Patent Publication Number: US-9430661-B2

Title: Image forming apparatus performing control of browsing of a file by a terminal, terminal, file browsing control system, image forming method, and recording medium

Description:
INCORPORATION BY REFERENCE 
     This application is based on and claims the benefit of priority from Japanese Patent Application No. 2013-114935 filed on May 31, 2013, the contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to an image forming apparatus, a terminal, a file browsing control system, an image forming method, and a recording medium, and particularly to an image forming apparatus, a terminal, a file browsing control system, an image forming method, and a recording medium for causing an encrypted file to be browsed. 
     A typical image forming apparatus, such as a multifunctional peripheral (MFP), can print a document or an image. 
     Further, in recent years, there has been available a technique for a file browsing control system that performs control of access to documents, and the like, which have been digitized and accumulated as files. In such a file browsing control system, a dedicated browsing terminal causes a file subjected to encryption, or the like, to be browsed. 
     In such a file browsing control system, even if there has occurred an outflow or illegal copy of a file, or the like, browsing can be inhibited to make it impossible to display the file, and so on, whereby the security can be enhanced. 
     SUMMARY 
     The image forming apparatus of the present disclosure is an image forming apparatus that performs control of browsing of a file with a terminal. An encryption portion encrypts the file with a public key. A browsing permitting position information setting portion sets position information, which is to permit browsing of the file encrypted by the encryption portion, in a viewer for causing the file to be browsed at the terminal. 
     The terminal of the present disclosure is a terminal for browsing a file encrypted by the image forming apparatus. A position information storage unit stores position information to permit browsing of the file. A position information determination portion determines whether or not the position information stored in the position information storage unit coincide with a current position. Upon the position information determination portion having determined that the position information included in a viewer coincides with a current position, a browsing execution portion uses the viewer stored in the position information storage unit to decrypt the file for causing it to be browsed. 
     The file browsing control system of the present disclosure is a file browsing control system that performs control of browsing of a file with the image forming apparatus and the terminal. The encryption portion of the image forming apparatus encrypts the file with a public key. The browsing permitting position information setting portion of the image forming apparatus sets position information, which is to permit browsing of the file encrypted by the encryption portion, in a viewer for causing the file to be browsed at the terminal. The position information storage unit of the terminal stores the position information set in the viewer by the browsing permitting position information setting portion. The position information determination portion of the terminal determines whether or not the position information included in the viewer stored in the position information storage unit coincides with a current position. Upon the position information determination portion having determined that the position information included in the viewer coincides with a current position, the browsing execution portion of the terminal uses the viewer stored in the position information storage unit to decrypt the file for causing it to be browsed. 
     The image forming method of the present disclosure is an image forming method by an image forming apparatus that performs control of browsing of a file with a terminal. With this method, the file is encrypted with a public key, and position information to permit browsing of the file encrypted is set in a viewer for causing the file to be browsed at the terminal. 
     The recording medium of the present disclosure is a recording medium that is non-transitory and stores a program for implementing an image forming method that is executed by an image forming apparatus that performs control of browsing of a file with a terminal is recorded. The program encrypts the file with a public key, and sets position information to permit browsing of the file encrypted in a viewer for causing the file to be browsed at the terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an internal configuration of an image forming apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is a block diagram illustrating a control configuration of the image forming apparatus and the terminal according to the embodiment of the present disclosure; 
         FIG. 3A  is a block diagram illustrating the details of the functional configuration and data of the image forming apparatus according to the embodiment of the present disclosure; 
         FIG. 3B  is a block diagram illustrating the details of the functional configuration and data of the terminal according to the embodiment of the present disclosure; 
         FIG. 4  is a flowchart of browsing file preparation process according to the embodiment of the present disclosure; 
         FIG. 5  is a conceptual drawing illustrating the relationship among the respective files resulting from the browsing file preparation process according to the embodiment of the present disclosure; 
         FIG. 6  is a flowchart of file browsing process according to the embodiment of the present disclosure; 
         FIG. 7  is an example of screen for dialog display process according to the embodiment of the present disclosure; 
         FIG. 8  is a conceptual drawing for file decryption process according to the embodiment of the present disclosure; and 
         FIG. 9  is an example of screen for file display process according to the embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     &lt;Embodiment&gt; 
     [Configuration of Image Forming Apparatus  1 ] 
     Next, with reference to  FIG. 1 , a configuration of an image forming apparatus  1  according to an embodiment of the present disclosure will be explained in detail. 
     Referring to  FIG. 1 , the image forming apparatus  1  of the present embodiment includes a document reading unit  2 , a document feeding unit  3 , a main unit  4 , a stack tray  5 , an operation panel unit  6 , and a recording medium connection unit  63 . 
     The document reading unit  2  is disposed on top of the main unit  4 , and the document feeding unit  3  is disposed on top of the document reading unit  2 . The stack tray  5  is disposed on the side of a delivery port  41  for recording sheets that is formed in the main unit  4 , and the operation panel unit  6  is disposed on the front side of the image forming apparatus  1 . 
     The document reading unit  2  includes a scanner  21 , a platen glass  22 , and a document reading slit  23 . The scanner  21  is constituted by an exposure lamp, an imaging sensor, and the like, being configured to be movable in a direction of conveyance of a document by the document feeding unit  3 . 
     The platen glass  22  is a document table formed of a transparent material, such as a glass. The document reading slit  23  has a slit that is formed in a direction orthogonal to the direction of conveyance of a document by the document feeding unit  3 . 
     The document reading unit  2  can automatically recognize the size of a document sheet by sheet, reading an image within the range of that size. 
     When the scanner  21  is to read a document placed on the platen glass  22 , it is moved to a position opposed to the platen glass  22 , and reads the document placed on the platen glass  22  while scanning the document for acquiring image data, outputting the acquired image data to the main unit  4 . 
     Further, when the scanner  21  is to read a document carried by the document feeding unit  3 , the scanner  21  is moved to a position opposed to the document reading slit  23 . And the scanner  21  reads the document through the document reading slit  23  in synchronization with the document carrying operation of the document feeding unit  3  for acquiring image data, outputting the acquired image data to the main unit  4 . 
