Abstract:
There is provided a multifunction peripheral comprising an operation unit, a key definition unit to define usable keys for password setting depending on a type of a certain function, a password setting unit to accept a password through the usable keys defined by the key definition unit and to set the password in the multifunction peripheral, a password authentication unit configured such that when execution of the certain function is instructed, the password authentication unit accepts a password through the plurality of keys of the operation unit and judges whether the password accepted through the plurality of keys matches the password set by the password setting unit, and a function control unit configured to permit execution of the certain function if it is judged by the password authentication unit that the password accepted through the plurality of keys matches the password set by the password setting unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 U.S.C. § 119 from Japanese Patent Application No. 2007-039205, filed on Feb. 20, 2007. The entire subject matter of the application is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    Aspects of the present invention relate to a password setting system and a multifunction peripheral used for password setting. 
         [0004]    2. Related Art 
         [0005]    Multifunction peripherals (MFPs) having a print function, a facsimile function, a copying function and a scanner function have been widely used. For example, such a multifunction peripheral is used in an environment where a single MFP is shared by a plurality of personal computers via a network. In such an environment, a possibility that a confidential document made by printing out confidential data may be exposed to another person arises. A possibility that scanned data made by reading a confidential original may be exposed to another person also arises. Since the MFP is shared by a plurality of users, the setting of the MFP may be modified in contradiction to a certain user, which is very inconvenient for the certain user. 
         [0006]    Recent MFPs are provided with a function of password setting and authentication. According to such a configuration of the MFP, it is possible to control the MFP such that when a user who transmitted confidential data to the MFP inputs a password (which has been set in the MFP) to the MFP, the MFP prints the confidential data (i.e., a secured printing operation). It is also possible to control the MFP to transmit scanned data of a confidential document to a particular personal computer. On the MFP, a particular administrator is authorized to change settings of the MFP. That is, in this case, the MFP permits change of settings of the MFP only when a password inputted by the particular administrator is authenticated. 
         [0007]    Regarding password setting, the number of combinations of numbers becomes small if a password is set only by a train of numbers. Therefore, in this case, the level of security is relatively low. On the other hand, if the number of usable letters for a password is increased, it becomes hard for a user to keep such a password in mind. In general, the MFP is provided with function keys for setting and executing functions of the MFP in addition to having a ten-key. 
         [0008]    Japanese Patent Provisional Publication No. 2005-275943 discloses a multifunction peripheral configured to allow a user to set a password as a combination of a ten-key and function keys and to permit a user to use a function only when an inputted password (which is formed by a ten-key and function keys) matches a registered password (which is also formed by a ten-key and function keys). According to such a configuration, the number of keys to be used for password setting can be reduced while making it possible to form a relatively complicated password. Consequently, it becomes possible to prevent unauthorized use of the MFP from occurring. 
         [0009]    However, regarding a user operation for inputting a password, another person easily watches the user operation conducted through an operation unit of the MFP. Therefore, there is a possibility that a password is stolen by another person. That is, the level of security of the above mentioned MFP is relatively low. 
       SUMMARY 
       [0010]    Aspects of the present invention are advantageous in that at least one of a multifunction peripheral, a password setting system, a method and a computer readable medium for password setting capable of enhancing the level of security is provided. 
         [0011]    According to an aspect of the invention, there is provided a multifunction peripheral having a plurality of functions. The multifunction peripheral comprises an operation unit that has a plurality of keys to be operated, a key definition unit configured to define usable keys for password setting depending on a type of a certain function selected from the plurality of functions, the usable keys being chosen from among the plurality of the keys of the operation unit, a password setting unit configured to accept a password through the usable keys defined by the key definition unit and to set the password in the multifunction peripheral, a password authentication unit configured such that when execution of the certain function is instructed, the password authentication unit accepts a password through the plurality of keys of the operation unit and judges whether the password accepted through the plurality of keys matches the password set by the password setting unit, and a function control unit configured to permit execution of the certain function if it is judged by the password authentication unit that the password accepted through the plurality of keys matches the password set by the password setting unit. 
         [0012]    The above mention configuration of the multifunction peripheral makes it possible to limit keys to be used for password setting depending on a type of a certain function of the plurality of functions, and thereby to complicate passwords so that the security level can be enhanced. 
         [0013]    According to another aspect of the invention, there is provided a password setting system, comprising an information processing device; and a multifunction peripheral having a plurality of functions. In this system, the information processing unit and the multifunction peripheral being communicatably connected with each other. The information processing device comprises: a display control unit configured to display a virtual key operation unit corresponding to an image of an operation unit of the multifunction peripheral; a password setting unit configured to accept an password through the virtual key operation unit and to set the password in the information processing device; and a password transmission unit configured to transmit the password set by the password setting unit to the multifunction peripheral. The multifunction peripheral comprising: the operation unit having a plurality of keys; a password receiving unit configured to receive the password from the information processing device; a password authentication unit configured such that when execution of a certain function is instructed, the password authentication unit accepts a password through the operation unit and judges whether the password accepted through the plurality of keys of the operation unit matches the password received by the password receiving unit; and a function control unit configured to permit execution of the certain function if it is judged by the password authentication unit that the password accepted through the operation unit matches the password received by the password receiving unit. 
