Patent Publication Number: US-2013232407-A1

Title: Systems and methods for producing, reproducing, and maintaining electronic books

Description:
TECHNICAL FIELD 
     The present invention relates to an electronic book reproducing apparatus, a history obtaining apparatus, an electronic book producing apparatus, an electronic book providing system, an electronic book reproducing method, history obtaining method, an electronic book producing method, an electronic book reproducing program, a history obtaining program, and an electronic book producing program, which is preferably applied to an electronic book providing system providing an electronic book via a disc-shaped recording medium or a network, for example. 
     BACKGROUND ART 
     According to a conventional electronic book reading system, determination is made regarding whether or not pages and a plurality of constituents within the pages have been read by a user based on display time of individual pages of an electronic book when the electronic book is displayed in response to a user operation. 
     In addition, the electronic book reading system stores an operation history for display showing the pages and the constituents of the electronic book displayed in response to the user operation associated with the determination result regarding whether or not the pages and the constituents have been read. 
     Moreover, the electronic book reading system selects and displays the pages and the constituents which have already been read and the pages and the constituents which have not yet been read based on the operation history when the electronic book is displayed again (see PTL 1, for example). 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Unexamined Patent Application Publication No. 2001-109769 (pages 4 to 6, FIGS. 2, 3, and 5) 
     SUMMARY OF INVENTION 
     The electronic book reading system with such a configuration can determine the pages and the constituents, which have been read by a user, in the electronic book based on an operation history by storing the operation history including the determination result showing whether or not the pages and the constituents have been read by the user. 
     In addition, it is considered to be possible to specify contents of the read pages and the constituents and use the contents to manufacture an electronic book advertisement and a new electronic book and to extract user preference and the like by determining the pages and the constituents, which have been read by the user, in the electronic book, according to the electronic book reading system. 
     In other words, it is considered to be possible to effectively use an operation history to manufacture an electronic book advertisement and a new electronic book and to extract user preference and the like by storing the operation history from which it is possible to determine the pages and the constituents, which have been read by the user, in the electronic book, according to the electronic book reading system. 
     In addition, it is considered to be possible to more effectively use the operation history to manufacture an electronic book advertisement and a new electronic book and to extract user preference and the like if parts in pages, which have been actually read by the user, in the electronic book can be specifically determined based on the operation history, according to the electronic book reading system. 
     However, if the display time of a page of the electronic book is within a predetermined time range, the determination is simply made that the entire page and all constituents included in the page have been read regardless of which parts in the page have actually been read. Moreover, the electronic book reading system stores the operation history including the determination result. 
     Therefore, there is a problem in the conventional electronic book reading system in that it is not possible to specifically determine parts, which have been actually read by a user, in a page in the electronic book based on the operation history and it is not possible to effectively use the operation history. 
     The present invention was made in view of the above circumstances and provides an electronic book reproducing apparatus, a history obtaining apparatus, an electronic book producing apparatus, an electronic book providing system, an electronic book reproducing method, a history obtaining method, an electronic book producing method, an electronic book reproducing program, a history obtaining program, and an electronic book producing program, in which it is possible to more effectively use the display history of the displayed electronic book. 
     Thus, a device for reproducing an electronic book is provided. The device may include a control unit configured to determine a target area based on a selection of at least one selectable displayed portion of a page image of the electronic book, and, selectively reproduce, within the target area, content associated with the selected displayed portion of the page image of the electronic book in a predetermined manner. The control unit may be further configured to associate area position information with the selectable displayed portion of the page image of the electronic book, where the area position information may be used by the control unit to determine the content reproduced within the target area. 
     In a further aspect, the control unit may be further configured to display the target area such that the displayed target area overlaps a portion of the page image of the electronic book. Further, the control unit may also be configured to display a surrounding frame image including the displayed target area, where the surrounding frame image may be displayed such that the surrounding frame image overlaps the selectable displayed portion of the page image of the electronic book. 
     In various aspects, the determined target area may be larger than the selectable displayed portion of the page image of the electronic book. Further, the content associated with the selectable displayed portion of the page image of the electronic book may include text content, image content, movie content, and/or audio content. Yet further, the text content associated with the selectable displayed portion of the page image of the electronic book may be displayed within the target area in an enlarged format. 
     In another aspect, the control unit may be further configured to provide an indication that a portion of the page image of the electronic book is not selectable by a user. In yet another aspect, the control unit may also be further configured to provide the indication that the portion of the page image of the electronic book is not selectable by displaying a synthesized message overlapping a displayed portion of the page image of the electronic book. 
     In still another aspect, the control unit may be further configured to receive an indication to change the selection of the at least one selectable displayed portion of the page image of the electronic book to another displayed portion of the page image of the electronic book, determine that the another displayed portion of the page image of the electronic book is not selectable, and, provide an indication of such determination by displaying a synthesized message overlapping a displayed portion of the page image of the electronic book to a user. 
     In yet another aspect, the control unit may be further configured to receive an indication to change the selection of the at least one selectable displayed portion of the page image of the electronic book to another selectable displayed portion of the page image of the electronic book; determine another target area based on the selection of the another selectable displayed portion of the page image of the electronic book, and, selectively reproduce, within the another target area, content associated with the another selectable displayed portion of the page image of the electronic hook in a predetermined manner. 
     In another aspect, the page image of the electronic book may include a plurality of selectable displayed portions, and, the control unit may be further configured to selectively reproduce, within a respective target area determined for each selected displayed portion, content associated with the respective selected displayed portion of the page image of the electronic book in a predetermined manner. In yet aspect, the plurality of selectable displayed portions may be sequentially selectable. 
     In one aspect, the control unit may be further configured to provide history information regarding (i) the selection of each of the at least one selectable displayed portion of the page image of the electronic book by a user and (ii) the selective reproduction, within the determined target area, of the content associated with the selected displayed portion of the page image of the electronic book to the user. 
     A device for producing an electronic book is provided. The device may include a control unit configured to create at least one page image for the electronic book including reproducible content, create at least one selectable portion within the page image and associate a part of the reproducible content of the electronic book with the at least one selectable portion, and, associate data with one or more selectable portions of the page image, where the data associated with the one or more selectable portions may be reproduced upon selection of a respective selectable portion of the page image. 
     In one aspect, the data associated with at least one selectable portion of the page image may include audio data, were the audio data may be reproduced upon selection of said selectable portion of the page image of the electronic book. In another aspect, the data associated with the at least one selectable portion of the page image may include image data. In yet another aspect, the data associated with at least one selectable portion of the page image may include a combination of audio and image data. In still another aspect, the audio data may include a narration of the reproducible content of the electronic book. In still another aspect, the reproducible content of the electronic book may include textual or image content. 
     In one aspect, the control unit may be further configured to differentiate a display state of the part of the reproducible content of the electronic book associated with the at least one selectable portion from other parts of the reproducible content of the electronic book. In another aspect, the control unit may be configured to associate another part of the reproducible content of the electronic book with a non-selectable portion of the page image of the electronic book. In still another aspect, the control unit may be configured to differentiate a display state of the at least one page image from other page images of the electronic book. 
     In one aspect, the control unit may further configured to emphasize the part of the reproducible content of the electronic book associated with the at least one selectable portion from other parts of the reproducible content of the electronic book. In another aspect, the control unit may be configured to emphasize the part of the reproducible content of the electronic book associated with the at least one selectable portion by enlarging a textual content included in the part of the reproducible content of the electronic book associated with the at least one selectable portion. 