     The document feeding unit  3  includes a document mounting unit  31 , a document discharge unit  32 , and a document carrying mechanism  33 . The documents placed in the document mounting unit  31  are fed in turn sheet by sheet by the document carrying mechanism  33 . The documents are carried to a position opposed to the document reading slit  23 , and thereafter are discharged into the document discharge unit  32 . The document feeding unit  3  is configured to be tiltable, and by bringing the document feeding unit  3  upward, the top face of the platen glass  22  can be opened. 
     The main unit  4  includes an image forming unit  7 , and also includes a paper feeding unit  42 , a paper carrying passage  43 , conveyance rollers  44 , and discharge rollers  45 . The paper feeding unit  42  includes a paper feeding cassette  421 , and a feed roller  422 . In order to store recording sheets that are different in size or orientation, respectively, there are provided a plurality of paper feeding cassettes  421 . The feed roller  422  feeds the recording sheets one by one from the paper feeding cassette  421  to the paper carrying passage  43 . 
     The feed roller  422 , the conveyance rollers  44 , and the discharge rollers  45  function as a conveyance unit. The recording sheet is conveyed by this conveyance unit. The recording sheet fed by the feed roller  422  into the paper carrying passage  43  is conveyed by the conveyance rollers  44  into the image forming unit  7 . 
     And, the recording sheet provided with a record by the image forming unit  7  is discharged into the stack tray  5  by the discharge rollers  45 . 
     The operation panel unit  6  includes a display unit; a start key; ten keys; buttons for selecting an operation mode, such as copying, facsimile transmission, and scanner; buttons or a touch panel for giving an instruction related to execution of a job, such as printing, transmission, saving, or recording of the selected document, and the like. 
     The operation panel unit  6  acquires instructions given by the user for various jobs to be made by the image forming apparatus  1 . The operation panel unit  6  can also receive or modify a particular user&#39;s information in an account setting  90  on the basis of an instruction given by the user to the operation panel unit  6 . 
     The recording medium connection unit  63  is a reader/writer, or the like, which is connected to a recording medium  100 . The recording medium connection unit  63  may be connected to the recording medium  100  or a particular piece of equipment by wireless or optical connection, or may be wired-connected thereto with direct contact between terminals. In the case where the recording medium connection unit  63  is to be wired-connected, it includes terminals, connectors, and the like, for performing reading and writing the recording medium  100 . 
     Further, the recording medium connection unit  63  controls access to the recording medium  100 , and controls communications with another terminal. 
     The recording medium  100  connected to the recording medium connection unit  63  functions in the same manner as a storage unit  9  (see  FIG. 2 ). 
     The recording medium  100  is a particular piece of equipment, or the like, incorporating a recording medium. 
     The recording medium  100  stores image data scanned by the image forming apparatus  1 , or another terminal (not shown), information for use in user authentication, and the like, and other document data, and the like. 
     Further, the recording medium  100  is also capable of storing a viewer  97  ( FIGS. 3A and 3B ) in which a browsing file  96 , a secret key  191 , and position information  192  are set, as described later. 
     The image forming unit  7  includes a photosensitive drum  71 , an exposure unit  72 , a developing unit  73 , a transfer unit  74 , and a fixing unit  75 . 
     The exposure unit  72  is an optical unit, and exposes the photosensitive drum  71  to form an electrostatic latent image on the surface of the photosensitive drum  71  on the basis of the image data. 
     The developing unit  73  is a developing unit that uses toner for developing the electrostatic latent image formed on the photosensitive drum  71 , and causes a toner image to be formed on the photosensitive drum  71  on the basis of the electrostatic latent image. The transfer unit  74  causes the toner image formed on the photosensitive drum  71  by the developing unit  73  to be transferred onto the recording sheet. The fixing unit  75  causes the toner image to be fixed on the recording sheet by heating the recording sheet onto which the toner image has been transferred by the transfer unit  74 . 
     [Configuration of File Browsing Control System] 
     In  FIG. 2 , there is given a block diagram illustrating a schematic control configuration of a file browsing control system that uses the image forming apparatus  1  and a terminal  200  to perform control of browsing a file. 
     {Configuration of Image Forming Apparatus  1 } 
     In the image forming apparatus  1 , the document reading unit  2 , the document feeding unit  3 , the conveyance unit (the feed roller  422 , the conveyance rollers  44 , and the discharge rollers  45 ), the operation panel unit  6 , and the image forming unit  7  of the image forming apparatus  1  are connected to the control unit  8  to be operation-controlled by the control unit  8 . Further, to the control unit  8 , a storage unit  9 , an image processing unit  10 , a network transmission/reception unit  12 , and the like, are connected. 
     The control unit  8  is an information processing unit. The control unit  8  and the image processing unit  10  read a control program stored, and by executing this control program, performs control of the entire apparatus in response to predetermined instruction information inputted from the operation panel unit  6 . 
     Further, the control unit  8  includes a document browsing control unit  81  (an encryption portion, a browsing permitting position information setting portion, and a secret key setting portion). The document browsing control unit  81  is implemented by the control unit  8  executing a program stored in the storage unit  9 . The details of the function configuration of the document browsing control unit  81  will be described later. 
     The storage unit  9  is a storage unit that uses a recording medium that is non-transitory. The storage unit  9  stores image data that has been scanned by the document reading unit  2 ; image data that has been image-processed by the image processing unit  10 ; print document data that has been transmitted from the user&#39;s terminal; various files that have been read from the recording medium  100 ; thumbnail image data; a control program for performing operation control of the image forming apparatus  1 , and the like. The storage unit  9  may contain an area for a saving folder for each user. The details of data to be stored in the storage unit  9  will be described later. 
     The image processing unit  10  is a control arithmetic unit for image processes. The image processing unit  10  performs various image processes, such as enlargement/reduction process, density adjustment, gradation adjustment, and image improvement process. 
     The image processing unit  10  converts an image read by the document reading unit  2  to data, such as a file, before storing it in the storage unit  9  as document data  95 . 
     The network transmission/reception unit  12  is a network connection device for connecting the image forming apparatus  1  to a network  150 . 