         [0014]    The above mentioned configuration of the password setting system makes it possible to conduct password entry on the information processing device located at a hidden position. Therefore, it is possible to prevent passwords from being stolen by another person. Consequently, the security level can be increased. 
         [0015]    According to another aspect of the invention, there is provided a computer readable medium having computer readable instruction stored thereon, which, when executed by a processor of an information processing device communicatably connected to a multifunction peripheral, configures the processor to perform the steps of: displaying a virtual key operation unit corresponding to an image of an operation unit of the multifunction peripheral; accepting a password through the virtual key operation unit; and transmitting the accepted password to the multifunction peripheral. 
         [0016]    Such a configuration makes it possible to conduct password entry on the information processing device located at a hidden position. Therefore, it is possible to prevent passwords from being stolen by another person. Consequently, the security level can be increased. 
         [0017]    According to another aspect of the invention, there is provided a method for controlling a multifunction peripheral for executing a certain function selected from a plurality of functions of the multifunction peripheral. The method comprises the steps of: defining usable keys for password setting depending on a type of the certain function selected from the plurality of functions, the usable keys being chosen from among a plurality of keys of an operation unit of the multifunction peripheral; accepting a password through the defined usable keys to set the password in the multifunction peripheral; accepting a password through the plurality of keys of the operation unit to judge whether the password accepted through the plurality of keys matches the password set in the multifunction peripheral when execution of the certain function is instructed; and permitting execution of the certain function if it is judged that the password accepted through the plurality of keys matches the password set in the multifunction peripheral. 
         [0018]    The above mention configuration of the method makes it possible to limit keys to be used for password setting depending on a type of a certain function of the plurality of functions of the multifunction peripheral, and thereby to complicate passwords so that the security level can be enhanced. 
         [0019]    It is noted that various connections are set forth between elements in the following description. It is noted that these connections in general and unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. Aspects of the invention may be implemented in computer software as programs storable on computer-readable media including but not limited to RAMs, ROMs, flash memory, EEPROMs, CD-media, DVD-media, temporary storage, hard disk drives, floppy drives, permanent storage, and the like. 
     
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         [0020]      FIG. 1  is a conceptual block diagram illustrating a password setting system according to a first embodiment. 
           [0021]      FIG. 2  illustrates an inner structure of an MFP (Multifunction Peripheral). 
           [0022]      FIG. 3  is a plan view of an operation unit of the MFP. 
           [0023]      FIG. 4  illustrates a block diagram of a control unit of the MFP. 
           [0024]      FIG. 5  is a flowchart illustrating a password input program. 
           [0025]      FIG. 6  is a sub-flowchart illustrating a password string input process. 
           [0026]      FIG. 7  is a flowchart illustrating a password authentication process corresponding to a password authentication program. 
           [0027]      FIG. 8  illustrates a system configuration of a password setting system according to a second embodiment. 
           [0028]      FIG. 9  is a flowchart illustrating a password setting process corresponding to a password setting program. 
           [0029]      FIG. 10  is a flowchart illustrating a setting process for a secured printing operation. 
           [0030]      FIG. 11  illustrates an example of a print setting screen displayed during execution of the password setting process shown in  FIG. 9 . 
           [0031]      FIG. 12  is an example of a password setting screen displayed during the setting process for a secured printing operation shown in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Hereafter, an embodiment according to the invention will be described with reference to the accompanying drawings. 
       First Embodiment 
       [0033]      FIG. 1  is a conceptual block diagram illustrating a password setting system  1  according to a first embodiment. As shown in  FIG. 1 , in the password setting system  1 , PCs (Personal Computers)  2  each of which functions as an information processing device are communicatably connected to an MFP (Multifunction Peripheral)  10  via a LAN  3 . 
         [0034]    The PC  2  is configured to load a printer driver into an inner memory thereof to communicate with the MFP  10  via the printer driver. The MFP  10  has a plurality of functions including a print function, a facsimile function, a copying function, and a scanner function. By operating an operation unit  25 , one of the functions can be selected and executed. 
         [0035]      FIG. 2  illustrates an inner structure of the MFP  10 . As shown in  FIG. 2 , the MFP  10  has an image formation unit  11  which forms an image on a recording sheet, and an image reading unit  21  which reads an image from an original. The image formation unit  11  and the image reading unit  21  are arranged such that the image formation unit  11  is stacked on the image reading unit  12 . 
