Communication system, function execution device, and computer program for function execution device

Abstract

To provide a novel technology for securely notifying errors occurring in a function execution device. [Solution] This specification discloses a communication system comprising a function execution device and a terminal device. When an error occurs in the function execution device, the function execution device transmits encrypted information to the terminal device using the Wi-Fi network to which both the terminal device and the function execution device belong. The encrypted information is transmitted to the terminal device by using communication that does not utilize the network layer or above of the OSI reference model, but only the data link layer or below of the OSI reference model, and is obtained by encrypting the error information using key information. The terminal device receives the encrypted information from the function execution device using the Wi-Fi network and displays the error information obtained by decrypting the encrypted information using the key information.

Description

[Technical Field]

[0001] The present specification relates to a technique for notifying information related to a function execution device. [Background Art]

[0002] Patent Document 1 discloses a communication system including a communication device, a terminal device, and an access point. In this communication system, when communication between the communication device and the terminal device cannot be performed via the access point, Bluetooth, Wi-Fi Aware, NFC (abbreviation for Near Field Communication) or the like is used to establish a P2P connection such as Wi-Fi Direct between the communication device and the terminal device. Bluetooth is a registered trademark of Bluetooth SIG. Wi-Fi Direct is a registered trademark of Wi-Fi Alliance. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2024-150633 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The present specification provides a novel technique for securely notifying an error occurring in a function execution device. [Means for Solving the Problem]

[0005] This specification discloses a communication system. The communication system may include a function execution device and a terminal device. The function execution device may include a device-side interface for performing wireless communication in accordance with the Wi-Fi standard. The function execution device may include a device-side memory for storing key information for performing encryption and decryption of information. The function execution device may include an encryption information transmission unit that, when an error occurs in the function execution device, transmits encrypted information to the terminal device via the device-side interface using the Wi-Fi network to which both the terminal device and the function execution device belong, wherein the encrypted information is transmitted to the terminal device using the Wi-Fi network by using communication that does not utilize the network layer or above of the OSI reference model, but only the data link layer or below of the OSI reference model, and the encrypted information is information obtained by encrypting error information indicating the error using the key information. The terminal device may include a terminal-side interface for performing wireless communication in accordance with the Wi-Fi standard. The terminal device may include a terminal-side memory for storing the key information. The terminal device may include a terminal-side display unit. The terminal device may include an encryption information receiving unit that receives the encryption information from the function execution device via the terminal-side interface using the Wi-Fi network. The terminal device may also include a terminal-side display control unit that, when the encryption information is received from the function execution device, displays the error information obtained by decrypting the encryption information using the key information on the terminal-side display unit.

[0006] According to the above configuration, when an error occurs, the function execution device transmits encrypted information to the terminal device using the Wi-Fi network. Here, the encrypted information is transmitted to the terminal device using only the data link layer and below of the OSI reference model, without using the network layer or above of the OSI reference model. The encrypted information is obtained by encrypting error information using key information. As a result, the error information obtained by decrypting the encrypted information using the key information is displayed on the terminal device. In this way, the function execution device can be notified of errors that have occurred using communication that utilizes the data link layer and below. In particular, since the function execution device performs the transmission of encrypted information in which the error information has been encrypted, errors can be notified securely.

[0007] This specification also discloses a function execution device. The function execution device may include a device-side interface for performing wireless communication in accordance with the Wi-Fi standard. The function execution device may include a device-side memory for storing key information for performing encryption and decryption of information. The function execution device may include an encryption information transmission unit that, when an error occurs in the function execution device, transmits encrypted information to the terminal device via the device-side interface using the Wi-Fi network to which both the terminal device and the function execution device belong, wherein the encrypted information is transmitted to the terminal device using the Wi-Fi network by using communication that does not utilize the network layer or above of the OSI reference model, but only the data link layer or below of the OSI reference model, and the encrypted information is information obtained by encrypting error information indicating the error using the key information.

[0008] The function execution device can notify other function execution devices of errors that occur using communication at the data link layer and below. In particular, the function execution device can securely notify errors because it performs encrypted communication of the error information.

[0009] The computer program for the above-mentioned functional execution device, the computer-readable recording medium for storing the computer program, and the method of execution by the functional execution device are also novel and useful. Here, the above-mentioned recording medium may be a single medium or multiple mediums. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram illustrating the configuration of a communication system. [Figure 2] This is a sequence diagram of the processes performed between each device. [Figure 3] This is a sequence diagram for Case A. [Figure 4] This is a sequence diagram of the communication process used to determine distance. [Figure 5] This is the sequence diagram for Case B. [Modes for carrying out the invention]

[0011] (Configuration of communication system 2; Figure 1) As shown in Figure 1, the communication system 2 comprises a printer 10, a terminal 100, and an access point (hereinafter referred to as "AP") 6. The printer 10 and the terminal 100 belong to the same NAN (Neighbor Awareness Networking) cluster. A NAN cluster is a wireless network defined in the Wi-Fi Aware method of the Wi-Fi standard. The printer 10 and the terminal 100 also belong to the wireless network formed by AP 6. The terminal 100 can transmit print data representing the image to be printed to the printer 10 via AP 6. In this embodiment, a technique is disclosed for displaying information regarding an error on the terminal 100 when an error occurs in the printer 10.

[0012] (Printer 10 configuration) The printer 10 is a peripheral device capable of performing printing functions, such as a peripheral device for terminal 100. In a modified example, the printer 10 may be a multi-function device capable of performing scanning functions, facsimile functions, etc., in addition to printing functions. The printer 10 comprises an operation unit 12, a display unit 14, a Wi-Fi interface 16, a print execution unit 18, and a control unit 30. Each unit 12 to 30 is connected to a bus line. Hereafter, the interface will be referred to as "I / F".

[0013] The operation unit 12 is a user interface that allows the user to input various information to the printer 10. The operation unit 12 includes, for example, a touch panel, hardware keys, or both for displaying software keys (operation objects). Hardware keys include, for example, buttons or switches. The display unit 14 is a display or panel for displaying various information. The panel may or may not be a touch panel. The panel may also be, for example, a liquid crystal panel or an organic EL panel. The print execution unit 18 includes an inkjet, electrophotographic, or thermal print engine.