     A device for maintaining information regarding an electronic book including at least one page image having at least one selectable portion including a part of reproducible content of the electronic book is provided. The device may include a control unit configured to receive information regarding a selection, by a user, of each of the at least one selectable portion of each respective page image displayed to the user. In one aspect, the control unit may be configured to determine, based on the information regarding a selected respective portion of the respective page image displayed to the user, the part of the reproducible content of the electronic book included within the selected respective portion. The control unit may then analyze the part of reproducible content of the electronic book included within the selected respective portion and one or more attributes associated with the reproducible content of the electronic book to extract a user preference from the selected respective portion of the page image displayed to the user. In yet another aspect, the control unit may be configured to extract the user preference using natural language processing on the part of the reproducible content of the electronic book included within the selected respective portion. 
     An electronic book system is provided. The system may include an electronic book producing device. The electronic book producing device may be configured to create at least one page image for an electronic book including reproducible content; create at least one selectable portion within the page image and associate a part of the reproducible content of the electronic book with each respective selectable portion; and, associate data with each respective selectable portion of the page image, the data associated with each respective selectable portion being reproducible upon selection of the respective selectable portion of the page image. 
     In addition, the system may also include an electronic book reproducing device. The electronic book reproducing device may be configured to determine a target area based on a selection by a user of the at least one selectable portion of the page image displayed to the user, and, selectively reproduce, within the target area and in a predetermined manner, the reproducible content and/or the data associated with the at least one selectable portion selected by the user. 
     In addition to the foregoing, the system may also include a history information device. The history information device may be configured to receive information regarding the selection, by the user, of the at least one selectable portion selected by the user. 
     A method for reproducing an electronic book is provided. The method may include determining, using a processor, a target area based on a selection of at least one selectable displayed portion of a page image of the electronic book, and, selectively reproducing, within the target area, content associated with the selected displayed portion of the page image of the electronic book in a predetermined manner. 
     A non-transitory computer-readable medium on which computer executable instructions of a program for reproducing an electronic book are stored is provided. The instructions, when executed by a control unit, may cause the control unit to determine a target area based on a selection of at least one selectable displayed portion of a page image of the electronic book, and, selectively reproduce, within the target area, content associated with the selected displayed portion of the page image of the electronic book in a predetermined manner. 
     A method for producing an electronic book is provided. The method may include creating, using a processor, at least one page image for the electronic book including reproducible content; creating at least one selectable portion within the page image and associating a part of the reproducible content of the electronic book with the at least one selectable portion; and, associating data with one or more selectable portions of the page image, where the data associated with the one or more selectable portions may be reproducible upon selection of a respective selectable portion of the page image. 
     A non-transitory computer-readable medium on which computer executable instructions of a program for producing an electronic book are stored is provided. The instructions, when executed by a control unit, may cause the control unit to create at least one page image for the electronic book including reproducible content; create at least one selectable portion within the page image and associate a part of the reproducible content of the electronic book with the at least one selectable portion; and, associate data with one or more selectable portions of the page image, the data associated with the one or more selectable portions being reproducible upon selection of a respective selectable portion of the page image. 
     A method for maintaining information regarding an electronic book including at least one page image having at least one selectable portion including a part of reproducible content of the electronic book is provided, where the method may include receiving, using a processor, information regarding a selection, by a user, of each of the at least one selectable portion of each respective page image displayed to the user. 
     A non-transitory computer-readable medium on which computer executable instructions of a program for maintaining information regarding an electronic book including at least one page image having at least one selectable portion including a part of reproducible content of the electronic book are stored is provided. The instructions, when executed by a control unit, may configure the control unit to receive information regarding a selection, by a user, of each of the at least one selectable portion of each respective page image displayed to the user. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram showing an outline of a configuration of an electronic book providing system according to an embodiment. 
         FIG. 2  is an outlined line drawing showing a specific configuration of an electronic hook providing system according to an embodiment. 
         FIG. 3  is a block diagram showing a circuit configuration of an electronic book producing apparatus. 
         FIG. 4  is an outlined line drawing showing a configuration of an electronic book producing screen. 
         FIG. 5  is an outlined line drawing showing a configuration of book information. 
         FIG. 6  is an outlined line drawing showing a configuration of an electronic book producing screen when an electronic hook page image is selected. 
         FIG. 7  is an outlined line drawing showing a configuration of page information. 
         FIG. 8  is an outlined line drawing showing a configuration of an electronic book producing screen when an enlargement target area is chosen in a book page image. 
         FIG. 9  is an outlined line drawing showing a configuration of area information. 
         FIG. 10  is an outlined line drawing for illustrating production of electronic book data. 
         FIG. 11  is an outlined line drawing for illustrating production of electronic book data. 
         FIG. 12  is an outlined line drawing showing a configuration of book information. 
         FIG. 13  is an outlined line drawing showing a configuration of a book providing disc. 
         FIG. 14  is a block diagram showing a circuit configuration of an electronic book reproducing apparatus. 
         FIG. 15  is an outlined line drawing for illustrating display of book page image on a display apparatus. 
         FIG. 16  is an outlined line drawing for illustrating display of a thumbnail image for selecting another book page image on a hook page image. 
         FIG. 17  is an outlined line drawing for illustrating choosing of an enlargement target area on a book page image. 
         FIG. 18  is an outlined line drawing for illustrating enlargement and display of an enlargement target area. 
         FIG. 19  is an outlined line drawing showing a configuration of a display history. 
         FIG. 20  is an outlined line drawing showing a configuration of a program module mounted on an electronic book reproducing apparatus. 
         FIG. 21  is a block diagram showing a circuit configuration of a history obtaining apparatus. 
         FIG. 22  is a flowchart showing a procedure of image data producing processing for an electronic book. 
         FIG. 23  is a flowchart showing a procedure of electronic book data producing processing. 
         FIG. 24  is a flowchart showing a procedure of electronic book data producing processing. 
         FIG. 25  is a flowchart showing a procedure of electronic book registration processing. 
         FIG. 26  is a flowchart showing a procedure of electronic book reproducing processing. 
         FIG. 27  is a flowchart showing procedures of display history providing and obtaining processing where (A) shows a procedure of history providing processing by an electronic book reproducing apparatus and (B) shows a procedure of history obtaining processing by a history obtaining apparatus. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, description will be made of best embodiments (hereinafter, also referred to as embodiments) for implementing the present invention with reference to the drawings. In addition, the description will be made in the following order. 
     1. Embodiments 
     2. Modified Examples 
     1. EMBODIMENTS 
     1-1. Outline of Embodiments 
     First, description will be made of an outline of embodiments. In addition, specific examples of embodiments will be described after the description of the outline. In  FIG. 1 ,  1  shows an outline of a configuration of an electronic book providing system according to this embodiment as a whole. The electronic book providing system  1  is constituted by an electronic book producing apparatus  2 , an electronic book reproducing apparatus  3 , and a history obtaining apparatus  4 . 
     In the electronic book producing apparatus  2 , an importing unit  10  imports image data including images in one or a plurality of pages. In addition, in the electronic book producing apparatus  2 , a producing unit  11  produces electronic book data for an electronic book, which includes one or a plurality of partially-selectable book page images including reproducible content of the electronic book, in which one or a plurality of parts or portions chosen in the book page images are individually set as selectable enlargement target areas which can be enlarged and displayed, based on the original document data imported by the importing unit  10 . 