         [0036]    In the lower part of the image formation unit  11 , a sheet supply cassette  12  which accommodates a stack of recording sheets is located. The sheet supply cassette  12  can be detachable attached to the lower part of the mage formation unit  11  from the front side. In the image formation unit  11 , a sheet supply unit  13  supplies sheets to an image forming portion  14  one-by-one, and an image is formed on the sheet at the position of the image forming portion  14 . An output tray  16  is formed on the top surface of the image formation unit  11  so that the sheet on which an image is formed is ejected to the output tray  16  through an ejection unit  15 . 
         [0037]    The image reading unit  21  is rotatably attached to the image formation unit  11  to enable a user to easily pick up the sheet ejected on the output tray  16 . In the image reading unit  21 , a reading sensor  22  is provided to be movable along a platen glass  23  so that an image can be read from an original placed on the platen glass  23 . The image reading unit  21  includes an ADF (Automatic Document Feeder)  24  so that an original can be automatically carried to the platen glass  23  and an image can be read from the original carried to the platen glass  23 . On the front side of the image formation unit  1 , the operation unit  25  is provided. The user is allowed to operate the MFP  10  through the operation unit  25 . 
         [0038]      FIG. 3  is a plan view of the operation unit  25 . As shown in  FIG. 3 , the operation unit  25  is formed such that a plurality of keys  27  are exposed through a cover plate  28 . An LCD (Liquid Crystal Display)  26  is placed in a central portion of the operation unit  25 , and various keys are placed around the LCD  26 . 
         [0039]    The keys  27  include a ten-key  27   a  and function keys used to input instructions to the MFP  10 . For example, the function keys include a Stop/Exit key  27   b  for suspending or canceling an operation of the MFP  10 , a Start key  27   c  for instructing the MFP  10  to start an operation, arrow keys  27   d  used to switch onscreen representations of the LCD  26  or to select instructions, an OK key  27   e  for confirming an operation, a clear key  27   f  for displaying a menu of the functions of the MFP  10  on the LCD  26 , abbreviated dialing keys  27   h  for managing registered telephone numbers as abbreviated numbers, Print-specific keys  27   i  dedicated to the print function, FAX-specific keys  27   j  dedicated to the facsimile function, Copy-specific keys  27   k  dedicated to the copying function, and mode switch keys  27   l  used to switch operations between the facsimile function, the copying function and the scanner function. 
         [0040]    The MFP  10  includes a control unit  30  which controls internal units including the sheet supply unit  13 , the image formation unit  14 , the ejection unit  15 , the reading sensor  22 , the LCD  26  and the keys  27  to execute the functions. 
         [0041]      FIG. 4  illustrates a block diagram of the control unit  30 . The control unit  30  has a general configuration as a computer. As shown in  FIG. 4 , the control unit  30  includes a CPU  31 , a ROM  32 , a RAM  33 , an NVRAM  34 . In the ROM  33 , a password input program  42  which, when executed by the CPU  31 , controls input of passwords, a password authentication program  43  which, when executed by the CPU  31 , executes user authentication and executes a particular function. In the NVRAM  34 , a password memory area  41  for storing an inputted password is provided. 
         [0042]    The CPU  31  is connected to the LAN  3  via an input/output interface  35 , and is able to communicate with the PC  2  via the input/output interface  35 . The sheet supply unit  13 , the image formation unit  14 , the ejection unit  15 , the reading sensor  22  and the ADF  24  are connected to the input/output interface  35  via the CPU  31 . In this configuration, the CPU  31  controls a printing operation where data read by the reading sensor  22  or image data transmitted from the PC  2  is printed on a recording sheet. Further, the CPU  31  is able to connect to a public switched telephone network (PSTN)  37  or the Internet (not shown) via a communication control unit  36  to execute transmission of data (e.g., facsimile data or image data) to and receive data from an external device located outside the password setting system  1 . 
         [0043]    Hereafter, the password input program  42  is explained.  FIG. 5  is a flowchart illustrating the password input program. The password input program  42  is loaded from the ROM  32  when the user operates the keys  27  of the operation unit  25 , and is executed by the CPU  31 . When executed by the CPU  31 , the password input program  42  selects keys to be used for operation of password setting from among the keys  27  on the operation unit  25  depending on the operation mode currently set (i.e., a current function). That is, usable keys for password setting are changed depending on the type of the currently set function. Further, by the password input program  42 , a password inputted by the user through the usable keys is stored in the password memory area  41 . 
         [0044]    As shown in  FIG. 5 , in step S 11 , the CPU  31  checks the type of the current function which is currently selected by the user, for example, by detecting operations conducted for the Print-specific keys  27   i , the FAX-specific keys  27   j , the Copy-specific keys  27   k  or the mode switch keys  27   l.    
         [0045]    If the CPU  31  detects that the Print-specific keys  27   i  are operated, the CPU  31  judges that the current function is the print function (S 11 : Print Function), and control proceeds to step S 12  where the CPU  31  defines the ten-key  27   a , the abbreviated dialing keys  27   h , the FAX-specific keys  27   j , and the Copy-specific keys  27   k  as usable keys for password setting. Then, control proceeds to step S 16 . 