[0014] Wi-FiI / F16 is a wireless interface for performing Wi-Fi communication in accordance with the Wi-Fi standard. The Wi-Fi standard is a wireless communication standard for performing wireless communication in accordance with the IEEE (The Institute of Electrical and Electronics Engineers, Inc.) 802.11 standard and equivalent standards such as 802.11a, 11b, 11n, and 11ac. In particular, Wi-FiI / F16 supports the Wi-Fi Aware method developed by the Wi-Fi Alliance. Details of the Wi-Fi Aware method are described in the standard document "Wi-Fi Aware Specification Version 4.0" created by the Wi-Fi Alliance. Wi-Fi Aware is also called Wi-Fi Neighbor Awareness Networking (NAN).

[0015] As will be explained in more detail later, each device 10 and 100 can participate in a Wi-Fi Aware NAN cluster. The Discovery Window, the period during which signals are transmitted and received, is synchronized for each device participating in the same NAN class. NAN clusters are used for communications that utilize only the data link layer and below, without using the network layer or above in the OSI reference model.

[0016] Each device participating in a NAN cluster is assigned one of three roles: Master, Anchor Master, or Non-Master. A Master can share timer information, perform service lookups, and invite other devices to the NAN cluster. An Anchor Master can perform all the functions of a Master, plus configure timer information for synchronization. A Non-Master can share timer information and perform service lookups, but cannot invite other devices to the cluster.

[0017] Each device participating in a NAN cluster can search for other devices within the NAN cluster (more specifically, the services provided by those other devices). The signal used to search for services is called Subscribe. A device that receives a Subscribe sends a response signal called Publish. In this embodiment, printer 10 sends a Subscribe to search for other devices that can provide a monitoring service to monitor the status of the printer. Specifically, printer 10 sends the Subscribe when an error occurs on printer 10. In this embodiment, terminal 100 can provide the above monitoring service. Therefore, when terminal 100 receives a Subscribe from printer 10, it sends a Publish to printer 10 indicating that it can provide the monitoring service.

[0018] In addition, the Wi-Fi I / F 16 can execute wireless communication in accordance with a normal Wi-Fi scheme different from the Wi-Fi Aware scheme. Generally speaking, wireless communication in accordance with a normal Wi-Fi scheme is wireless communication in which an AP is used, and wireless communication in accordance with the Wi-Fi Aware scheme is wireless communication in which no AP is used. For example, the printer 10 can belong to a normal Wi-Fi network by establishing a wireless connection with an AP. Hereinafter, the wireless connection with an AP may be referred to as "AP connection". The printer 10 can execute wireless communication with other devices belonging to a normal Wi-Fi network via the AP 6.

[0019] The control unit 30 includes a CPU 32 and a memory 34. The memory 34 includes a main storage device and an auxiliary storage device. As an example, the main storage device includes a RAM and a cache memory. As an example, the auxiliary storage device may be a ROM, a flash memory, an SSD (abbreviation of Solid State Drive), an HDD (abbreviation of Hard Disk Drive), or a combination thereof. A program 36 and a device list 40 are stored in the auxiliary storage device of the memory 34. The CPU 32 implements various processes in accordance with the program 36 loaded from the auxiliary storage device to the main storage device.

[0020] The device list 40 is a list that stores devices capable of providing a monitoring service. In the device list 40, the serial number of the device and a shared key shared with the device are stored in association with each other. As will be described later in detail, the shared key is information used for encrypting error information and decrypting encrypted information.

[0021] (Configuration of Terminal 100) The terminal 100 is a portable terminal device such as a mobile phone, a smartphone, a PDA, or a tablet PC. In a modification, the terminal 100 may be a stationary PC, a laptop PC, or the like. A serial number T1 for identifying the terminal 100 is assigned to the terminal 100. The terminal 100 is capable of providing a monitoring service. The terminal 100 includes an operation unit 112, a display unit 114, a Wi-Fi I / F 116, and a control unit 130. Each of the units 112 to 130 is connected to a bus line.

[0022] The operation unit 112 is a user interface that enables a user to input various information to the terminal 100. The operation unit 112 includes, for example, a touch panel for displaying software keys (operation objects), hardware keys, or both of them. The hardware keys include, for example, buttons, switches, or the like. The display unit 114 is a display or a panel for displaying various information. The panel may or may not be a touch panel. Further, the panel is, for example, a liquid crystal panel or an organic EL panel. The Wi-Fi I / F 116 is the same as the Wi-Fi I / F 16 of the printer 10. That is, the Wi-Fi I / F 116 supports the Wi-Fi Aware scheme and is also capable of executing wireless communication in accordance with a normal Wi-Fi scheme.

[0023] The control unit 130 includes a CPU 132 and a memory 134. The memory 134 includes a main storage device and an auxiliary storage device. By way of example, the main storage device includes a RAM and a cache memory. By way of example, the auxiliary storage device may be a ROM, a flash memory, an SSD, an HDD, or a combination thereof. An OS program 136, an application program, a device list 140, and a monitoring service flag are stored in the auxiliary storage device of the memory 134. The CPU 132 implements various processes in accordance with the programs 136 and 138 loaded from the auxiliary storage device to the main storage device. Hereinafter, the OS program is referred to as "OS". The application program is referred to as "app".

[0024] OS136 controls the basic operation of terminal 100. Application 138 can assign terminal 100 to the NAN cluster by causing OS136 to execute processing according to the Wi-Fi Awara method. Application 138 can use the NAN cluster to perform various communications with other devices belonging to the NAN cluster. Application 138 can send print data representing the image to be printed to printer 10 via AP. Application 138 also provides monitoring services. Application 138 is downloaded from, for example, a server on the internet and installed on terminal 100.

[0025] The device list 140 is a list that stores the devices to be monitored by the monitoring service provided by the application 138. The device list 140 is installed on the terminal 100 along with the application 138. The device list 140 stores the serial number of the monitored device and the shared key shared with that device, in association with each other.

[0026] The monitoring service flag is a flag held by app 138, and it indicates either "ON," which means that the monitoring service is being provided, or "OFF," which means that the monitoring service is not being provided. Specifically, when the monitoring service flag is "ON," the app sends a Publish in response to receiving a Subscribe request to search for the monitoring service. On the other hand, when the monitoring service flag is "OFF," the app does not send a Publish in response to receiving the above Subscribe request. The monitoring service flag can be specified by the user.

