol, and mutual authentication is performed between the power transmitting device and the power receiving device using the WPC protocol. The control unit of the power transmitting device controls the transmitted power based on the USB authentication result and the WPC authentication result. This allows multiple authentication results to be effectively utilized in a wireless power transmission system capable of executing processes based on multiple authentication protocols. As a result, for example, appropriate power transmission control can be achieved that reduces the likelihood of excessive heat generation in devices present on the power supply path.

[0123] [Modification] In the above system configuration, an example has been shown in which the TX and RX perform WPT authentication with each other in the authentication phase. Below, a modification of the system configuration will be described with reference to Figures 11 and 12. Note that for matters similar to those described above, detailed explanations will be omitted by using the same symbols and signs already used. This omission method will also be adopted in the description of the embodiments described below.

[0124] In this modified example, if the first WPT authentication performed by the TX and the RX is unsuccessful, the other WPT authentication that was scheduled to be performed later is not performed, and a GP is determined. This modified example shortens the processing time of the authentication phase, enabling the GP to be determined quickly.

[0125] In addition, in a modified example, the control unit 101 of the TX determines the control content of power transmission based on the result of the WPT authentication that is performed first between the WPT authentications performed by the TX and the RX. For example, the control content of power transmission is whether or not the TX will transmit power, or the maximum power value that the TX can tolerate if it transmits power. Meanwhile, the control unit 201 of the RX determines the control content of power reception based on the result of the WPT authentication that is performed first between the WPT authentications performed by the TX and the RX. For example, the control content of power reception is whether or not the RX will receive power, or the maximum power value that the RX will request from the TX if it receives power. In the modified example, a case will be described in which the power receiving device becomes the initiator first and authenticates the authenticity of the power transmitting device, but the same effect can be achieved even if the power transmitting device becomes the initiator first and authenticates the authenticity of the power receiving device.

[0126] Fig. 11 is a flowchart illustrating the process up to power transmission by the control unit of the power receiving device (RX). Fig. 12 is a flowchart illustrating the process up to power transmission by the control unit of the power transmitting device (TX). In the following, in order to focus on the process in the authentication phase, it is assumed that both the TX and the RX are version A.

[0127] 11, the processing from S1100 to S1107, which differs from that in FIG. 9, will be mainly described. In S901, the version A RX transmits a Configuration Packet with "1" stored in the Auth Bit to the TX. If the RX receives an ACK (auth) (Yes in S903), it determines that the TX supports WPT authentication and proceeds to the processing of S1100. Note that the RX may determine whether the TX supports WPT authentication by acquiring version information in addition to receiving an ACK (auth). In S1100, the RX transmits an Auth_request (hereinafter referred to as "Auth_req") to the TX within a predetermined time. The Auth_req is a packet indicating the intention of the RX as the initiator to start authentication processing with the TX, which is the destination, as the responder. After S1100, the process proceeds to S1101.

[0128] In S1101, the RX determines whether or not it has received an ACK from the TX. If the RX determines that it has received an ACK (Yes in S1101), it proceeds to the processing of S906b. If the RX determines that it has not received an ACK (No in S1101), it proceeds to the processing of S1107. In S906b, the RX sends a GET_DIGEST to the TX within a predetermined time period to authenticate the authenticity of the TX. Subsequently, in S1102, the RX determines whether or not the WPT authentication was successful. If it is determined that the WPT authentication was successful (Yes in S1102), it proceeds to the processing of S1103. If it is determined that the WPT authentication was not successful (No in S1102), it proceeds to the processing of S1107. If the RX determines that the TX supports WPT authentication, it sends a RESULT (Success) to the TX. In S1103, the RX sends an Auth_req to the TX within a predetermined time after sending the RESULT (Success), inquiring whether the TX intends to perform WPT authentication. Since the TX has the initiator function, the TX sends an ACK to the RX within a predetermined time after receiving the Auth_req. In S1104, the RX determines whether or not an ACK has been received from the TX. If the RX determines that an ACK has been received (Yes in S1104), the RX proceeds to the processing of S1105, and if the RX determines that an ACK has not been received (No in S1104), the RX proceeds to the processing of S1107.

[0129] In S1105, the RX determines whether or not it has received GET_DIGEST from the TX. If the RX determines that it has received GET_DIGEST (Yes in S1105), it proceeds to the process of S906a and receives authentication from the TX. If the RX determines that it has not received GET_DIGEST (No in S1105), it proceeds to the process of S1107. After S906a, in S1106, the RX receives the WPT authentication result from the TX and determines whether or not the WPT authentication was successful. If it is determined that the WPT authentication was successful (Yes in S1106), it transitions to the negotiation phase in S909. In this case, since the RX recognizes the authenticity of the TX (Yes in S1102), it requests a maximum GP of 15 watts from the TX as a Specific Request based on the information shown in Fig. 6B. That is, the control unit 201 of the RX determines the maximum power value to be requested of the TX as the power reception control content based on the results of the WPT authentication of both parties. On the other hand, if it is determined that the WPT authentication has not been successful (No in S1106), the process proceeds to S1107.