         [0046]    If the CPU  31  detects that the FAX-specific keys  27   j  or a FAX key in the mode switch keys  27   l  are operated, the CPU  31  judges that the current function is the facsimile function (S 11 : Facsimile Function), and control proceeds to step S 13  where the CPU  31  defines the ten-key  27   a , and the Copy-specific keys  27   k  as usable keys for password setting. Then, control proceeds to step S 16 . 
         [0047]    If the CPU  31  detects that the Copy-specific keys  27   k  or a Copy key in the mode switch keys  27   l  are operated, the CPU  31  judges that the current function is the copying function (S 11 : Copying Function), and control proceeds to step S 14  where the CPU  31  defines the ten-key  27   a , the abbreviated dialing keys  27   h , and the FAX-specific keys  27   j  as usable keys for password setting. Then, control proceeds to step S 16 . 
         [0048]    If the CPU  31  detects that a SCAN key in the mode switch keys  27   l  is operated, the CPU  31  judges that the current function is the scanner function (S 11 : Scanner Function), and control proceeds to step S 13  where the CPU  31  defines the ten-key  27   a , the FAX-specific keys  27   j  and the Copy-specific keys  27   k  as usable keys for password setting. Then, control proceeds to step S 16 . 
         [0049]    By thus processing the steps S 11 -S 15 , the usable keys which can be used for password setting can be changed depending on the type of the current function. 
         [0050]    After the usable keys are thus defined depending on the type of the current function, the CPU  31  executes a password string input process (step S 16 ) where a password (i.e., a character string) is accepted. 
         [0051]      FIG. 6  is a sub-flowchart illustrating the password string input process. The password input process is executed each time one of the keys  27  provided on the operation unit  25  is pressed. In step S 161 , the CPU  31  accepts pressing of one of the keys  27  provided on the operation unit  25 . Then, the CPU  31  judges whether the OK key  27   e  is pressed to indicate completion of input of a password or the Stop/Exit key  27   b  is pressed to stop input of a password. If none of the OK key  27   e  and the Stop/Exit key  27   b  is pressed (S 162 : NO), control proceeds to step S 163  where the CPU  31  judges whether the pressed key belongs to the usable keys (i.e., keys for password setting) defined in one of steps S 12 -S 15 . 
         [0052]    If the pressed key does not belong to the usable keys for password setting (S 163 : NO), the pressed key is neglected and control returns to step S 161  to wait for key operation. If the pressed key belongs to the usable keys for password setting (S 163 : YES), data of the pressed key is added to a password string. In this case, the inputted key is displayed as an asterisk (*) so as to prevent the inputted password from being stolen by another person. Then, control returns to step S 161 . 
         [0053]    Thus, the user is allowed to input a desired password while the CPU  31  repeatedly executes steps S 161 -S 164 . If the OK key  27   e  is pressed (S 162 : YES, S 165 : YES), the CPU  31  recognizes that input of a password is completed and the CPU  31  stores the inputted password in the password memory area  41  (step S 166 ). Then, the password input process terminates, and control returns to the process shown in  FIG. 5 . Then, the process of the password input program shown in  FIG. 5  terminates. 
         [0054]    If the Stop/Exit key  27   b  is pressed (S 162 : YES, S 165 : NO), control proceeds to step S 167  where the inputted password (i.e., the keys which have been inputted before now) is cleared. Then, control returns to the process shown in  FIG. 5 . Then, the process of the password input program shown in  FIG. 5  terminates. 
         [0055]    Hereafter, the password authentication program is explained.  FIG. 7  is a flowchart illustrating a password authentication process corresponding to the password authentication program. The password authentication program is loaded by the CPU  31  from the ROM  32  when a command for executing the function for which the password is inputted is inputted to the MFP  10  through the operation unit  25 , and is executed under control of the CPU  31 . 
         [0056]    First, the CPU  31  detects user operation conducted through the operation unit  25  (step S 21 ). Then, the CPU  31  judges whether the detected user operation corresponds to pressing of a key requiring execution of a particular function (step S 22 ). If the CPU  31  judges that the detected user operation corresponds to a key not requiring execution of a particular function (e.g., the ten-key  27   a ) (S 22 : NO), the CPU  31  repeats step S 22 . 
         [0057]    If the CPU  31  judges that the detected user operation corresponds to pressing of a key requiring execution of a particular function (S 22 : YES), the CPU  31  judges whether the particular function requires input of a password (step S 23 ). For example, if the user operates the operation unit  25  to check the remaining amount of toner, input of a password is not required (S 23 : NO). Therefore, in this case, control proceeds to step S 28 . On the other hand, if the detected user operation corresponds to a command for execution of the function requiring input of a password (e.g., the print function or scanner function) (S 23 : YES), the CPU  31  displays a message requesting the user to input a password on the LCD  26  (step S 24 ). For example, in step S 24 , a message “Please input a password” is displayed. 