[0027] (AP6 configuration) AP6 is a standard access point, also known as a wireless access point or wireless LAN router. AP6 relays communication between devices belonging to a wireless network on which AP6 acts as the master station.

[0028] (Processing performed between each device; Figure 2) Next, referring to Figure 2, we will explain the processes performed between each device. For the sake of clarity, in the following explanation, instead of describing each CPU (e.g., 32, 132) as the primary processor, we will describe each device (e.g., printer 10, terminal 100) as the primary processor. Furthermore, communication between each device is performed via a Wi-Fi interface (e.g., 16, 116). Therefore, in the following explanation, we will omit the phrase "via Wi-Fi interface" when describing communication.

[0029] In the initial state shown in Figure 2, an AP connection has already been established between terminal 100 and AP6. That is, terminal 100 has stored the connection information necessary to establish an AP connection with AP6. The connection information is, for example, a combination of SSID (abbreviation for Service Set Identifier) ​​and password. Also, in the initial state shown in Figure 2, the monitoring service flag shows "OFF". In this state, printer 10 is newly installed.

[0030] The newly installed printer 10 accepts a power-on operation from the user at T10. In this case, the printer 10 starts SoftAP at T12 to form a wireless network. This SoftAP is started for the initial setup of the printer 10. The SSID of the wireless network formed by the start of this SoftAP may include, for example, the serial number P1 of the printer 10. Hereinafter, a wireless connection using SoftAP will be referred to as a "SoftAP connection".

[0031] Terminal 100 receives an application launch operation from the user to start application 138 in T20. The application launch operation is, for example, an operation to select an application icon included in the home screen of OS 136. In this case, application 138 of terminal 100 displays its home screen on the display unit 114. This home screen includes a print button to initiate printing to the printer, a settings button to perform initial printer settings, and so on.

[0032] Terminal 100 accepts the selection of a settings button on the home screen at T22. In this case, terminal 100 displays an SSID selection screen on the display unit 114. This SSID selection screen includes the SSIDs of wireless networks present around terminal 100. Then, terminal 100 accepts the selection of an SSID including the serial number P1 of printer 10 and the input of a password on the SSID selection screen. Here, the password is written in, for example, the instruction manual for printer 10. As a result, at T24, various processes are executed to establish a SoftAP connection between printer 10 and terminal 100, and a SoftAP connection is established between printer 10 and terminal 100. The above processes include authentication of the SSID and password.

[0033] Terminal 100, using SoftAP connection on T26, sends AP6 connection information to printer 10.

[0034] At T26, printer 10 receives connection information for AP6 from terminal 100 using SoftAP connection. In this case, at T28, various processes are executed to establish an AP connection between printer 10 and AP6, and an AP connection is established between printer 10 and AP6. The above processes include authentication of connection information, etc.

[0035] Furthermore, as described above, the application 138 of terminal 100 in this embodiment can provide a monitoring service. When a SoftAP connection is established with printer 10, terminal 100 executes the following process according to application 138. That is, in T30, terminal 100 uses the SoftAP connection to send a serial number request to printer 10. The serial number request is a signal requesting printer 10 to send a serial number, and includes the serial number T1 of terminal 100 and a shared key SK. Here, the shared key SK may be generated by terminal 100 in response to the execution of operation T24, or it may be stored in memory 134 beforehand. In particular, in the former case, a different shared key may be generated each time operation T24 is executed. In this embodiment, the former case will be described as an example. Note that in this embodiment, the process of T30 is executed whether the monitoring service flag indicates "ON" or "OFF". In a modified example, the process of T30 may be executed only when the monitoring service flag indicates "ON".

[0036] At T30, printer 10 receives a serial number request from terminal 100 using a SoftAP connection. In this case, at T32, printer 10 updates the device list 40. Specifically, printer 10 associates the serial number T1 included in the serial number request with the shared key SK included in the serial number request and stores it in the device list 40. Then, at T34, printer 10 sends its own serial number P1 to terminal 100 using a SoftAP connection.

[0037] Terminal 100 receives serial number P1 from printer 10 using SoftAP connection at T34. In this case, terminal 100 updates device list 140 at T36. Specifically, terminal 100 associates the received serial number P1 with the generated shared key SK and stores it in device list 140. Subsequently, at T38, the SoftAP connection between printer 10 and terminal 100 is disconnected.

[0038] Printer 10 accepts a NAN activation operation from the user at T40. In this case, printer 10 transitions from the NAN disabled state to the NAN enabled state. Here, "NAN disabled state" means a state in which signals according to the Wi-Fi Aware method cannot be transmitted. "NAN enabled state" means a state in which signals according to the Wi-Fi Aware method can be transmitted. When printer 10 transitions to the NAN enabled state, it forms a NAN cluster. That is, at T40, a NAN cluster is formed to which only printer 10 belongs. In this NAN cluster, printer 10 operates as an Anchor Master. In a modified example, if the SoftAP connection with terminal 100 is disconnected at T38, printer 10 may automatically transition from the NAN disabled state to the NAN enabled state without accepting a NAN activation operation from the user.

[0039] At T50, terminal 100 receives a NAN activation operation from the user. In this case, terminal 100 transitions from the NAN disabled state to the NAN enabled state. Once terminal 100 transitions to the NAN enabled state, it forms a NAN cluster. That is, at T50, a NAN cluster is formed to which only terminal 100 belongs. In this NAN cluster, terminal 100 operates as the Anchor Master. Thus, at T50, there are two NAN clusters: one to which only printer 10 belongs, and another to which terminal 100 belongs. In a modified example, if the SoftAP connection with printer 10 is disconnected at T38, terminal 100 may automatically transition from the NAN disabled state to the NAN enabled state without receiving a NAN activation operation from the user.

[0040] Furthermore, terminal 100 accepts a monitoring service activation operation from the user at T50. The monitoring service activation operation is an operation to change the monitoring service flag from "OFF" to "ON". For example, the user can change the monitoring service flag from "OFF" to "ON" by selecting a button to change settings on the home screen of application 138. In this case, terminal 100 changes the monitoring service flag in memory 134 from "OFF" to "ON" at T52. In a modified example, terminal 100 may automatically change the monitoring service flag from "OFF" to "ON" at T52 without accepting a monitoring service activation operation from the user if the SoftAP connection with printer 10 is disconnected at T38.

[0041] Printer 10 broadcasts a NAN Discovery Beacon frame at T54. Hereafter, this signal will simply be referred to as "Discovery." Discovery is a signal that conforms to the Wi-Fi Aware method and is used to notify the outside world of information about the NAN cluster to which printer 10 belongs. Devices that do not belong to the NAN cluster can join the NAN cluster in response to receiving Discovery. In other words, Discovery can also be said to be a signal that invites devices that do not belong to the NAN cluster to join the NAN cluster. Note that printer 10 periodically transmits Discovery while the NAN is enabled.

[0042] Terminal 100 is in a NAN-enabled state at T54. Therefore, at T54, terminal 100 receives a Discovery from printer 10. In this case, at T56, terminal 100 joins the NAN cluster to which printer 10 belongs. As a result, printer 10 and terminal 100 belong to the same NAN cluster. In this case, the NAN cluster to which only terminal 100 belonged, i.e., the NAN cluster formed at T50, disappears. At T56, there is one NAN cluster to which both printer 10 and terminal 100 belong. Although not shown in the diagram, once terminal 100 joins the NAN cluster, it communicates with printer 10 to determine its role within the NAN cluster. In this case, printer 10 operates as the Anchor Master, and terminal 100 operates as the Non-Master.

[0043] (Case A; Figure 3) Next, we will explain Case A with reference to Figure 3. The process of T60 in Figure 3 is a continuation of the process in Figure 2. Case A is a case in which an error occurs in printer 10 where the paper for printing the image runs out of paper tray. Hereafter, this type of error will be referred to as a "paper shortage error".

[0044] Printer 10 detects a paper shortage error at T60 in Figure 3. That is, at T60, printer 10 detects that the paper tray has run out of printing paper. In this case, at T62, printer 10 displays notification screen SC1 on the display unit 14. Notification screen SC1 is a screen that notifies the user that a paper shortage error has occurred. By viewing notification screen SC1, the user can recognize that a paper shortage error has occurred in printer 10.

[0045] However, there is a possibility that the user may not look at the display unit 14 of the printer 10 when a paper shortage error occurs. In other words, the user may not immediately look at the notification screen SC1 displayed on the printer 10. For this reason, the printer 10 performs the following process to notify the terminal 100 of a paper shortage error, indicating that a paper shortage error has occurred.

[0046] Furthermore, when printer 10 detects a paper shortage error, it uses the NAN cluster in T64 to send a Subscribe to search for the monitoring service. This Subscribe includes the serial number P1 of printer 10.

[0047] The application 138 on terminal 100 receives a Subscribe from printer 10 at T64. In this case, terminal 100 performs the following processing according to application 138. Specifically, terminal 100 first determines whether the monitoring service flag in memory 134 indicates "ON" or "OFF". In this case, the monitoring service flag indicates "ON" (T52 in Figure 2). In this case, terminal 100 determines whether printer 10, the source of the Subscribe, is a monitored device. Specifically, terminal 100 determines whether the serial number P1 included in the Subscribe is already stored in device list 140. In this case, serial number P1 is already stored in device list 140 (T36 in Figure 2). Therefore, terminal 100 determines at T66 that printer 10 is a monitored device. In this case, terminal 100 uses the NAN cluster at T68 to send a Publish to printer 10. The Publish includes the serial number T1 of terminal 100. Furthermore, terminal 100 does not send a Publish to printer 10 if the monitoring service flag indicates "OFF" or if the serial number P1 included in Subscribe is not stored in device list 140. In this way, terminal 100 can only send a Publish if the user desires the provision of monitoring services. Also, terminal 100 can only send a Publish if the printer 10 that is the source of the Subscribe is the target of monitoring.

[0048] At T68, printer 10 uses the NAN cluster to receive a Publish from terminal 100. In this case, printer 10 determines whether the serial number T1 included in the Publish is already stored in device list 40. In this case, at T69, printer 10 determines that the serial number T1 is already stored in device list 40 (see T32 in Figure 2). In this case, at T70, printer 10 uses the NAN cluster to send a Ranging Request frame to terminal 100. The Ranging Request frame is a signal requesting printer 10 to perform a process to measure the distance between printer 10 and terminal 100.

[0049] Terminal 100 receives a Rangering Request frame from printer 10 using the NAN cluster at T70. In this case, terminal 100 sends a Rangering Response frame to printer 10 using the NAN cluster at T72. Information necessary for the communication at T74, described later, such as parameters for measurement, is communicated at T70 and T72. In other words, the communication at T70 and T72 is preliminary communication for the communication at T74.

[0050] At T72, printer 10 receives a Ranged Response frame from terminal 100. In this case, at T74, a Fine Timing Measurement (FTM) sequence is executed between printer 10 and terminal 100. FTM is a distance calculation algorithm used in the Wi-Fi Aware method. NAN clusters are used in the FTM sequence.

[0051] (FTM Sequence: Figure 4) Here, with reference to Figure 4, the FTM sequence of T74 in Figure 3 will be explained. At T100, the printer 10 sends an FTM request to the terminal 100. The FTM request is a signal requesting the start of FTM and includes, for example, information on the frequency bands used in various FTM communications.

[0052] When terminal 100 receives an FTM request from printer 10 at T100, it sends an ACK to printer 10 at T102. As a result, FTM is executed from T110 onwards.

[0053] In FTM, terminal 100 first sends an FTM response to printer 10 at T110. At this time, terminal 100 stores the transmission time t1 of the FTM response.

[0054] At time T110, printer 10 receives an FTM response from terminal 100. At this time, printer 10 stores the time t2 when the FTM response was received. Then, at time T112, printer 10 sends an ACK to terminal 100. At this time, printer 10 stores the time t3 when the ACK was sent.

[0055] Terminal 100 receives an ACK from printer 10 at T112. At this time, terminal 100 stores the time t4 when the ACK was received.