     The network transmission/reception unit  12  transmits/receives data with a data communication channel, while transmitting/receiving an audio signal with an audio telephone line. 
     Further, the image forming apparatus  1  is connected to the terminal  200  through the network transmission/reception unit  12 . The image forming apparatus  1  and the terminal  200  constitutes a file browsing control system. 
     In the image forming apparatus  1 , the control unit  8  and the image processing unit  10  may be integrally formed like a CPU containing GPU, or the like, or a chip-on-module package. 
     Further, the image forming apparatus  1  may include a facsimile transmission/reception unit for performing facsimile transmission/reception. 
     Further, the control unit  8  may store a control program for performing operation control of the image forming apparatus  1  in an ROM, or the like. 
     {Configuration of Terminal  200 } 
     The terminal  200  includes a network transmission/reception unit  220 , an I/O unit  230 , a GPS reception unit  240  (a current position acquisition unit), an input unit  250 , a display unit  260 , a control unit  280 , a storage unit  290  (a position information storage unit and a viewer storage unit). 
     The network transmission/reception unit  220  is a transmission/reception device for connecting the terminal  200  to the network  150 . The terminal  200  is capable of transmitting/receiving a document data  95  ( FIG. 3 ), a browsing file  96 , a viewer  97 , a user ID or password for login, and the like, through the network transmission/reception unit  220 . 
     The network transmission/reception unit  220  may be connected to an external hub or router, or the like, and therethrough connected to the network  150 . 
     The I/O unit  230  is a constitutional portion that provides an interface for connection to various pieces of peripheral equipment. The I/O unit  230  is connected to the input unit  250  and the display unit  260 . 
     Further, like the recording medium connection unit  63  in the image forming apparatus  1 , the I/O unit  230  is capable of connecting the recording medium  100  for reading and writing data. 
     The GPS reception unit  240  is a position information acquisition unit that includes a receiver and an antenna for the GPS (Global Positioning System), a gyro sensor, and the like. The GPS reception unit  240  may acquire a signal, such as a GPS repeater, in addition to various GPS signals. Further, the GPS reception unit  240  may acquire a positional signal by a radio wave of a portable network, or the like. 
     The GPS reception unit  240  is capable of calculating a current position of the terminal  200 , using such a signal received, the address on the network, and the like. 
     The input unit  250  inputs information, such as various settings, and user authentication. 
     The display unit  260  is capable of making a screen display for drawing for an application, security setting, and the like. 
     The control unit  280  is a device having an arithmetic/control capability. The control unit  280  executes each program stored in the storage unit  290 , using a hardware resource. 
     Further, the control unit  280  includes a document browsing unit  210  (a position information determination portion, and a browsing execution portion). The detailed configuration of the document browsing unit  210  will be described later. The document browsing unit  210  is implemented by the control unit  280  executing a program stored in the storage unit  290 . 
     The storage unit  290  is a storage device. The storage unit  290  stores various programs and document data for browsing for causing the terminal  200  to function as a terminal for document browsing. The details of these programs and data will be described later. 
     Further, the storage unit  290  also stores an OS (Operating System) including a GUI (Graphical User Interface), various application softwares (hereinafter to be called applications), other programs and data, and the like. These programs and data can be read for execution, and written by the control unit  280 . In other words, the storage unit  290  can also once store printing data prepared by the document browsing unit  210 . The terminal  200  can also transmit this printing data to the image forming apparatus  1  as the document data  95 . 
     {Details of Function Configurations and Data of Image Forming Apparatus  1  and Terminal  200 } 
     Here, with reference to  FIG. 3A  and  FIG. 3B , the details of the function configurations and data of the image forming apparatus  1  and the terminal  200  will be explained. 
     The image forming apparatus  1  and the terminal  200  encrypt the document data  95  with a public key  190  to prepare a browsing file  96  such that it cannot be browsed in an ordinary manner. 
     In order to browse this browsing file  96 , the terminal  200  must be execute a dedicated viewer  97 . The viewer  97  includes a secret key  191  for decrypting the browsing file  96  that has been encrypted by the public key  190 . 
       FIG. 3A  and  FIG. 3B  show a configuration of the image forming apparatus  1  and the terminal  200  after the browsing file  96  and the set viewer  97  having been transmitted by the later described process to the terminal  200 . 
     Referring to  FIG. 3A , the document browsing control unit  81  in the control unit  8  of the image forming apparatus  1  includes a user authentication portion  82 , a document acquisition portion  83 , a document encryption portion  84  (an encryption portion), a secret key setting portion  85 , a position information setting portion  86  (a browsing permitting position information setting portion), and a file viewer transmission portion  87  (a file transmission portion and a viewer transmission portion). Further, the storage unit  9  of the image forming apparatus  1  stores the account setting  90 , the key information  91  (the public key  190  and the secret key  191 ), the base position data  92  (position information), the document data  95 , the browsing file  96 , and the viewer  97 . 
     Referring to  FIG. 3B , the document browsing unit  210  of the terminal  200  includes a file viewer acquisition portion  211  (a file acquisition portion and a viewer acquisition portion), a position information determination portion  212  (a position information determination portion), a browsing execution portion  213  (a browsing execution portion), and a viewer setting change portion  214  (a viewer setting change portion). Further, the storage unit  290  (the viewer storage unit) of the terminal  200  stores the browsing file  96  and the viewer  97  that have been acquired from the image forming apparatus  1 . The viewer  97  may be separately installed in the terminal  200 . 
     (Configuration of Document Browsing Control Unit  81 ) 
     The user authentication portion  82  references the account setting  90  for performing user authentication. The user authentication portion  82  receives the user ID and the password inputted from the operation panel unit  6  or the terminal  200 , and reads the account setting  90  for performing comparison and authentication. 
     The document acquisition portion  83  saves the image data read by the document reading unit  2  in the storage unit  9  as the document data  95 . Further, the document acquisition portion  83  may prepare the document data  95  from the printing data, and the like, transmitted from the terminal  200  or another terminal (not shown). Further, the document acquisition portion  83  may acquire the document data  95  from the recording medium  100 , the terminal  200 , the user saving folder (not shown) in the storage unit  9 , and the like, to store it in the storage unit  9 . 