         [0058]    Next, in step S 25 , the CPU  31  detects operations conducted through the operation unit  25 . In this case, asterisks “** . . . ” are displayed in response to entry of keys of the password so as to prevent the inputted password from being stolen by another person. 
         [0059]    Then, the CPU  31  judges whether the inputted password (which is inputted in step S 25 ) matches the password stored in the password memory area  41  (step S 26 ). That is, the CPU  31  judges whether the password inputted through the operation unit  25  to execute the particular function matches the password inputted in the process shown in  FIG. 5 . 
         [0060]    If the password inputted through the operation unit  25  does not match the password stored in the password memory area  41  (S 26 : NO), the CPU  31  displays an error message (e.g., a message “A requested command can not be executed because the passwords do not match.”) on the LCD  26 . In this case, the password authentication process terminates without executing the requested function. 
         [0061]    If the password inputted through the operation unit  25  matches the password stored in the password memory area  41  (S 26 : YES), the particular function is executed (step S 28 ). 
         [0062]    Hereafter, operation modes of the MFP  1  and the password setting system  1  are explained. First, a secured printing operation is described. The secured printing operation means an operation where print data transmitted from the PC  2  to the MFP  10  is temporarily stored in the MFP  10  without immediately printing the received print data and thereafter the MFP  10  prints the stored print data when a sender of the print data operates the MFP  10  and inputs a print command. 
         [0063]    For example, to print confidential data, the user selects a secured printing operation by operating the operation unit  25  before printing the confidential data. Since the secured printing operation belongs to the print function, the ten-key  27   a , the abbreviated dialing keys  27   h , the FAX-specific keys  27   j  and the Copy-specific keys  27   k  become usable during password setting. 
         [0064]    The user inputs a password string by operating some or all of the ten-key  27   a , the abbreviated dialing keys  27   h , the FAX-specific keys  27   j  and the Copy-specific keys  27   k , and presses the OK key  27   e  to store the inputted password string to the password memory area  41 . For example, the user may press a key “1” of the ten-key  27   a , a key “2” of the abbreviated dialing keys  27   h , a key “3” of the ten-key  27   a , a key “on-hook” of the FAX-specific keys  27   j , and a key “5” of the abbreviated dialing keys  27   h . The user may input a password string by using the usable keys (the ten-key  27   a , the abbreviated dialing key  27   h , the FAX-specific keys  27   j  and the Copy-specific keys  27   k ) in combination. The user is also able to input a password string by simultaneously pressing a plurality of keys of the usable keys. 
         [0065]    Thereafter, the user moves to the place of the PC  2  and transmits confidential data from the PC  2  to the MFP  10  along with a command for a secured printing operation. 
         [0066]    In response to receipt of the confidential data, the MFP  10  analyses the command for a secured printing operation, and temporarily stores the confidential data in the RAM  33 . If the user moves to the place of the MFP  10  and selects the secured printing operation by operating the Print-specific keys  27   i , the MFP  10  judges that input of a password is necessary, and displays a password input screen on the LCD  26  (see S 21 , S 22 : YES, S 23 : YES, and S 24  of  FIG. 7 ). When the user presses the OK key  27   e  after inputting a password string through the operation unit  25 , the MFP  10  judges whether the inputted password matches the password stored in the password memory area  41  (see S 25 , S 26  of  FIG. 7 ). 
         [0067]    For example, if the user presses a key “1” of the ten-key  27   a , a key “2” of the abbreviated dialing keys  27   h , a key “3” of the ten-key  27   a , a key “on-hook” of the FAX-specific keys  27   j  and a key “5” of the abbreviated dialing keys  27   h  in this order, and then presses the OK key  27   e , the inputted password string matches the password stored in the password memory area  41 . In this case, the confidential data is read from the RAM  33  and is printed (see S 26 : YES, S 28  of  FIG. 7 ). 
         [0068]    On the other hand, if the user presses a key “1” of the abbreviated dialing keys  27   h , a key “2” of the abbreviated dialing keys  27   h , a key “3” of the ten-key  27   a , a key “on-hook” of the FAX-specific keys  27   j  and a key “5” of the abbreviated dialing keys  27   h  in this order, and then presses the OK key  27   e , the inputted password string does not match the password stored in the password memory area  41  because the key “1” of the abbreviated dialing keys  27   h  in the inputted password string is different from the key “1” of the ten-key  27   a  of the stored password. In this case, the confidential data stored in the password memory area  41  is not printed, and an error message is displayed on the LCD  26  (see S 26 : NO, S 27 ). 
         [0069]    Hereafter, an example of an operation in which a confidential drawing is scanned by the MFP  10  and the scanned data is transmitted to the PC  2  is explained. 
         [0070]    In the MFP  10 , authorized users who are permitted to use the scanner function of the MFP  10  are registered. Each authorized user registers a password and an address of the user&#39;s own PC  2  in the MFP  10 . In this case, the user presses a Scan key of the mode switch keys  27   l  on the operation unit  25  to select a security function (see S 11  of  FIG. 5 ). 
