Patent Publication Number: US-2012044528-A1

Title: Material Printing System for Distributing Updated Meeting Material to Participants

Description:
This application is based on Japanese Patent Application No. 2010-184235 filed with the Japan Patent Office on Aug. 19, 2010, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a material printing system, and more particularly to a material printing system for distributing updated meeting materials to participants. 
     2. Description of the Background Art 
     In meetings, organizers often distribute materials to be used in meetings to participants (prospective participants) beforehand in order to notify them of the contents of the meetings. Even when the materials are electronically created, the participants tend to obtain the materials printed on a recording medium such as paper in order to easily taking notes and viewing the materials. 
     However, a material creator often updates a material once after distributing the material to participants, for example, because the material includes fluid contents. In such a case, the participants may attend the meeting without noticing that the material has been updated, or the participants cannot obtain the updated material, for example, because their PCs are not connected to a network. As a result, in the actual meeting, the versions of the material held by the participants may differ from each other. 
     Then, a technique has been devised in which when a meeting material to be distributed is updated, participants are notified that the material is updated. According to another technique, whether participants have printed a material is determined when the participants enter a meeting room, and if not printed, the materials is printed. A technique is also devised to specify which participant should print which material in an event and to prompt the participant to print the material. 
     For example, Document 1 below discloses a multifunction peripheral including a document management device. The multifunction peripheral includes a history management unit that obtains a version of meeting material data and records, in a print history, that a user corresponding to identification information has printed the obtained version of meeting material data, an information management unit that updates the meeting material data to new meeting material data and updates the version of the meeting material data, and an information notification unit that refers to the print history to recognize the identification information wherein the previous version of meeting material data has been printed, and gives a notification that the meeting material data has been updated, based on destination information corresponding to the recognized identification information. The multifunction peripheral automatically obtains information of a page of the meeting material that is required for each user name (the unprinted page of the meeting material), for the latest version of meeting material data, and prints the page of the meeting material that is required for each user name, based on the obtained information.
     Document 1: Japanese Laid-Open Patent Publication No. 2007-207049   

     However, the meeting material data having the latest creation date and time is not always formal meeting material data (that is, meeting material data actually used in a meeting). A material creator may revise a meeting material and create a new version of meeting material data but in the end use an old version of meeting material data before revision as formal meeting material data. In this case, the multifunction peripheral in Document 1 is inconvenient in that the formal meeting material data cannot be distributed to participants. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a convenient material printing system responsive to actual meeting materials. 
     A material printing system according to an aspect of the present invention includes: a first reference setting unit for setting any given version of material data as reference material data, among plural versions of material data concerning a particular meeting, in accordance with an instruction from a user; a history obtaining unit for obtaining a printing history of material data concerning the particular meeting for a participant in the particular meeting; a calculation unit for calculating a difference between material data printed by a participant in the particular meeting and the reference material data concerning the particular meeting, based on the printing history obtained by the history obtaining unit; and a printing unit for printing differential data corresponding to the difference. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a configuration of a material printing system in an embodiment of the present invention. 
         FIG. 2  is a diagram conceptually showing conversion of data formats when printing is done. 
         FIG. 3  is a conceptual diagram showing the relation between a material created by a meeting organizer and printing data corresponding to the material. 
         FIG. 4  is a block diagram functionally showing a configuration of an MFP  110  in the embodiment of the present invention. 
         FIG. 5  shows an exemplary meeting information table stored in an HDD  101  of an MFP  110   a.    
         FIG. 6  shows an exemplary print information table stored in HDD  101  of MFP  110   a.    
         FIG. 7  shows exemplary printing history data stored in HDD  101  of MFP  110 . 
         FIG. 8  shows an exemplary ID information table stored in HDD  101  of MFP  110 . 
         FIG. 9  shows an exemplary printing dialog box appearing on a display unit  196  of a PC  190   a  when reference material data is set. 
         FIG. 10  is a flowchart showing a material data printing process and a reference material data setting process executed by a control unit  130  of MFP  110   a  in the embodiment of the present invention. 
         FIG. 11  shows an exemplary dialog box appearing on a display unit of a PC of a meeting organizer in step S 111  in  FIG. 10 . 
         FIG. 12  shows an exemplary dialog box appearing on a display unit of a PC of a meeting participant in step S 106  in  FIG. 10 . 
         FIG. 13  is a flowchart of a print data printing process executed by control unit  130  of MFP  110   a.    
         FIG. 14  shows an exemplary warning dialog box appearing in step S 133  in  FIG. 13 . 
         FIG. 15  shows an exemplary screen appearing on an operation panel unit  154  of MFP  110  when a meeting organizer is going to print a material to be distributed to meeting participants. 
         FIG. 16  is a flowchart showing a differential printing process executed by control unit  130  of MFP  110   a  in the embodiment of the present invention. 
         FIG. 17  shows an exemplary meeting material in which printing data is printed. 
         FIG. 18  shows exemplary display of display unit  196  of PC  190   a  when a notification of a participant having a difference detected is given in step S 17  in  FIG. 16 . 
         FIG. 19  is the first half of a flowchart showing a modification of the differential printing process executed by control unit  130  of MFP  110   a  in the embodiment of the present invention. 
         FIG. 20  is the second half of the flowchart showing a modification of the differential printing process executed by control unit  130  of MFP  110   a  in the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, an embodiment of the present invention will be described based on the figures. 
     [Configuration of Material Printing System] 
     Referring to  FIG. 1 , a material printing system in the present embodiment includes, for example, MFPs (Multi Function Peripherals) (an example of the material printing apparatus)  110   a ,  110   b ,  110   c  (MFP  110   a ,  110   b ,  110   c  may also be collectively called MFP  110  hereinafter), and PCs  190   a  and  190   b  (PCs  190   a  and  190   b  may also be collectively called PC  190  hereinafter). A plurality of MFPs  110  are connected with each other via a network  200 . Each of MFPs  110  are connected with each of PCs  190  via a network  200 . MFP  110   a  is installed, for example, in a meeting room A, MFP  110   b  is installed, for example, in a meeting room B, and MFP  110   c  is installed, for example, in a meeting room C. 
     MFP  110  includes a scanner function, a facsimile function, a copy function, a printer function, a data communication function, and a server function. In particular, when the printer function is used, a meeting material can be output in the form of a paper printout. MFP  110  includes an HDD (Hard Disk Drive)  101 , a CPU (Central Processing Unit)  102 , a ROM (Read Only Memory)  103 , a RAM (Random Access Memory)  104 , and a network controller  105 . 
     HDD  101  stores data such as printing data externally sent through network controller  105  (for example, print data in PDL (Page Description Language)) and image data scanned by a scanner unit. HDD  101  also stores a meeting information table ( FIG. 5 ) and a print information table ( FIG. 6 ) as described later. HDD  101  further stores printing history data ( FIG. 7 ) in the given MFP and an ID information table ( FIG. 8 ). HDD  101  may store raster data after an RIP (raster image processing) process, in place of PDL print data (or in addition to PDL print data). 
     CPU  102  performs control of the entire MFP  110 , such as a scan job, a copy job, and a print job. CPU  102  reads data from ROM  103  or writes data into ROM  103  through prescribed processing. 
     ROM  103  is, for example, a flash ROM (Flash Memory). ROM  103  stores a variety of programs for performing operations of MFP  110 , including a program for a material printing process, and a variety of fixed data. ROM  103  may be non-rewritable. 
     RAM  104  is a main memory of CPU  102 . RAM  104  is used to store data required when CPU  102  executes a control program. 
     Network controller  105  communicates with an external device such as any other MFP  110  or PC  190 , for example, via a LAN using a communication protocol such as TCP/IP in accordance with an instruction from CPU  102 . 
     PC  190   a  is, for example, a terminal device for a meeting organizer (or a material creator) and is used to create a material or meeting information to be used in a meeting. PC  190   b  is, for example, a terminal device for a meeting participant and is used by the meeting participant to give MFP  110  an instruction to print a material to be used in a meeting or to view a material to be used in a meeting. 
     A user who serves as a meeting organizer can access HDD  101  of MFP  110   a  using PC  190   a  to create or view meeting information in the meeting information table. CPU  102  of MFP  110   a  may perform user authentication with password entry, a request for an ID card, or any other methods, and permits only the authenticated user to create or view the meeting information in the meeting information table. 
     PC  190  includes an HDD  191 , a CPU  192 , a ROM  193 , a RAM  194 , a network controller  195 , a display unit  196  such as a monitor, and an input unit  197  such as a keyboard and a mouse. PC  190  contains application software in its storage for creating documents and graphics. In place of PC  190 , a workstation, a portable information terminal, or a mobile phone terminal, for example, may be used as a terminal device for a meeting organizer. 
     Network  200  is a wired or wireless LAN (Local Area Network). Network  200  is connected using a protocol such as TCP/IP (Transmission Control Protocol/Internet Protocol). Devices connected to network  200  can mutually exchange a variety of data. Devices may be connected using a wide area network such as the Internet or a private line, in place of network  200 . 
     In the present embodiment, an MFP, which is one of image forming apparatuses, is shown as a material printing apparatus. However, the material printing apparatus in the present invention may be any other image forming apparatus such as a facsimile machine, a copier, or a printer. 
     [Conversion of Data Format in Printing] 
       FIG. 2  is a diagram conceptually showing conversion of data formats when printing is done. 
     Referring to  FIG. 2 , upon receiving from a user an instruction to print application data of a material to be used in a meeting, CPU  192  of PC  190  converts the application data into print data using a printer driver. The application data is data created, for example, in a file format with an extension such as “.doc,” “.ppt,” or “.xls,” and the print data is data described in a printer language (PDL language) such as “PDF (R),” “Post Script (R),” or “PCL (R).” CPU  192  then transmits the converted print data to MFP  110  which executes printing. CPU  102  of MFP  110  receives the print data and then stores the print data into HDD  101  of MFP  110  as printing data. CPU  102  thereafter converts the print data into raster data through an RIP process and performs printing based on the raster data. After printing, CPU  102  stores the history of the printing as printing history data ( FIG. 7 ), which will be described later, into HDD  101 . 
       FIG. 3  is a conceptual diagram showing the relation between a material created by a meeting organizer and printing data corresponding to the material. 
     Referring to  FIG. 3 , it is assumed that a meeting organizer creates application data AD 1  having a file name “multifunction peripheral search result. ppt” as a material to be used in a meeting and intends to distribute this material to participants. In this case, the organizer (or material creator) creates application data AD 1  having a file name “multifunction peripheral search result. ppt” at his/her own PC  190  and stores application data AD 1  into a location (for example, HDD  101  of MFP  110 ) from which the participants can execute printing. 
     For example, upon receiving an instruction to print application data AD 1  from the meeting organizer or participant, PC  190  converts the application data into print data PD 1  using a printer driver. PC  190  then transmits the converted print data PD 1  to MFP  110  which executes printing. Upon receiving print data PD 1 , MFP  110  stores print data PD 1  into HDD  101 . MFP  110  thereafter converts print data PD 1  into raster data RD 1  through an RIP process and performs printing based on raster data RD 1 . It is noted that MFP  110  may store raster data in place of print data or in addition to print data, into HDD  101 . After printing, MFP  110  stores the history of the printing in HDD  101 . The printing history includes the file creation date and time of application data AD 1  (2008-12-01-14:51:50) and the print date and time thereof (2008-12-10-19:17:29). 
     When the organizer revises application data AD 1  after application data AD 1  is printed, application data AD 1  stored in HDD  101  of MFP  110  is overwritten with the revised application data AD 2  (or the revised application data AD 2  is saved in a location different from that of application data AD 1 ). When an instruction to print application data AD 2  is received from the organizer (or participant), print data PD 2  obtained by converting application data AD 2  is automatically stored into HDD  101  together with the file creation date and time of application data AD 2  (2008-12-11-09:25:01) and the print date and time thereof (2008-12-11-09:27:10). 
     When the organizer revises application data AD 2  after application data AD 2  is printed, application data AD 2  stored in HDD  101  of MFP  110  is overwritten with the revised application data AD 3  (or the revised application data AD 3  is saved in a location different from that of application data AD 2 ). When an instruction to print application data AD 3  is received from the organizer (or participant), print data PD 3  obtained by converting application data AD 3  is automatically stored into HDD  101  together with the file creation date and time of application data AD 3  (2008-12-14-19:50:22) and the print date and time thereof (2008-12-14-19:52:15). 
     When the organizer further revises application data AD 3  after application data AD 3  is printed, application data AD 3  stored in HDD  101  of MFP  110  is overwritten with the revised application data AD 4  (or the revised application data AD 4  is saved in a location different from that of application data AD 3 ). When an instruction to print application data AD 4  is received from the organizer (or participant), print data PD 4  obtained by converting application data AD 4  is automatically stored into HDD  101  together with the file creation date and time of application data AD 4  (2008-12-14-20:35:55) and the print date and time thereof (2008-12-14-20:36:42). 
     Therefore, when application data is repeatedly revised and the revised application data is printed each time at the MFP, print data PD 1  to PD 4  each corresponding to each version of application data AD 1  to AD 4  is automatically stored in MFP  110  together with the file creation date and time and the print date and time for each of application data AD 1  to AD 4 . 
     Here, the formal meeting material to be actually used in a meeting may be updated (changed) by the organizer from application data AD 1  to application data AD 3 , which is any given version of application data, after application data AD 1  is provided in a printable state to the participants. In such a case, it can be assumed that the participants may have printed application data AD 1 , AD 2 , or AD 4 , which is a different version from application data AD 3  serving as the formal meeting material. 
     Then, the material printing system in the present embodiment searches for the printing histories of the participants in HDD  101  of each MFP  110  and obtains the printing history for each participant. Then, the material printing system specifies print data obtained by converting application data that is printed by each participant, and calculates the difference between the print data of each participant and print data PD 3  obtained by converting application data AD 3 . Accordingly, the material printing system grasps the participant who has printed a different version of application data AD 1 , AD 2 , or AD 4  (the participant who has printed a different version of print data PD 1 , PD 2 , or PD 4 ). The material printing system then provides the participant who has printed a different version of application data AD 1 , AD 2 , or AD 4  with the formal meeting material by printing only the portion corresponding to the difference between print data PD 3  and the print data of each participant (that portion of print data PD 3  which is different from print data PD 1 , PD 2 , or PD 4  of the participant). 
     In the foregoing case, application data AD 3  is application data concerning the formal meeting material, that is, application data concerning the meeting material that the meeting organizer is going to actually use in the meeting. Print data PD 3  obtained by converting application data AD 3  is material data serving as a reference in calculating a difference. Print data equivalent to print data PD 3  may be referred to as “reference material data” in the specification of the subject application. 
     In the specification of the subject application, “a different version of print data” means the old reference material data specified by the meeting information table before updating, or print data obtained by converting application data that has a file name matching the file name of application data corresponding to the current reference material data but has a different file creation date and time. 
     [Configuration of MFP] 
       FIG. 4  is a block diagram functionally showing a configuration of MFP  110  in the embodiment of the present invention. 
     Referring to  FIG. 4 , MFP  110  includes a control unit  130 , a power supply unit  151 , a scanner unit  152 , a printing unit  153 , an operation panel unit  154 , and a card authentication unit  155 . 
     Control unit  130  performs sequence control of the entire processing such as scanning, print, transmission, and reception and controls the operation of each unit of MFP  110 . Control unit  130  is mainly configured with HDD  101 , CPU  102 , ROM  103 , RAM  104 , network controller  105  ( FIG. 1 ), and a circuit for controlling each unit. 
     Control unit  130  includes, for example, a reference setting unit  131 , a meeting information storage unit  132 , a detection unit  133 , a printing history search unit  134 , an operation unit  135 , a notification unit  136 , a count unit  137 , and a printing history data storage unit  138 . 
     Reference setting unit  131  sets any given version of print data as reference material data, among plural versions of print data concerning a meeting (an example of material data), in accordance with an instruction from the user. Meeting information storage unit  132  stores, in the meeting information table ( FIG. 5 ), meeting information indicating the relation among a meeting, reference material data concerning the meeting, and the participants in the meeting. In other words, meeting information storage unit  132  stores information for grasping who takes part in which meeting and which print data is to be used as a material. Detection unit  133  detects whether reference material data concerning a particular meeting is set. Printing history search unit  134  (an example of a history obtaining unit) searches for (obtains) a printing history of print data concerning a particular meeting for a participant in the particular meeting. Operation unit  135  (an example of a calculation unit) calculates the difference between print data printed by a participant in a particular meeting and reference material data concerning the particular meeting (difference between print data) based on the printing history obtained by printing history search unit  134 . Notification unit  136  transmits a variety of messages, for example, indicating that a meeting material is updated, to PC  190 . Count unit  137  counts the number of sheets printed by printing unit  153 . Printing history data storage unit  138  stores printing history data as described later. 
     The programs or data for implementing these functions are installed in HDD  101  ( FIG. 1 ). These programs or data may be loaded into RAM  104  as necessary so that the programs are executed by CPU  102 . Part or all of these functions may be implemented by a processor (a control circuit). 
     Power supply unit  151  is provided in the casing of MFP  110 . Power supply unit  151  is connected to a commercial power supply. Power supply unit  151  supplies power to control unit  130 , printing unit  153 , and the like, based on the commercial power supply. 
     Scanner unit  152  performs a scanner function. Scanner unit  152  scans a document placed on a transparent platen using a contact image sensor and reads the document as image data. Scanner unit  152  has an ADF (Automatic Document Feeder) and scans image data using the contact image sensor while successively taking in multiple sheets of a document set on a document tray using the ADF. The scanned image data is converted into an application data format, for example, in control unit  130  and stored, for example, into HDD  101 . 
     Printing unit  153  mainly includes a toner image formation unit  161 , a paper conveyance unit  162 , and a fixing unit  163 . Printing unit  153  forms an image on paper, for example, by electrophotography. Printing unit  153  is configured to combine four colors of images in tandem and form a color image on paper. 
     Toner image formation unit  161  includes photoconductors for cyan (C), magenta (M), yellow (Y), and black (K), an intermediate transfer belt onto which toner images are transferred from the photoconductors (primary transfer), and a transfer unit for transferring an image from the intermediate transfer belt onto paper (secondary transfer). 
     Paper conveyance unit  162  is a unit for conveying paper and mainly includes a paper feeding roller, a conveyance roller, and a motor for driving them. Paper conveyance unit  162  feeds paper from a paper feed cassette and discharges paper to a paper output tray through toner image formation unit  161  and fixing unit  163 . 
     Fixing unit  163  has a heating roller and a pressing roller. Fixing unit  163  conveys paper having a toner image sandwiched between the heating roller and the pressing roller, and heats and presses the paper. Fixing unit  163  thus fuses toner adhered on the paper and fixes the toner on paper thereby forming an image on the paper. 
     Operation panel unit  154  mainly includes a liquid crystal display. The liquid crystal display is formed as a touch panel and can be used for a variety of display and settings. More specifically, the liquid crystal display displays a guide screen or an operation button to the user and accepts an instruction from the user through a touch operation. The liquid crystal display is controlled by control unit  130  for display. When the operation button of operation panel unit  154  is operated by the user, operation panel unit  154  sends an operation signal or a prescribed command corresponding to the operation to control unit  130 . In other words, the user can allow MFP  110  to perform a variety of operations by performing operations from operation panel unit  154 . 
     Card authentication unit  155  performs personal authentication using an ID card (authentication card). More specifically, card authentication unit  155  communicates with an ID card held by a user in a contact or noncontact manner to accept entry of the user&#39;s ID stored in a storage unit of the ID card and sends the accepted user ID to CPU  102 . Card authentication unit  155  mainly has an antenna and a radio circuit for generating a magnetic field for communicating with an ID card, and a circuit for demodulating and decoding information received from the ID card. Card authentication unit  155  may be installed in MFP  110  as shown in  FIG. 4  or may be provided in the vicinity of MFP  110  independently from MFP  110  and connected with MFP  110  so as to be able to communicate therewith, for example, through a USB cable. 
     [Meeting Information Table and Print Information Table] 
     The meeting information table and the print information table stored in HDD  101  of MFP  110   a  will now be described. It is noted that the meeting information table and the print information table may be stored in HDD  101  of any other MFP (MFP  110   b  or MFP  110   c ). 
       FIG. 5  shows an example of the meeting information table stored in HDD  101  of MFP  110   a.    
     Referring to  FIG. 5 , the meeting information table includes at least one piece of meeting information. In the meeting information table, the items “meeting ID,” “starting date and time,” “organizer ID” (the user ID of an organizer), “participant ID” (the user ID of a participant), “material file name” (material list), and “file creation date and time” are associated with each other for one piece of meeting information in the horizontal direction (row direction) of the table. Of these items, “material file name” means the file name of application data of a material to be used in the meeting. “File creation date and time” means the creation date and time of application data (application data before conversion into print data set as reference material data) corresponding to the reference material data. The reference material data obtained by converting application data of the formal meeting material to be used in the meeting can be specified by the items “material file name” and “file creation date and time.” 
     It can be understood from the meeting information in  FIG. 5  that, for a meeting having a meeting ID “001-00001,” for example, the starting date and time is 10:00 on Dec. 15, 2008, the meeting organizer is the one having a user ID “e15835,” and the meeting participants include the one having a user ID “e15830.” It can be also understood that print data that is obtained by converting application data having a file name “multifunction peripheral search result. ppt” and having a creation date and time of 2008-12-14-19:50:22 is set as reference material data. 
     For example, when plural versions of print data PD 1 -PD 4  ( FIG. 3 ) having a file name “multifunction peripheral search result. ppt” are stored in HDD  101  of MFP  110 , print data PD 3  set as the reference material data can be specified by the file creation date and time “2008-12-14-19:50:22.” When no reference material data is set, the item “file creation date and time” is empty. In the vertical direction (column direction) of the table, the meeting information is arranged from the top to the bottom in the order of date and time of holding meetings. 
     The meeting information excluding the item “file creation date and time” is created, for example, by the meeting organizer accessing HDD  101  of MFP  110   a  from his/her own PC  190   a  via network  200  and entering each item. The material to be used in the meeting is also created, for example, by the meeting organizer before the start of the meeting and is saved, for example, in HDD  101  of any one of MFP  110  (or the location in HDD  191  of the meeting organizer&#39;s PC  190   a  that is accessible from an external device connected via network  200 ). It is noted that the item “file creation date and time” in the meeting information is automatically entered, for example, by CPU  102  of MFP  110   a  when the meeting organizer sets reference material data as described later. 
     Information for specifying a meeting, such as a meeting name, may be stored as meeting information in place of a meeting ID, and information for specifying an individual, such as a name, may be stored in place of a user ID of an organizer or participant. Each meeting information may be deleted automatically (without an instruction from the meeting organizer) from the meeting information table immediately after the meeting or after a certain time period has passed since the end of the meeting. 
       FIG. 6  shows an example of the print information table stored in HDD  101  of MFP  110   a.    
     Referring to  FIG. 6 , the print information table includes print information in which at least one participant ID and a printing method (print method) are associated with each other. In the horizontal direction (row direction) of the table, the user ID (participant ID) of one user is related with a print method desired by the user. In the vertical direction (column direction) of the table, for example, print information is arranged from the top to the bottom in increasing order of user IDs (participant IDs). 
     It can be understood from the print information table in  FIG. 6  that, for example, a person having a user ID “e03762” wishes printing of the material in full-text print and a person having a user ID “04946” wishes printing of the material in differential print. 
     The print information table is created, for example, by the administrator of the material printing system entering each item at the time of initial settings of the material printing system (or before the start of the meeting). 
     [Printing History Data and ID Information Table] 
     The printing history data and the ID information table stored in HDD  101  of each MFP  110  will now be described. 
       FIG. 7  shows an example of the printing history data stored in HDD  101  of MFP  110 . 
     Referring to  FIG. 7 , the printing history data shows printing histories in a given MFP  110 . In the printing history data, the items “printing date and time,” “user who did printing,” “file name,” and “file creation date and time” are associated each other for each printing history in the horizontal direction (row direction) of the table. Among the items arranged in the horizontal direction of the table, “file name” means the file name of application data concerned with the given printing, and “file creation date and time” means the date and time at which application data concerned with the given printing was created (saved). Each printing history is associated with print data (data before the RIP process) or raster data (data after the RIP process) obtained by converting application data during the given printing. Printing histories are arranged from the top to the bottom, for example, in the order of printing date and time in the vertical direction (column direction) of the table. 
     It can be understood from the printing history data in  FIG. 7  that, for example, a user having an ID “e15835” printed application data having a file name “multifunction peripheral search result. ppt” at 19:17:29 on Dec. 10, 2008. It can be also understood that this application data was created at 14:51:50 on Dec. 1, 2008. 
     Each printing history in the printing history data and print data or raster data are created by CPU  102  of MFP  110  at the time of printing. When the number of printing histories and print data or raster data reaches a certain value (or when a certain time has passed since printing), they are deleted in the order of occurrence. The print data (print data PD 3  in  FIG. 3 ) set as reference material data is desirably not deleted since it is used later to calculate the difference. 
       FIG. 8  shows an example of the ID information table stored in HDD  101  of MFP  110 . 
     Referring to  FIG. 8 , the ID information table includes the ID of a user who is permitted to use the given MFP  110 , the mail address of the user, and the IP address of the PC used by the user. In the ID information table, the items “ID,” “mail address,” and “IP address” are associated with each other for one user in the horizontal direction (row direction) of the table. The ID information table may include only one of “mail address” and “IP address” as long as it includes a contact of a user. The ID information table may include information for specifying an individual, such as a name, in place of a user ID, and may additionally include a password of each user. 
     The ID information table is used, for example, when MFP  110  notifies each user of a variety of messages. The ID information table is created, for example, by the administrator of the material printing system entering each item at the time of initial settings of the material printing system (or before the start of the meeting). 
     [Method of Setting Reference Material Data] 
     A method of setting reference material data will now be described. 
     In the present embodiment, it will be described by way of example that print data (print data PD 3  in  FIG. 3 ) obtained by converting application data having a material file name “multifunction peripheral search result. ppt” is set as reference material data in a meeting having an ID “001-00001” in the meeting information table shown in  FIG. 5 . 
       FIG. 9  shows an exemplary printing dialog box appearing on display unit  196  of PC  190   a  when reference material data is set. 
     Referring to  FIG. 9 , application data (application data AD 3 ) named “multifunction peripheral search result. ppt” to be used in the meeting is opened by a user as a meeting organizer at PC  190   a . This application data is saved, for example, in HDD  101  of MFP  110 . 
     A printing dialog box  10  (printing execution screen) appears on display unit  196  of PC  190   a . Printing dialog box  10  has, for example, a plurality of tabs  11   a - 11   e , an OK button  14 , and a cancel button  15 . A plurality of tabs  11   a - 11   e  are horizontally arranged at the top of printing dialog box  10  in  FIG. 9 . OK button  14  and cancel button  15  are arranged on the lower right of printing dialog box  10 . 
     When the user presses tab  11   e  serving as a tab for reference setting, a message “Set as a reference material?” as well as a “YES” button  13   a  and a “NO” button  13   b  appear on the right side of printing dialog box  10 . A thumbnail  12 , for example, of the first page of the opened application data appears on the left side of printing dialog box  10 . Thus, CPU  192  of PC  190   a  (or control unit  130  of MFP  110   a ) asks the user whether to set the print data (print data PD 3 ) obtained by converting the application data, as reference material data. In the state of initial settings, for example, button  13   b  is selected. 
     When the user presses OK button  14  in the state in which “YES” button  13   a  is selected, control unit  130  of MFP  110   a  accepts an instruction to print the application data and an instruction to set the print data obtained by converting the application data as reference material data, through CPU  192  of PC  190   a , and executes an application data printing process and a reference material data setting process as described later. On the other hand, when the user presses OK button  14  in the state in which “NO” button  13   b  is selected, control unit  130  of MFP  110   a  only executes the application data printing process without executing the reference material data setting process. When the user presses cancel button  15 , the display of printing dialog box  10  is gone. 
     Control unit  130  of MFP  110   a  may perform user authentication with password entry or any other similar method and may accept an instruction to set reference material data only when the user is authenticated. 
       FIG. 10  is a flowchart showing the application data printing process and the reference material data setting process executed by control unit  130  of MFP  110   a  in the embodiment of the present invention. It is noted that the process according to the flowchart shown in  FIG. 10  may be performed by control unit  130  of any other MFP  110  (MFP  110   b  or  110   c ) or CPU  192  of PC  190   a.    
     Referring to  FIG. 10 , control unit  130  of MFP  110   a  determines whether there exists, in the meeting information table ( FIG. 5 ), meeting information that includes the file name matching the file name (“multifunction peripheral search result. ppt”) of the application data (application data AD 3 ) for which the print instruction is accepted (S 101 ). If there exists, in the meeting information table, meeting information that includes the file name matching the file name of the application data for which the print instruction is accepted (YES in S 101 ), control unit  130  executes printing of the application data (S 102 ). Control unit  130  then creates a printing history in the printing history data ( FIG. 7 ) and saves the print data (print data PD 3 ) obtained by converting the application data during printing, into HDD  101  (S 103 ). Control unit  130  then updates the meeting information table by entering the creation date and time of the printed application data (2008-12-14-19:50:22) into the item “file creation date and time” in the meeting information that includes the file name matching the file name of the application data for which the print instruction is accepted (S 104 ). Accordingly, the print data (PD 3 ) obtained by converting the application data (AD 3 ) during printing is set as reference material data. The print data set as reference material data is specified by the file name (“multifunction peripheral search result. ppt”) of the application data before conversion and by the file creation date and time (2008-12-14-19:50:22). Control unit  130  then obtains, from the printing history data ( FIG. 7 ) in HDD  101  of each MFP  110   a - 110   c , the printing history of the file name matching the file name of the application data for a participant in the meeting concerning the updated meeting information. Then, control unit  130  determines whether there exists a participant who has printed a different version of print data (print data PD 1 , PD 2 , or PD 4 ), based on the obtained printing history (S 105 ). If there exists a participant who has printed a different version of print data (YES in S 105 ), control unit  130  notifies that participant that the meeting material (reference material data) is updated, based on the ID information table ( FIG. 8 ) (S 106 ). The process then ends. If there exists no participant who has printed a different version of print data (NO in S 105 ), control unit  130  ends the process. 
     If there exists, in the meeting information table, no meeting information that includes the file name matching the file name of the application data for which the print instruction is accepted, in S 101  (NO in S 101 ), it means that it is unknown which meeting the print data to be set as reference material data is concerned with. In this case, control unit  130  notifies the user that the file name of the application data for which the print instruction is accepted is not registered in the meeting information table (S 111 ). The process then ends. 
       FIG. 11  shows an exemplary dialog box appearing on the display unit of the PC of the meeting organizer in step S 111  in  FIG. 10 . 
     Referring to  FIG. 11 , when the user as a meeting organizer is going to set, as reference material data, the print data obtained by converting application data having a file name not registered in the meeting information list, a dialog box  16  including a message “Not registered in the meeting material list” and an OK button  21  appears on display unit  196  of PC  190   a  to notify the user that the print data cannot be set as reference material data. Dialog box  16  is displayed until OK button  21  is pressed. In this case, the user can set reference material data by entering the item “material file name” in the meeting information table ( FIG. 5 ). 
       FIG. 12  shows an exemplary dialog box appearing on the display unit of the PC of the meeting participant in step S 106  in  FIG. 10 . 
     Referring to  FIG. 12 , when the reference material data of a meeting is updated, display unit  196  of PC  190   b  of the meeting participant who has printed a different version of print data displays a message box  17  including a message “Material ‘xxx. ppt’ is updated” for a certain period of time (‘xxx. ppt’ is, in this case, ‘multifunction peripheral search result. ppt’), thereby prompting the participant to print the updated reference material data. An email may be sent to the meeting participant who has printed a different version of print data to give a notification that the reference material data is updated. 
     [Print Data Printing Process] 
     A meeting participant usually accesses HDD  101  of MFP  110   a  (or HDD  191  of PC  190   a  of a meeting organizer) via network  200  from his/her own PC  190   b  and obtains a meeting material by printing application data (application data corresponding to reference material data) of a formal meeting material to be actually used in a meeting. Otherwise, a meeting participant may refer to the printing history data saved in HDD  101  of MFP  110   a  and obtain a meeting material by selecting the print data assumed to be set as reference material data, from the printing history data, and printing the selected print data. However, in this case, the meeting participant may erroneously print a different version of print data (for example, print data PD 4  in  FIG. 3 ). In order to prevent such a situation, control unit  130  of MFP  110   a  may perform the print data printing process according to the flowchart shown below. 
       FIG. 13  is a flowchart of the print data printing process executed by control unit  130  of MFP  110   a.    
     Referring to  FIG. 13 , when a print instruction for print data is accepted from a user as a meeting participant (YES in S 121 ), control unit  130  of MFP  110  determines whether there exists, in the meeting information table ( FIG. 5 ), meeting information that includes the material file name matching the file name of the application data corresponding to the print data for which the print instruction is accepted (S 123 ). If there exists meeting information that includes the matching material file name (YES in S 123 ), control unit  130  determines whether the file creation date and time of the application data corresponding to the print data for which the print instruction is accepted agrees with the file creation date and time in the meeting information having the matching file name (S 125 ). If the file creation dates and times agree (YES in S 125 ), it means that the print data that the user is going to print is the file set as a reference. In this case, control unit  130  prints the print data for which the print instruction is accepted (S 127 ). The process then ends. 
     If there exists no meeting information that includes the matching material file name in S 123  (NO in S 123 ), it means that the print data that the user is going to print is irrelevant with the meeting material. In this case, control unit  130  prints the print data for which the print instruction is accepted (S 127 ). The process then ends. 
     If the file creation date and time in the meeting information does not agree in step S 125  (NO in S 125 ), it means that the print data that the user is going to print is a different version of print data. In this case, control unit  130  displays a warning dialog box on display unit  196  of PC  190  (S 133 ) and asks the user whether to correctly print the reference material data (S 135 ). If an instruction to print the reference material data is accepted (YES in S 135 ), control unit  130  prints the reference material data (S 137 ). The process then ends. If an instruction to print the reference material data is not accepted (NO in S 135 ), it means that the user wishes to print a different version of print data. In this case, control unit  130  prints the print data for which the print instruction is accepted (S 127 ). The process then ends. 
       FIG. 14  shows an example of the warning dialog box displayed in step S 133  in  FIG. 13 . 
     Referring to  FIG. 14 , display unit  196  of PC  190   b  of the meeting participant displays a dialog box  18  (the warning dialog box) including a message “The material you are going to print is the material before update. Do you want to print the latest material?” as well as a “YES” button  22   a  and a “NO” button  22   b . Accordingly, PC  190   b  notifies the meeting participant that the print data the user is going to print is not the reference material data, and also asks the meeting participant whether to print the reference material data. 
     If the user presses “YES” button  22   a , control unit  130  of MFP  110   a  accepts an instruction to print the reference material data through PC  190   b  and then prints the reference material data. On the other hand, if the user presses “NO” button  22   b , control unit  130  of MFP  110   a  prints the print data for which the print instruction is accepted. 
     [Differential Printing Method for Meeting Participant] 
     A differential printing method for a meeting participant will now be described. 
     For example, control unit  130  of MFP  110   a  installed in meeting room A shown in  FIG. 1  automatically executes the differential printing process at the starting date and time of a meeting in meeting room A that is included in the meeting information, or at a certain time before the starting date and time. In this case, an instruction of differential printing from a user is not necessary. 
     Control unit  130  may execute the differential printing process when an instruction of differential printing is accepted from a user such as a meeting organizer, rather than automatically executing the differential printing process in accordance with the time. In this case, the instruction from a user may be accepted through operation panel unit  154  of MFP  110  as shown in  FIG. 15 . 
       FIG. 15  shows an exemplary screen appearing on operation panel unit  154  of MFP  110  when a meeting organizer is going to print a material to be distributed to meeting participants. 
     Referring to  FIG. 15 , for example, when a user as a meeting organizer presses a differential printing button displayed on operation panel unit  154 , control unit  130  of MFP  110   a  allows operation panel unit  154  to display a message “Which meeting material do you want to differential-print?” to ask the user to select a meeting for which differential printing is to be executed. The meeting information included in the meeting information table is displayed together with the above-noted message on operation panel unit  154 . Each of the displayed meeting information includes, for example, a meeting name and a date and time of a meeting. The displayed meeting information is associated with PRINT buttons  81 - 85  for executing printing. In  FIG. 15 , since there are too much meeting information to be displayed in a single screen, the display region can be shifted by moving a knob  95   a  of a scroll bar  95  up and down. When the user presses any one of PRINT buttons  81 - 85 , control unit  130  of MFP  110   a  executes the differential printing process as described below for the meeting information corresponding to the pressed PRINT button. 
     In a case other than that show in  FIG. 15 , the instruction of differential printing may be accepted through PC  190   a  of a meeting organizer, for example. In addition, control unit  130  may perform user authentication with password entry or any other similar method and may accept the instruction of differential printing only when the user is authenticated. 
       FIG. 16  is a flowchart showing the differential printing process executed by control unit  130  of MFP  110   a  in the embodiment of the present invention. It is noted that the differential printing process shown in  FIG. 16  may be executed by control unit  130  of any other MFP  110  (MFP  110   b  or  110   c ) or CPU  192  of PC  190 . The differential printing process shown in  FIG. 16  also includes a process executed when full-text printing is performed without performing differential printing at the participant&#39;s wish. 
     Referring to  FIG. 16 , this flowchart mainly includes a process P 1  (steps S 1 -S 7 ), which is a process of calculating the difference between printing data of each participant and printing data (hereinafter also referred to as the latest printing data) corresponding to a formal meeting material to be actually used in a meeting, and a process P 2  (steps S 9 -S 17 ), which is a process of printing the latest printing data for the participant who has printed printing data of a version different from the latest printing data. In  FIG. 16 , the printing data typically means print data but may mean raster data. 
     Control unit  130  of MFP  110   a  obtains the meeting information concerning a meeting to be held from now on, from the meeting information table ( FIG. 5 ) stored in HDD  101  (S 1 ). Control unit  130  then determines whether reference material data is set in the meeting information, based on the obtained meeting information (whether the printing data concerned with the meeting information has been printed as specified as “reference”) (S 3 ). This determination is made based on whether the item “file creation date and time” in the meeting information is entered. If reference material data is set (YES in S 3 ), control unit  130  determines whether the printing data set as reference material data is corrupted (S 4 ). This determination is made, for example, based on whether the printing history corresponding to the reference material data and the reference material data exist in HDD  101 . If the printing history corresponding to the reference material data and the reference material data exist in HDD  101 , it is determined that the printing data is not corrupted. If the printing history corresponding to the reference material data or the reference material data has already been deleted from HDD  101 , it is determined that the printing data is corrupted. If the printing data is not corrupted (NO in S 4 ), control unit  130  determines that the reference material data (the printing data specified as “reference”) is the latest printing data (S 5 ), and then proceeds to step S 7 . 
     If it is determined in step S 3  that the reference material data is not set (NO in S 3 ) or if it is determined in step S 4  that the reference material data is corrupted (YES in S 4 ), the reference material data is not available. In this case, control unit  130  obtains, from the printing history data stored in HDD  101  of each MFP  110 , the printing histories of the file name matching the material file name of the obtained meeting information for all the participants in the meeting to be held from now on (searches for and refers to the printing history for each participant). Control unit  130  then finds printing data corresponding to the printing history having the latest printing date and time from the obtained printing histories for all the participants (S 21 ). Then, control unit  130  determines whether the found printing data is corrupted (S 23 ). This determination is made similarly to step S 4 . If the printing data is not corrupted (NO in S 23 ), control unit  130  determines that the printing data corresponding to the printing history having the latest printing date and time is the latest printing data (S 25 ), and then proceeds to step S 7 . If the printing data is corrupted in step S 23  (YES in S 23 ), printing data corresponding to the printing history having the latest printing date and time is found from the obtained (other) printing histories for all the participants, excluding the printing history corresponding to the corrupted printing data (S 31 ). The process then proceeds to step S 23 . 
     In step S 7 , (if no printing history has been obtained yet) control unit  130  obtains, from the printing history data stored in HDD  101  of each MFP  110 , the printing histories of the file name matching the material file name in the meeting information for all the participants of the meeting to be held from now on, based on the obtained meeting information (searches for a printing history for each participant). Control unit  130  then calculates the difference between the latest printing data and the printing data corresponding to the printing history for one of the participants from which the difference has not yet been calculated (the printing data corresponding to the printing history having the latest printing date and time, for example, if there are a plurality of printing histories for that participant), based on the obtained printing histories (S 7 ), and then determines whether a difference is detected (S 9 ). If a difference is detected (YES in S 9 ), it means that the participant has the meeting material obtained by printing the printing data of a version different from that of the latest printing data. In this case, control unit  130  determines whether the printing method for the participant is full-text print, with reference to the print information table ( FIG. 6 ) (S 11 ). If the printing method for the participant is full-text print (YES in S 11 ), control unit  130  allows printing unit  153  to full-text print the latest printing data (S 13 ), and then proceeds to step S 15 . On the other hand, if the printing method for the participant is differential print in step S 11  (NO in S 11 ), control unit  130  allows printing unit  153  to print the latest printing data only at the differential part (the differential part in the latest printing data) (S 27 ), and then proceeds to step S 15 . If no printing method is included for the participant in the print information table, control unit  130  may perform either full-text printing or differential printing. The differential part printed in step S 27  may be either sentence by sentence or by page by page. 
     If no difference is detected in step S 9  (NO in S 9 ), it means that the participant has the meeting material obtained by printing the latest printing data. In this case, it is unnecessary to do printing again, and therefore, control unit  130  proceeds to step S 15 . 
     In step S 15 , control unit  130  determines whether the difference has been calculated for all the participants in the meeting (whether the calculation is repeated for all the participants). If the difference is not calculated for all the participants (NO in S 15 ), control unit  130  returns to step S 7  and calculates the difference for another participant from which the difference has not yet been calculated. If the difference is calculated for all the participants (YES in S 15 ), control unit  130  notifies the meeting organizer of the participant from which the difference is detected (S 17 ). The process then ends. It is noted that step S 17  may be omitted if there is no participant from which the difference is detected. 
     Here, the arrow D in  FIG. 1  conceptually shows that MFP  110   a  obtains (searches for) the printing histories of the file name matching the material file name of meeting information for all the participants in a meeting, for example, in step S 7  in  FIG. 16 . Control unit  130  of MFP  110   a  searches the printing history data stored in HDD  101  of each MFP  110  connected to network  200 , based on the item “participant ID” of the meeting information, and obtains the printing history for each participant. 
       FIG. 17  shows an exemplary meeting material in which printing data is printed. 
     Referring to  FIG. 17 , a printout  30  (meeting material) in which printing data to be used in a meeting is printed has a participant name  31  printed thereon to indicate the owner of the printout. Accordingly, it can be easily grasped which participant printout  30  belongs to. 
       FIG. 18  shows exemplary display of display unit  196  of PC  190   a  when a notification of a participant having a difference detected is given in step S 17  in  FIG. 16 . 
     Referring to  FIG. 18 , if there is a participant from which a difference is detected in step S 9  in  FIG. 16 , control unit  130  (or CPU  192  of PC  190   a ) may display a list  40  including the detected participant&#39;s name (a list of old version material holders) on display unit  196  of PC  190   a  of the meeting organizer. This can notify the meeting organizer of a participant to which the meeting material in which the latest printing data is printed should be distributed. The notification shown in  FIG. 18  may be given at regular time intervals. In place of the notification shown in  FIG. 18 , emails may be sent to meeting participants to give notification of a participant to which the meeting material in which the latest printing data is printed should be distributed. 
     [Modification of Differential Printing] 
     A modification of the differential printing method for a meeting participant will now be described. 
       FIG. 19  and  FIG. 20  show a flowchart showing a modification of the differential printing process executed by control unit  130  of MFP  110   a  in the embodiment of the present invention. 
     Referring to  FIG. 19  and  FIG. 20 , this flowchart mainly differs from the flowchart shown in  FIG. 16  in that a process P 3 , which is a process of counting the number of printed sheets of printing data, is added. In this modification, the number of printed sheets is counted in different ways between the participant who has not printed the meeting material at all and the participant who has printed the printing data of a version different from that of the latest printing data. 
     Control unit  130  executes the processing similar to the processing illustrated in the flowchart shown in  FIG. 16 , starting from step S 1  shown in  FIG. 16 . Then, after the latest printing data is determined in step S 5  or step S 25 , or if the difference is not calculated for all the participants in step S 15  (NO in S 15 ), the process proceeds to step S 41 . 
     In step S 41 , (if no printing history has been obtained yet) control unit  130  obtains, from the printing history data stored in HDD  101  of each MFP  110 , the printing histories of the file name matching the material file name of the meeting information for all the participants in the meeting to be held from now on, based on the obtained meeting information. Control unit  130  then determines, based on the obtained printing histories, whether the printing history of the file name matching the material file name of the meeting information is included in the printing histories of one of the participants for which the difference has not yet been calculated (S 41 ). If the printing history of the matching file name is included (YES in S 41 ), it means that the participant has already printed the meeting material (whether it is reference material data or not). In this case, in step S 13  or step S 27 , control unit  130  sets count unit  137  ( FIG. 4 ) such that the printing counting method in printing for that participant is different from the usual counting method (for example, such that the count is 50% (half) of the normal count) (S 43 ). Thereafter, control unit  130  performs the processing similar to the processing following step S 7  shown in  FIG. 16 . 
     On the other hand, if the printing history of the printing data concerning the meeting to be held from now on is not included (NO in S 41 ), it means that the participant has not printed the meeting material at all in the past. In this case, control unit  130  proceeds to step S 13  shown in  FIG. 20  and full-text prints the latest printing data (S 13 ). In this case, the setting of count unit  137  is not changed, and the printing counting method in the full-text printing remains as usual (full count). Thereafter, control unit  130  performs the processing similar to the processing following step S 15  shown in  FIG. 16 . 
     EFFECT OF EMBODIMENT 
     The foregoing embodiment provides a convenient material printing system responsive to actual meeting materials, a material printing apparatus, and a program for controlling the material printing system. 
     According to the foregoing embodiment, the difference between printing data set as reference material data by a meeting organizer and printing data printed by each participant is calculated based on the printing history of each participant, and differential data corresponding to the calculated difference is printed. Accordingly, the MFP can eliminate a difference between materials held by the participants only by comparing the printing histories of the participants, without configuring any complicated system. As a result, the convenience of the material printing system and the MFP can be improved. 
     When the reference material data is updated, the meeting participant who has printed a different version of print data is notified that the reference material data is updated, so that the meeting participant who has printed a different version of printing data is prompted to print the updated reference material data. 
     When a meeting participant is going to print a different version of print data, the participant is notified that the print data is not reference material data, thereby preventing erroneous printing of a different version of print data. Furthermore, the participant can be provided with reference material data. 
     If a difference is calculated, the meeting organizer is notified of the meeting participant having the printing history from which the difference is calculated. Therefore, the meeting organizer can be notified of the participant who has not yet obtained the material in which the latest printing data is printed. 
     When reference material data is not set or when reference material data is corrupted, the printing data having the latest printing date and time can be set as the latest printing data, among printing data printed by meeting participants. Therefore, even when reference material data cannot be printed, the printing data assumed as the reference material data can be printed instead. 
     Furthermore, the number of printed sheets is counted in different ways between when the latest printing data is printed for the participant who has printed a different version of print data and when the material is printed for the participant who has not printed the material at all. Therefore, the charges based on the number of printed sheets are varied between those participants. 
     [Others] 
     In the foregoing embodiment, the material printing system has the configuration shown in  FIG. 1 . However, the material printing system may be configured arbitrarily. For example, the number of MFPs and PCs connected to the network is not limited. A meeting management server connected to MFP  110   a  via a network may perform the process executed by the control unit of MFP  110   a  as described above. 
     In the foregoing embodiment, the printing data of the material to be used in a meeting is saved in HDD  101  of MFP  110   a . However, the printing data of the material to be used in a meeting may be saved in any location. For example, it may be saved in HDD  101  of MFP  110   b  or MFP  110   c , or may be saved in HDD  191  of PC  190 , or may be saved in a recording medium such as a USB memory connected to PC  190  or MFP  110 . 
     In the foregoing embodiment, the program for the material printing process is saved in HDD  101  of MFP  110   a . However, the program for the material printing process may be saved in any location. For example, it may be saved in HDD  101  of MFP  110   b  or MFP  110   c , or may be saved in HDD  191  of PC  190 , or may be saved in a recording medium such as a USB memory connected to PC  190  or MFP  110 . 
     In the foregoing embodiment, the meeting information table is saved in HDD  101  of MFP  110   a . However, the meeting information table may be saved in any location. For example, the meeting information table may be saved in HDD  101  of MFP  110   b  or MFP  110   c , or may be saved in HDD  191  of PC  190 , or may be saved in a recording medium such as a USB memory connected to PC  190  or MFP  110 . The number of pieces of information included in the meeting information table is not limited. 
     The printing data set as reference material data may be raster data in place of print data. In this case, the difference between raster data is calculated. In place of printing data, application data may be set as reference material data, and the difference between application data may be calculated. 
     The processing in the foregoing embodiment may be performed by software or using a hardware circuit. 
     A program executing the processing in the foregoing embodiment may be provided. A recording medium encoded with the program, such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card, may be provided to users. The program is executed by a computer such as a CPU. The program may be downloaded to the apparatus over a communication circuit such as the Internet. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.