     The document encryption portion  84  encrypts the document data  95  with the public key  190  included in the key information  91  to prepare the browsing file  96 . Since the document data  95  is encrypted with the public key  190 , this public key  190  may be transmitted to the terminal  200  or another terminal, a server, or the like, (not shown), for encrypting it in such a piece of equipment. 
     The secret key setting portion  85  sets the secret key  191  for decrypting the browsing file  96  in the viewer  97  stored in the storage unit  9 . This secret key  191  is also included in the key information  91 . 
     The position information setting portion  86  sets the position information  192 , which is to permit browsing of the browsing file  96  encrypted by the document encryption portion  84 , in the viewer  97 . The position information  192  is set on the basis of the base position data  92 . 
     The file viewer transmission portion  87  transmits prepared browsing file  96  and the viewer  97  in which the secret key  191  and the position information  192  are set, to the terminal  200 , or writes them to the recording medium  100 . 
     (Configuration of Storage Unit  9 ) 
     The account setting  90  is a database including attribute information, such as the user ID (the user name), the password, the authority information, the IP address of the terminal  200 , and the mail address, for each user account. The user ID and the password in the account setting  90  are used for login to the image forming apparatus  1 . The authority information in the account setting  90  includes information about authority of handling, such as printing, transmission or browsing, of a highly confidential, browsing-controlled document, in other words, information about the type of a “general user” or “authorized user”. The account setting  90  is registered with the use of various pieces of information that are inputted by the user from the operation panel unit  6  or the terminal  200 . 
     The key information  91  includes the public key  190  for encrypting the browsing file  96 , and the secret key  191  for decrypting the browsing file  96 . For each user, a separate piece of key information  91  may be included. Further, the key information  91  may be acquired from the terminal  200 . Further, the key information  91  may be prepared on the basis of the user password, or the like, in the account setting  90 . Further, the key information  91  may include data, such as the installation location (the position) of the image forming apparatus  1 , and the manufacturing number and ID thereof. 
     The base position data  92  includes the position where the image forming apparatus  1  is installed, the position where to permit browsing of the browsing file  96  for respective user authorities, and the like. On the basis of this base position data  92 , the position information  192  is set in the viewer  97 . 
     The document data  95  is data of the document acquired by the document acquisition portion  83 . The document data  95  includes character data, image data, and other types of data. The document data  95  may be image data that has been read by the document reading unit  2  and subjected to image process by the image processing unit  10 . In addition, the document data  95  may be data that has already been converted into a prescribed format by the image processing unit  10  or the control unit  8 . Further, the document data  95  may be data prepared by reading map or document data, image data, or the like, stored in the recording medium  100  that has been brought about by the user and connected to the recording medium connection unit  63 . 
     The browsing file  96  is a file of the document data  95  that has been prepared, being encrypted by the document encryption portion  84 . The browsing file  96  is decrypted by the viewer  97  in the terminal  200  to be provided for browsing. 
     The viewer  97  is a file viewer program, or the like, for allowing the browsing file  96  to be browsed with the terminal  200 . In the present embodiment, the viewer  97  is transmitted from the image forming apparatus  1  to the terminal  200 , stored in the storage unit  290  of the terminal  200 , and executed by the browsing execution portion  213  of the document browsing unit  210  of the terminal  200 . The viewer  97  may be configured so as to be executable also in the image forming apparatus  1 . Further, the viewer  97  may be installed by causing the terminal  200  to read the recording medium. Even in this case, the secret key  191  and the position information  192  are set with the image forming apparatus  1 . 
     The public key  190  and the secret key  191  provide a public key/secret key pair, or the like, for encoding (encrypting) and decrypting with a hash function, or the like. 
     The position information  192  is data including the coordinate data, such as the latitude or longitude that is acquirable with a GPS, the altitude, or the like; the positional data that is acquirable with a portable telephone network; and the positional information, such as the address data, the name of the area or that of the building, and the IP address of the image forming apparatus  1  on the network. In the position information  192 , a plurality of base positions where to permit browsing can be set with the allowable range in which browsing is possible even away from such a position being able to be specified as a value of from a several ten meters to a several hundred meters, or a value like a subnet mask on the network of an IP address, respectively. The position information  192  may also include setting information, such as the permissible time of browsing by the viewer  97 , the number of permissible times of browsing, the permissible date of browsing, and the deadline of browsing, for each position. 
     (Configuration of Document Browsing Unit  210 ) 
     The file viewer acquisition portion  211  acquires the browsing file  96  and the viewer  97  transmitted by the file viewer transmission portion  87 , and stores them in the storage unit  290 . Further, the file viewer acquisition portion  211  is also capable of acquiring the browsing file  96  and the viewer  97  that are recorded in the recording medium  100 , and storing or installing them into the storage unit  290 . 
     The position information determination portion  212  determines whether or not the position information  192  included in the viewer  97  stored in the storage unit  290  coincides with a current position acquired from the GPS reception unit  240 . At this time, the position information determination portion  212  determines whether or not the current position is a position within a prescribed allowable range in the position information  192 . 
     In the case where the position information determination portion  212  has determined that the position information  192  included in the viewer  97  coincides with the current position, the browsing execution portion  213  uses the secret key  191  included in the viewer  97  stored in the storage unit  290  to decrypt the browsing file  96  for causing it to be browsed. 
     [Browsing File Preparation Process by Image Forming Apparatus  1 ] 
     Here, with reference to  FIG. 4  and  FIG. 5 , the browsing file preparation process with the image forming apparatus  1  according to the embodiment of the present disclosure will be explained. 
     In the browsing file preparation process, the document data  95  is encrypted mainly with the image forming apparatus  1  to prepare the browsing file  96 . Thereafter, the secret key  191  and the position information  192  are set in the viewer  97  for this browsing file  96  to be transmitted to the terminal  200 . 
     In this browsing file preparation process, mainly the control unit  8  executes the program stored in the storage unit  9  in cooperation with each unit, using the hardware resource. 