         [0071]    Regarding the scanner function, the ten-key  27   a , the FAX-specific keys  27   j , the Copy-specific keys  27   k  become usable for the password setting (see S 11 : the scanner function, and S 15  of  FIG. 5 ). The user inputs a password string (e.g., a key “fax transmission” of the FAX-specific keys  27   j , a key “scaling” of the Copy-specific keys  27   k , and a key “1” of the ten-key  27   a ) and then presses the OK key  27   e . In this case, the inputted password string is stored in the password memory area  41  (see S 16  of  FIG. 5  and  FIG. 6 ). Further, when the user registers the address of the PC  2  in the MFP  10 , the MFP  10  stores the address in the NVRAM  34  in association with the inputted password string. 
         [0072]    To scan the confidential drawings, the user presses the Scan key of the mode switch keys  27   l  to specify the function to be executed (see S 21 , S 22 : YES f  FIG. 7 ). In this case, since only the authorized users are permitted to use the scanner function and each of the authorized uses has inputted the password, the MFP  10  displays the password input screen on the LCD  26  (see S 23 : YES, S 24  of  FIG. 7 ). 
         [0073]    If the user inputs a password string (e.g., a key “fax transmission” of the FAX-specific keys  27   j , a key “scaling” of the Copy-specific keys  27   k , and a key “1” of the ten-key  27   a ) and presses the OK key  27   e , the MFP  10  judges that the inputted password string matches the password stored in the password memory area  41  (S 25 , S 26 : YES of  FIG. 7 ). Then, the MFP  10  displays a message “Scan is permitted.” on the LCD  26  and moves to a state where the user operation regarding the scanner function is accepted. Therefore, the user places the confidential drawing on the image reading unit  21  and presses the Start key  27   c  to scan the confidential drawing. Then, the scanned data is transmitted to the address of the PC  2  stored in association with the inputted password string. 
         [0074]    After the scanning operation is finished and the user returns to the place of the PC  2 , the user is able to open the file of the confidential drawing and to view the scanned confidential drawing on the PC  2 . 
         [0075]    It is understood that the above mentioned configuration makes it possible to avoid another PC  2  of another user from accidentally receiving the confidential drawing and thereby being interrupted by receipt of the confidential drawing and to avoid the confidential drawing from being transmitted to another device of an outside person. 
         [0076]    Settings of the MFP  10  are modified, for example, to add an authorized user of the scanner function to the MFP  10 . In such a case where the settings of the MFP  10  are modified, it is possible to prevent the settings of the MFP  10  from being modified by an unauthorized user by requesting a user who intends to modify the settings of the MFP  10  to input a password. 
         [0077]    Hereafter, advantages of the first embodiment are described. As described above, the MFP  10  changes the usable keys for the password setting of the keys  27  depending on the type of the function of the MFP  10  (see S 11 -S 15  of  FIG. 5 ). To set the password, the user inputs the password string by using the usable keys defined depending on the type of the current function of the MFP  10  (S 16  of  FIG. 5 , S 163 : YES, S 164  of  FIG. 6 ). To select a particular function (e.g., a secured printing operation) trough the operation unit  25  and to execute the selected function, the MFP  10  compares the password string inputted through the operation unit  35  with the password stored in advance in the password memory area  41 . Only if these passwords match each other, the MFP  10  executes the particular function (S 26 : YES, S 27  of  FIG. 7 ). 
         [0078]    Since usable keys which can be used in password setting are limited depending on the type of the function and therefore the types of keys to be used for password setting become complicated, security against unauthorized access is enhanced in comparison with the case where the user is allowed to use all of the keys  27  with respect to all of the functions of the MFP  10 . 
         [0079]    Regarding the password setting for a particular function (e.g., a scan-to-mail function), the MFP  10  defines keys which are not used for the scanner function (i.e., the ten-key  27   a , the FAX-specific keys  27   j  and the Copy-specific keys  27   k ) as the usable keys for the password setting. Such a configuration makes it possible to prevent the user from mistakenly inputting a command for execution of the scanner function during the password setting and thereby to prevent the scanned data from erroneously being transmitted to the PC  2  of another user. 
         [0080]    The MFP  10  defines the abbreviated dialing keys  27   h  as the usable keys for the password setting, and the abbreviated dialing keys  27   h  are managed as a train of numbers. Therefore, by using the abbreviated dialing keys  27   h  with the ten-key  27   a , it is possible to achieve the level of security more than twice as much as the level of security of the case where only ten-key  27   a  is used for the password setting. 
       Second Embodiment 
       [0081]      FIG. 8  illustrates a system configuration of a password setting system  1 A according to a second embodiment. Similarly to the first embodiment, in the password setting system  1 A a plurality of PCs ( 2 A,  2 A, . . . ) are connected to the MFP  10 . In  FIG. 8 , to elements which are substantially the same as those of the first embodiment, the same reference numbers are assigned, and explanations thereof will not be repeated. The feature of the second embodiment is that the PC  2 A accepts password entry. Therefore, the following explanations focus on the features of the second embodiment. 