[0130] In S1107, the RX limits the GP to 5 watts. The control unit 201 of the RX determines the power value that the RX requests from the TX as the power reception control content based on the result of the WPT authentication that was performed earlier. After S1107, in S909, the process transitions to the negotiation phase.

[0131] Next, Fig. 12 will be used to mainly explain the processing from S1200 to S1206, which differs from Fig. 7. If the version A TX determines that the RX supports WPT authentication based on the Auth Bit in the Configuration Packet (Yes in S703), it sends an ACK(auth) to the RX in S705. After receiving the ACK(auth), the RX sends an Auth_req to the TX within a predetermined time (Fig. 11: S1100).

[0132] After transmitting ACK (auth) in S705, the TX determines in S1200 whether or not it has received Auth_req from the RX within a predetermined time. If the TX determines that it has received Auth_req from the RX (Yes in S1200), it proceeds to the processing of S1201, and if it determines that it has not received Auth_req from the RX (No in S1200), it proceeds to the processing of S1206. By receiving Auth_req, the TX can recognize that WPT authentication will begin.

[0133] When the TX receives Auth_req (Yes in S1200), it determines whether or not it can become a responder and perform WPT authentication. Specifically, the control unit 101 of the TX makes this determination based on the load state. More specifically, the following determination processes are performed: - Determination process of whether the control unit 101 has the capacity to control the second authentication unit 109. - Determination process of whether or not the second authentication unit 109 is controlled by another control unit (not shown) connected to the RX. After receiving Auth_req, the TX performs the above determination process within a predetermined time. If the TX determines that it can be authenticated as a responder, it transmits an ACK to the RX in response to Auth_req.

[0134] In S1201, the TX determines whether or not it has transmitted an ACK to the RX. If the TX determines that it has transmitted an ACK to the RX (Yes in S1201), it transitions to the authentication phase in S706. In this case, when the RX receives an ACK (Yes in S1101 in FIG. 11), it transmits a GET_DIGEST to the TX within a predetermined time after receiving the ACK, and authenticates the authenticity of the TX (S906b in FIG. 11). If the TX determines that it has not transmitted an ACK to the RX (No in S1201), it proceeds to the processing of S1206. After S706, the TX receives a GET_DIGEST in S707b and is authenticated by the RX.

[0135] If the result of the WPT authentication is successful (FIG. 11: Yes in S1102) and the RX determines that the TX supports WPT authentication, the RX sends a RESULT (Success) to the TX. By receiving the RESULT (Success) from the RX, the TX knows that the authentication was successful. In this case, the TX waits a predetermined time for the RX to send an Auth_req inquiring whether the TX intends to perform authentication processing with the TX as the initiator and the RX as the responder. Within a predetermined time after sending the RESULT (Success), the RX sends an Auth_req to the TX inquiring whether the TX intends to perform WPT authentication (FIG. 11: S1103).

[0136] After S707b, the process proceeds to S1202. The TX determines whether or not the WPT authentication of the TX has been successful through the RX. If it is determined that the WPT authentication of the TX has been successful (Yes in S1202), the process proceeds to S1203. If it is determined that the WPT authentication of the TX has not been successful (No in S1202), the process proceeds to S1206. In S1203, the TX determines whether or not it has received an Auth_req from the RX within a predetermined time. If the TX determines that it has received an Auth_req from the RX (Yes in S1203), the process proceeds to S1204. If the TX determines that it has not received an Auth_req from the RX (No in S1203), the process proceeds to S1206. Since the TX has the initiator function, it transmits an ACK to the RX within a predetermined time after receiving the Auth_req.

[0137] In S1204, the TX determines whether or not it has transmitted an ACK to the RX. If the TX determines that it has transmitted an ACK to the RX (Yes in S1204), it proceeds to the processing of S707a. The RX receives this ACK (FIG. 11: Yes in S1104). If the TX determines that it has not transmitted an ACK to the RX (No in S1204), it proceeds to the processing of S1206.

[0138] In S707a, the TX sends a GET_DIGEST to the RX within a predetermined time after sending the ACK, and starts WPT authentication of the RX. The RX receives the GET_DIGEST, and authentication by the TX starts (FIG. 11: Yes in S1105, S906a). Next, in S1205, the TX determines whether the WPT authentication of the RX was successful. If the TX determines that the WPT authentication of the RX was successful (Yes in S1205), it sends a RESULT (Success) to the RX, and transitions to the negotiation phase in S709. In this case, the TX also recognizes the legitimacy of the RX, so a maximum GP of 15 watts is allowed based on the information shown in FIG. 6(A). On the other hand, when the RX receives the WPT authentication result from the TX and the authentication is successful (FIG. 11: Yes in S1106), the RX transitions to the negotiation phase (S909). Because the RX recognizes the legitimacy of the TX (FIG. 11: Yes in S1102), the RX requests a GP of a maximum value of 15 watts from the TX as a specific request based on the information shown in FIG. 6B. In this way, the control unit 101 of the TX and the control unit 201 of the RX determine the maximum transmission power value that the RX can tolerate when transmitting power and the maximum power value that the TX is requested to transmit power to, respectively, as the control contents for power transmission and power reception, based on the WPT authentication results of both.

[0139] In S1206, the TX limits the GP to 5 watts. Next, in S709, the process transitions to the negotiation phase. While an example has been shown in which the RX and TX limit the GP to a predetermined power (5 watts), other methods can be used to suppress or prevent excessive heat generation, etc., without being limited to this. Specifically, if the WPT authentication is unsuccessful, the RX determines the following power reception control: - The RX requests a lower power value from the TX compared to when mutual WPT authentication is successful. - The RX does not receive power from the TX (for example, the RX requests the TX to stop power transmission). The RX sends a packet to the TX to stop power transmission and does not request power. Alternatively, the RX blocks a current path (not shown) to the power receiving coil 205 so as not to receive power from the TX.

[0140] Furthermore, if WPT authentication is not successful, the TX decides to control power transmission as follows: - The TX sets the maximum allowable power value to be transmitted to the RX to a smaller value compared to when mutual WPT authentication is successful. - The TX stops transmitting power to the RX.

[0141] As shown in Figures 11 and 12, if authentication is not successful in the earlier WPT authentication process (S707b, S906b), the later scheduled WPT authentication process (S707a, S906a) is not performed. Specifically, the control unit 201 of the RX does not send the Auth_req in S1103 so as not to give the TX an opportunity to act as the initiator. This is because, since the RX did not succeed in the authentication as the initiator, it has already determined the requested GP to be 5 watts (see Figure 6(B)), and this determination does not change whether the authentication result in which the TX becomes the initiator is successful or not. This shortens the processing time of the authentication phase and enables a prompt transition to the negotiation phase.

[0142] The RX does not succeed in WPT authentication in the following cases: - When the validity of the TX cannot be confirmed in the WPT authentication process in which the RX is the initiator, that is, when the authentication fails (No in S1102). - When the TX transmits a negative acknowledgement NAK in response to Auth_req because it is unable to operate the second authentication unit 109 (No in S1101, No in S1201). - When an ACK is not received from the TX within a predetermined time after the RX transmits Auth_req (No in S1201). - When an expected packet is not received from the TX within a predetermined time after the RX transmits the following packet in the WPT authentication process. Specifically, there are cases where the RX does not receive a DIGEST packet in response to a GET_DIGEST packet transmitted by the RX, or receives another packet. There are cases where the RX does not receive a CERTIFICATE packet in response to a GET_CERTIFICATE packet, or receives another packet. The RX may not receive a response packet to the CHALLENGE packet, or may receive some other packet.

[0143] On the other hand, if the TX determines that the WPT authentication has not been successful, the control unit 101 does not transmit a GET_DIGEST to the RX, i.e., the TX does not transmit a packet related to the WPT authentication process to the RX.

[0144] The TX determines that the WPT authentication was not successful in the following cases: - After the TX sends an ACK (auth) (S705), it does not receive an Auth_req within a predetermined time (No in S1200). - After the TX receives an Auth_req (Yes in S1200), it does not send an ACK within a predetermined time (No in S1201). - In the WPT authentication process, after the TX sends the following packets, it does not receive an expected packet from the RX within a predetermined time. Specifically, after the TX sends an ACK (Yes in S1201), there are cases where the TX does not receive a GET_DIGEST packet or receives another packet. After the TX sends a DIGEST packet, there are cases where the TX does not receive a GET_CERTIFICATE packet or receives another packet. After the TX sends a CERTIFICATE packet, there are cases where the TX does not receive a CHALLENGE packet or receives another packet. After the TX sends a RESPONSE packet, there are cases where the TX does not receive a RESULT packet or receives another packet. - When WPT authentication with the RX as the initiator is not successful (No in S1201). If the WPT authentication is not successful, this also includes the case where the TX does not receive a RESULT (Success) packet within a predetermined time after sending a RESPONSE packet. - When the TX receives a RESULT (Fail) packet indicating that the WPT authentication has failed.

[0145] Similarly, in the process of S707a (S906a), if the TX does not succeed in authenticating the RX as the initiator (No in S1205, No in S1106), the following process is performed: The RX requests a smaller power value as GP from the TX compared to when mutual WPT authentication was successful in the negotiation phase. The RX requests the TX to stop power transmission or not to request power.

[0146] On the other hand, the TX determines whether to allow a lower power as GP compared to when mutual WPT authentication is successful in the negotiation phase, or to stop power transmission to the RX, etc. In S1107 of Fig. 11, the RX determines the GP to be 5 watts, and in S1206 of Fig. 12, the TX determines the GP to be 5 watts.

[0147] The RX determines that the WPT authentication was not successful in the following cases: - After the RX sends an Auth Req in S1103, it does not receive an ACK from the TX within a predetermined time (No in S1104). - After the RX receives an ACK (Yes in S1104), it does not receive a GET_DIGEST within a predetermined time (No in S1105). - After the RX sends a packet described below in the WPT authentication process, it does not receive an expected packet from the TX within a predetermined time. Specifically, the RX may not receive a GET_CERTIFICATE packet or may receive another packet after sending a DIGEST packet. The RX may not receive a CHALLENGE packet or may receive another packet after sending a CERTIFICATE packet. The RX may not receive a RESULT packet or may receive another packet after sending a RESPONSE packet.

[0148] The TX determines that the WPT authentication was not successful in the following cases: - When the TX does not receive an Auth_req within a predetermined time after receiving a RESULT (Success) packet (No in S1203). - When the TX does not send an ACK in response to the Auth_req within a predetermined time (No in S1204), or when it sends a NAK indicating that it cannot operate the second authentication unit 109. - When the TX does not receive an expected packet from the RX within a predetermined time after sending the following packet in the WPC authentication processing of S707a (No in S1205). Specifically, the TX may not receive a DIGEST packet in response to a GET_DIGEST packet it sends, or may receive another packet. Also, the TX may not receive a CERTIFICATE packet in response to a GET_CERTIFICATE packet it sends, or may receive another packet. There are cases where the TX does not receive a response packet or receives some other packet in response to the CHALLENGE packet it sent.

[0149] In S1103, the RX transmits an Auth_req inquiring whether the TX intends to perform a process in which the TX acts as an initiator and the RX acts as a responder. However, the RX may transmit the Auth_req after determining whether the TX can become an initiator. For example, the TX may store information indicating whether the TX has initiator functionality or responder functionality in a part of the Transmitter Capability Packet. Similarly, the RX may store information indicating whether the TX has initiator functionality or responder functionality in a part of the Configuration Packet. If the TX has initiator functionality, the RX transmits the Auth_req to the TX in S1103, and if the TX does not have initiator functionality, the RX does not transmit the Auth_req to the TX. This reduces the time wasted by the RX sending an Auth_req even though the TX does not have the initiator function, thereby shortening the processing time.

[0150] Furthermore, the Auth_req in S1103 is a packet that triggers the TX to send a GET_DIGEST. In this case, the packet may be a packet inquiring of the TX as to whether it has data to transmit to the RX, or a packet indicating that the right to transmit data is to be granted to the TX. When the TX determines that it has data to transmit to the RX or that it needs the right to transmit data, it transmits an acknowledgment (ACK) to the RX (Yes in S1204). When the TX determines that it has no data to transmit to the RX or that it does not need the right to transmit data, it transmits a negative acknowledgment (NAK) to the RX. This achieves the same effect as the above example.

[0151] Prior to sending the Auth_req in S1100, the RX may transmit a General Request (ID) to the TX to acquire identification information from the TX. The General Request (ID) is a packet for acquiring the TX's identification information, and the identification information may be stored in the Auth_req as the responder's identification information. In this way, the TX that receives the Auth_req knows that it should be the responder. The TX then waits to receive a GET_DIGEST and becomes able to undergo WPT authentication. Here, the RX may store its own identification information as the initiator's identification information in the Auth_req, or store the TX's identification information as the responder's identification information. In this way, the TX can clearly know that the RX wants to verify the TX's authenticity. In addition, in S1103, the RX stores the identification information of its own device as the identification information of the responder in the Auth_req, or stores the identification information of the TX as the identification information of the initiator. By doing so, the TX that receives the Auth_req knows that its own device should become the initiator.

[0152] 11 and 12 show an example of processing performed by the control units of RX and TX when RX becomes the initiator first and authenticates the legitimacy of TX. Alternatively, the same effect can be achieved when TX becomes the initiator first and authenticates the legitimacy of RX. The flowchart showing the processing of the control unit 201 of RX in this case is obtained by interchanging the series of processing steps S1100, S1101, S906b, and S1102 with the series of processing steps S1103, S1104, S1105, S906a, and S1106 in FIG. 11. The flowchart showing the processing of the control unit 101 of TX is obtained by interchanging the series of processing steps S1200, S1201, S706, S707b, and S1202 with the series of processing steps S1203, S1204, S707a, and S1205 in FIG. 12.

[0153] The above-described configuration allows for more accurate determination of power transmission or reception control, thereby further enhancing security. The TX and RX of the present disclosure have initiator functions related to WPT authentication. The TX or RX may store the results of operating as an initiator (i.e., confirming the legitimacy of a responder) and the responder's identification information (device ID, manufacturer ID, certificate information, etc.) in a non-volatile memory (not shown). Furthermore, the TX or RX may store only the identification information of a responder whose authentication failed in the non-volatile memory. The TX and RX may then operate to prevent a device identical to the responder whose identification information is stored in the non-volatile memory from performing authentication processing as the initiator. Specifically, when the TX and RX receive a request from a device whose identification information is stored in the non-volatile memory as a responder whose authentication failed, requesting that the TX and RX operate as a responder to confirm its legitimacy, the TX and RX reject the request.

[0154] For example, assume that the RX operates as an initiator and fails to authenticate the TX. In this case, the RX stores the TX's identification information as a responder in a nonvolatile memory. Next, the RX transmits to the TX a packet inquiring whether the TX has data to transmit or a packet granting the TX the right to transmit data. The RX then receives an ACK for the transmitted packet. This ACK is a positive response indicating that the TX has data to transmit to the RX or that the TX has obtained the right to transmit data. Next, when the RX receives a packet (Auth_req) indicating its intention to initiate a WPT authentication process with the TX as the initiator and the RX as the responder, it transmits a negative acknowledgement (NAK) based on the identification information stored in the nonvolatile memory. This prevents the device that failed authentication (in this case, the TX) from operating as the initiator as a result of the RX's WPT authentication from performing authentication processing. In other words, if the earlier WPT authentication is not successful, the execution of the later WPT authentication process can be prevented, thereby shortening the processing time of the authentication phase if the earlier WPT authentication does not confirm the validity.

[0155] The same applies when the TX fails to authenticate the RX as an initiator. For example, the TX stores the identification information of the RX as a responder whose authentication has failed in non-volatile memory. In this state, when the TX receives a packet (Auth_req) from the RX indicating the intention of the RX to act as the initiator and start WPT authentication processing with the TX as the responder, the TX transmits a negative acknowledgement (NAK). Since the TX can prevent authentication processing from being performed by a device that has failed authentication and is operating as the initiator, the processing time of the authentication phase can be shortened.

[0156] Furthermore, the TX and RX may operate to prevent a device whose identification information is stored in non-volatile memory as a responder whose authentication has failed from requesting that the TX and RX act as responders to confirm their legitimacy. For example, the RX has a function of transmitting a packet inquiring the TX about whether it has data to transmit to the RX, or a packet granting the TX the right to transmit data. The RX decides not to transmit the above-mentioned packet to a device whose identification information is stored in non-volatile memory as a responder whose authentication has failed (i.e., the TX). The TX also has a function of transmitting a packet inquiring the RX about whether it has data to transmit to the TX, or a packet granting the RX the right to transmit data. The TX decides not to transmit the above-mentioned packet to a device whose identification information is stored in non-volatile memory as a responder whose authentication has failed (i.e., the RX).

[0157] In a variant example, when a preceding authentication fails in a WPC authentication that is scheduled to be performed in both directions, the subsequent WPC authentication is avoided and a GP is determined, thereby shortening the processing time of the authentication phase and enabling the GP to be determined earlier.

[0158] [Another Modification] This modification shows an example of processing by the RX when a situation occurs in which the TX (responder) cannot be authenticated or the authentication challenge fails when the RX of WPC standard version A (v1.3EPP) performs authentication as an initiator. When authentication fails when the RX becomes the initiator, suitable power reception control of the RX is performed. Furthermore, in this modification, the control unit 201 of the RX determines the power reception control content based on the WPT authentication result. For example, the power reception control content is whether or not to receive power, or the maximum power value requested of the TX if receiving power. Below, a case will be described in which the power receiving device (RX) is version A and the power transmitting device (TX) is any version specified in the WPC standard.

[0159] First, the version A RX performs authentication processing with the TX, and then determines whether the TX is a power transmitting device that supports an authentication function compatible with version A of the WPC standard. Next, if the RX determines that the TX is a power transmitting device that does not support the authentication function, it checks whether the TX is an EPP power transmitting device. If the RX is an EPP power transmitting device, the RX performs power receiving control so as to allow GP, for example, up to 15 W, as the received power from the TX. On the other hand, if the RX determines that the TX is not an EPP power transmitting device or is an EPP power transmitting device that does not support the authentication function, it performs power receiving control so as to allow GP, for example, up to 5 W, as the received power from the TX.

[0160] When the version A RX determines that the TX is a power transmitting device that supports an authentication function compatible with version A of the WPC standard, the version A RX performs authentication processing using a digital certificate. The following describes processing in the authentication phase using a digital certificate when both the TX and the RX are version A (EPP of v1.3 of the WPC standard).

[0161] If the authentication using the digital certificate executed between the RX and the TX using the authentication unit 208 fails, the control unit 201 of the RX checks the validity and defects of the contents of the digital certificate. If it is determined that the TX cannot be trusted due to some defect, the RX controls the received power under the following conditions.

[0162] If the RX determines that the TX is an unreliable power transmitting device due to a flaw in the electronic certificate, it performs power reception control to allow a maximum of 5 W of GP as the received power from the TX. Also, if the RX determines that there is a flaw in the electronic certificate due to a communication error with the TX, it performs power reception control to allow a maximum of 15 W of GP.

[0163] If the authentication performed between the RX and the TX using the authentication unit 208 and the control unit 201 detects no defects in the electronic certificate, the control unit 201 of the RX checks whether the electronic certificate has been revoked. Here, "revocation" means that the validity of the electronic certificate has been revoked for some reason. For example, a product equipped with the TX or RX may be subject to a recall due to a defect. In this case, even if the electronic certificate is legitimately issued and valid, if the product equipped with the TX or RX is defective, it is necessary to limit the power transmitted or received in consideration of safety during use. Furthermore, information identifying the revoked TX or RX may be stored in advance in the device's memory at the time of manufacture as a revocation list containing the device's identification information, such as its Qi-ID.

[0164] If the result of the check for electronic certificate revocation is no problem and authentication is successful, the RX may perform power reception control so as to allow a maximum GP of 15 W as the power received from the TX. Furthermore, if the RX determines, as a result of the check for electronic certificate revocation, that the TX is not Qi certified or is an unsafe power transmitting device, it controls the RX not to receive power from the TX. At the same time, the RX displays an appropriate message or the like to the user to notify them that an error has occurred in the charging process. Furthermore, if, as a result of the check for electronic certificate revocation, the Qi-ID is revoked for some reason or authentication fails for reasons other than those mentioned above, the RX performs power reception control so as to allow a maximum GP of 5 W as the power received from the TX.

[0165] In this modification, if the power receiving device fails to authenticate the power transmitting device when the power receiving device becomes the initiator, the GP is determined depending on the cause of the authentication error, thereby performing suitable power receiving control.

[0166] [Embodiment] Based on the above-described two-way authentication technology, an embodiment of the present disclosure will be described. In this embodiment, an example of processing performed by a TX conforming to WPC Standard Version A (v1.3EPP) when the TX is unable to authenticate an RX (responder) or when an authentication challenge fails when the TX executes authentication processing as an initiator will be described in detail. When authentication fails in the TX's authentication processing of the RX, the cause of the authentication error can be determined, and appropriate control content can be determined to perform power transmission control.

[0167] Based on the WPT authentication result, the control unit 101 of the TX determines, as the power transmission control content, for example, whether to transmit power to the RX or the maximum allowable power value if power transmission is performed. On the other hand, based on the WPT authentication result, the control unit 201 of the RX determines, as the power reception control content, for example, whether to receive power from the TX or the maximum power value to request from the TX if power reception is performed. In this embodiment, a case will be described in which the TX becomes the initiator and authenticates the legitimacy of the RX.

[0168] 13 is a flowchart illustrating authentication by the control unit 101 of the TX. In S1301, the TX conforming to version A of the WPC standard starts authentication with the RX. Next, in S1302, the TX determines whether the RX is a power receiving device that supports an authentication function compatible with version A of the WPC standard. If it is determined that the RX is a power receiving device that supports the authentication function compatible with version A of the WPC standard (Yes in S1302), the TX proceeds to processing in S1303. On the other hand, if it is determined that the RX is a power receiving device that does not support the authentication function (No in S1302), the TX proceeds to processing in S1305.

[0169] In S1303, the version A TX executes authentication processing using an electronic certificate. Next, in S1304, the TX executes NLP determination processing in the authentication phase using an electronic certificate. In S1305, the TX determines whether the RX is an EPP power receiving device. If the TX determines that the RX is an EPP power receiving device (Yes in S1305), the TX proceeds to processing of S1306. If the TX determines that the RX is not an EPP power receiving device (No in S1305), the TX proceeds to processing of S1307.

[0170] In S1306, the TX determines the power that can be transmitted to the EPP RX and notifies the RX. Specifically, the TX sets transmission power information indicating that power is transmitted at a power range of 8 W or more and 15 W or less for the NLP, which is the capability information of the power transmitting device, and notifies the RX. In addition, in S1307, the TX determines the power that can be transmitted to the non-EPP RX and notifies the RX. Specifically, the TX sets transmission power information indicating that power is transmitted at a power of 5 W or less for the NLP, which is the capability information of the power transmitting device, and notifies the RX. After S1304, S1306, and S1307, the series of processes ends.

[0171] FIG. 14 is a flowchart explaining the authentication process by the control unit 101 of the TX. In the following, it is assumed that both the TX and the RX are version A (WPC standard v1.3EPP). In S1401, the control unit 101 of the TX determines whether or not the authentication has failed. The authentication is authentication using an electronic certificate performed with the RX using the second authentication unit 109. If the control unit 101 of the TX determines based on the authentication result that the authentication has failed (Yes in S1401), the control unit 101 proceeds to the process of S1409. On the other hand, if the control unit 101 of the TX determines based on the authentication result that the authentication has not failed (No in S1401), the control unit 101 proceeds to the process of S1402.

[0172] In S1409, the TX checks the validity and defects of the contents of the digital certificate. For example, the digital certificate may be formatted incorrectly, signed incorrectly, or not linked to the WPC's root CA (certificate authority). If the TX determines that the RX's digital certificate is defective and that the RX cannot be trusted (Yes in S1409), the TX proceeds to processing of S1412. If the TX determines that the RX's digital certificate is valid and has no defects (No in S1409), the TX proceeds to processing of S1410.

[0173] In S1412, the TX sets transmission power information indicating that power is transmitted at 5 W or less for the NLP, which is capability information of the power transmitting device, and notifies the RX, and then ends the series of processes. Also, in S1410, the TX determines that there is a defect in the electronic certificate due to, for example, an excessively high bit error rate in communication with the RX. In other words, the TX determines that the authentication in S1401 failed due to the occurrence of a communication error. Next, in S1411, the TX sets transmission power information indicating that power is transmitted at a maximum of 15 W or less for the NLP, which is capability information of the power transmitting device, and notifies the RX, and then ends the series of processes.

[0174] In S1402, the TX checks whether the electronic certificate has been revoked. If the TX determines that there is no problem in the check regarding the revocation of the electronic certificate and that authentication has been successful (Yes in S1402), it proceeds to processing of S1411. However, if the TX determines that authentication has not been successful (No in S1402), it proceeds to processing of S1403. In S1403, the TX determines that the electronic certificate of the product unit in which the RX is installed has been revoked. In S1404, the TX determines whether the serial number has been revoked. For example, if the electronic certificate has been revoked due to the revocation of the serial number of the electronic certificate, such as because a duplicated private key is being used (Yes in S1404), the TX determines that the RX is a power receiving device that is not Qi certified. In this case, it proceeds to processing of S1413.

[0175] If it is determined in S1404 that the serial number has not expired, the process proceeds to S1405. In S1405, based on the results of the check on the expiration of the electronic certificate, if the electronic certificate has expired due to the cancellation of the Qi-ID due to a product recall or the like (Yes in S1405), the TX determines that the RX is not secure. In this case, the process proceeds to S1413.

[0176] If it is discovered in S1404 and S1405 that the digital certificate has expired, the TX sets the NLP, which is the capability information of the power transmitting device, to zero watts in S1413. The TX controls so that power is not transmitted to the RX, and notifies the user of an error related to the charging process by displaying an appropriate message, etc. Then, the series of processes ends.

[0177] If it is determined in S1405 that the Qi-ID has not been revoked due to a product recall or the like, the process proceeds to S1406. In S1406, the TX determines whether the market inspection test results are a failure based on the check results regarding the revocation of the electronic certificate. If the electronic certificate has been revoked due to the revocation of the Qi-ID resulting from a failure in the market inspection test (Yes in S1406), the TX determines that the RX does not comply with the Qi specifications. In this case, the process proceeds to S1412 (see node 1414).

[0178] If it is determined in S1406 that the market inspection test result is not a failure, the process proceeds to S1407. In S1407, the TX determines whether the private key of the secure storage has been compromised multiple times or whether it has not been authenticated because it contains stolen credentials, based on the check result regarding the revocation of the electronic certificate. If the electronic certificate has been revoked because the determination condition is met (Yes in S1407), the TX determines that the RX is an unsecured power receiving device. In this case, the process proceeds to S1412 (see node 1414).

[0179] If the judgment condition of S1407 is not met, the process proceeds to S1408. In S1408, the TX judges whether the certificate of the manufacturer CA (manufacturer certificate) has been revoked based on the check result regarding the revocation of the electronic certificate. If it is judged that the manufacturer certificate has been revoked (Yes in S1408), the TX judges that the RX is an unauthenticated power receiving device. In this case, the process proceeds to S1412 (see node 1414). If it is judged that the manufacturer certificate has not been revoked (No in S1408), the series of processes ends.

[0180] If the TX satisfies the respective determination conditions in S1406, S1407, and S1408, the TX sets transmission power information indicating that power is transmitted at 5 W or less for NLP, which is capability information of the power transmitting device, and notifies the RX of this in S1412.

[0181] In this embodiment, when the TX becomes the initiator and fails to authenticate the RX, the TX sets information on the transmittable power (transmission power information) according to the cause of the authentication error in the NLP, which is the capability information of the power transmitting device, and notifies the RX of this information. Flexible and suitable power transmission control can be realized based on the result of the authentication performed by the TX on the RX.

[0182] Other Embodiments The wireless power transmission method according to the present disclosure is not limited to a specific method. For example, there is a magnetic resonance method in which power is transmitted by coupling due to magnetic resonance between a TX resonator (resonant element) and an RX resonator (resonant element). Alternatively, a power transmission method using electromagnetic induction, electric field resonance, microwaves, lasers, or the like may be used.

[0183] The present disclosure can also be realized by a process in which a program that realizes one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present disclosure can also be realized by a circuit (e.g., an ASIC) that realizes one or more functions.

[0184] The TX and RX may be, for example, an image input device such as an imaging device (still camera, video camera, etc.) or a scanner, or an image output device such as a printer, copier, projector, etc. The TX and RX may also be a hard disk drive, a memory device, or an information processing device such as a personal computer (PC), a smartphone, etc.

[0185] The power receiving device of the present disclosure may also be an information terminal device. For example, the information terminal device has a display unit (display) that receives power from a power receiving antenna and displays information to a user. The power received from the power receiving antenna is stored in a power storage unit (battery), and power is supplied from the battery to the display unit. In this case, the power receiving device may have a communication unit that communicates with another device different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC communication and the fifth generation mobile communication system (5G).

[0186] The power receiving device of the present disclosure may also be a vehicle such as an automobile. For example, the automobile serving as the power receiving device may receive power from a charger (power transmitting device) via a power transmitting antenna installed in a parking lot. The automobile serving as the power receiving device may also receive power from the charger (power transmitting device) via a power transmitting antenna embedded in the road. In such an automobile, the received power is supplied to a battery. The battery power may be supplied to a driving unit (motor, electric unit) that drives the wheels, or may be used to drive a sensor used for driving assistance or a communication unit that communicates with an external device. In other words, in this case, the power receiving device may include, in addition to the wheels, a battery, a motor or sensor that is driven using the received power, and even a communication unit that communicates with devices other than the power transmitting device. Furthermore, the power receiving device may have a storage unit for accommodating a person. For example, the sensor may be a sensor used to measure the distance between vehicles or the distance to other obstacles. The communication unit may be compatible with, for example, the Global Positioning System (GPS), or may be compatible with a communication standard such as the fifth generation mobile communication system (5G). The vehicle may be a bicycle or a motorcycle.

[0187] The power receiving device of the present disclosure may also be an electric tool, a home appliance, or the like. These devices, which are power receiving devices, may have a battery and a motor that is driven by the received power stored in the battery. These devices may also have a notification means for notifying the user of the remaining battery charge, etc. These devices may also have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC and the fifth generation mobile communication system (5G).

[0188] The power transmission device of the present disclosure may also be an on-board charger that transmits power to a mobile information terminal device, such as a smartphone or tablet, that supports wireless power transmission within the vehicle. Such an on-board charger may be installed anywhere within the vehicle. For example, the on-board charger may be installed in the console of the vehicle, on the instrument panel (instrument panel, dashboard), between passenger seats, on the ceiling, or in the door. However, it is preferable that the on-board charger not be installed in a location that interferes with driving. Furthermore, although the power transmission device has been described using the example of an on-board charger, such a charger is not limited to being installed in a vehicle, but may also be installed in transportation such as a train, airplane, or ship. In this case, the charger may also be installed between passenger seats, on the ceiling, or in the door.

[0189] The power transmitting device may also be a vehicle such as an automobile equipped with an on-board charger. In this case, the power transmitting device has wheels and a battery, and supplies power to the power receiving device via a power transmitting circuit unit and a power transmitting antenna using power from the battery.

[0190] The processes shown in FIGS. 5, 7, 9, and 11 to 14 are initiated, for example, when the control unit 101 or the control unit 201 is powered on. The processes shown in FIGS. 5(A), 7, and 12 to 14 are implemented by the CPU of the control unit 101 executing a program stored in the memory 107 of the TX. The processes shown in FIGS. 5(B), 9, and 11 are implemented by the CPU of the control unit 201 executing a program stored in the memory 209 of the RX. Part of the processes shown in FIGS. 5, 7, 9, and 11 to 14 may be implemented by hardware. For example, a specific compiler may be used to automatically generate a dedicated circuit on the FPGA from a program for implementing each step. Furthermore, a gate array circuit may be formed in the same manner as an FPGA and implemented as hardware.

[0191] (Cross-Reference to Related Applications) This application claims the benefit of Japanese Patent Application No. 2023-107045, filed on June 29, 2023. The contents of the above Japanese patent application are incorporated herein by reference in their entirety.

Claims

1. A power transmission device comprising: a power transmission means for wirelessly transmitting power to a power receiving device; and an authentication means for performing authentication processing between the power receiving device and the power transmission means, wherein if the authentication is unsuccessful, the power transmission means controls the power transmission based on the cause of the failure.

2. The power transmission device according to claim 1, characterized in that, when authentication by the authentication means is unsuccessful, the power transmission means limits the value of the allowable power to be transmitted to the power receiving device to a smaller value depending on the cause of the authentication error compared to when authentication by the authentication means is successful, or does not transmit power to the power receiving device.

3. The power transmitting device according to claim 1, further comprising a communication means for communicating with the power receiving device, wherein the communication means notifies the power receiving device of transmission power information indicating the transmittable power based on the power receiving capability of the power receiving device when the power receiving device does not have an authentication function.

4. The power transmission device according to claim 3, characterized in that the communication means notifies the power receiving device of information indicating that the power that the power transmitting device can transmit is limited power when the power receiving device is configured to receive a first power from the power transmitting device, or when the power receiving device does not have an authentication function and is configured to receive power from the power transmitting device that is greater than the first power and less than or equal to a second power.

5. The power transmitting device according to claim 4, characterized in that when the communication means determines, based on the result of authentication performed by the authentication means between the power receiving device and the power receiving device, that the power receiving device does not have an authentication function and is specified to receive power from the power transmitting device that is greater than the first power and less than the second power, the communication means notifies the power receiving device of information indicating that the power transmitting device can transmit a power ranging from a third power greater than the first power to a power less than the second power.

6. The power transmitting device according to claim 1, further comprising a communication means for communicating with the power receiving device, wherein the communication means notifies the power receiving device of transmission power information indicating the power that the power transmitting device can transmit if the authentication is unsuccessful due to a communication error.

7. A power transmitting device as described in claim 1, further comprising a communication means for communicating with the power receiving device, wherein, when it is determined that the electronic certificate has expired, the communication means notifies the power receiving device of transmission power information indicating that the power that the power transmitting device can transmit is limited power, or notifies the power receiving device of information indicating that power will not be transmitted to the power receiving device.

8. A power transmitting device as described in claim 1, further comprising a communication means for communicating with the power receiving device, wherein the communication means notifies the power receiving device of information indicating that power will not be transmitted to the power receiving device if it determines that the authentication is not successful due to the cancellation of the serial number of the electronic certificate or cancellation due to a recall.

9. A power transmitting device as described in claim 1, further comprising a communication means for communicating with the power receiving device, wherein the communication means notifies the power receiving device of transmission power information indicating that the power that the power transmitting device can transmit is limited power when the communication means determines that the electronic certificate has expired due to failure of an inspection test, or due to a compromise of a private key or stolen credentials, or when the communication means determines that the manufacturer certificate has expired.

10. A method executed by a power transmitting device, comprising: a power transmitting process for wirelessly transmitting power to a power receiving device; and an authentication process for performing authentication processing between the power transmitting device and the power receiving device using an electronic certificate, wherein if the authentication is not successful in the power transmitting process, power transmission to the power receiving device is controlled based on the cause.

11. A program for causing a computer to execute each step according to claim 10.