     Hereinbelow, with reference to a flow chart in  FIG. 4 , the outline of the browsing file preparation process will be explained for each step. 
     (Step S 101 ) 
     First, the document browsing control unit  81  uses the user authentication portion  82  to perform user authentication process. 
     The document browsing control unit  81  receives an instruction for preparing a file browsable with the viewer  97  from the operation panel unit  6 . Then, the document browsing control unit  81  displays a dialog for requesting inputting of the user ID and the password, and the like, on the display unit of the operation panel unit  6 . Upon the ID and the password being acquired, the document browsing control unit  81  reads the account setting  90  for comparison. 
     The document browsing control unit  81  may perform authentication by means of the recording medium  100 , such as an IC card in which the user ID information is stored, a biometric authentication sensor (not shown), or the like. 
     Further, the document browsing control unit  81  may cause the display unit  260  of the terminal  200  to display a dialog, or the like. Thereby, the document browsing control unit  81  may acquire the ID or password from the user through the network  150  for performing authentication. 
     (Step S 102 ) 
     Next, the document browsing control unit  81  uses the user authentication portion  82  to determine whether the user concerned is an authorized user. In the case where the user ID and the password coincide with those stored in the account setting  90 , the document browsing control unit  81  reads the authority information in the account setting  90  for the user that has been acquired. And, in the case where the user concerned is an authorized user, the document browsing control unit  81  makes a determination of Yes. In any other cases, the document browsing control unit  81  makes a determination of No. 
     If Yes is given, document browsing control unit  81  advances the process to Step S 103 . 
     If No is given, the document browsing control unit  81  gives a display, such as “You have no permission for preparing a file to be browsed with viewer”, on the display unit of the operation panel unit  6 , or the like, to terminate the browsing file preparation process. 
     (Step S 103 ) 
     In the case where the user who has been authenticated is an authorized user, the document browsing control unit  81  uses the document acquisition portion  83  to perform document data acquisition process. 
     The document browsing control unit  81  causes the document reading unit  2  to read a document set by the user, for example, and saves the image data of the read document in the storage unit  9  as the document data  95 . 
     Further, the document browsing control unit  81  may acquire PDL (Page Description Language) data, or the like, from the terminal  200  or another terminal (not shown), and prepare the document data  95  to save it in the storage unit  9 . This PDL data is prepared by application software that is executed by the terminal  200  or another terminal, or the like, and transmitted by the device driver in the image forming apparatus  1 . 
     Further, the document browsing control unit  81  may acquire the document data  95  that already exists in the recording medium  100  connected to the recording medium connection unit  63  or the user saving folder (not shown) in the storage unit  9 , or the like, and store it in the storage unit  9 . Further, the document acquisition portion  83  may acquire the document data  95  that already exists, from the saving folder (not shown) in the terminal  200  or another terminal, and store it in the storage unit  9 . 
     The document browsing control unit  81  may acquire the document data  95  from another image forming apparatus  1  or another server (not shown) through the network  150 . Further, the document browsing control unit  81  may acquire a document, or the like, received by facsimile as the document data  95 . 
     (Step S 104 ) 
     Next, the document browsing control unit  81  uses the document encryption portion  84  to perform document encryption process. 
     Referring to  FIG. 5 , the document browsing control unit  81  encrypts the document data  95  stored in the storage unit  9  with the public key  190  in the key information  91 , using a hash function, or the like. 
     The document browsing control unit  81  stores the encrypted document data  95  in the storage unit  9  as the browsing file  96 . At this time, in the present embodiment, the position information  192  is not caused to be included in the browsing file  96  itself. 
     (Step S 105 ) 
     Next, the document browsing control unit  81  uses the secret key setting portion  85  to perform secret key setting process. 
     The document browsing control unit  81  sets the secret key  191  included in the key information  91  in the viewer  97  stored in the storage unit  9 . In the case where the viewer  97  is executed at the terminal  200 , this secret key  191  can be used to decrypt the browsing file  96 . 
     (Step S 106 ) 
     Next, the document browsing control unit  81  uses the position information setting portion  86  to perform viewer position information setting process. 
     The document browsing control unit  81  sets the position information  192  in the viewer  97  on the basis of the user setting and the base position data  92 . The document browsing control unit  81  sets the position information  192  about the base (location or position) where to permit the user to browse the browsing file  96  encrypted by the document encryption portion  84 . 
     The document browsing control unit  81  specifies the allowable range of, for example, a several ten meters to a several hundred meters in radius out of the base position data  92  for the position where the image forming apparatus  1  is installed, or the like, and sets it in the viewer  97  as the position information  192 . Further, in indoors where the position cannot be acquired by means of the GPS, the document browsing control unit  81  may specify the allowable range on the basis of the radio wave information from the portable telephone network, and set it in the viewer  97  as the position information  192 . Further, the document browsing control unit  81  may set, in the viewer  97 , a subnet mask on the network, or the position information  192  about the allowable range, such as that to permit browsing in the case where the current position is in the same LAN as the image forming apparatus  1 . 
     Further, the document browsing control unit  81  is capable of setting a plurality of positions where to permit browsing of the browsing file  96 . The document browsing control unit  81  is capable of setting a plurality of base positions, such as “headquarter”, “branch A”, and “branch B”, in the viewer  97  as the position information  192 . The document browsing control unit  81  is also capable of setting the secret key  191  such that it varies for each of the plurality of base positions. 
     Further, the document browsing control unit  81  is capable of setting an allowable range in accordance with the type of the viewer  97  or the authority of the user caused to browse in the viewer  97  as the position information  192 . At this time, a plurality of viewers  97  may be prepared for setting the position information  192  and the secret key  191  in the respective viewers  97 . 
     For example, the document browsing control unit  81  can make such settings: 
     Viewer  97  for cooperative company: Browsable only at specific base 
     Viewer  97  for general partner: Browsable at any bases 
     Viewer  97  for senior management employee: Browsable at any location 
     Further, as the position information  192 , the document browsing control unit  81  is capable of setting such position information that can be specified by using a specific key word, or the like, such as “inside Shinkansen” or “National High Way Route No. - - - ”. 
     In this way, by setting the position information  192  and the secret key  191  in the viewer  97 , the browsing location for the browsing file  96  can be flexibly set. 
     (Step S 107 ) 
     Next, the document browsing control unit  81  uses the position information setting portion  86  to perform setting process of viewer browsing deadline, etc. 
     The document browsing control unit  81  is capable of setting the permissible time of browsing in the viewer  97  for each position. In other words, the document browsing control unit  81  can be set such that, in a prescribed location, after the viewer  97  having been started at the terminal  200 , browsing of the browsing file  96  is permitted only for a browsing time that has been set. 
     Further, the document browsing control unit  81  may set the number of permissible times of browsing in the viewer  97 . In other words, the document browsing control unit  81  can be set such that, at the terminal  200 , the viewer  97  can be started by the number of permissible times of browsing. Likewise, the document browsing control unit  81  may set the permissible date of browsing, the deadline of browsing, or the like. In other words, the document browsing control unit  81  can be set such that, if the terminal  200  is in a particular position, and the browsing time of day or period is not the permitted one for that position, the viewer  97  cannot be started. 
     The document browsing control unit  81  can set the browsing time, the number of permissible times of browsing, the permissible date of browsing, the deadline of browsing, and the like, including these in the position information  192 . 
     As described later, the document browsing control unit  81  allows the settings of the secret key  191  and the viewer  97  to be changed from the operation panel unit  6  or the terminal  200 . 
     (Step S 108 ) 
     Next, the document browsing control unit  81  uses the file viewer transmission portion  87  to perform file viewer transmission process. 
     The document browsing control unit  81  transmits the viewer  97  in which the position information  192  and the secret key  191  are set, and the browsing file  96  to the terminal  200 . The document browsing unit  210  in the terminal  200  acquires these by means of the file viewer acquisition portion  211 , and stores them in the storage unit  290 . 
     Further, the document browsing control unit  81  is capable of writing the viewer  97  and the browsing file  96  to the recording medium  100  connected to the recording medium connection unit  63  to store them therein. The file viewer acquisition portion  211  in the terminal  200  can also acquire the viewer  97  and the browsing file  96  stored in the recording medium  100 . 
     By the above way, the browsing file preparation process according to the embodiment of the present disclosure is terminated. 
     [File Browsing Process by Terminal  200 ] 
     Next, with reference to  FIG. 6  to  FIG. 9 , the details of file browsing process by the terminal  200  will be explained. 
     By the above browsing file preparation process, the terminal  200  acquires the encrypted browsing file  96  and the viewer  97  from the image forming apparatus  1 , and stores them in the storage unit  290 . In the viewer  97 , there are set the secret key  191  and the position information  192  for decrypting the browsing file  96 . 
     With the file browsing process of the present embodiment, if the user instructs the viewer  97  to start in this state, the following process will be performed. 
     This file browsing process is performed mainly by the control unit  280  executing the program stored in the storage unit  290  in cooperation with each unit, using the hardware resource. 
     Hereinbelow, with reference to a flowchart in  FIG. 6 , the file browsing process will be explained in detail for each step. 
     (Step S 201 ) 
     First, the document browsing unit  210  uses the position information determination portion  212  to determine whether or not the position information can be acquired. In the case where the GPS reception unit  240  ( FIG. 2 ) in the terminal  200  can be used, and the current position can be acquired, the document browsing unit  210  makes a determination of Yes. In any other cases, the document browsing unit  210  makes a determination of No. Further, in the case where, in the viewer  97 , the number of permissible times of browsing, the deadline of browsing, the permissible time of day of browsing, and the like, are set, and these browsing conditions are not met, the document browsing unit  210  makes a determination of No. In other words, in such a case as that where the number of times of browsing exceeds the permissible value, or the browsing time of day or period is not the permitted one, the document browsing unit  210  makes a determination of No. Further, also in the case where, in the first place, neither the secret key  191  nor the position information  192  is set in the viewer  97 , the document browsing unit  210  makes a determination of No. 
     If Yes is given, the document browsing unit  210  advances the process to Step S 202 . 
     If No is given, the document browsing unit  210  advances the process to Step S 204 . 
     (Step S 202 ) 
     Next, the document browsing unit  210  uses the position information determination portion  212  to perform current position acquisition process. 
     In this process, the document browsing unit  210  acquires the current position of the terminal  200  by means of the GPS reception unit  240 . 
     The document browsing unit  210  may calculate the latitude and longitude of the terminal  200  from a plurality of GPS satellites, or may use information of the base station of the portable telephone network, or the like, to identify the current position. Further, the document browsing unit  210  may identify the current position from the radio wave of the GPS repeater, or the like. In addition, the document browsing unit  210  may identify the indoor current position from the magnitude of the radio wave from an access point of a wireless LAN, or the like. Further, the document browsing unit  210  may use the value of a gyro sensor or atmospheric pressure sensor (not shown) for identifying the current position more accurately. 
     Further, the document browsing unit  210  may identify the position on the network in a specific LAN, or the like. At this time, the document browsing unit  210  may specify the information of whether or not the image forming apparatus  1  is on the same LAN as the terminal  200  as the current position. The document browsing unit  210  may make broadcasting, or the like, to communicate with the image forming apparatus  1  for referencing the manufacturing number, the ID, and the like, in the key information  91 , and the installation position, and the like, included in the base position data  92  to identify the current position. 
     The document browsing unit  210  may cause the user to make the login to the terminal  200 , or the like, to check for whether or not the user is the same one who is expected to use the viewer  97 . 
     (Step S 203 ) 
     Next, the document browsing unit  210  uses the position information determination portion  212  to determine whether or not the browsing location coincides with the permitted one. The document browsing unit  210  determines whether or not the position information  192  included in the viewer  97  stored in the storage unit  290  coincides with the current position acquired from the GPS reception unit  240 . At this time, in the case where the current position acquired is a position within the allowable range of the position information  192 , the document browsing unit  210  gives a determination of coincidence. In the case where the current position acquired is a position within the allowable range of the position information  192 , the document browsing unit  210  makes a determination of Yes. In any other cases, the document browsing unit  210  makes a determination of No. 