         [0082]    In the password setting system  1 A, the MFP  10  and the PCs  2 A can communicate with each other via the LAN  3 . The PC  2 A has a general configuration as a computer, and includes a control unit  51 , an input unit (e.g., a keyboard  57  and a mouse  58 ), an LCD  59 , and a disc drive  60  through which information is read from a recording medium  61  (e.g., a CD). 
         [0083]    The control unit  51  includes a CPU  52 , a ROM  53 , a RAM  54 , an HDD (hard disk drive)  55 , and an input/output interface  56 . In the HDD  55 , a password setting program  62  is stored. For example, the password setting program  62  is read from the recording medium  61  via the disc drive  60 , and is stored in the HDD  55 . 
         [0084]      FIG. 9  is a flowchart illustrating a password setting process corresponding to the password setting program  62 . When the PC  2 A is turned on, the password setting program  62  is loaded from the HDD  55  and is executed under control of the CPU  52 .  FIG. 11  illustrates an example of a print setting screen displayed during execution of the password setting process shown in  FIG. 9 . As described below, the password setting program  62  controls password setting. 
         [0085]    As shown in  FIG. 9 , in step S 31 , the CPU  52  displays a print setting screen  101  shown in  FIG. 11  on the LCD  59 . The print setting screen  101  includes a setting column  74  for a secured printing operation as well as a setting column  73  for a normal printing operation. Through the setting column  73  for a normal printing operation, various types of settings, such as a paper size and margins, can be inputted. The print setting screen  101  also includes an OK button  71  and a CANCEL button  72 . 
         [0086]    In step S 32 , a user operation is accepted. That is, the user is allowed to input desired print settings into the print setting screen  101  by operating the keyboard  57  and the mouse  58 . Next, in step S 33 , the CPU  52  judges whether the OK button  71  or the CANCEL button  72  is pressed. If none of the OK button  71  and the CANCEL button  72  is pressed (S 33 : NO), control proceeds to step S 34  where the CPU  52  judges whether the user operates the print setting screen to open the setting column  73  for a secured printing operation. If the user does not operate the print setting screen  101  to open the setting column  73  (S 34 : NO), the CPU  52  executes a setting operation for setting items not concerning the secured printing operation (step S 35 ). If the user operates the print setting screen  101  to open the setting column  73  (S 34 : YES), the CPU  52  executes a setting process for a secured printing operation (step S 36 ). 
         [0087]      FIG. 10  is a flowchart illustrating the setting process for a secured printing operation.  FIG. 12  is an example of a password setting screen displayed during the setting process for a secured printing operation. 
         [0088]    As shown in  FIG. 10 , first, the CPU  52  judges whether a setting item of secured print is set to ON (step S 361 ). More specifically, the CPU  52  judges whether a radio button “ON” has been clicked on a secured print setting field  75 . If a radio button “OFF” has been clicked on the secured print setting field  75  (S 361 : NO), the setting process for a secured printing operation terminates. Then, control returns to step S 32  of  FIG. 9 . 
         [0089]    If the radio button “ON” has been clicked on the secured print setting field  75  (S 361 : YES), the CPU  52  displays the password setting screen shown in  FIG. 12  on the LCD  59  (S 362 ). As shown in  FIG. 12 , the password setting screen includes a virtual key operation unit  81  which is a virtual image of the operation unit  25  of the MFP  10 , a password display field  82  in which a password string inputted by operating the virtual key operation unit  81  is displayed, an OK button  83  used to instruct the PC  2 A that entry of the password string is completed, and a RETURN button  84  used to stop the password setting. 
         [0090]    In step S 16 , the CPU  52  executes the password string input process where the user inputs a password string as indicated in step S 16  of  FIG. 5  and in  FIG. 6 . In this embodiment, a password string is inputted by locating a cursor  70  to a position of a desired key on the virtual key operation unit  81 . In this case, virtual keys corresponding to the usable keys in the print function (i.e., the ten-key  27   a , the abbreviated dialing keys  27   h , the FAX-specific keys  27   j , and the Copy-specific keys  27   k ) are displayed in red color so as to be easily distinguishable from other keys. 
         [0091]    Since the inputted password string is displayed in the password display field  82 , the user is able to recognize the password string that the user inputted. After completing entry of the password string, the user clicks the OK button  83 . If the user wants to stop the password setting, the user clicks the RETURN button  84 . 