[0056] Subsequently, terminal 100 sends an FTM response to printer 10 at T114. The FTM response sent here includes the stored times t1 and t4. Terminal 100 also stores the transmission time t5 of the FTM response at T114.

[0057] At time T114, printer 10 receives an FTM response from terminal 100. At this time, printer 10 stores the time t6 when the FTM response was received.

[0058] Printer 10 calculates the distance between itself and terminal 100 using the stored times t2 and t3, and the times t1 and t4 included in the FTM response of T114. Specifically, printer 10 first calculates RTT1 = (t4 - t1) - (t3 - t2). RTT1 is the sum of the time required to send the FTM response of T110 and the time required to send the ACK of T112. That is, RTT1 is the time required for one round-trip communication between printer 10 and terminal 100. Then, printer 10 calculates the distance between itself and terminal 100 using the formula ((c × RTT1) / 2), where c is the speed of light. In this way, printer 10 can calculate the distance between itself and terminal 100 using the times t1 and t2 related to the FTM response communication and the times t3 and t4 related to the ACK communication.

[0059] At T116, printer 10 sends an ACK to terminal 100. At this time, printer 10 stores the transmission time t7 of the ACK.

[0060] Terminal 100 receives an ACK from printer 10 at T116. At this time, terminal 100 stores the time t8 when the ACK was received.

[0061] The printer 10 and terminal 100 continue to perform FTM response and ACK communication a predetermined number of times. The printer 10 calculates the distance between the printer 10 and terminal 100 for each round trip of FTM response and ACK communication. For example, for the FTM response at T114 and the ACK at T116, the distance between the printer 10 and terminal 100 is calculated by the formula ((c × RTT2) / 2). Here, RTT2 = (t8 - t5) - (t7 - t6).

[0062] (Continuation of processing: Figure 3) Returning to the explanation of Figure 3, printer 10 determines the distance between printer 10 and terminal 100 by calculating the average value of multiple distances calculated in the FTM Sequence of T74 at T76.

[0063] In S10, printer 10 determines whether the distance determined in T76 is less than or equal to a predetermined threshold. Here, the threshold is, for example, 10m. However, 10m is just an example, and the threshold may be less than 10m or greater than 10m. If printer 10 determines that the determined distance is less than or equal to the threshold (YES in S10), it proceeds to T80. On the other hand, if printer 10 determines that the determined distance is greater than the threshold (NO in S10), it does not execute the processes from T80 onward.

[0064] Printer 10 encrypts the paper shortage error information at T80 to generate encrypted information EI1. Specifically, printer 10 identifies the shared key SK associated with the serial number T1 included in the Publish received at T68 from the device list 40. Then, printer 10 encrypts the paper shortage error information using the identified shared key SK to generate encrypted information EI1. Subsequently, printer 10 uses the NAN cluster at T82 to send a Follow-up to terminal 100. The Follow-up is a signal that follows the Wi-Fi Aware method. The Follow-up at T82 includes the serial number P1 of printer 10 and the encrypted information EI1.

[0065] Terminal 100 receives a Follow-up message from printer 10 using the NAN cluster at T82. In this case, at T84, terminal 100 identifies the shared key SK associated with serial number P1 included in the Follow-up message from the device list 140. Then, at T86, terminal 100 decrypts the encrypted information EI1 using the identified shared key SK. As described above, in this case, the same shared key SK is shared between printer 10 and terminal 100. Therefore, at T86, terminal 100 can obtain paper shortage error information by decrypting the encrypted information EI1. In other words, terminal 100 can recognize that a paper shortage error has occurred in printer 10 by performing communication using the NAN cluster.

[0066] When terminal 100 acquires paper shortage error information in T86, it displays notification screen SC2 on the display unit 114 in T88. Notification screen SC2 contains information indicating that a paper shortage error has occurred in printer 10, which is identified by serial number P1 included in Follow-up in T82. By viewing notification screen SC2, the user can learn that a paper shortage error has occurred in printer 10. After viewing notification screen SC2, the user can replenish the paper tray of printer 10 with printer paper.

[0067] (Case B; Figure 5) Next, we will explain Case B with reference to Figure 5. The process of T160 in Figure 5 is a continuation of the process in Figure 2. Case B is a case in which an error occurs in the AP connection with AP6 at printer 10, and the AP connection with AP6 is disconnected. Hereafter, such an error will be referred to as an "AP connection error". AP connection errors occur, for example, when a new AP is installed in place of AP6 and AP6 is removed, or when the connection information of AP6 is changed.

[0068] Printer 10 detects an AP connection error at T160 in Figure 5. That is, at T160, printer 10 detects that the AP connection with AP6 has been disconnected. In this case, at T162, printer 10 displays notification screen SC3 on the display unit 14. Notification screen SC3 is a screen for notifying the user that an AP connection error has occurred. By viewing notification screen SC3, the user can recognize that an AP connection error has occurred in printer 10, that is, that the AP connection between printer 10 and AP6 has been disconnected. In this case as well, the user may not immediately view notification screen SC3 displayed in printer 10. Therefore, printer 10 executes the following process to notify terminal 100 of the AP connection error information indicating that an AP connection error has occurred. The processes at T164 to T176 and S110 are the same as the processes at T64 to T74 and S10 in Figure 2, respectively.

[0069] Printer 10 encrypts AP connection error information at T180 to generate encrypted information EI2. Specifically, printer 10 identifies the shared key SK associated with serial number T1 included in the Publish received at T168 from the device list 40. Then, printer 10 encrypts the AP connection error information using the identified shared key SK to generate encrypted information EI2. Subsequently, printer 10 uses the NAN cluster at T182 to send a Follow-up to terminal 100. This Follow-up includes the serial number P1 of printer 10 and the encrypted information EI2.

[0070] Terminal 100 receives a Follow-up message from printer 10 using the NAN cluster at T182. In this case, at T184, terminal 100 identifies the shared key SK associated with serial number P1 included in the Follow-up message from the device list 140. Then, at T186, terminal 100 decrypts the encrypted information EI2 using the identified shared key SK. As described above, in this case, the same shared key SK is shared between printer 10 and terminal 100. Therefore, at T186, terminal 100 can obtain AP connection error information by decrypting the encrypted information EI2. In other words, terminal 100 can recognize that an AP connection error has occurred in printer 10 by performing communication using the NAN cluster.

[0071] When terminal 100 obtains AP connection error information in T186, it displays notification screen SC4 on the display unit 114 in T188. Notification screen SC4 contains information indicating that an AP connection error has occurred in printer 10, which is identified by serial number P1 included in Follow-up in T182. By viewing notification screen SC4, the user can learn that an AP connection error has occurred in printer 10. After viewing notification screen SC4, the user can perform operations to establish an AP connection with printer 10. Such operations include, for example, entering new AP connection information or entering modified connection information.

[0072] (Effects of the example) According to the above configuration, when an error such as a paper shortage error occurs, the printer 10 uses the NAN cluster to send encrypted information EI1 to the terminal 100 (T82 in Figure 3). That is, encrypted information EI1 is sent to the terminal 100 using only the data link layer and below of the OSI reference model, without using the network layer or above of the OSI reference model. Encrypted information EI1 is information obtained by encrypting the paper shortage error information using the shared key SK. As a result, the terminal 100 displays a notification screen SC2 containing the paper shortage error information obtained by decrypting encrypted information EI1 using the shared key SK (T88). In this way, the printer 10 can be notified of errors that have occurred to the printer 10 by using communication that utilizes the data link layer and below, i.e., the NAN cluster. In particular, since the printer 10 performs the communication of encrypted information EI1, in which the paper shortage error information is encrypted using the shared key SK, it can notify errors securely.

[0073] Furthermore, terminal 100 displays the notification screen SC2 when printer 10 determines that S10 is YES. In other words, terminal 100 can only display the notification screen SC2 when terminal 100 is located near printer 10. As described above, a user who sees the notification screen SC2 needs to go near printer 10 to replenish the paper tray of printer 10. If the notification screen SC2 is displayed on terminal 100 located far from printer 10, the user who sees the notification screen SC2 needs to go to the printer which is far away. In order to avoid forcing users to perform such a burdensome task, this embodiment employs a configuration in which the notification screen SC2 is not displayed on terminal 100 located far from printer 10.

[0074] (Correspondence) Printer 10 and terminal 100 are examples of "function execution device" and "terminal device," respectively. AP6 is an example of an "access point." The serial number P1 of printer 10 is an example of "identification information." Display unit 14 and display unit 114 are examples of "device-side display unit" and "terminal-side display unit," respectively. Wi-Fi I / F 16 and Wi-Fi I / F 116 are examples of "device-side interface" and "terminal-side interface," respectively. Memory 34 and memory 134 are examples of "device-side memory" and "terminal-side memory," respectively. The monitoring service flag is an example of "flag information." In particular, the values ​​"ON" and "OFF" of the monitoring service flag are examples of "first value" and "second value," respectively. Shared key SK is an example of "key information." NAN cluster is an example of a "Wi-Fi network." Cryptographic information EI1 and EI2 are examples of "cryptographic information." Subscribe is an example of a "predetermined signal." Publish is an example of a "response signal." Printing paper is an example of a "consumable."

[0075] The correspondence between the processes executed by the "function execution device" is as follows: Process T62 in Figure 3 and process T162 in Figure 5 are examples of processes executed by the "device-side display control unit". Process T64 in Figure 3 and process T164 in Figure 5 are examples of processes executed by the "determined signal transmission unit". Process T68 in Figure 3 and process T168 in Figure 5 are examples of processes executed by the "response signal receiving unit". Processes T70 to T76 in Figure 3 and processes T1170 to T176 in Figure 5 are examples of processes executed by the "specification unit". Process T82 in Figure 3 and process T182 in Figure 5 are examples of processes executed by the "encrypted information transmission unit".

[0076] The correspondence between the processes performed by the "terminal device" is as follows: Process T64 in Figure 3 and process T164 in Figure 5 are examples of processes performed by the "predetermined signal receiving unit". Process T68 in Figure 3 and process T168 in Figure 5 are examples of processes performed by the "response signal transmitting unit". Process T82 in Figure 3 and process T182 in Figure 5 are examples of processes performed by the "encrypted information receiving unit". Process T88 in Figure 3 and process T188 in Figure 5 are examples of processes performed by the "terminal-side display control unit".

[0077] The specific examples of the technology disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. Modifications of the above embodiments are listed below.

[0078] (Modification 1) In the above embodiment, the situations in which a paper shortage error occurs (Case A) and an AP connection error occurs (Case B) were described. This technology is also useful in situations in which errors other than those described in the above embodiment occur. For example, when the printer 10 runs out of ink for printing, it may perform the same processing as T64-T76 and S10 in Figure 3. The printer 10 may then use a NAN cluster to encrypt the error information indicating that the ink has run out and send the encrypted information obtained from this encryption to the terminal 100. In this modification, ink is an example of a "consumable item". In another modification, for example, when the printer 10 detects a physical failure in the ink head of the print execution unit 18, it may perform the same processing as T64-T76 and S10 in Figure 3. The printer 10 may then use a NAN cluster to encrypt the error information indicating the physical failure and send the encrypted information obtained from this encryption to the terminal 100. The printer 10 may also be equipped with a scan execution unit for performing scans, for example. Furthermore, if the printer 10 detects a physical failure in the scanning execution unit, it may use the NAN cluster to encrypt the error information and send the resulting encrypted information to the terminal 100. Generally speaking, an "error" can be any error that occurs in the "function execution device".

[0079] (Modification 2) The processes T64 to T69 in Figure 3 can be omitted. In this case, for example, the printer 10 may use a NAN cluster to send the encrypted information EI1 to a device located near the printer 10. If the device has the shared key SK stored, it can decrypt the encrypted information EI1 and obtain error information. In this modification, the "predetermined signal transmission unit" and the "response signal reception unit" of the "function execution device" can be omitted. Also, in this modification, the "predetermined signal reception unit" and the "response signal transmission unit" of the "terminal device" can be omitted.

[0080] (Modification 3) Terminal 100 can omit the processing of T66 in Figure 3. In this case, the Subscribe in T64 does not need to include the serial number P1 of the printer 10. Then, when terminal 100 receives Subscribe in T64, it may send Publish to the printer 10 in T68.

[0081] (Modification 4) The memory 134 of terminal 100 does not need to store the monitoring service flag. In this case, when terminal 100 receives Subscribe from printer 10 in T64, it may execute the processing from T54 onwards without determining whether the monitoring service flag in memory 134 indicates "ON". That is, terminal 100 may be configured to always provide the monitoring service. In this modification, the monitoring service activation operation at T50 and the processing at T52 in Figure 2 can be omitted.

[0082] (Modification 5) The processes T70 to T76 and S10 in Figure 3 can be omitted. In this modification, the "specific unit" of the "function execution device" can be omitted.

[0083] (Modification 6) Printer 10 can omit the processing of T62 in Figure 3. In this modification, the "device-side display control unit" of the "function execution device" can be omitted.

[0084] (Modification 7) In T64, the printer 10 may send a Publish indicating that an error has occurred instead of a Subscribe to search for a monitoring service. In this case, the terminal 100 that receives the Publish may send a Follow-up in T68 instead of a Publish. In this modification, the above Publish and Follow-up are examples of a "predetermined signal" and a "response signal," respectively. The printer 10 may also send encrypted information EI1 in T82 using a signal different from Follow-up. In another modification, a method different from the Wi-Fi Awara method may be adopted in the technology described in the above embodiment. For example, the printer 10 may send a signal containing encrypted information to the terminal 100 using a wireless network formed according to the different method. The signal only needs to use communication that does not use the network layer or above of the OSI reference model, but uses the data link layer or below of the OSI reference model.

[0085] (Modification 8) In the above embodiment, the processing of each step in Figures 2 to 5 is implemented by software (for example, program 36, OS 136, application 138), but at least one of these processes may be implemented by hardware such as a logic circuit.

[0086] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself.

[0087] Even if, in the claims of this patent application, each claim depends on only some of the claims, it is not limited to the claim being dependent only on those specific claims. To the extent that it is not technically contradictory, each claim may be dependent on other claims that were not dependent at the time of application. That is, the technologies of each claim can be combined in various ways as follows: (Item 1) It is a communication system, Function execution device and Terminal device and Equipped with, The aforementioned function execution device is A device-side interface for performing wireless communication in accordance with the Wi-Fi standard, A device-side memory that stores key information for encrypting and decrypting information, An encrypted information transmission unit transmits encrypted information to the terminal device via the device-side interface using the Wi-Fi network to which both the terminal device and the function execution device belong, in the event that an error occurs in the function execution device, wherein the encrypted information is transmitted to the terminal device using the Wi-Fi network by utilizing communication that uses the data link layer or lower of the OSI reference model without using the network layer or higher of the OSI reference model, and the encrypted information is information obtained by encrypting error information indicating the error using the key information, the encrypted information transmission unit Equipped with, The aforementioned terminal device is A terminal-side interface for performing wireless communication in accordance with the Wi-Fi standard, A terminal-side memory that stores the aforementioned key information, The terminal display unit, An encrypted information receiving unit that uses the Wi-Fi network to receive the encrypted information from the function execution device via the terminal-side interface, A terminal-side display control unit that, when the encrypted information is received from the function execution device, displays the error information obtained by decrypting the encrypted information using the key information on the terminal-side display unit, Equipped with, Communication system. (Item 2) The aforementioned function execution device further, When the aforementioned error occurs, the device includes a predetermined signal transmission unit that transmits a predetermined signal to the terminal device via the device-side interface using the Wi-Fi network, The aforementioned terminal device further, A predetermined signal receiving unit that uses the Wi-Fi network to receive the predetermined signal from the function execution device via the terminal-side interface, A response signal transmission unit that, when the predetermined signal is received from the function execution device, transmits a response signal to the predetermined signal to the function execution device via the terminal interface using the Wi-Fi network, Equipped with, The aforementioned function execution device further, The device includes a response signal receiving unit that uses the Wi-Fi network to receive the response signal from the terminal device via the device-side interface, The communication system according to item 1, wherein the encrypted information transmission unit transmits the encrypted information to the terminal device when the response signal is received from the terminal device. (Item 3) The predetermined signal includes identification information for identifying the function execution device, The response signal transmission unit, When the predetermined signal is received from the function execution device and the identification information is stored in the terminal-side memory, the response signal is transmitted to the function execution device. If the predetermined signal is received from the function execution device and the identification information is not stored in the terminal-side memory, the response signal is not transmitted to the function execution device. The communication system described in item 2. (Item 4) The terminal-side memory further stores flag information indicating either a first value indicating the transmission of the response signal or a second value indicating the non-transmission of the response signal. The response signal transmission unit, When the predetermined signal is received from the function execution device and the flag information indicates the first value, the response signal is transmitted to the function execution device. When the predetermined signal is received from the function execution device and the flag information indicates the second value, the response signal is not transmitted to the function execution device. The communication system described in item 2 or 3. (Item 5) The Wi-Fi network is a Neighbor Awareness Networking (NAN) cluster formed in accordance with the Wi-Fi Aware method of the Wi-Fi standard. The predetermined signal is Subscribe as defined in the Wi-Fi Aware method, The communication system according to any one of items 2 to 4, wherein the response signal is a Publish as defined by the Wi-Fi Aware method. (Item 6) The aforementioned function execution device further, The terminal device is equipped with a unit that identifies the distance between it and the function execution device, The aforementioned encrypted information transmission unit, If the distance is less than or equal to the threshold, the encrypted information is transmitted to the terminal device. If the distance is greater than the threshold, the encrypted information is not transmitted to the terminal device. A communication system as described in any one of items 1 through 5. (Item 7) The aforementioned function execution device further, The display unit on the device side, When the aforementioned error occurs, the device-side display control unit displays the error information on the device-side display unit, A communication system comprising any one of items 1 to 6. (Item 8) The aforementioned function execution device is capable of performing a printing function. The aforementioned error is a communication system as described in any one of items 1 to 7, including a shortage of consumables necessary to perform the printing function. (Item 9) The communication system described in any one of items 1 to 8, wherein the error includes the inability to perform wireless communication with the access point via the device-side interface. (Item 10) The Wi-Fi network is a Neighbor Awareness Networking (NAN) cluster formed in accordance with the Wi-Fi Aware method of the Wi-Fi standard, as described in any one of items 1 to 9. (Item 11) The encrypted information is communicated by Follow-up as defined in the Wi-Fi Aware method, according to the communication system described in item 10. [Explanation of Symbols]