     If Yes is given, the document browsing unit  210  advances the process to Step S 205 . 
     If No is given, the document browsing unit  210  advances the process to Step S 204 . 
     (Step S 204 ) 
     In such a case as that where the current position has not been acquired, the current position does not coincide with the browsing permitted location, or any other browsing condition is not met, the document browsing unit  210  uses the position information determination portion  212  to perform dialog display process. 
     Referring to  FIG. 7 , for example, in the case where the GPS function is off, the document browsing unit  210  may give such a display of “Turn GPS on” as in a display example  500  to notify the user of the situation. Further, in the case where the current position does not coincide with the browsing permitted location, the document browsing unit  210  may display a dialog box giving a message “Position information error: In this location, browsing is impossible”, or the like, as in a display column  600 . Further, also in the case where any other browsing condition is not met, or neither the secret key  191  nor the position information  192  is set, the document browsing unit  210  may give a display of that effect. 
     Thereafter, the document browsing unit  210  advances the process to Step S 208 . 
     (Step S 205 ) 
     In the case where the current position coincides with the browsing permitted location, the document browsing unit  210  uses the browsing execution portion  213  to perform file decryption process. 
     With reference to  FIG. 8 , the file decryption process will be explained. The document browsing unit  210  decrypts the browsing file  96  by means of the secret key  191  included in the viewer  97  stored in the storage unit  290 . 
     At this time, the document browsing unit  210  can successively read and decrypt only the part of the browsing file  96  that has been displayed in the display unit  260  of the terminal  200 . 
     Further, the document browsing unit  210  may save the decrypted data of the browsing file  96  in the protected storage area of the storage unit  290 . Thereby, only the viewer  97  can read the decrypted data. 
     (Step S 206 ) 
     Next, the document browsing unit  210  uses the browsing execution portion  213  to perform file display process. 
     Referring to  FIG. 9 , such a window as a display column  610  is displayed in a screen, such as that in a display example  501 , for displaying the decrypted data of the browsing file  96 . At this time, in the case where the browsing file  96  is to be successively decrypted, the document browsing unit  210  acquires the user&#39;s instruction at the input unit  250 , and successively reads the browsing file  96  for display in response to the user depressing the scroll bar, or the like. 
     The document browsing unit  210  may perform printing, facsimile-transmitting, saving in the recording medium  100 , file-transmitting, or the like, of the decrypted data of the browsing file  96  at the image forming apparatus  1 . 
     Further, the document browsing unit  210  may transmit that the user is making browsing to the image forming apparatus  1  in order to cause it to monitor the situation. 
     (Step S 207 ) 
     Next, the document browsing unit  210  uses the browsing execution portion  213  to determine whether or not an instruction for terminating the browsing has been given by the user. In such a case as that where the user has depressed a “terminate” button  710  in  FIG. 9 , has selected a choice of “terminate” from the file menu (not shown) for the viewer  97 , or has depressed a button for closing the window of the viewer  97 , the document browsing unit  210  makes a determination of Yes. Further, also in the case where a browsing permissible time has been set, and the browsing permissible time has elapsed from the start of the viewer  97 , the document browsing unit  210  makes a determination of Yes. In any other case, the document browsing unit  210  makes a determination of No. 
     If Yes is given, the document browsing unit  210  advances the process to Step S 208 . 
     If No is given, the document browsing unit  210  waits for a predetermined time period, and then returns the process to Step S 201  to make the user to continue the browsing. This allows a process scheme that, during browsing of a document, the current position of the terminal  200  is acquired at fixed intervals of time, and when the terminal  200  comes out of the area in which the browsing file  96  can be decrypted, the browsing file  96  that is currently being browsed is closed. 
     (Step S 208 ) 
     In the case where an instruction for terminating the browsing has been given by the user, the current position could not have been acquired, or the current position of the terminal  200  has been shifted to a position where browsing is not permitted, the document browsing unit  210  uses the browsing execution portion  213  to perform browsing termination process. 
     Then, the document browsing unit  210  closes the window of the viewer  97 , and makes the other necessary operations. Thereafter, the document browsing unit  210  deletes the decrypted data of the browsing file  96 . At this time, the document browsing unit  210  may transmit that the browsing has been terminated, to the image forming apparatus  1 . 
     Further, in such a case as that where the number of permissible times of browsing has been set, and the number of starts of the viewer  97  has exceeded the number of permissible times of browsing, or where the deadline of browsing has been exceeded, the document browsing unit  210  may delete the secret key  191  or the viewer  97  itself from the storage unit  290  such that the viewer  97  cannot be started. 
     (Step S 209 ) 
     Here, the document browsing unit  210  uses the viewer setting change portion  214  to perform viewer setting change process. 
     The document browsing unit  210  is capable of changing the position information  192  set in the viewer  97  after the browsing having been terminated. This change may be performed from the input unit  250  of the terminal  200 , from the operation panel unit  6  of the image forming apparatus  1  with the terminal  200  being connected to the image forming apparatus  1 , or through the recording medium  100 . This allows the setting of the position information  192  of the viewer  97  to be changed for flexibly changing the position where a confidential file is to be browsed. 
     The document browsing unit  210  may also change the position information  192  by causing the user to make such an operation as inputting the password during the file display process. This allows the setting to be changed such that even the viewer  97  for cooperative company can make browsing at the respective bases of, for example, “headquarter”, “branch A”, and “branch B”. 
     By the above way, the file browsing process according to the embodiment of the present disclosure terminated. 
     By configuring as above, the following advantages will be obtained. 
     The image forming apparatus  1  according to the embodiment of the present disclosure is an image forming apparatus featuring a file browsing control system that performs control of browsing of the browsing file  96  with the image forming apparatus  1  and the terminal  200 . The image forming apparatus  1  includes the document acquisition portion  83  for acquiring the document data  95 ; the document encryption portion  84  for encrypting the document data  95  as the browsing file  96  with the public key  190 ; and the position information setting portion  86  for setting position information in the viewer  97  to permit browsing of the browsing file  96  encrypted by the document encryption portion  84  for causing the browsing file  96  to be browsed at the terminal  200 , while the terminal  200  includes the storage unit  290  for storing the viewer  97  including the secret key  191  for decrypting the browsing file  96  encrypted by the document encryption portion  84 , and the position information  192  set by the position information setting portion  86 ; the position information determination portion  212  for determining whether or not the position information  192  included in the viewer  97  stored in the storage unit  290  coincides with a current position; and the browsing execution portion  213  that, in the case where the position information determination portion  212  has determined that the position information  192  included in the viewer  97  coincides with the current position, uses the secret key  191  included in the viewer  97  stored in the storage unit  290  to decrypt the browsing file  96  for causing it to be browsed. 
     By thus configuring, a current position of the terminal  200  can be acquired from the GPS reception unit  240 , and in the case where the current position of the terminal  200  is the location that has been previously set in the position information  192  in the viewer  97 , the secret key  191  can be used to decrypt the document for making it browsable. 
     In other words, in the present embodiment, for the browsing file  96  saved in the terminal  200 , such a position information  192  as that, for example, to permit the user to browse it in the office, but not permit the user to browse it outside of the office, can be set in the viewer  97 . That is to say, it becomes possible to encrypt the document itself, limit the access thereto, and in the case where it has been determined that the user is in the office, decrypt the browsing file  96  for permitting the user to brows it. This can prevent occurrence of information leakage, and the like, resulting from the document being brought to outside of the office. 
     Further, the position information  192  to permit browsing of the browsing file  96 , such as an internal document, saved in the terminal  200  can be changed under prescribed conditions. In other words, in the case where the position where to permit browsing is to be changed, simply by exchanging viewers  97 , the encrypted browsing file  96  can be used as it is. In other words, the location where to permit browsing of a file can be simply specified and changed. 
     Therefore, for a browsing-restricted file, such as an internal document, there is no need for separately preparing a file with which the position information to permit browsing has been changed, every time in accordance with the user being a partner or a person of a cooperative company, or the like, whereby labor saving can be achieved. 
     Further, since determination of the position information is performed with the viewer  97 , it is not required that the browsing location be set for each particular document data  95 , and delivery or distribution thereof can be performed by causing the browsing file  96  to be downloaded from on the Internet, or the like. 
     Thereby, it becomes possible to easily handle the encrypted browsing file  96 , whereby the convenience of the user can be improved. 
     Further, as in the present embodiment, by setting the position information  192  on the side of the viewer  97 , it becomes possible to manage the security by means of the viewer  97 . Therefore, the need for the authorized user performing detailed security settings, such as the position information  192 , in the browsing file  96  is eliminated, whereby the possibility of occurrence of a wrong security setting can be lowered. 
     Further, even if a wrong security setting has been caused, the problem can be solved on the side of the viewer  97  by taking such a measure as updating the viewer  97 . 
     Further, in the present embodiment, even after the browsing file  96  having been distributed, the security setting, such as the browsing location of the position information  192 , can be changed. 
     Up to now, it has been substantially difficult to update the browsing file  96  that has been already distributed. Contrarily to this, since the viewer  97  is set in each user&#39;s terminal  200 , by updating the setting of the viewer  97 , or providing an expiration date, or the like, the browsing file  96  can be forcedly subjected to periodical updating. Therefore, even after the browsing file  96  having been prepared, the location where to permit browsing thereof can be easily changed. 
     Further, with the file browsing control system of the present embodiment, since the secret key  191  for decryption is set in the viewer  97 , the browsing file  96  can be browsed even in the environment in which the terminal  200  is not connected to the network  150 , whereby the convenience is enhanced. 
     Further, by browsing without connecting to the network  150 , the possibility of being subjected to an attack through the network  150 , and the like, can be minimized, whereby outflow of the key information can be suppressed. Accordingly the security can be enhanced. 
     Further, with the file browsing control system of the present embodiment, the browsing file  96  is encrypted with the public key  190 , and by setting the secret key  191  in the viewer  97 , the browsing file  96  is encrypted and decrypted with different keys in the browsing file  96  and the viewer  97 . 
     Therefore, the risk of outflow of the secret key  191  to outside of the image forming apparatus  1  and the terminal  200  is minimized, thereby the security can be enhanced. Further, in the present embodiment, even if the browsing file  96  has been acquired, and the position information to permit browsing has been known, with them alone, the browsing file  96  cannot be decrypted, whereby the security can be enhanced. 
     In the present embodiment, there may be a number of authorized users, preparing the browsing file  96  from the document data  95 . Further, in the present embodiment, since the public key  190  is used for encryption, even a general user can prepare the browsing file  96 , thereby the convenience can be enhanced. 
     Further, the image forming apparatus  1  of the present disclosure includes the storage unit  9  for storing the viewer  97 ; the secret key setting portion  85  for setting the secret key  191  for decrypting the browsing file  96  in the viewer  97  stored in the storage unit  9 ; and the file viewer transmission portion  87  for transmitting, to the terminal  200 , the viewer  97  in which the secret key  191  has been set by the secret key setting portion  85 , and the browsing file  96 . 
     By thus configuring, the viewer  97  itself in which the secret key  191  has been set can be transmitted to the terminal  200 . Thereby, the need for delivering the secret key  191  itself from the image forming apparatus  1  to the terminal  200  is eliminated, and every time the position information  192  is set, the secret key  191  can be updated, whereby the security can be improved. 
     Further, the terminal  200  of the present embodiment is configured such that it will not permit browsing in the event where a current position cannot be acquired, whereby the security can be enhanced. 
     The terminal  200  of the present disclosure may be implemented by the driver (driver software) of the terminal, such as a PC or a smart phone, or a dedicated application (application software). 
     Further, the present disclosure is also applicable to information process apparatuses other than the image forming apparatus. In other words, the image forming apparatus may be configured to use a network scanner, a server to which a scanner is separately connected with a USB, or the like. 
     Further, a configuration that transmits the browsing file  96  to the terminal  200  without encrypting it may be provided. 
     The configuration and operation of the above embodiment are examples, and of course it is possible to alter them as appropriate for implementation within the scope of the gist of the present disclosure for execution.