         [0092]    Next, in step S 363 , the CPU  52  sets a normal user name in a user name input field  77  and sets a normal job name (e.g., a first character string of a name of print data) into a job name input field  78  so that the user name and the job name identify print data targeted for the secured print from another print data. Then, the CPU  52  judges whether the user has inputted a user name and a job name in the user name input field  77  and the job name input field  78 , respectively. If the user name and the job name have been inputted by the user (S 364 : YES), the CPU  52  changes a user name of a job from the normal user name set at step S 363  to the user name inputted by the user and changes a job name for a job from the normal job name set at step S 363  to the job name inputted by the user (step S 365 ). Then, control proceeds to step S 366 . 
         [0093]    If the CPU  52  judges that the user name and the job name have not been inputted by the user (S 364 : NO), control proceeds to S 366  while retaining the normal user name and the normal job name. In step S 366 , the settings for the secured print are stored in a job. Then, control returns to step S 32  of  FIG. 9 . 
         [0094]    Referring back to  FIG. 9 , if the user has finished the print setting as described above and presses the OK button  71  or the CANCEL button  72  through the keyboard  57  or the mouse  58  (S 33 : YES), control proceeds to step S 37  where the CPU  52  judges whether the clicked button is the OK button  71 . If the clicked button is the OK button  71  (S 37 : YES), the CPU  52  transmits the job to the MFP  10  via the input/output interface  56  and the LAN  3 . 
         [0095]    If the CPU  52  judges that the clicked button is the CANCEL button  72  (S 37 : NO), the CPU  52  terminates the password setting process without transmitting the job to the MFP  10  because in this case the user does not intend to execute the printing operation. 
         [0096]    When receiving the job containing a command for the secured print from the PC  2 A, the MFP  10  temporarily stores the print data in the NVRAM  34 . In this case, the print data is stored in the NVRAM  34  in association with the user name, the job name, and the password set by the PC  2 A so that the print data can be distinguished from another print data. 
         [0097]    In this embodiment, the same password authentication process as that shown in  FIG. 7  is executed to print the print data. That is, the user inputs a secured print command by specifying the user name and the file name through the operation unit  25  of the MFP  10 . Then, a password input screen is displayed on the LCD  26  so as to allow the user to input a password. Then, the MFP  10  checks whether the inputted password matches the password associated with the print data specified by the user name and the job name. If these passwords match each other, an image corresponding to the specified print data is printed on a recording sheet. If these passwords do not match, the specified print data is not printed. In this case, an error message may be displayed on the LCD  26 . 
         [0098]    Hereafter, advantages of the second embodiment are described. In the password setting system according to the second embodiment, the virtual operation unit  81  which is an virtual image of the operation unit  25  of the MFP  10  is displayed on the LCD  59  of the PC  2 A, and the user inputs a password on the screen of the LCD  59  of the PC  2 A (see S 363  of  FIG. 10 , S 16 , and  FIG. 12 ). Then, the inputted password is transmitted from the PC  2 A to the MFP  10  via the LAN  3  (see S 38  of  FIG. 9 ). The MFP  10  receives the password from the PC  2 A via the LAN  3 . When a password is inputted to the MFP  10  to execute a particular function, the MFP  10  compares the inputted password with the password received form the PC  2 A. Then, if the inputted password and the password received form the PC  2 A mach each other, the MFP  10  permits execution of a print operation for printing the print data contained in the job for the secured print (see  FIG. 7 ). 
         [0099]    As described above, in the password setting system  1 A, the password entry is conducted on the PC  2 A which can be located at a hidden position. Therefore, according to the password setting system  1 A of the second embodiment, it is possible to prevent passwords from being stolen by another person. Consequently, the security level can be increased. 
         [0100]    A password is inputted using the virtual operation unit  81  corresponding to a virtual image of the operation unit  25  of the MFP  10 . Such a configuration enables the user, who is operating the operation unit  25  of the MFP  10  to input a password, to easily recall the password which the user has set in advance. 
         [0101]    As described above, on the virtual operation unit  81 , the usable keys for the password setting are displayed in red color so that the usable keys for the password setting can be distinguished from other keys (see  FIG. 12 ). Such a configuration enables the user to easily distinguish the usable keys form other keys and thereby to easily input a password on the PC  2 A. Since types of keys (i.e., virtual keys on the virtual operation unit  81 ) which can be used for the password setting are limited depending on the current function, a password can be complicated and thereby it becomes possible to enhance the security level. 
         [0102]    According to the password setting program  62  of the second embodiment, the virtual operation unit  81  corresponding to an image of the operation unit  25  is displayed on the LCD  59  of the PC  2 A, and the password inputted through the virtual operation unit  81  is transmitted from the PC  2 A to the MFP  10  (S 36  of  FIG. 9 ,  FIG. 10 , and S 38  of  FIG. 9 ). Such a configuration prevents another person from easily stealing the password during the password setting. Consequently, the security level can be enhanced. 
         [0103]    According to the password setting program  62  of the second embodiment, the usable keys for the password setting are displayed in red color (see  FIG. 12 ). Such a configuration enables the user to easily input a password. Since keys to be used for the password setting are limited depending on the current function, it is possible to complicate a password and to enhance the security level. 
         [0104]    Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible.