Patent Publication Number: US-2021182843-A1

Title: Settlement processing method and settlement processing system

Description:
TECHNICAL FIELD 
     The present invention relates to a settlement processing method and a settlement processing system and, in particular, to a technology for performing a settlement process using a settlement code. 
     Priority is claimed on Japanese Patent Application No. 2018-181850 and Japanese Patent Application No. 2018-181851, filed Sep. 27, 2018, the contents of which are incorporated herein by reference. 
     BACKGROUND ART 
     Electronic settlement in which settlement is electronically carried out without using commodity money such as bills and coins has become widespread. In electronic settlement, users paying prices of commodities or services are authenticated as a precondition for settlement. However, structures for realizing authentication processes by reading imaged codes with code readers such as cameras in user authentication have become widespread (for example, see Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     [Patent Document 1] 
     
         
         Published Japanese Translation No. 2017-503253 of the PCT International Publication 
       
    
     SUMMARY OF INVENTION 
     Problems to be Solved by the Invention 
     According to the technology disclosed in Patent Document 1, an authentication process is performed based on information embedded in a barcode or a QR code (registered trademark). However, standards of structures for embedding in codes or encoding of information are in disarray and different kinds of standards have not been compatible in some situations. Therefore, users who want to use the foregoing electronic settlement may be at a loss as to what standard for electronic settlement should be used. As a result, the spreading of electronic settlement can be disturbed. 
     The present invention has been achieved in view of such circumstances and an objective of the present invention is to provide a technology for a user who carries out settlement without being aware of the kind of electronic settlement. 
     Means for Solving the Problems 
     According to a first aspect of the present invention, a settlement processing method includes: transmitting a request for acquiring a settlement token to a first settlement server managed by a first settlement service provider available t a first user by a first user terminal used by the first user; transmitting a settlement token associated with a first service provider identifier for identifying the first settlement service provider to the first user terminal by the first settlement server; displaying a settlement code generated on the basis of the settlement token by the first user terminal; transmitting settlement information including a settlement token and a settlement price obtained by reading the settlement code to a relay server by a second user terminal registered in a second settlement server managed by a second settlement service provider different from the first settlement service provider; acquiring the first service provider identifier associated with the settlement token by the relay server; transmitting the settlement token to the first settlement sever generating the settlement token by the relay server; and performing user authentication of the first user on the basis of the settlement token by the first settlement server. 
     According to a second aspect of the present invention, a settlement processing method includes: transmitting a request for acquiring a settlement token to a first settlement server managed by a first settlement service provider available to a first user by a first user terminal used by the first user; transmitting a token associated with a first service provider identifier for identifying the first settlement service provider to the first user terminal by the first settlement server; displaying a settlement code generated on the basis of the settlement token by the first user terminal; transmitting settlement information including a settlement token and a settlement price obtained by reading the settlement code to a second settlement server managed by a second settlement service provider available to a second user using a second user terminal by the second user terminal; transmitting the settlement information received to a relay server by the second settlement server by the second user terminal; extracting the first service provider identifier from the settlement token included in the settlement information received from the second settlement server by the relay server; transmitting the settlement token to the first settlement server managed by the first settlement service provider identified with the first service provider identifier by the relay server; and authenticating the first user on the basis of the settlement token by the first settlement server. 
     According to a third aspect of the present invention, a settlement processing method includes: transmitting a request for acquiring a settlement token to a first settlement server managed by a first settlement service provider available to a first user by a first user terminal used by the first user; encrypting a settlement token associated with a first service provider identifier for identifying the first settlement service provider using a first encryption key which is an encryption key used by the first settlement server and transmitting the encrypted settlement token to the first user terminal by the first settlement server; decoding the encrypted settlement token received from the first settlement server using the first encryption key by the first user terminal; displaying a settlement code generated on the basis of the settlement token by the first user terminal; encrypting settlement information including a settlement token and a settlement price obtained by reading the settlement code using a second encryption key which is an encryption key used by the first settlement server and transmitting the encrypted settlement information to a relay server by a second user terminal registered in a second settlement server managed by a second settlement service provider different from the first settlement service provider; decoding the encrypted settlement information received from the second user terminal using the second encryption key by the relay server; acquiring the first service provider identifier associated with the settlement token included in the settlement information obtained through the decoding by the relay server; encrypting the settlement token included in the decoded settlement information using the first encryption key by the relay server; transmitting the encrypted settlement token to the first settlement server generating the settlement token by the relay server; decoding the encrypted settlement token acquired from the relay server using the first encryption key by the first settlement server; and performing user authentication of the first user on the basis of the decoded settlement token by the first settlement server. 
     The settlement processing method according to the first to third aspects of the present invention may further include: generating a token associated with the first service provider identifier for identifying the first settlement service provider and transmitting the token to the relay server by the first settlement server; and stopping the settlement process by the relay server when the settlement token received from the first settlement server does not match the settlement token received from the second user terminal. 
     According to a fourth aspect of the present invention, a settlement processing method includes: transmitting a request for acquiring a settlement token for performing settlement using a first settlement server managed by a first settlement service provider available to a first user to a relay server by a first user terminal used by the first user; transmitting a token associated with a first service provider identifier for identifying the first settlement service provider to the first user terminal by the relay server; displaying a settlement code generated on the basis of the settlement token by the first user terminal; transmitting settlement information including the settlement token and a settlement price obtained by reading the settlement code to the relay server by the second user terminal; acquiring the first service provider identifier associated with the settlement token by the relay server; transmitting the settlement token to the first settlement server generating the settlement token by the relay server; and authenticating the first user on the basis of the settlement token by the first settlement server. 
     According to a fifth aspect of the present invention, a settlement processing method includes: receiving a request for acquiring a settlement token for performing settlement using a first settlement server managed by a first settlement service provider available to a first user from a first user terminal used by the user; transmitting a token associated with a first service provider identifier for identifying the first settlement service provider to the first user terminal; receiving settlement information including a settlement token and a settlement price obtained by reading a settlement code generated by the first user terminal on the basis of the settlement token from a second user terminal reading the settlement code; transmitting the settlement token to a first settlement server which is a settlement server of a settlement service provider corresponding to the settlement token; and receiving information regarding a settlement approval which is based on the settlement token from the first settlement server. 
     According to a sixth aspect of the present invention, a settlement processing method includes: transmitting a request for acquiring a settlement token to a first settlement server managed by a first settlement service provider and available in a store by a store terminal installed in the store; transmitting a settlement token associated with a first service provider identifier for identifying the first settlement service provider to the store terminal by the first settlement server; displaying a settlement code generated on the basis of the settlement token by the store terminal; acquiring a settlement token obtained by reading the settlement code by a customer terminal which is a terminal of a customer using the store; encrypting settlement information including the settlement token and a settlement price with an encryption key used by the first settlement server by the customer terminal; transmitting the encrypted settlement information to the relay server by the customer terminal; transmitting the settlement information received from the customer terminal to the first settlement server by the relay server; and performing user authentication on the basis of the settlement information transmitted from the relay server by the first settlement server. 
     The settlement processing method according to the sixth aspect of the present invention may further include: generating a settlement token including a first service provider identifier for identifying the first settlement service provider and transmitting the settlement token to the relay server by the first settlement server; and stopping a settlement process by the relay server when the settlement token received from the first settlement server does not match a settlement token received from the customer terminal. 
     According to a seventh aspect of the present invention, a settlement processing method includes: transmitting a request for acquiring a settlement token for performing settlement using a first settlement server managed by a first settlement service provider and available in a store to a relay server by a store terminal installed in the store; transmitting a settlement token associated with a first service provider identifier for identifying the first settlement service provider to the store terminal by the relay server; displaying a settlement code generated on the basis of the settlement token by the store terminal; acquiring the settlement token obtained by reading the settlement code by a customer terminal which is a terminal of a customer using the store; encrypting settlement information including the settlement token and a settlement price with an encryption key used by the first settlement server by the customer terminal; transmitting the encrypted settlement information to the relay server by the customer terminal; transmitting the settlement information acquired from the customer terminal to the first settlement server by the relay server; and performing user authentication on the basis of the settlement information transmitted from the relay server by the first settlement server. 
     According to an eighth aspect of the present invention, a settlement processing system includes: a store terminal installed in a store; a customer terminal carried by a customer using the store; a settlement server managed by a first settlement service provider and available in the store, the first settlement service provider different from a second settlement service provider available to the customer terminal; and a relay server. The store terminal includes a token request unit and a display control unit. The settlement server includes a token transmission unit and a settlement management unit. The customer terminal includes a code reading unit, a settlement information transmission unit, and an encryption unit. The relay server includes a settlement request unit. The token request unit of the store terminal is configured to transmit a request for acquiring a settlement token to the settlement server. The token transmission unit of the settlement server is configured to transmit a settlement token associated with a first service provider identifier for identifying the first settlement service provider to the store terminal. The display control unit of the store terminal is configured to display a settlement code generated on the basis of the settlement token on a display unit. The code reading unit of the customer terminal reads the settlement code displayed on the display unit of the store terminal. The encryption unit of the customer terminal is configured to encrypt settlement information including the settlement token and a settlement price with an encryption key used by the settlement server. The settlement information transmission unit of the customer terminal is configured to transmit the settlement information encrypted by the encryption unit to the relay server. The settlement request unit of the relay server is configured to transmit the settlement information acquired from the customer terminal to the settlement server. The settlement management unit of the settlement server performs user authentication on the basis of the settlement information transmitted from the relay server. 
     Advantageous Effects of the Invention 
     According to the present invention, it is possible to provide a technology for a user who carries out settlement without being aware of a kind of electronic settlement. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a preliminary registration process performed by a settlement processing system according to a first embodiment. 
         FIG. 2  is a block diagram illustrating a functional configuration of each device included in the settlement processing system according to the first embodiment. 
         FIG. 3  is a diagram illustrating a settlement process performed by the settlement processing system according to the first embodiment. 
         FIG. 4  is a table schematically illustrating the data structure of a settlement token database stored in a storage unit according to the first embodiment. 
         FIG. 5  is a diagram illustrating a settlement process performed by the settlement processing system according to a first modification example of the first embodiment. 
         FIG. 6  is a diagram illustrating a settlement process performed by the settlement processing system according to a second modification example of the first embodiment. 
         FIG. 7  is a diagram illustrating a settlement process performed by the settlement processing system according to a third modification example of the first embodiment. 
         FIG. 8  is a diagram illustrating a settlement process performed by the settlement processing system according to a fourth modification example of the first embodiment. 
         FIG. 9  is a diagram illustrating a settlement process performed by the settlement processing system according to a fifth modification example of the first embodiment. 
         FIG. 10  is a diagram illustrating a settlement process performed by the settlement processing system according to a sixth modification example of the first embodiment. 
         FIG. 11  is a block diagram illustrating a functional configuration of each device included in a settlement processing system according to a second embodiment. 
         FIG. 12  is a diagram illustrating a settlement process performed by the settlement processing system according to the second embodiment. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     Overview of First Embodiment 
     An overview of a first embodiment will be described. A relay server according to the first embodiment is a device that relays electronic settlement in which a QR code or the like is used. A relay server according to the first embodiment relays exchange of information among four parties, a user terminal used by a user who tries to carry out electronic settlement, a store terminal installed in a store which the user uses, a settlement server of a settlement service provider available to the user, and a settlement server of a settlement service provider which the store can use. 
     Here, a technology for electronic settlement in which a code is used is broadly classified into two types of schemes, a “user suggestion scheme” and a “store suggestion scheme.” The “user suggestion scheme” is a scheme in which the store terminal reads a code displayed on the user terminal of the user using the store and transmits the code to the settlement server. The “store suggestion scheme” is a scheme in which the user terminal reads a code displayed on the store terminal and transmits the code to the settlement server. 
     Hereinafter, in the first embodiment, a user of a terminal displaying a code is referred to as a “first user,” a terminal used by the first user is referred to as a “first user terminal,” a settlement service provider with which the first user makes a contract is referred to as a “first settlement service provider, and a settlement server managed by the first settlement service provider is referred to as a “first settlement server.” A terminal reading a code displayed by the first user terminal is a “second user terminal,” a user using the second user terminal is referred to as a “second user,” a settlement service provider with which the second user makes a contract is referred to as a “second settlement service provider,” and a settlement server managed by the second settlement service provider is referred to as a “second settlement server.” 
     Accordingly, in a settlement system of the user suggestion scheme, a user terminal of a user using a store is the first user terminal and a store terminal installed in the store used by the user is the second user terminal. In this case, the second user is a manager or the like of the store. In a settlement system of the store suggestion scheme, a user terminal of a user using a store is the second user terminal and a store terminal installed in the store used by the user is the first user terminal. 
     In general, information exchanged for a settlement service provider of a certain electronic settlement to perform settlement with each user terminal is encrypted with an encryption key used individually by each settlement service provider. Accordingly, when the first settlement service provider and the second settlement service provider are different, the second settlement service provider cannot normally carry out the settlement process although the second settlement service provider receives settlement information encrypted with an encryption key used by the first service provider to communicate with the first settlement service provider. 
     The relay server according to the first embodiment is configured to acquire the encryption key used by each settlement service provider from a plurality of settlement service providers in advance and read encrypted information which is used in communication by each company. Therefore, the relay server according to the first embodiment can receive settlement information including a token for the first settlement server transmitted by the first user terminal, read content of the settlement information, and transmit the settlement information to the second settlement server. 
     In this way, the relay server according to the first embodiment can realize the settlement process by relaying settlement between both service providers even when a settlement service provider of the electronic settlement with which a user trying to carry out the electronic settlement makes a contract is different for a settlement service provider with which a store used by the user makes a contract. Accordingly, the relay server according to the first embodiment can carry out settlement so that the user is not aware of the kind of electronic settlement. 
     &lt;Preliminary Registration Process&gt; 
       FIG. 1  is a diagram illustrating a preliminary registration process of a settlement processing system S according to the first embodiment. Hereinafter, to facilitate description, the settlement processing system S is assumed to be a system that processes settlement of the user suggestion scheme in the following description. 
     As illustrated in  FIG. 1 , the settlement processing system S according to the first embodiment includes a first user terminal T 1  which is a terminal used by a first user U 1 , a second user terminal T 2  which is a terminal installed in a store R used by the first user U 1 , a first settlement server Q 1  which is a settlement server Q managed by a settlement service provider with which the first user U 1  makes a contract, a second settlement server Q 2  which is a settlement server Q of a settlement service provider with which a second user U 2  who is a manager of the store R makes a contract, and a relay server M. 
     Hereinafter, a preliminary registration process of the settlement processing system S according to the first embodiment will be described in the order of  1 -( 1 ) to  1 -( 5 ) with reference to  FIG. 1 . These reference numbers correspond to  1 -( 1 ) to  1 -( 5 ) in  FIG. 1 . 
       1 -( 1 ) The second user U 2  carries out user registration to the second settlement server Q 2  managed by the second settlement service provider in order to use an electronic settlement service provided by the second settlement service provider. Thus, the second user U 2  opens an electronic settlement account managed by the second settlement server Q 2 . 
       1 -( 2 ) The second user U 2  performs user registration in the relay server M. 
       1 -( 3 ) The second settlement service provider carries out service provider registration in the relay server M and the second settlement service provider supplies an encryption key for encrypting information in communication to the relay server M. 
       1 -( 4 ) The first settlement service provider carries out service provider registration in the relay server M and the first settlement service provider supplies an encryption key for encrypting information in communication to the relay server M. 
       1 -( 5 ) The first user U 1  carries out user registration in the first settlement server Q 1  managed by the first settlement service provider in order to use an electronic settlement service provided by the first settlement service provider. Thus, the first user U 1  opens an electronic settlement account managed by the first settlement server Q 1 . 
     Here, the “settlement token” is a random character string transmitted to the first user terminal T 1  of the first user U 1  by the first settlement server Q 1  when the first user U 1  tries to carry out settlement in the first settlement server Q 1 . The first settlement server Q 1  generates each settlement token so that a settlement token to be transmitted to each first user U 1  is not duplicate. The first settlement server Q 1  generates a settlement token when there is a request from the first user terminal T 1  and stores the settlement token in a storage unit in association with a user identifier of the first user U 1 . 
     The first settlement server Q 1  determines a valid period in each settlement token to be issued. The first settlement server Q 1  deletes the settlement token of which the valid period has expired from the storage unit. The valid period may be determined in consideration of security or the like required for settlement and is in a range, for example, from several minutes to tens of minutes. 
     The first user terminal T 1  generates a settlement code (for example, an image such as a QR code or a bar code) based on the settlement token and displays the settlement code on a display unit of the first user terminal T 1 . When the settlement code can be read by the second user terminal T 2  and can be transmitted along with a settlement price to the first settlement server Q 1 , the first settlement server Q 1  can identify the first user U 1  from the user identifier associated with the received settlement token. When the first user U 1  can be identified, the first settlement server Q 1  can perform settlement from an account of the first user U 1  at the settlement price received from the second user terminal T 2 . 
     Incidentally, when the second user U 2  does not carry out user registration to use the electronic settlement service of the first settlement service provider, there is no method of transmitting the settlement information to the first settlement server Q 1  although the second user terminal T 2  reads the settlement code displayed on the display unit by the first user terminal T 1  reads. 
     In general, encrypted information is exchanged between the user terminal T and the settlement server Q, but an encryption key used for each settlement server Q to encrypt the information is mutually different. Accordingly, when the second user U 2  does not carry out member store registration in order to use the electronic settlement service of the first settlement service provider, the second user terminal T 2  does not have an encryption key used by the first settlement server Q 1  although the second user terminal T 2  reads the settlement code displayed on the display unit by the first user terminal T 1 . Therefore, the settlement code cannot be encrypted so that the settlement code can be decoded by the first settlement server Q 1 . 
     Accordingly, the relay server M relays transmission and reception of information between the second user terminal T 2  and the first settlement server Q 1 , converts information received from the second user terminal T 2  into information which can be handled by the first settlement server Q 1 , and transmits the converted information to the first settlement server Q 1 . Thus, the relay server M cab realize the electronic settlement although a kind of electronic settlement for which the first user U 1  makes a contract is different from a kind of electronic settlement for which the second user U 2  makes a contract. 
     Functional Configuration of Settlement Processing System S According to First Embodiment 
       FIG. 2  is a block diagram schematically illustrating a functional configuration of each device included in the settlement processing system S according to the first embodiment. The settlement processing system S includes the first user terminal T 1 , the second user terminal T 2 , the relay server M, the first settlement server Q 1 , and the second settlement server Q 2  which are connected to be communicable via a communication network N. The first user terminal T 1  includes a storage unit  10  and a control unit  11 . The second user terminal T 2  also includes a storage unit  20  and a control unit  21 . Similarly, the relay sever M includes a storage unit  30  and a control unit  31 , the first settlement server Q 1  includes a storage unit  40  and a control unit  41 , and the second settlement server Q 2  includes a storage unit  50  and a control unit  51 . 
     In  FIG. 2 , an arrow indicates a flow of main data or may also indicate a flow of data not illustrated in  FIG. 2 . In  FIG. 2 , each functional block indicates a configuration of a function unit rather than a configuration of a hardware (device) unit. Exchange of data between the functional blocks may be performed via any means such as a data bus, a network, or a portable storage medium. 
     The storage unit  10  is a mass storage device such as a read-only memory (ROM) that stores a basic input output system (BIOS) or the like of a computer realizing the first user terminal T 1 , a random access memory (RAM) serving as a working area of the first user terminal T 1 , or a hard disk drive (HDD) or a solid-state drive (SSD) that stores an operating system (OS) and an application program and various kinds of information referred to in execution of the application program. 
     The control unit  11  is a processor such as a central processing unit (CPU) or a graphics processing unit (GPU) of the first user terminal T 1  and functions as a token request unit  110  and a display control unit  111  by executing a program stored in the storage unit  10 . 
     Similarly, the storage unit  20  is a mass storage device such as a ROM that stores a BIOS of a computer realizing the second user terminal T 2 , a RAM serving as a working area of the second user terminal T 2 , or an HDD or an SSD that stores an OS and an application program and various kinds of information referred to in execution of the application program. The control unit  21  is a processor such as a CPU or a GPU of the second user terminal T 2  and functions as a code reading unit  210  and a settlement information transmission unit  211  by executing a program stored in the storage unit  20 . 
     The storage unit  30  is a mass storage device such as a ROM that stores a BIOS of a computer realizing the relay server M, a RAM serving as a working area of the relay server M, or an HDD or an SSD that stores an OS and an application program and various kinds of information referred to in execution of the application program. The control unit  31  is a processor such as a CPU or a GPU of the relay server M and functions as a settlement information reception unit  310 , a settlement request unit  311 , and a notification unit  312  by executing a program stored in the storage unit  30 . 
     The storage unit  40  is a mass storage device such as a ROM that stores a BIOS of a computer realizing the first settlement server Q 1 , a RAM serving as a working area of the relay server M, or an HDD or an SSD that stores an OS and an application program and various kinds of information referred to in execution of the application program. The control unit  41  is a processor such as a CPU or a GPU of the first settlement server Q 1  and functions as a token transmission unit  410 , a settlement management unit  411 , and an adjustment management unit  412  by executing a program stored in the storage unit  40 . 
     The storage unit  50  is a mass storage device such as a ROM that stores a BIOS of a computer realizing the second settlement server Q 2 , a RAM serving as a working area of the relay server M, or an HDD or an SSD that stores an OS and an application program and various kinds of information referred to in execution of the application program. The control unit  51  is a processor such as a CPU or a GPU of the second settlement server Q 2  and functions as a token transmission unit  510 , a settlement management unit  511 , and an adjustment management unit  512  by executing a program stored in the storage unit  50 . 
       FIG. 3  is a diagram illustrating a settlement process performed by the settlement processing system S according to the first embodiment. Hereinafter, a settlement process performed by the settlement processing system S according to the first embodiment will be described in the order of  3 -( 1 ) to  3 -( 13 ) with reference to  FIGS. 2 and 3 . These reference numbers correspond to  3 -( 1 ) to  3 -( 13 ) in  FIG. 3 . 
       3 -( 1 ) The token request unit  110  of the first user terminal T 1  transmits a request for acquiring a settlement token to the first settlement server Q 1  managed by the first settlement service provider available to the first user U 1 . 
       3 -( 2 ) The token transmission unit  410  of the first settlement server Q 1  generates a token associated with a first service provider identifier for identifying the first settlement service provider in response to the acquisition request acquired from the first user terminal T 1  and transmits the token to the first user terminal T 1 . The token transmission unit  410  stores the settlement token transmitted to the first user terminal T 1  in the storage unit  40  in association with a first user identifier for identifying the first user U 1 . The first settlement server Q 1  performs user authentication of the user using the first user terminal T 1  when there is a request for the token from the token request unit  110  of the first user terminal T 1  or before there is the request for the token. Under the condition that the user authentication is successful, the token transmission unit  410  of the first settlement server Q 1  generates the settlement token. 
       FIG. 4  is a table schematically illustrating the data structure of a settlement token database stored in the storage unit  40  according to the first embodiment. The settlement token database stores each user identifier, each settlement token, and each valid period in association. 
     The settlement token database illustrated in  FIG. 4  is stored in the storage unit  40  of the first settlement server Q 1 . As illustrated in  FIG. 4 , the settlement token is basically a random character string and three beginning characters are a character string “001” that is common to all. The character string corresponds to the first service provider identifier. In this way, in the example illustrated in  FIG. 4 , the settlement token and the service provider identifier are associated in a format in which the service provider identifier is included in the settlement token. Thus, a device acquiring the settlement token can determine which settlement server Q handles the settlement token. 
       FIG. 3  is referred back for description. 
       3 -( 3 ) The display control unit  111  of the first user terminal T 1  displays the settlement code generated based on the settlement token received from the first settlement server Q 1  on the display unit of the first user terminal T 1 . 
       3 -( 4 ) The code reading unit  210  of the second user terminal T 2  reads the settlement code displayed on the display unit of the first user terminal T 1  to acquire the settlement token. 
       3 -( 5 ) The settlement information transmission unit  211  of the second user terminal T 2  transmits settlement information including the settlement token read and acquired by the code reading unit  210 , a second user identifier for identifying the second user U 2  using the second user terminal T 2 , a settlement price, and a second service provider identifier for identifying the second settlement service provider available to the second user U 2  to the relay server M. 
       3 -( 6 ) The settlement information reception unit  310  of the relay server M receives the settlement information from the second user terminal T 2 . 
       3 -( 7 ) The settlement request unit  311  of the relay server M transmits the settlement token and the settlement price to the first settlement server Q 1  of the first settlement service provider identified by the first service provider identifier acquired from the settlement token included in the settlement information received by the settlement information reception unit  310 . 
       3 -( 8 ) The settlement management unit  411  of the first settlement server Q 1  performs user authentication by determining whether the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M. The settlement management unit  411  of the first settlement server Q 1  acquires the first user identifier associated with the settlement token received from the relay server M from the storage unit  40  under the condition that the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M, determines whether the settlement price can be settled with a balance of an account of the first user U 1  identified with the first user identifier, and notifies the relay server M of a result as information regarding a settlement approval. 
       3 -( 9 ) When the settlement price can be settled with the balance of the account of the first user U 1 , the settlement request unit  311  of the relay server M transmits the second user identifier and a request for settling the settlement price included in the settlement information to the second settlement server Q 2  managed by the second settlement service provider. When the settlement price cannot be settled with the balance of the account of the first user U 1 , the settlement request unit  311  stops the settlement process. 
       3 -( 10 ) The settlement management unit  511  of the second settlement server Q 2  performs settlement of the settlement price received from the relay server M under the condition that user authentication based on the second user identifier received from the settlement request unit  311  of the relay server M is successful. Specifically, the settlement management unit  511  makes payment of an amount equivalent to the settlement price to an account opened by the second user U 2 . This means that the second settlement server Q 2  makes the payment on behalf of the first user U 1 . When the user authentication fails, that is, the second user U 2  does not perform user registration with the second settlement service provider, the settlement management unit  511  of the second settlement server Q 2  stops the settlement process. 
       3 -( 11 ) The settlement management unit  511  notifies the second user terminal T 2  of the completion of the settlement. 
       3 -( 12 ) When a settlement request is transmitted to the second settlement server Q 2 , the notification unit  312  of the relay server M notifies the first user terminal T 1  of the completion of the settlement. 
       3 -( 13 ) The adjustment management unit  512  of the second settlement server Q 2  requests the adjustment management unit  412  of the first settlement server Q 1  to perform adjustment. As a result, an amount of money equivalent to the settlement price is remitted from the account of the first user U 1  managed by the first settlement server Q 1  to the second settlement server Q 2  and the payment of the second settlement server Q 2  on behalf of the first user U 1  is adjusted. The relay server M may relay the adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . For example, an adjustment relay unit (not illustrated) of the relay server M may receive an adjustment request from the adjustment management unit  512  of the second settlement server Q 2  and transmit the adjustment request to the adjustment management unit  412  of the first settlement server Q 1 . 
     In this way, the relay server M according to the first embodiment relays the adjustment process performed among the first user terminal T 1 , the second user terminal T 2 , the first settlement server Q 1 , and the second settlement server Q 2 . Thus, the relay server M can realize the electronic settlement even when the kind of electronic settlement contracted by the first user U 1  is different from the kind of electronic settlement contracted by the second user U 2 . 
     Advantageous Effects Obtained by Relay Server M According to First Embodiment 
     As described above, according to the relay server M according to the embodiment, the user U can carry out the settlement without being aware of the kind of electronic settlement. 
     First Modification Example of First Embodiment 
       FIG. 5  is a diagram illustrating a settlement process performed by the settlement processing system S according to a first modification example of the first embodiment. The settlement processing system S according to the first modification example of the first embodiment is different from the settlement processing system S according to the first embodiment in that the first settlement server Q 1  performs a settlement process based on settlement information. 
     Hereinafter, a settlement process performed by the settlement processing system S according to the first modification example of the first embodiment will be described in the order of  5 -( 1 ) to  5 -( 12 ) with reference to  FIG. 5 . These reference numbers correspond to  5 -( 1 ) to  5 -( 12 ) in  FIG. 5 . Since the processes from  5 -( 1 ) to  5 -( 7 ) are the same as the processes from  3 -( 1 ) to  3 -( 7 ) in  FIG. 3 , description thereof will be omitted. 
       5 -( 8 ) The settlement management unit  411  of the first settlement server Q 1  performs user authentication by determining whether the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M. The settlement management unit  411  of the first settlement server Q 1  acquires the first user identifier associated with the settlement token received from the relay server M from the storage unit  40  under the condition that the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M, determines whether the settlement price can be settled with a balance from the account of the first user U 1  identified with the first user identifier, and performs settlement when settlement is possible to withdraw an amount of money equivalent to the settlement price from the account of the first user U 1 . 
       5 -( 9 ) The settlement management unit  411  of the first settlement server Q 1  transmits a settlement result to the relay server M. 
       5 -( 10 ) The notification unit  312  of the relay server M transmits the settlement result received from the first settlement server Q 1  to the second user terminal T 2 . 
       5 -( 11 ) The notification unit  312  of the relay server M transmits the settlement result received from the first settlement server Q 1  to the first user terminal T 1 . 
       5 -( 12 ) The adjustment management unit  412  of the first settlement server Q 1  requests the adjustment management unit  512  of the second settlement server Q 2  to perform adjustment. As a result, the amount of money equivalent to the settlement price withdrawn from the account of the first user U 1  managed by the first settlement server Q 1  is paid to the account of the second user U 2  managed by the second settlement server Q 2 . The relay server M may relay the adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . 
     In this way, the settlement processing system S according to the first modification example of the first embodiment is different from the settlement processing system S according to the first embodiment, the first settlement server Q 1  of the settlement service provider available to the first user U 1  performs a settlement process. Therefore, the settlement processing system S according to the first modification example of the first embodiment can immediately perform the settlement process because the process of notifying the relay server M of a balance confirmation result is omitted when there is a balance equivalent to the payment price in the account of the first user U 1 . Therefore, it is possible to accelerate the payment process. 
     In consideration of the settlement processing system S according to the first embodiment and the settlement processing system S according to the first modification example of the first embodiment, it can be said that the settlement request unit  311  of the relay server M may transmit a request for settling the settlement price to one settlement server Q between the first settlement server Q 1  and the second settlement server Q 2 . When one settlement server Q receiving the settlement request performs the settlement process and the other settlement server Q transmits the settlement request, the settlement processing system S can realize the electronic settlement although the kind of electronic settlement contracted by the first user U 1  is different from the kind of electronic settlement contracted by the second user U 2 . 
     Second Modification Example of First Embodiment 
       FIG. 6  is a diagram illustrating a settlement process performed by the settlement processing system S according to a second modification example of the first embodiment. The settlement processing system S according to the second modification example of the first embodiment is different from the settlement processing system S according to the first embodiment in that the relay server M encrypts information exchanged between the first user terminal T 1  and the first settlement server Q 1  with an encryption key used by the first settlement server Q 1 . The relay server M encrypts information exchanged between the second user terminal T 2  and the second settlement server Q 2  with an encryption key used by the second settlement server Q 2 . 
     Hereinafter, a settlement process performed by the settlement processing system S according to the second modification example of the first embodiment will be described in the order of  6 -( 1 ) to  6 -( 14 ) with reference to  FIG. 6 . These reference numbers correspond to  6 -( 1 ) to  6 -( 14 ) in  FIG. 6 . Since the process of  6 -( 1 ) is the same as the process of  3 -( 1 ) in  FIG. 3 , a description thereof will be omitted. 
       6 -( 2 ) The token transmission unit  410  of the first settlement server Q 1  generates a token associated with the first service provider identifier for identifying the first settlement service provider in response to the acquisition request acquired from the first user terminal T 1 , encrypts the generated settlement token with the encryption key used by the first settlement server Q 1 , and then transmits the encrypted settlement token to the first user terminal T 1 . The token transmission unit  410  stores the settlement token transmitted to the first user terminal T 1  in the storage unit  40  in association with the first user identifier for identifying the first user U 1 . The first settlement server Q 1  performs user authentication of the user using the first user terminal T 1  when there is a request for the token from the token request unit  110  of the first user terminal T 1  or before there is the request for the token. Under the condition that the user authentication is successful, the token transmission unit  410  of the first settlement server Q 1  generates the settlement token. 
       6 -( 3 ) The display control unit  111  of the first user terminal T 1  decodes the encrypted settlement token received from the first settlement server Q 1  and displays the settlement code generated based on the obtained settlement token on the display unit of the first user terminal T 1 . 
       6 -( 4 ) The code reading unit  210  of the second user terminal T 2  reads the settlement code displayed on the display unit of the first user terminal T 1  to acquire the settlement token. 
       6 -( 5 ) The settlement information transmission unit  211  of the second user terminal T 2  encrypts settlement information including the settlement token acquired by the code reading unit  210 , the second user identifier for identifying the second user U 2  using the second user terminal T 2 , the settlement price, and the second service provider identifier for identifying the second settlement service provider available to the second user U 2  with the encryption key used by the second settlement server Q 2  and transmits the encrypted settlement information to the relay server M. 
       6 -( 6 ) The settlement information reception unit  310  of the relay server M receives the encrypted settlement information from the second user terminal T 2 . 
       6 -( 7 ) The settlement information reception unit  310  decodes the encrypted settlement information received from the second user terminal T 2  with the encryption key used by the second settlement server Q 2 . 
       6 -( 8 ) The settlement request unit  311  of the relay server M encrypts information including the settlement token and the settlement price with the encryption key used by the first settlement server Q 1  and transmits the encrypted information to the first settlement server Q 1  of the first settlement service provider identified with the first service provider identifier acquired from the settlement token included in the settlement information received by the settlement information reception unit  310 . 
       6 -( 9 ) The settlement management unit  411  of the first settlement server Q 1  performs user authentication by determining whether the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M. The settlement management unit  411  of the first settlement server Q 1  acquires the first user identifier associated with the settlement token from the storage unit  40  by decoding the information received from the relay server M under the condition that the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M. The settlement management unit  411  determines whether the settlement price can be settled with a balance of an account of the first user U 1  identified with the first user identifier, encrypts a result, and notifies the relay server M of the encrypted result. 
       6 -( 10 ) The settlement request unit  311  of the relay server M decodes the notification received from the settlement management unit  411  with the encryption key used by the first settlement server Q 1 . When the settlement price can be settled with the balance of the account of the first user U 1  (that is, the user authentication of the first user U 1  is successful in the first settlement server Q 1  and there is the balance), the settlement request unit  311  of the relay server M encrypts the request for settling the settlement price included in the settlement information and the second user identifier with the encryption key used by the second settlement server Q 2  and transmits the encrypted information to the second settlement server Q 2  managed by the second settlement service provider. 
       6 -( 11 ) The settlement management unit  511  of the second settlement server Q 2  decodes the information received from the relay server M under the condition that user authentication based on the second user identifier received from the settlement request unit  311  of the relay server M is successful, and performs settlement of the settlement price. 
       6 -( 12 ) The settlement management unit  511  encrypts information indicating completion of the settlement with the encryption key used by the second settlement server Q 2  and notifies the second user terminal T 2  of the encrypted information. 
       6 -( 13 ) When the settlement request is transmitted to the second settlement server Q 2 , the notification unit  312  of the relay server M encrypts information indicating the completion of the settlement with the encryption key used by the first settlement server Q 1  and notifies the first user terminal T 1  of the encrypted information. 
       6 -( 14 ) The adjustment management unit  512  of the second settlement server Q 2  requests the adjustment management unit  412  of the first settlement server Q 1  to perform adjustment. The relay server M may relay an adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . 
     In this way, the relay server M encrypts information exchanged between the first user terminal T 1  and the first settlement server Q 1  with an encryption key used by the first settlement server Q 1 . The relay server M encrypts information exchanged between the second user terminal T 2  and the second settlement server Q 2  with an encryption key used by the second settlement server Q 2 . Thus, the relay server M can further improve the security of the settlement process. 
     Third Modification Example of First Embodiment 
       FIG. 7  is a diagram illustrating a settlement process performed by the settlement processing system S according to a third modification example of the first embodiment. The settlement processing system S according to the third modification example of the first embodiment is different from the settlement processing system S according to the first embodiment in that the first settlement server Q 1  transmits the generated settlement token to the relay server M. 
     Hereinafter, a settlement process performed by the settlement processing system S according to the third modification example of the first embodiment will be described in the order of  7 -( 1 ) to  7 -( 15 ) with reference to  FIG. 7 . These reference numbers correspond to  7 -( 1 ) to  7 -( 15 ) in  FIG. 7 . Since the processes of  7 -( 1 ) and  7 -( 2 ) are the same as the processes of  3 -( 1 ) and  3 -( 2 ) in  FIG. 3 , description thereof will be omitted. 
       7 -( 3 ) The token transmission unit  410  transmits the generated settlement token to the relay server M. 
       7 -( 4 ) The display control unit  111  of the first user terminal T 1  displays the settlement code generated based on the settlement token received from the first settlement server Q 1  on the display unit of the first user terminal T 1 . 
       7 -( 5 ) The code reading unit  210  of the second user terminal T 2  reads the settlement code displayed on the display unit of the first user terminal T 1  to acquire the settlement token. 
       7 -( 6 ) The settlement information transmission unit  211  of the second user terminal T 2  transmits settlement information including the settlement token acquired by the code reading unit  210 , the second user identifier for identifying the second user U 2  using the second user terminal T 2 , the settlement price, and the second service provider identifier for identifying the second settlement service provider available to the second user U 2  to the relay server M. 
       7 -( 7 ) The settlement information reception unit  310  of the relay server M receives the settlement information from the second user terminal T 2 . 
       7 -( 8 ) The settlement request unit  311  of the relay server M stops the settlement process when the settlement token received from the first settlement server Q 1  does not match the settlement token received from the second user terminal T 2 . Specifically, the settlement request unit  311  determines that the settlement tokens do not match when the settlement token received from the second user terminal T 2  is not included as one settlement token whose a valid period has not expired among the settlement tokens received from the first settlement server Q 1 . 
       7 -( 9 ) When the settlement token received from the first settlement server Q 1  matches the settlement token received from the second user terminal T 2 , the settlement request unit  311  of the relay server M transmits the settlement token and the settlement price to the first settlement server Q 1 . 
       7 -( 10 ) The settlement management unit  411  of the first settlement server Q 1  acquires the first user identifier associated with the settlement token received from the relay server M from the storage unit  40 , determines whether the settlement price can be settled with a balance of an account of the first user U 1  identified with the first user identifier, and notifies the relay server M of a result. 
       7 -( 11 ) When the settlement price can be settled with the balance of the account of the first user U 1 , the settlement request unit  311  of the relay server M transmits a request for settling the settlement price included in the settlement information to the second settlement server Q 2  managed by the second settlement service provider. 
       7 -( 12 ) The settlement management unit  511  of the second settlement server Q 2  performs settlement of the settlement price received from the relay server M. Specifically, the settlement management unit  511  makes payment of an amount equivalent to the settlement price to an account opened by the second user U 2 . 
       7 -( 13 ) The settlement management unit  511  notifies the second user terminal T 2  of the completion of the settlement. 
       7 -( 14 ) When a settlement request is transmitted to the second settlement server Q 2 , the notification unit  312  of the relay server M notifies the first user terminal T 1  of the completion of the settlement. 
       7 -( 15 ) The adjustment management unit  512  of the second settlement server Q 2  requests the adjustment management unit  412  of the first settlement server Q 1  to perform adjustment. As a result, an amount of money equivalent to the settlement price is remitted from the account of the first user U 1  managed by the first settlement server Q 1  to the second settlement server Q 2 . The relay server M may relay the adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . 
     In this way, in the relay server M according to the third modification example of the first embodiment, the settlement request unit  311  stops the settlement process when the settlement token received from the first settlement server Q 1  does not match the settlement token received from the second user terminal T 2 . Thus, since the relay server M can inhibit the first settlement server Q 1  from performing a process such as balance confirmation, a load on the first settlement server Q 1  can be reduced. 
     The first settlement server Q 1  may not include the first service provider identifier in the settlement token generated in response to the request for acquiring the settlement token of the first user terminal T 1 . In this case, when the settlement token is received from the first settlement server Q 1 , the relay server M stores the received settlement token in the storage unit  30  in association with the first service provider identifier. The relay server M can identify the settlement service provider available to the first user U 1  by reading the settlement token matching the settlement token included in the settlement information received from the second user terminal T 2  from the storage unit  30  and acquiring the first service provider associated with the settlement token. 
     Fourth Modification Example of First Embodiment 
       FIG. 8  is a diagram illustrating a settlement process performed by the settlement processing system S according to a fourth modification example of the first embodiment. The settlement processing system S according to the fourth modification example of the first embodiment is different from the settlement processing system S according to the first embodiment in that the second user terminal T 2  reading the settlement code transmits the settlement information to the second settlement server Q 2  rather than the relay server M. 
     Hereinafter, a settlement process performed by the settlement processing system S according to the fourth modification example of the first embodiment will be described in the order of  8 -( 1 ) to  8 -( 14 ) with reference to  FIG. 8 . These reference numbers correspond to  8 -( 1 ) to  8 -( 14 ) in  FIG. 8 . Since the processes of  8 -( 1 ) to  8 -( 4 ) are the same as the processes of  3 -( 1 ) to  3 -( 4 ) in  FIG. 3 , a description thereof will be omitted. 
       8 -( 5 ) The settlement information transmission unit  211  of the second user terminal T 2  transmits the settlement information including the settlement token and the settlement price acquired by the code reading unit  210  to the second settlement server Q 2 . 
       8 -( 6 ) The settlement management unit  511  of the second settlement server Q 2  transmits the settlement information received from the second user terminal T 2  to the relay server M when the settlement token included in the settlement information received from the second user terminal T 2  is different from the settlement token used by the second settlement server Q 2 . 
       8 -( 7 ) The settlement information reception unit  310  of the relay server M receives the settlement information from the second settlement server Q 2 . 
       8 -( 8 ) The settlement request unit  311  of the relay server M transmits the settlement token and the settlement price to the first settlement server Q 1  of the first settlement service provider identified by the first service provider identifier acquired from the settlement token included in the settlement information received by the settlement information reception unit  310 . 
       8 -( 9 ) The settlement management unit  411  of the first settlement server Q 1  performs user authentication by determining whether the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M. The settlement management unit  411  of the first settlement server Q 1  acquires the first user identifier associated with the settlement token received from the relay server M from the storage unit  40  under the condition that the settlement token transmitted to the first user terminal T 1  matches the settlement token received from the relay server M, determines whether the settlement price can be settled with a balance of an account of the first user U 1  identified with the first user identifier, and notifies the relay server M of a result as information regarding a settlement approval. 
       8 -( 10 ) When the settlement price can be settled with the balance of the account of the first user U 1 , the settlement request unit  311  of the relay server M transmits a request for settling the settlement price included in the settlement information to the second settlement server Q 2  managed by the second settlement service provider. 
       8 -( 11 ) The settlement management unit  511  of the second settlement server Q 2  performs settlement of the settlement price received from the relay server M under the condition that user authentication based on the second user identifier received from the settlement request unit  311  of the relay server M is successful. 
       8 -( 12 ) The settlement management unit  511  notifies the second user terminal T 2  of the completion of the settlement. 
       8 -( 13 ) When a settlement request is transmitted to the second settlement server Q 2 , the notification unit  312  of the relay server M notifies the first user terminal T 1  of the completion of the settlement. 
       8 -( 14 ) The adjustment management unit  512  of the second settlement server Q 2  requests the adjustment management unit  412  of the first settlement server Q 1  to perform adjustment. The relay server M may relay the adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . 
     In this way, in the settlement processing system S according to the fourth modification example of the first embodiment, the second user terminal T 2  transmits the settlement information to the second settlement server Q 2  rather than the relay server M. The second settlement server Q 2  cannot perform the settlement process since the settlement token included in the received settlement information is generated by the first settlement server Q 1 . Therefore, the settlement information is transmitted to the relay server M. It is not necessary to exchange information between the second user terminal T 2  and the relay server M. Therefore, even when the second user U 2  does not designate member store registration in the relay server M, the relay server M can relay the settlement process as long as the second settlement server Q 2  registers the service provider in the relay server M. 
     Fifth Modification Example of First Embodiment 
       FIG. 9  is a diagram illustrating a settlement process performed by the settlement processing system S according to a fifth modification example of the first embodiment. The settlement processing system S according to the fifth modification example of the first embodiment is different from the settlement processing system S according to the first embodiment in that the first user terminal T 1  transmits a request for acquiring the settlement token to the relay server M. 
     Hereinafter, a settlement process performed by the settlement processing system S according to the fifth modification example of the first embodiment will be described in the order of  9 -( 1 ) to  9 -( 13 ) with reference to  FIG. 9 . These reference numbers correspond to  9 -( 1 ) to  9 -( 13 ) in  FIG. 9 . 
       9 -( 1 ) The token request unit  110  of the first user terminal T 1  transmits a request for acquiring a settlement token for performing settlement using the first settlement server Q 1  to the relay server M. 
       9 -( 2 ) The token transmission unit (not illustrated) of the relay server M generates a token associated with the first service provider identifier for identifying the first settlement service provider in response to the acquisition request acquired from the first user terminal T 1  and transmits the generated settlement token to the first user terminal T 1 . The storage unit  30  stores the settlement token transmitted to the first user terminal T 1  in association with the first user identifier for identifying the first user U 1 . 
     The relay server M performs user authentication of the user using the first user terminal T 1  when there is a request for the token from the token request unit  110  of the first user terminal T 1  or before there is the request for the token. Specifically, when the first user terminal T 1  signs in the relay server M with an identifier associated with the first user identifier, the relay server M can realize the user authentication. When there is a request for the token from the token request unit  110  of the first user terminal T 1 , the relay server M may consider the user authentication to be successful under the condition that the first service provider identifier is acquired from the token request unit  110 . Under the condition that the user authentication is successful, the token transmission unit  410  of the first settlement server Q 1  generates the settlement token. 
     Since the processes of  9 -( 3 ) to  9 -( 13 ) in  FIG. 9  are the same as the processes of  3 -( 3 ) to  3 -( 13 ) in  FIG. 3 , description thereof will be omitted. In the settlement processing system S according to the fifth modification example of the first embodiment, the relay server M generates the settlement token when there is a request for acquiring the settlement token from the user terminal T in the user registration in the relay server M. In this way, since the relay server M is in charge of a part of the settlement token generation process, the settlement processing system S according to the fifth modification example of the first embodiment can distribute a processing load on the first settlement server Q 1 . 
     Sixth Modification Example of First Embodiment 
       FIG. 10  is a diagram illustrating a settlement process performed by the settlement processing system S according to a sixth modification example of the first embodiment. Specifically, the settlement processing system S according to the sixth modification example is a settlement system in conformity with the store suggestion scheme. Accordingly, the first user terminal T 1  is a store terminal and the first user U 1  is a manager or the like of a store R in which the store terminal is installed. A customer of the store R is the second user U 2  and a user terminal of the second user U 2  is the second user terminal T 2 . 
     Hereinafter, a settlement process performed by the settlement processing system  5  according to the sixth modification example of the first embodiment will be described in the order of  10 -( 1 ) to  10 -( 13 ) with reference to  FIG. 10 . These reference numbers correspond to  10 -( 1 ) to  10 -( 13 ) in  FIG. 10 . 
       10 -( 1 ) The token request unit  110  of the first user terminal T 1  transmits a request for acquiring the settlement token to the first settlement server Q 1  managed by the first settlement service provider available to the first user U 1 . 
       10 -( 2 ) The token transmission unit  410  of the first settlement server Q 1  generates a token associated with the first service provider identifier for specifying the first settlement service provider in response to the acquisition request acquired from the first user terminal T 1  and transmits the acquired token to the first user terminal T 1 . 
       10 -( 3 ) The display control unit  111  of the first user terminal T 1  displays the settlement code generated based on the settlement token received from the first settlement server Q 1  on the display unit of the first user terminal T 1 . 
       10 -( 4 ) The code reading unit  210  of the second user terminal T 2  reads the settlement code displayed on the display unit of the first user terminal T 1  to acquire the settlement token. 
       10 -( 5 ) The settlement information transmission unit  211  of the second user terminal T 2  transmits settlement information including the settlement token acquired by the code reading unit  210 , a second user identifier for identifying the second user U 2  using the second user terminal T 2 , a settlement price, and a second service provider identifier for identifying the second settlement service provider available to the second user U 2  to the relay server M. 
       10 -( 6 ) The settlement information reception unit  310  of the relay server M receives the settlement information from the second user terminal T 2 . 
       10 -( 7 ) The settlement request unit  311  of the relay server M transmits the settlement price and the second user identifier for specifying the second user U 2  to the second settlement server Q 2  of the second settlement service provider with which the second user U 2  carrying the second user terminal T 2  makes a contract. 
       10 -( 8 ) The settlement management unit  511  of the second settlement server Q 2  performs user authentication using the second user identifier received from the relay server M. When the authentication is successful, the settlement management unit  511  of the second settlement server Q 2  determines whether the settlement price can be settled with a balance of an account of the second user U 2  specified with the second user identifier and notifies the relay server M of a result. 
       10 -( 9 ) When the settlement price can be settled with the balance of the account of the second user U 2 , the settlement request unit  311  of the relay server M transmits a request for settling the settlement price included in the settlement information to the first settlement server Q 1  managed by the first settlement service provider. 
       10 -( 10 ) The settlement management unit  411  of the first settlement server Q 1  performs settlement of the settlement price received from the relay server M. Specifically, the settlement management unit  411  makes payment of an amount equivalent to the settlement price on an account opened by the first user U 1 . 
       10 -( 11 ) The settlement management unit  411  notifies the first user terminal T 1  of the completion of the settlement. 
       10 -( 12 ) When a settlement request is transmitted to the first settlement server Q 1 , the notification unit  312  of the relay server M notifies the second user terminal T 2  of the completion of the settlement. 
       10 -( 13 ) The adjustment management unit  412  of the first settlement server Q 1  requests the adjustment management unit  512  of the second settlement server Q 2  to perform adjustment. As a result, an amount of money equivalent to the settlement price is remitted from the account of the second user U 2  managed by the second settlement server Q 2  to the first settlement server Q 1 . The relay server M may relay the adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . 
     Thus, the settlement processing system S can realize the electronic settlement even when the kind of electronic settlement contracted by the first user U 1  is different from the kind of electronic settlement contracted by the second user U 2 . 
     Second Embodiment 
     Overview of Second Embodiment 
     An overview of a second embodiment will be described. A settlement processing system S according to the second embodiment is a settlement system in conformity with the store suggestion scheme. Accordingly, in the settlement processing system S according to the second embodiment, the first user terminal T 1  is a store terminal installed in a store R and the second user terminal is a customer terminal carried by a customer using the store R. Hereinafter, in the settlement processing system S according to the second embodiment, a store terminal which is the first user terminal T 1  is referred to as a “store terminal T 1 ” and a customer terminal which is the second user terminal T 2  is referred to as a “customer terminal T 2 .” 
     In the customer terminal T 2  according to the second embodiment, a code generation algorithm used in a plurality of different settlement server Q and application software (hereinafter referred to as a “settlement app”) that has an encryption key are installed in advance. Specifically, when an owner of the customer terminal T 2  carries out user registration with the relay server M, the customer terminal T 2  can download the settlement app from the relay server M. 
     Since the customer terminal T 2  according to the second embodiment has the settlement app, the customer terminal T 2  can encode a settlement token read from the store terminal T 1  using an algorithm used by the settlement server Q using the settlement token or can encrypt the settlement token with an encryption key used by the settlement server Q. In the settlement processing system S according to the second embodiment, the customer terminal T 2  converts information received from the store terminal T 1  into information which can be handled by the first settlement server Q 1  and encrypts the converted information with an encryption key used by the first settlement server Q 1 . From this viewpoint, the settlement processing system S is different from the settlement processing system S according to particularly the second modification example of the first embodiment. 
     Hereinafter, a functional configuration of each device included in the settlement processing system S according to the second embodiment and a settlement process performed by the settlement processing system S according to the second embodiment will be described. The repeated description of the settlement processing system S according to the first embodiment or the various modification examples will be appropriately omitted or described in brief. 
       FIG. 11  is a block diagram schematically illustrating a functional configuration of each device included in the settlement processing system S according to a second embodiment. In  FIG. 11 , since the relay server M, the first settlement server Q 1 , and the second settlement server Q 2  have the same functional configurations as the relay server M, the first settlement server Q 1 , and the second settlement server Q 2  according to the first embodiment illustrated in  FIG. 2 , detailed illustration is omitted. As illustrated in  FIG. 11 , the control unit  21  of the customer terminal T 2  according to the second embodiment is different from the second user terminal T 2  according to the first embodiment in that an encryption unit  212  is included. 
       FIG. 12  is a diagram illustrating a settlement process performed by the settlement processing system S according to the second embodiment. Hereinafter, a settlement process performed by the settlement processing system S according to the second embodiment will be described in the order of  12 -( 1 ) to  12 -( 15 ) with reference to  FIGS. 11 and 12 . These reference numbers correspond to  12 -( 1 ) to  12 -( 15 ) in  FIG. 12 . 
       12 -( 1 ) The token request unit  110  of the store terminal T 1  transmits a request for acquiring a settlement token to the first settlement server Q 1  managed by the first settlement service provider available to the manager or the store R in which the store terminal T 1  is installed. 
       12 -( 2 ) The token transmission unit  410  of the first settlement server Q 1  generates a token associated with a first service provider identifier for identifying the first settlement service provider in response to the acquisition request acquired from the store terminal T 1  and transmits the token to the store terminal T 1 . 
       12 -( 3 ) The display control unit  111  of the store terminal T 1  displays the settlement code generated based on the settlement token received from the first settlement server Q 1  on the display unit of the store terminal T 1 . 
       12 -( 4 ) The code reading unit  210  of the second user terminal T 2  reads the settlement code displayed on the display unit of the store terminal T 1  to acquire the settlement token. 
       12 -( 5 ) The encryption unit  212  of the customer terminal T 2  encrypts the settlement information including the second service provider identifier for identifying the second settlement service provider available to a customer carrying the customer terminal T 2 , the settlement token, and the settlement price with the encryption key used by the first settlement server Q 1  which is a settlement server of the first settlement service provider. 
       12 -( 6 ) The settlement information transmission unit  211  of the customer terminal T 2  transmit the settlement information encrypted by the encryption unit  212  to the relay server M. 
       12 -( 7 ) The settlement information reception unit  310  of the relay server M receives the encrypted settlement information from the customer terminal T 2 . 
       12 -( 8 ) The encryption unit  212  of the relay server M decodes the settlement information received from the customer terminal T 2  to acquire the first service provider identifier included in the settlement token. 
       12 -( 9 ) The settlement request unit  311  of the relay server M transmits the encrypted settlement information acquired from the customer terminal T 2  to the first settlement server Q 1 . 
       12 -( 10 ) The settlement management unit  411  of the first settlement server performs user authentication of the customer who is the user of the store terminal T 1  based on the settlement information transmitted from the relay server M and transmits an authentication result to the relay server M. Specifically, when the settlement token transmitted to the store terminal T 1  by the token transmission unit  410  matches the settlement token included in the settlement information received from the relay server M, the settlement management unit  411  of the first settlement server determines the authentication of the customer is successful. 
       12 -( 11 ) When the authentication is successful, the settlement request unit  311  of the relay server M transmits a request for settling the settlement price to the second settlement server Q 2 . 
       12 -( 12 ) When the settlement can be paid with the balance of the account of the customer, the settlement management unit  511  of the second settlement server Q 2  performs the settlement. 
       12 -( 13 ) The settlement management unit  511  of the second settlement server Q 2  transmits a notification indicating completion of the settlement to the relay server M. 
       12 -( 14 ) The notification unit  312  of the relay server M notifies the first settlement server Q 1  and the customer terminal T 2  of the completion of the settlement. 
       12 -( 15 ) The adjustment management unit  412  of the first settlement server Q 1  requests the adjustment management unit  512  of the second settlement server Q 2  to perform adjustment. As a result, an amount of money equivalent to the settlement price is remitted from the account of the customer managed by the second settlement server Q 2  to the first settlement server Q 1 . The relay server M may relay the adjustment process performed between the first settlement server Q 1  and the second settlement server Q 2 . 
     Advantageous Effects Obtained by Settlement Processing System S According to Second Embodiment 
     As described above, according to the settlement processing system S according to the second embodiment, the user U can carry out the settlement without being aware of the kind of electronic settlement. 
     In particular, in the settlement processing system S according to the second embodiment, the customer terminal T 2  converts the information received from the store terminal T 1  into the information which can be handled by the first settlement server Q 1  or encrypts the converted information with the encryption key used by the first settlement server Q 1 . In the settlement processing system S according to the second embodiment, the customer terminal T 2  subrogates some of the processes which are performed by the relay server M or the settlement server Q. Therefore, a load can be distributed in the entire system. 
     First Modification Example of Second Embodiment 
     As described above, the second settlement server Q 2  performs the settlement based on the settlement information and the first settlement server Q 1  is requested to perform the adjustment later. Instead of this, the first settlement server Q 1  may perform the settlement based on the settlement information and the second settlement server may be requested to perform the adjustment later. That is, it can be said that the settlement request unit  311  of the relay server M can transmit a request for settling the settlement price to one settlement server Q between the first settlement server Q 1  and the second settlement server Q 2 . When one settlement server Q receiving the settlement request performs the settlement process and the adjustment request is transmitted to the other settlement server Q, the settlement processing system S can realize the electronic settlement although the kind of electronic settlement for which the manager of the store R makes the contract is different from the kind of electronic settlement for which the customer makes the contract. 
     Second Modification Example of Second Embodiment 
     The settlement processing system S according to the second modification example of the second embodiment is different from the settlement processing system S according to the second embodiment in that the first settlement server Q 1  transmits the generated settlement token to the relay server M. 
     In the relay server M according to the second modification example of the second embodiment, the settlement request unit  311  stops the settlement process when the settlement token received from the first settlement server Q 1  does not match the settlement token received from the customer terminal T 2 . More specifically, the relay server M receives a settlement token encrypted with the encryption key used by the first settlement server Q 1  from the first settlement server Q 1  and acquires the settlement token by performing decoding using the same encryption key. The relay server M receives the settlement information encrypted with the encryption key used by the first settlement server Q 1  from the customer terminal T 2 , decodes the settlement information using the same encryption code, and then extracts the settlement token. The relay server M compares the settlement token originating from the first settlement server Q 1  with the settlement token originating from the customer terminal T 2  and determines whether both the settlement tokens match each other. Thus, since the relay server M performs a process equivalent to the authentication process for the store terminal T 1  by the first settlement server Q 1 , a load on the first settlement server Q 1  can be reduced. 
     Third Modification Example of Second Embodiment 
     The settlement processing system S according to the third modification example of the second embodiment is different from the settlement processing system S according to the second embodiment in that the store terminal T 1  transmits a request for acquiring the settlement token to the relay server M. Thus, since the relay server M can be in charge of a part of the settlement token generation process, the settlement processing system S according to the third modification example of the second embodiment can distribute a processing load on the first settlement server Q 1 . 
     The embodiments of the present invention have been described, but the technical scope of the present invention is not limited to the scope describe in the foregoing embodiments and various modifications and changes can be made within the scope of the gist of the present invention. For example, specific embodiments of distribution and integration of devices are not limited to the foregoing embodiments and all or some of the specific embodiments can be distributed or integrated functionally or physically in any units. New embodiments obtained in any combination of the plurality of embodiments are also included in the embodiments of the present invention. Advantageous effects obtained in the combination include the advantageous effects of the original embodiments. 
     REFERENCE SIGNS LIST 
     
         
         
           
             T 1  First user terminal 
               10  Storage unit 
               11  Control unit 
               110  Token request unit 
               111  Display control unit 
             T 2  Second user terminal 
               20  Storage unit 
               21  Control unit 
               210  Code reading unit 
               211  Settlement information transmission unit 
               212  Encryption unit 
             M Relay server 
               30  Storage unit 
               31  Control unit 
               310  Settlement information reception unit 
               311  Settlement request unit 
               312  Notification unit 
             Q 1  First settlement server 
               40  Storage unit 
               41  Control unit 
               410  Token transmission unit 
               411  Settlement management unit 
               412  Adjustment management unit 
             Q 2  Second settlement server 
               50  Storage unit 
               51  Control unit 
               510  Token transmission unit 
               511  Settlement management unit 
               512  Adjustment management unit 
             N Communication network 
             S Settlement processing system