[0088] 2: Communication system, 6: AP, 10: Printer, 12, 112: Operation unit, 14, 114: Display unit, 16, 116: Wi-Fi I / F, 18: Print execution unit, 30, 130: Control unit, 32, 132: CPU, 34, 134: Memory, 36: Program, 40, 140: Device list, 100: Terminal, 136: OS program, 138: Application program

Claims

1. It is a communication system, Function execution device and Terminal device and Equipped with, The aforementioned function execution device is A device-side interface for performing wireless communication in accordance with the Wi-Fi standard, A device-side memory that stores key information for encrypting and decrypting information, An encrypted information transmission unit transmits encrypted information to the terminal device via the device-side interface using the Wi-Fi network to which both the terminal device and the function execution device belong, in the event that an error occurs in the function execution device, wherein the encrypted information is transmitted to the terminal device using the Wi-Fi network by utilizing communication that uses the data link layer or lower of the OSI reference model without using the network layer or higher of the OSI reference model, and the encrypted information is information obtained by encrypting error information indicating the error using the key information, the encrypted information transmission unit Equipped with, The aforementioned terminal device is A terminal-side interface for performing wireless communication in accordance with the Wi-Fi standard, A terminal-side memory that stores the aforementioned key information, The terminal display unit, An encrypted information receiving unit that receives the encrypted information from the function execution device via the terminal-side interface using the Wi-Fi network, A terminal-side display control unit that, when the encrypted information is received from the function execution device, displays the error information obtained by decrypting the encrypted information using the key information on the terminal-side display unit, Equipped with, Communication system.

2. The aforementioned function execution device further, When the aforementioned error occurs, the device includes a predetermined signal transmission unit that transmits a predetermined signal to the terminal device via the device-side interface using the Wi-Fi network. The aforementioned terminal device further, A predetermined signal receiving unit that uses the Wi-Fi network to receive the predetermined signal from the function execution device via the terminal-side interface, A response signal transmission unit that, when the predetermined signal is received from the function execution device, transmits a response signal to the predetermined signal to the function execution device via the terminal interface using the Wi-Fi network, Equipped with, The aforementioned function execution device further, The system includes a response signal receiving unit that receives the response signal from the terminal device via the device-side interface using the Wi-Fi network, The communication system according to claim 1, wherein the encrypted information transmission unit transmits the encrypted information to the terminal device when the response signal is received from the terminal device.

3. The predetermined signal includes identification information for identifying the function execution device, The response signal transmission unit is When the predetermined signal is received from the function execution device and the identification information is stored in the terminal-side memory, the response signal is transmitted to the function execution device. If the predetermined signal is received from the function execution device and the identification information is not stored in the terminal-side memory, the response signal is not transmitted to the function execution device. The communication system according to claim 2.

4. The terminal-side memory further stores flag information indicating either a first value indicating that the response signal is to be transmitted, or a second value indicating that the response signal is not to be transmitted. The response signal transmission unit is When the predetermined signal is received from the function execution device and the flag information indicates the first value, the response signal is transmitted to the function execution device. When the predetermined signal is received from the function execution device and the flag information indicates the second value, the response signal is not transmitted to the function execution device. The communication system according to claim 2.

5. The Wi-Fi network is a Neighbor Awareness Network (NAN) cluster formed according to the Wi-Fi Aware method of the Wi-Fi standard. The predetermined signal is a Subscribe defined in the Wi-Fi Aware method, The communication system according to claim 2, wherein the response signal is a publish as defined by the Wi-Fi Aware method.

6. The aforementioned function execution device further, The terminal device is equipped with a unit that identifies the distance between it and the function execution device, The aforementioned encrypted information transmission unit, If the distance is less than or equal to the threshold, the encrypted information is transmitted to the terminal device. If the distance is greater than the threshold, the encrypted information is not transmitted to the terminal device. The communication system according to claim 1.

7. The aforementioned function execution device further, The display unit on the device side, When the aforementioned error occurs, the device-side display control unit displays the error information on the device-side display unit, The communication system according to claim 1, comprising:

8. The aforementioned function execution device is capable of performing a printing function. The communication system according to claim 1, wherein the error includes a shortage of consumables necessary to realize the printing function.

9. The communication system according to claim 1, wherein the error includes the inability to perform wireless communication with the access point via the device-side interface.

10. The communication system according to claim 1, wherein the Wi-Fi network is a Neighbor Awareness Network (NAN) cluster formed in accordance with the Wi-Fi Aware method of the Wi-Fi standard.

11. The communication system according to claim 10, wherein the encrypted information is communicated by Follow-up as defined in the Wi-Fi Aware method.

12. A function execution device, A device-side interface for performing wireless communication in accordance with the Wi-Fi standard, A device-side memory that stores key information for encrypting and decrypting information, An encrypted information transmission unit transmits encrypted information to the terminal device via the device-side interface using the Wi-Fi network to which both the terminal device and the function execution device belong, when an error occurs in the function execution device, wherein the encrypted information is transmitted to the terminal device using the Wi-Fi network by using communication that does not utilize the network layer or above of the OSI reference model, but only the data link layer or below of the OSI reference model, and the encrypted information is information obtained by encrypting error information indicating the error using the key information, the encrypted information transmission unit A functional execution device equipped with the following features.

13. A computer program for a functional execution device, The aforementioned function execution device is A device-side interface for performing wireless communication in accordance with the Wi-Fi standard, A device-side memory that stores key information for encrypting and decrypting information, Computers and, Equipped with, The aforementioned computer program controls the computer, A computer program that causes the encrypted information transmission unit to function as such, wherein, when an error occurs in the function execution device, the encrypted information is transmitted to the terminal device via the device-side interface using the Wi-Fi network to which both the terminal device and the function execution device belong, and the encrypted information is transmitted to the terminal device using the Wi-Fi network by using communication that does not use the network layer or above of the OSI reference model, but only the data link layer or below of the OSI reference model, and the encrypted information is obtained by encrypting error information indicating the error using the key information.

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