     On the other hand, in the electronic book reproducing apparatus  3 , a reproducing unit  12  performs reproducing processing on the electronic book data produced by the electronic book producing apparatus  2  and displays book page images on a display unit  13 . In addition, in the electronic book reproducing apparatus  3 , an operation unit  14  is used for arbitrarily designating an enlargement target area in book page images displayed on the display unit  13 . 
     Moreover, in the electronic book reproducing apparatus  3 , a controller or control unit  15  controls the reproducing unit so as to enlarge and display the designated enlargement target area on the display unit  13  when the enlargement target area is designated in the document page image via the operation unit  14 . Furthermore, in the electronic book reproducing apparatus  3 , a transmission unit  16  transmits a display history of an electronic book whose enlargement target areas enlarged and displayed on the display unit  13  are shown. 
     In addition, although the display unit  13  may be provided in the electronic book reproducing apparatus  3 , it is not necessary that the display unit  13  is provided in the electronic book reproducing apparatus  3 , and the display unit  13  may be externally attached to the electronic book reproducing apparatus  3 . 
     In addition to this, in the history obtaining apparatus  4 , the receiving unit  17  receives the display history transmitted from the electronic book reproducing apparatus  3 . Moreover, in the history obtaining apparatus  4 , the storage unit  18  stores the display history received by the receiving unit  17 . 
     With such a configuration, the electronic book providing system  1  can specifically determine which parts in the book page images of an electronic book have been actually read by the user based on the display history, by the history obtaining apparatus  4 . Accordingly, it is possible to more effectively use the display history of the displayed electronic book according to the electronic book providing system  1 . 
     1-2. Specific Configuration of Electronic Book Providing System According to Embodiment 
     Next, description will be made of a configuration of an electronic book providing system  20  as a specific example of the electronic book providing system  1  shown in the aforementioned outline with the use of  FIG. 2 . In the electronic book providing system  20 , an electronic book producing apparatus  21  as a specific example of the electronic book producing apparatus  2  shown in the aforementioned outline and a history obtaining apparatus  22  as a specific example of the history obtaining apparatus  4  shown in the aforementioned outline are connected to the network  23 . 
     In addition, in the electronic book providing system  20 , an electronic book reproducing apparatus  24 , which is owned by a user, for example, as a specific example of the electronic book reproducing apparatus  3  shown in the aforementioned outline is also connected to the network  23 . Moreover, a display apparatus  25  such as a television receiver, for example, which is owned by a user, as a specific example of the display unit  13  shown in the aforementioned outline is connected to the electronic book reproducing apparatus  24 . Furthermore, in the electronic book providing system  20 , a settlement server  26  which performs settlement processing when an electronic book is purchased by a user is also connected to the network  23 . 
     The electronic book producing apparatus  21  produces electronic book data for an electronic book which is obtained by computerizing (digitizing) a publication based on original document data of an original document of the publication such as a novel, a magazine, a picture book, a reference book, a catalog, a brochure, or the like. 
     In addition, the electronic book producing apparatus  21  transmits the electronic book data to the history obtaining apparatus  22  via the network  23 , causes the history obtaining apparatus  22  to store and manage the electronic book data, and causes the history obtaining apparatus  22  to provide the electronic book data via the network  23 . That is, the history obtaining apparatus  22  manages a book selling site on the network  23  which can provide the electronic book data along with the electronic book reproducing program which is for reproducing the electronic book data. 
     In addition, the electronic data reproducing apparatus  24  is configured to be capable of accessing the book selling site on the network  23  for purchasing the electronic book data in response to an operation of a remote controller (hereinafter, also referred to as remote control)  27 , for example. 
     If the electronic book reproducing apparatus  24  accesses the hook selling site and requests the purchase of desired electronic book data, the history obtaining apparatus  22  transmits the electronic book data along with the electronic book reproducing program to the electronic book reproducing apparatus  24  via the network  23 . In so doing, the electronic book reproducing apparatus  24  receives the electronic book data and the electronic book reproducing program transmitted from the history obtaining apparatus  22  and stores the electronic book data and the electronic book reproducing program in an internal hard disk, for example. 
     In so doing, the electronic book providing system  20  allows a user to obtain the electronic hook data along with the electronic book reproducing program via the network  23 . In addition, if the user uses the book selling site and obtains the electronic book data, the settlement server  26  electronically performs settlement processing for the purchasing charge of the electronic book data and allows the user to pay the purchasing charge with the electronic book providing system  20 . 
     In addition, if the remote control  27  is operated, for example, in the state in which the electronic book data and the electronic book reproducing program are stored in the hard disk, the electronic book reproducing apparatus  24  reads the electronic book reproducing program from the hard disk in response to this. 
     At this time, the electronic book reproducing apparatus  24  reads the electronic book data from the hard disk based on the electronic book reproducing program and performs reproducing processing in so doing, the electronic book reproducing apparatus  24  appropriately switches and displays individual book page images of the electronic book on the display apparatus  25  based on the electronic book data. In so doing, the electronic book providing system  20  can provide an electronic book to a user with the use of the network  23  and allows the user to freely read the electronic book. 
     In addition, the electronic book producing apparatus  21  produces a disc-shaped recording medium (hereinafter, also referred to as a book providing disc)  27  such as a BD (Blu-ray Disc) or a DVD (Digital Versatile Disc) for providing an electronic book with the use of the electronic book data. 
     Actually, the electronic book producing apparatus  21  records one or a plurality of electronic book data items and the electronic book reproducing program for reproducing the electronic book data items on the disc-shaped recording medium, on which data has not been recorded, to produce the book providing disc  28 . 
     In addition, the electronic book producing apparatus  21  records book specifying information, which is obtained from the history obtaining apparatus  22 , with which one or a plurality of electronic book data items can be specified, and the electronic book reproducing program on the disc-shaped recording medium, on which data has not been recorded, to produce the book providing disc  28 . 
     That is, the electronic book producing apparatus  21  can produce the book providing disc  28  which can provide an electronic book without particularly recording the electronic book data itself on the disc-shaped recording medium, on which data has not been recorded. 
     The electronic book providing system  20  sells the book providing disc  28  produced by the electronic book producing apparatus  21  as described above to a user through a real disc selling shop or a virtual disc selling site on the network  23 , which is managed by the history obtaining apparatus  22 , for example. 
     In addition, when the electronic book providing disc  28  is purchased by a user using a disk selling shop, the electronic book providing system  20  allows the user to directly pay the purchasing charge of the book providing disc  28  at the disk selling shop. 
     In addition, the electronic book reproducing apparatus  24  is configured to be capable of accessing a disk selling site on the network  23  to purchase the book providing disc  28  in response to the operation of the remote control  27 , for example. 
     Moreover, even when the book providing disc  28  is purchased by a user using a disc selling site, the settlement server  26  electronically performs settlement processing for the purchasing charge of the book providing disc  28  and allows the user to pay the purchasing charge, with the electronic book providing system  20 . 
     If the book providing disc  28  is purchased by the user as described above, the electronic book providing system  20  provides one or a plurality of electronic book data items to the user with the use of the purchased book providing disc  28 . 
     That is, if the remote control  27  is operated, for example, in the state in which the book providing disc  28  with the electronic book data recorded thereon is loaded, the electronic book reproducing apparatus  24  reads the electronic book reproducing program from the book providing disc  28  in response to this. 
     In addition, the electronic book reproducing apparatus  24  reads the electronic book data from the book providing disc  28  based on the electronic book reproducing program and performs reproducing processing. In so doing, the electronic book reproducing apparatus  24  appropriately switches and displays images (hereinafter, also referred to as book page images) of individual pages of the electronic book on the display apparatus  25  based on the electronic book data. 
     Moreover, if the remote control  27  is operated, for example, in the state in which the book providing disc  28  without electronic book data recorded thereon is loaded, the electronic book reproducing apparatus  24  reads the electronic book reproducing program from the book providing disc  28  in response to this. 
     At this time, the electronic book reproducing apparatus  24  reads the book specifying information from the book providing disc  28  based on the electronic book reproducing program, obtains electronic book data, which is specified by the book specifying information, from the history obtaining apparatus  22  via the network  23 , and performs reproducing processing. In so doing, the electronic book reproducing apparatus  24  appropriately switches individual book page images of the electronic book on the display apparatus  25  based on the electronic book data. 
     As described above, the electronic book providing system  20  can provide an electronic book to a user even with the use of the book providing disc  28  and thus allow the user to freely read the electronic book provided with the use of the book providing disc  28 . Then, when the display of the electronic book is completed, the electronic book reproducing apparatus  24  transmits the display history of the electronic book displayed in response to the user operation to the history obtaining apparatus  22  via the network  23 . 
     In addition, if the display history is transmitted from the electronic book reproducing apparatus  24  via the network  23 , the history obtaining apparatus  22  receives and stores the display history. Accordingly, the history obtaining apparatus  22  can use the stored display history to manufacture an electronic book advertisement read by the user or a new electronic book. In addition, the history obtaining apparatus  22  can also use the display history to extract user preference and the like. 
     1-3. Circuit Configuration of Electronic Book Producing Apparatus  21   
     Next, description will be made of a circuit configuration of the electronic book producing apparatus  21  with the use of  FIG. 3 . The electronic book producing apparatus  21  includes a controller or control unit  30  constituted by a CPU (Central Processing Unit), for example. The control unit  30  reads various programs including a basic program stored in advance in a non-transitory computer-readable medium such as a ROM (Read Only Memory)  31 , an electronic book producing program such as desktop publishing software, and the like, for example, via the input output bus  32 . 
     The control unit  30  transfers various programs to the RAM (Random Access Memory)  34  as a work area of the control unit  30  via the memory bus  33  and executes the various programs. In addition, the control unit  30  controls the whole apparatus via the input output bus  32  and the system bus  35  based on the various programs executed on the RAM  34 . Moreover, the control unit  30  executes predetermined computation processing based on the various programs. 
     Furthermore, the control unit  30  also executes various kinds of processing in response to the operation commands given from the operation unit  36  via the external interface unit  37  and the input output bus  32  in this order in response to the operation of the operation unit  36  constituted by a keyboard, a mouse, or the like based on the various programs. 
     In so doing, the control unit  30  imports the original document data of the original document of the publication such as a novel, a magazine, a picture book, a reference book, a catalog, a brochure, or the like as an original of the electronic book from the outside via the external interface unit  37  and the input output bus  32  in this order. 
     Here, the publication as the original of the electronic book is constituted by a front cover and a back cover, or a front cover and a spine and a back cover, and one or a plurality of pages. In addition, the front cover and the back cover, or the front cover and the spine and the back cover are also simply referred to as a cover as a whale in the following description. 
     The cover of a publication is constituted by arranging at least one of text describing the title of the publication, the author, the publisher, or the like, a picture image for the cover, an illustration image, and the like. In addition, the picture image for the cover, the illustration image, and the like are also referred to as a cover image as a whole in the following description. 
     In addition, the individual pages of the publication are constituted by arranging at least one of the text of at least one line, a picture image or an illustration image for artwork, a picture image or an illustration image for an advertisement, and the like. In addition, the picture image or the illustration image for artwork and the picture image or the illustration image for an advertisement are also referred to as an in-page image as a whole in the following description. 
     In addition, the control unit  30  imports the original data from the outside when the original document data of the original document of the publication is produced so as to be printed on a paper medium for manufacturing a publication, for example. 
     The original document data for printing the original document on a paper medium is constituted by connecting image data in which text, in-page images, and the like for each page with a page number added thereto are arranged to cover image data in which text, a cover image, and the like are arranged in the order of the page number, for example. In addition, the original document data is produced in a predetermined first format such as a desktop publishing format, a PDF (Portable Document Format), or the like. 
     In addition, when the publication was produced in the past and there was no original document data of the publication for printing the original document on the paper medium, the control unit  30  imported the original data produced by sequentially scanning the cover and the facing pages from the outside. 
     The original document data produced by scanning the publication is constituted such that the image data for each facing page in which text, in-page images, and the like are arranged, are arranged after the image data of the cover in which text, a cover image, and the like are arranged, in the order of being filed in the publication. 
     In addition, the original document data is produced in a predetermined second format such as TIFF (Togged Image File Format), JPEG (Joint Photographic Experts Group), or the like. 
     When the original document is imported, the control unit  30  determines a type of the original document data (that is, which format is the original document data based on among the first format and the second format) based on the format. 
     Then, when the original document data in the first format is imported, the control unit  30  cuts the decoded original document data into the image data for the cover of the publication and the image data for each facing page of the publication after decoding the original document data. 
     In addition, the control unit  30  detects the total page number of the publication, which is to be produced based on the original data, based on the page number added in advance in the image data for each facing page cut from the original data at this time. 
     On the other hand, when the original document data in the second format is imported, the control unit  30  adds page numbers to image data for one or a plurality of facing pages included in the original document data in turn. In addition, the control unit  30  detects the total page number of the publication as an original of the original document data based on the page numbers added to the image data for one or a plurality of facing pages included in the original document data at this time. 
     In so doing, the control unit  30  obtains the image data for the cover and one or a plurality of facing pages (that is, the image data in the first or second format) from the original document data in the first format or the second format. 
     Then, the control unit  30  respectively performs size conversion processing such as enlargement processing by interpolating of pixels or the like or downsize processing by thinning out or the like on the image data for the cover and the image data for one or a plurality of facing pages. 
     In so doing, the control unit  30  produces image data for an electronic book (that is, image data in the first or second format) with an image size of HDTV (High Definition Television) standard, for example, from the image data for the cover of the publication. 
     In addition, the control unit  30  produces image data for the electronic book (that is, image data in the first or second format) with an image size of HDTV standard even from the image data for each facing page of the publication. 
     In addition, the image data for the cover with an image size of HDTV standard (that is, each image size is matched to the image size of HDTV standard) for the electronic book will also be referred to as book cover image data in the following description. 
     In addition, the image data for each facing page with an image size of HDTV standard (that is, each image size is matched to the image size of HDTV standard) for the electronic book will also be referred to as book page image data in the following description. 
     The control unit  30  produces the book cover image data and the control page image data for the electronic book as described above and sends the produced book cover image data and the book page image data to a graphic engine  38 . 
     When the book cover image data and the book page image data are given from the control unit  30 , the graphic engine  38  produces the electronic book producing screen data for producing the electronic book based on the hook cover image data and the book page image data, 
     Then, the graphic engine  38  sends the electronic book producing screen data to the display unit  40  constituted by a liquid crystal display, an organic EL (Electro Luminescence) display, or the like via a video output unit  39 . In so doing, the control unit  30  displays an electronic book producing screen  42 A as shown in  FIG. 4  on the display unit  40  via the graphic engine  38  based on the electronic book producing screen data. 
     In such a case, an image list display unit  43  is provided on the left side in the horizontal direction while an information input unit  44  which is for inputting various kinds of information relating to the electronic book is provided on the right side in the horizontal direction, for example, on the electronic book producing screen  42 A. 
     A book cover image (not shown) based on the book cover image data and one or a plurality of book page images  45  to  48  based on one or a plurality of book page image data items are arranged and displayed in a line in the vertical direction of the screen, for example, in the image list display unit  43  on the electronic book producing screen  42 A. 
     In addition, in the information input unit  44  on the electronic book producing screen  42 A, a book attribute input image  49  which is for inputting attribute information of an electronic book to be produced at this time (hereinafter, also referred to as book attribute information) is displayed as an initial state, for example. 
     In the book attribute input image  49 , a title input section  50  which is for inputting the title of the electronic book (the title of the original publication, for example) and an issue date input section  51  which is for inputting the issued data of the electronic book (the issue date of the original publication, for example, as the book attribute information are provided. In addition, the title of the electronic book will also be referred to as the book title, and the issue date of the electronic book will also be referred to as the book issued data in the following description. 
     In addition, a book number input section  52  which is for inputting an international standard book number called an ISBN (International Standard Book Number), given to the publication as the original of the electronic book as the book attribute information is also provided in the book attribute input image  49 . 
     A non-transitory computer-readable medium such as a hard disk drive  53  is provided in the electronic book producing apparatus  21 . In addition, the control unit  30  stores on the hard disk driver  53  audio data of various kinds of audio such as music, narration, reading of texts in the electronic book, or the like for being associated with all or portions of the electronic book and being reproduced and allowing a user to listen while the electronic book is purchased and displayed by the user. 
     That is, the control unit  30  prepares in advance various kinds of audio data to be reproduced while the book cover image and the book page images are displayed by the user. Moreover, the control unit  30  reads the audio data from the hard disk driver  53  is the switcher  54  and sends the audio data to an audio processor  55  in response to the operation of the operation unit  36  by an operator. 
     The audio processor  55  sends the audio data to a speaker  57  is an audio output unit  56  after decoding the audio data and causes the speaker  57  to output the audio based on the audio data. As described above, the control unit  30  can reproduce the audio data stored in the hard disk driver  53  for reproducing the electronic book and allow the operator to listen to the audio such as music, narration, and the like. 
     Moreover, the control unit  30  is configured to be capable of allowing the operator to arbitrarily choose the audio data to be reproduced during the display of the electronic book by the user from among the various kinds of audio data prepared in advance with the use of the hard disk drive  53 . 
     Therefore, an audio specifying information input section  58  which is for inputting audio specifying information capable of specifying audio data chosen from the hard disk driver  53  is also provided for the reproduction during the display of the electronic book by the user, as the book attribute information in the book attribute input image  49 . 
     That is, the audio specifying information input section  58  which is for setting audio data to be commonly reproduced during the display of the book cover image and each of the book page images  45  to  48  as the electronic book by the user is provided in the book attribute input image  49 . 
     In addition, the audio data set to be commonly reproduced while the book cover image and each of the book page images  45  to  48  of the electronic book are displayed will be particularly referred to as common audio data in the following description. 
     In addition, a key word input section  59  which is for inputting a keyword (that is, a keyword representing a feature of the electronic book) arbitrarily chosen in accordance with the content of the electronic book as the book attribute information is also provided in the book attribute input image  49 . 
     Moreover, a type input section  60  which is for arbitrarily choosing and inputting a type of an electronic book (hereinafter, this is also referred to as a book type) as the book attribute information from among a plurality of candidates prepared in advance as a pull-down menu or the like, for example is also provided in the book attribute input image  49 . 
     Furthermore, a category input section  61  which is for arbitrarily choosing and inputting a category to which the electronic book belongs as the book attribute information from among a plurality of candidates prepared in advance as a pull-down menu or the like is also provided in the book attribute input image  49 . 
     Accordingly, when the book attribute input image  49  is displayed in the information input unit  44  on the electronic book producing screen  42 A, the control unit  30  allows the operator to input the book attribute information on the book attribute input image  49  via the operation unit  36 . 
     That is, the control unit  30  allows the operator to input a book title, a book issue date, an ISBN, a keyword, a book type, and a category on the book attribute input image  49  at this time. In addition, the control unit  30  also allows the user to input the audio specifying information for common audio data to be reproduced as BGM (Back Ground Music), for example, while the electronic book is displayed by the user, on the book attribute input image  49 . 
     In addition, if the input of the book attribute information is finalized by the operator via the operation unit  36 , the control unit  30  organizes the book attribute information in the book attribute input image  49  along with the total page number as the book attribute information of the electronic book. In so doing, the control unit  30  produces the book information  65  constituted by various book attribute information items of the electronic book as shown in  FIG. 5 . 
     That is, the control unit  30  produces the book information  65  storing the book title  66 , the book issue date  67 , the international standard book number  68 , the audio specifying information  69 , the keyword  70 , the book type  71 , and the category  72  along with the total page number  73 , which are input by the operator. 
     The control unit  30  sets the keyword  70 , the category  72 , and the like of the electronic book by the book information  65  by producing the book information  65  of the electronic book as described above. In addition, the control unit  30  sets the common audio data to be reproduced while the electronic book is displayed by the user to the audio data to be specified by the audio specifying information  69  in the book information  65  by the book information  65 . 
     As publications as originals of the electronic books, however, there are publications such as a brochure to which the international standard book number is not added. Therefore, the control unit  30  can produce the book information  65  based on the other input book attribute information (that is, without the international standard book number) even if the international standard book number  68  is not input by the operator on the book attribute input image  49 . 
     When the electronic book producing screen  42 A is displayed on the display unit  40 , the control unit  30  can allow the operator to arbitrarily select the book page images  45  to  48  by the image list display unit  43  on the electronic book producing screen  42 A via the operation unit  36 . 
     In addition, if one of the book page images  45  to  48  is arbitrarily selected by the operator with the image list display unit  43  via the operation unit  36 , the control unit  30  notifies the graphic engine  38  of the selected book page image of the book page images  45  to  48 . 
     The graphic engine  38  updates the reproducible contents of the electronic book producing image data based on the book page images  45  to  48  in the notification from the control unit  30  at this time. In addition, the graphic engine  38  sends the electronic book producing screen data whose contents are updated to the display unit  40  via the video output unit  39 . 
     In so doing, the control unit  30  displays on the display unit  40  the electronic book producing screen  42 B as shown in  FIG. 6 , in which the same reference numerals are added to the parts corresponding those in  FIG. 4 , based on the electronic book producing screen data whose contents are updated. 
     In such a case, in the electronic book producing screen  42 B, the book page image  47  selected by the operator at this time is enlarged and displayed on the upper side in the information input unit  44  in the vertical direction of the screen. In addition, in the electronic book producing screen  42 B, the page attribute input image  75  which is for inputting the attribute information of the book page image  47  (hereinafter, also referred to as page attribute information) selected by the operator at this time on the lower side in the information input unit  44  in the vertical direction of the screen. 
     In the page attribute input image  75 , an audio specifying information input section  76  which is for inputting audio specifying information of the audio data chosen in the hard disk driver  53  so as to be reproduced during the display of the book page image  47  by the user as the page attribute information is provided. 
     That is, the audio specifying information input section  76  which is for setting the audio data to be reproduced during the display of the book page image  47  by the user is provided in the page attribute input image  75 . In addition, the audio data set to be reproduced during the display of the book page images  45  to  48  of the electronic book will also be referred to as page audio data in particular in the following description. 
     Moreover, a keyword input section  77  which is for inputting a keyword arbitrarily chosen in accordance with the contents of the book page image  47  (that is, the keyword representing the feature of the book page image  47 ) as the page attribute information is also provided in the page attribute input image  75 . 
     Furthermore, a category input section  78  which is for arbitrarily choosing and inputting the category to which the content of the book page image  47  belongs from among a plurality of candidates prepared in advance as a pull-down menu or the like as the page attribute information is also provided in the page attribute input image  75 . 
     Furthermore, a text display section  79  which is for displaying the text in the book page image  47  as the page attribute information is provided in the page attribute input image  75 . In addition, text in the book page image  47  (hereinafter, this is also referred to as in-page text) is automatically displayed on the text display section  79 . 
     Accordingly, if the page attribute input image  75  is displayed on the information input unit  44  in the electronic book producing screen  42 B, the control unit  30  allows the operator to input the page attribute information on the page attribute input image  75  via the operation unit  36 . 
     That is, the control unit  30  allows the operator to input the page attribute information of the book page image  47  via the page attribute input image  75  of the information input unit  44  while the book page image  47  selected at this time is enlarged and displayed to be shown. 
     By the way, the control unit stores on the hard disk driver  53  various kinds of data associated with the electronic book, such as audio data, movie data, and still image data to be reproduced in response to the selection of specific reproducible parts of the article (text), and the in-page images in the book page image  47 . 
     In addition, the specific parts of the article (text), the in-page images, and the like in the book page image  47  will also be referred to as associated parts in the following description. In addition, the various kinds of audio data, movie data, and still image data associated with the associated parts in the book page image  47  will also be referred to as associated data for reproduction as a whole in the following description. Moreover, the movie data associated with the associated parts is constituted by audio data and moving image data. 
     That is, the control unit  30  prepares in advance various kinds of associated data for reproduction to be reproduced in response to the instruction of the associated parts in the book page image  47  when the book page images  45  to  48  are displayed by the user. 
     In addition, the control unit  30  reads the associated data for reproduction from the hard disk driver  53  via the switcher  54  in response to the operation of the operation unit  36  by the operator. At this time, if the associated data for reproduction read from the hard disk drive  53  is audio data, or the associated data for reproduction is movie data including audio data, the control unit  30  sends the audio data to the audio processor  55 . 
     At this time, the audio processor  55  sends the audio data to the speaker  57  via the audio output unit  56  after decoding the audio data in the same manner as described above and causes the speaker  57  to output the audio based on the audio data. 
     In addition, if the associated data for reproduction read from the hard disk drive  53  is movie data including moving image data, or the associated data for reproduction is still image data, the control unit  30  sends the moving image data or the still image data to the video decoder  82 . 
     The video decoder  82  sends the moving image data or the still image data to the display unit  40  via the graphic engine  38  and the video output unit  39  in this order after decoding the moving image data or the still image data and causes the display unit  40  to display the moving image or the still image based on the moving image data or the still image data. 
     In so doing, the control unit  30  can reproduce the movie data or the still image data stored in the hard disk drive  53  for reproduction of the electronic book and allow the operator to view the movie or the still image. 
     In addition, the control unit  30  is configured to be capable of allowing the operator to arbitrarily choose the associated data for reproduction to be reproduced in response to the instruction of the associated parts during the display of the book page image  47  by the user from among various kinds of associated data for reproduction prepared in advance. 
     Moreover, the control unit  30  can allow the operator to arbitrarily designate an associated part in the article associated with the associated data for reproduction (at least a part of the text), the in-page image, and the like on the book page image  47  displayed in the information input unit  44 , via the operation unit  36 . 
     Furthermore, the control unit  30  allows the operator to input the association specifying information for reproduction (not shown) with which the associated data for reproduction associated with the associated part can be specified as the page attribute information on the page attribute input image  75  when the associated part associated with the associated data for reproduction is instructed. 
     Then, when the association specifying information for reproduction is input, the control unit  30  associates the association specifying information for reproduction with position information representing the position of the associated part chosen in the book page image  47  at this time to produce the associating information. In so doing, the control unit  30  associates the associated part in the book page image  47  with the associated data for reproduction associated therewith by the associating information. 
     Furthermore, the control unit  30  can also allow the operator to arbitrarily designate the associated part associated with the book page image of the same or another electronic book on the book page image  47  displayed in the information input unit  44 , via the operation unit  36 . 
     In addition, the electronic book including the book page image associated with the associated part in the book page image  47  in the electronic book will also be referred to as an associated electronic book, and the book page image associated with the associated part will also be referred to as an associated page image, in the following description. 
     In addition, when the associated part associated with the associated page image is chosen, the control unit  30  allows the operator to input the book title of the associated electronic book (not shown) including the associated page image associated with the associated part as the page attribute information on the page attribute input image  75 . 
     Moreover, when the associated part associated with the associated page image is chosen, the control unit  30  allows the operator to input the page number (not shown) of the associated page image associated with the associated part as the page attribute information on the page attribute input image  75 . In addition, the book title of the associated electronic book will also be referred to as an associated book title, and the page number of the associated page image will also be referred to as an associated page number, in the following description. 
     Then, when the associated book title and the associated page number are input as described above, the control unit  30  associates the input associated book title and the associated page number with the position information representing the position of the associated part chosen at this time to produce the associating information. In so doing, the control unit  30  associates the associated part in the book page image  47  with the associated page image associated therewith by the associating information. 
     In addition to this, the control unit  30  can also allow the operator to arbitrarily designate an associated part associated with movie data, homepages, and the like provided via the network  23 , on the book page image  47  displayed in the information input unit  44  via the operation unit  36 . In addition, movie data, homepages, and the like via the network  23 , which are associated with the associated parts, will also be referred to as associated data for provision as a whole in the following description. 
     In addition, the control unit  30  allows the operator to input a network address (not shown) representing the providing source of the associated data for provision associated with the associated part as the page attribute information on the page attribute input image  75  when the associated part associated with the provision associated data is chosen. In addition, the network address representing the providing source of the associated data for provision associated with the associated parts chosen by the operator will also be referred to as an associated address in the following description. 
     Then, when the associated address is input as described above, the control unit  30  associates the input associated address with the position information representing the position of the associated part chosen in the book page image  47  at this time to produce the associating information. In so doing, the control unit  30  associates the associated part in the book page image  47  with the associated data for provision associated therewith by the associating information. 
     In addition, when at least a part of the text is chosen as the associated part on the book page image  47 , the control unit  30  processes the book page image  47  so as to differentiate the display state of at least a part of the selected text from those of the other parts by an underline or the like. 
     In addition, when the in-page image is chosen as the associated part on the book page image  47 , the control unit  30  processes the book page image  47  so as to differentiate the display state from those of the other in-page images by surrounding the in-page image by a frame or the like. When the book page image  47  is processed as described above, the control unit  30  sets the processed book page image data of the book page image  47  to the book page image data for the electronic book. 
     Accordingly, the control unit  30  is configured to be capable of easily determining the associated parts associated with the associated data for reproduction, the associated page image, and the associated data for provision in the book page image  47  when the processed book page image  47  of the electronic book is displayed by the user. 
     Moreover, when the associated part is not specified and the book page image  47  is not particularly processed, the control unit  30  sets the unprocessed book page image data of the book page image  47  to the book page image data for the electronic book as it is. 
     In addition, when the input of the page attribute information is finalized by the operator via the operation unit  36 , the control unit  30  associates the page attribute information in the page attribute input image  75  with the page number as the page attribute information of the book page image  47 . In so doing, the control unit  30  produces the individual book page information constituted by various kinds of page attribute information of the hook page image  47  selected by the operator. 
     The control unit  30  sets the keyword and the category of the book page image  47  based on the individual book page information by producing the individual book page information of the book page image  47  as describe above. In addition, the control unit  30  sets audio data for the page such as BGM, or reading of the texts in the book page image  47 , for example, to be reproduced while the book page image  47  is displayed by the user who has purchased the electronic book, based on the individual book page information. 
     That is, the control unit  30  sets the audio data for the page to be reproduced while the book page image  47  is displayed by the user to the audio data specified by the audio specifying information in the individual book page information. 
     By the way, if the input of the page attribute information is finalized while the audio specifying information is not input on the page attribute input image  75 , for example, the control unit  30  produces the individual book page information based on the other input page attribute information (that is, without the audio specifying information). 
     Then, when the individual book page information is produced while the audio specifying information is not input on the page attribute input image  75  as described above, the control unit  30  makes a setting so as to reproduce the common audio data referring to the book information  65  during the display of the book page image  47 . 
     In addition, when text with various contents and various in-page images are included in the book page image  47 , and it is difficult to set a keyword and a category, for example, the control unit  30  can allow the finalization of the input of the page attribute information with the input of the keyword and the category. 
     In so doing, the control unit  30  can produce the individual book page information which does not include a keyword and a category (that is, in which a keyword and a category are not particularly set) for the hook page image  47  selected by the operator. 
     Then, when the individual book page information of the book page image  47  is produced, the control unit  30  performs downsize processing on the book page image data of the book page image  47  so as to interpolate the pixels. In so doing, the control unit  30  produces thumbnail image data for a thumbnail image as an index of the book page image  47  obtained by reducing the image size while the contents (designs) of the book page image  47  remain the same. 
     In addition, the control unit  30  adds the page number of the original book page image  47  to the thumbnail image data such that it is possible to specify which book page image  47  the thumbnail image data is for. 
     described above, the control unit  30  allows the operator to input the page attribute information for the selected one of the book page images  45  to  48  in the same manner as described above every time the book page  45  to  45  are selected by the operator via the operation unit  36 . 
     In addition, the control unit  30  associates the page attribute information of the book page images  45  to  48  with the page numbers of the book page images  45  to  45  and produces the individual book page information for each of the book page images  45  to  48 . 
     In addition, when respective individual book page information is produced for all of the book page images  45  to  48  of the electronic book, the control unit  30  organizes the individual book page information for each of the book page images  45  to  48  to produce the page information  85  as shown in  FIG. 7 . 
     That is, the control unit  30  produces the page information  85  which associates and stores the page number  86 , the audio specifying information  87 , the in-page text  88 , the keyword  89 , the category  90 , and the associating information which is not shown in the drawing for each of the book page image  45  to  48 . 
     By the way, the control unit  30  can allow the operator to draw square frames, for example, so as to surround the individual articles, the paragraphs in the articles, the in-page image, and the like on the book page image  47 , which is enlarged and displayed on the information input unit  44 , via the operation unit  36 . 
     In so doing, the control unit  30  can allow the operator to choose one or a plurality of areas surrounded by the square frames as enlargement target areas which can be individually enlarged and displayed by the user, in the book page image  47  enlarged and displayed on the information input unit  44 . 
     In addition, the control unit  30  issues area specifying information with which the enlargement target areas can be individually specified every time one enlargement target area is chosen in the book page image  47 . Moreover, the control unit  30  notifies the graphic engine  38  of the area specifying information of the enlargement target areas. 
     The graphic engine  38  updates the contents of the electronic book producing image data with the use of the area specifying information in the notification from the control unit  30  at this time. In addition, the graphic engine  39  sends the electronic book producing screen data whose contents are updated to the display unit  40  via the video output unit  39 . 
     In so doing, the control unit  30  displays on the display unit  40  the electronic book producing screen  42 C as shown in  FIG. 8 , in which the same reference numerals are given to the parts corresponding to those in  FIG. 6 , based on the electronic book producing screen data whose contents are updated. 
     In such a case, the book page image  47  is continuously enlarged and displayed on the upper side in the information input unit  44  in the vertical direction of the screen on the electronic book producing screen  42 C. In addition, a square frame image  93  representing the enlargement target area  92  chosen by the operator at this time (that is, drawn by the operator) on the book page image  47  in the information input unit  44  on the electronic book producing screen  42 C. 
     In addition, an area attribute input image  94  which is for inputting attribute information of the enlargement target area  92  (hereinafter, this is also referred to as area attribute information) chosen by the operator at this time is displayed on the lower side in the information input unit  44  in the vertical direction of the screen on the electronic book producing screen  42 C. 
     The area specifying information  95  for the enlargement target area  92  chosen at this time is displayed as the area attribute information in the area attribute input image  94 . In addition, an audio specifying information input section  96  which is for inputting the audio specifying information for the audio data chosen in the hard disk driver  53  to be reproduced during enlargement and display of the enlargement target area  92  by the user as the area attribute information is provided in the area attribute input image  94 . 
     That is, the audio specifying information input section  96  which is for setting the audio data to be reproduced while the enlargement target area  92  in the book page image  47  is enlarged and displayed by the user is provided in the area attribute input image  94 . 
     In addition, the audio specifying information in this case is also a file name of the audio data, for example, with which the audio data can be specified in the same manner as described above. Moreover, the audio data set to be reproduced during the display of the enlargement target area  92  will also be referred to as audio data for the area in particular in the following description. 
     In addition, a keyword input section  97  which is for inputting the keyword (that is, the keyword representing the feature of the enlargement target area  92 ) arbitrarily chosen in accordance with the content of the enlargement target area  92  as the area attribute information is also provided in the area attribute input image  94 . 
     Moreover, a category input section  98  which is for arbitrarily choosing and inputting the category to which the content of the enlargement target area  92  belongs to from among a plurality of candidates, for example, as the area attribute information is also provided in the area attribute input image  94 . 
     In addition, a text display section  99  which is for displaying the text in the enlargement target area  92  as the area attribute information is provided in the area attribute input image  94  when the text is included in the enlargement target area  92 . Moreover, the text in the enlargement target area  92  (hereinafter, this is also referred to as in-area text) is automatically displayed in the text display section  99 . 
     Accordingly, the control unit  30  allows the operator to input the area attribute information on the area attribute input image  94  via the operation unit  36  when the area attribute input image  94  is displayed on the information input unit  44  on the electronic book producing screen  420 . 
     That is, the control unit  30  allows the operator to input the area attribute information of the enlargement target area  92  while emphasizing, displaying, and showing the enlargement target area  92  chosen at this time with the frame image  93 , via the area attribute input image  94  of the information input unit  44 . 
     Then, if the input of the area attribute information is finalized by the operator via the operation unit  36 , the control unit  30  associates the area attribute information in the area attribute input image  94  with the area position information representing the position of the enlargement target area  92  in the book page image  47  as the area attribute information. 
     In addition, the control unit  30  also associates the area attribute information in the area attribute input image  94  with the page number of the book page image  47  including the enlargement target area  92 . In so doing, the control unit  30  produces the area individual information constituted by various kinds of area attribute information for the enlargement target area  92  chosen by the operator. 
     The control unit  30  sets the keywords and the category of the enlargement target area  92  based on the area individual information by producing the area individual information of the enlargement target area  92  as described above. In addition, the control unit  30  sets the audio data for the area such as BGM and the reading of the texts within the enlargement target area  92  to be reproduced while the enlargement target area  92  is enlarged and displayed by the user who has purchased the electronic book, by the area individual information. 
     That is, the control unit  30  sets the audio data for the area to be reproduced while the enlargement target area  92  is enlarged and displayed by the user to the audio data specified by the audio specifying information in the area individual information. 
     By the way, if the input of the area attribute information is finalized while the audio specifying information is not input on the area attribute input image  94 , for example, the control unit  30  produces the area individual information based on the other input area attribute information (that is, without the audio specifying information). 
     Then, when the area individual information is produced while the audio specifying information is not input on the area attribute input image  94 , the control unit  30  makes the setting so as to reproduce the common audio data referring to the book information  65  during enlargement and display of the enlargement target area  92 . 
     In addition, when text of various contents and various in-page images is included in the enlargement target area  92 , and it is difficult to set a keyword and a category, for example, the control unit  30  can allow the finalization of the input of the area attribute information without the input of the keyword and the category. 
     The control unit  30  can produce the area individual information which does not include a keyword and a category (that is, in which a keyword and a category are not particularly set) for the enlargement target area  92  chosen by the operator as described above. 
     In addition to this, when the input, of the area attribute information is finalized by the operator via the operation unit  36 , the control unit  30  extracts a part of the enlargement target area  92  chosen at this time as area data from the book page image data for the book page image  47 . 
     In addition, the control unit  30  adds the area specifying information for the original enlargement target area  92  after performing the enlargement processing on the area data by interpolating the pixels or the like and produces the area enlargement image data obtained by enlarging the enlargement target area  92  (that is, by increasing the image size of the enlargement target area  92 ). 
     In so doing, the control unit  30  allows the operator to input the area attribute information for the chosen enlargement target area  92  in the same manner as described above every time the enlargement target area  92  is chosen by the operator via the operation unit  36 . 
     In addition, the control unit  30  associates the area attribute information of the enlargement target area  92  with the page numbers of the book page images  45  to  48  including the enlargement target area  92  and produces the area individual information for each enlargement target area  92 . Moreover, the control unit  30  performs enlargement processing on the area data for the enlargement target area  92  and produces the area enlargement image data for enlarging and displaying the enlargement target area  92 . 
     In addition, when area individual information is respectively produced for all of the enlargement target areas  92  chosen in the electronic book, the control unit  30  organizes the area individual information for each enlargement target area  92  and produces the area information  100 , as shown in  FIG. 9 . 
     That is, the control unit  30  generates the area information  100  associating and storing the area specifying information  101 , the page number  102 , the area position information  103 , the audio specifying information  104 , the in-area text  105 , the keyword  106  and the category  107  for each enlargement target area  92 . 
     In addition, the area position information  103  stored in the area information  100  represents the position of the enlargement target area  92  by the x coordinate and the y coordinate of the left upper corner of the enlargement target area  92  in the book page images  45  to  48 , and the width and the height of the enlargement target area  92 , for example. 
     The control unit  30  produces the page information  85  and the area information  100  and reads the common audio data and the audio data for the page set to be reproduced during the display of the electronic book, and the audio data for the area via the switcher  54  from the hard disk drive  53 . 
     In addition, the common audio data, the audio data for the page set to be reproduced during the display of the electronic book and the audio data for the area will be referred to as audio data for the book as a whole in the following description. 
     In addition, the control unit  30  reads the associated data for reproduction set to be reproduced when the associated part in the book page images  45  to  48  are selected by the user, from the hard disk driver  53  via the switcher  54 . 
     Moreover, the control unit  30  sends the audio data for the book and the associated data for reproduction to a stream processor  109 . In so doing, the control unit  30  respectively codes the audio data for the book and the associated data for reproduction in the stream processor  109 . 
     Moreover, the control unit  30  organizes the book cover image data, the book page image data, the thumbnail image data, the area enlargement image data, which are produced at this time, and book information  65 , the page information  85 , the area information  100 , the coded audio data for the book and the associated data for reproduction. 
     In addition, the book cover image data, the book page image data, the thumbnail image data, and the area enlargement image data included in the electronic book data will also be referred to as book image data as a whole in the following description when the discrimination thereof is not particularly necessary. In addition, the coded audio data for the book will also be referred to as coded audio data, and the coded associated data for reproduction will also be referred to as coded associated data in the following description. 
     In so doing, the control unit  30  produces the electronic book data for one electronic book including the book image data, the book information  65 , the page information  85 , the area information  100 , the coded audio data, and the coded associated data. 
     That is, as shown in  FIG. 10 , the control unit  30  produces the electronic book data D 2  based on an electronic book producing program P 1  with the use of the original document data D 1  in the first format, which is imported from the outside and produced for manufacturing the publication  110 . 
     In addition, as shown in  FIG. 11 , the control unit  30  produces the electronic book data D 4  based on the electronic book producing program P 1  with the use of the original document data D 3  in the second format, which is produced by scanning the publication  112  which has already been published. 
     Then, when the electronic book data D 2  and D 4  are produced, the control unit  30  transmits the electronic book data D 2  and D 4  to the history obtaining apparatus  22  via the network controller  115 . In addition, the control unit  30  also sends the specification request information requesting the book specifying information with which the electronic book can be specified based on the electronic book data D 2  and D 4  to the history obtaining apparatus  22  via the network controller  115  at this time along with the electronic book data D 2  and D 4 . 
     When the electronic book data D 2  and D 4  and the specification request information sent from the electronic book producing apparatus  21  are received, the history obtaining apparatus  22  issues the book specifying information, with which the electronic book based on the electronic book data D 2  and D 4  can be specified, based on the specification request information. In addition, the history obtaining apparatus  22  replies the book specification information to the electronic book producing apparatus  21  via the network  23 . 
     At this time, the control unit  30  of the electronic book producing apparatus  21  receives and imports the book specifying information returned from the history obtaining apparatus  22  by the network controller  115 . Then, the control unit  30  stores the book specifying information  116  on the book information  65  produced at this time as shown in  FIG. 12 . In so doing, the control unit  30  updates the contents of the book information  65  for recording of the electronic book data D 2  and D 4  on the disc-shaped recording medium. 
     By the way, when the electronic book data D 2  and D 4  are produced, the control unit  30  allows the operator to input the condition for converting the first or second format of the book image data into the disc format for the book providing disc  20  via the operation unit  36 . 
     In addition, when the electronic book data D 2  and D 4  are produced, the control unit  30  allows the operator to input a parameter or the like for converting the first or second format of the book image data into the disc format for the book providing disc  28  via the operation unit  36 . 
     In addition, the condition, the parameter, and the like for converting the first or second format of the book image data included in the electronic book data D 2  and D 4  into the disc format for the book providing disc  28  will also be referred to as format conversion information as a whole in the following description. 
     Accordingly, when the book specifying information  116  is stored on the hook information  65 , the control unit  30  sequentially sends the electronic book data D 2  and D 4  including the book information  65  along with the format conversion information to the hard disk driver  53  via the switcher  54 . In so doing, the control unit  30  makes a correspondence relationship between the electronic book data D 2  and D 4  and the format conversion information and stores the electronic book data D 2  and D 4  on the hard disk drive  53 . 
     In so doing, the control unit  30  accumulates and stores a plurality of electronic book data items D 2  and D 4  on the hard disk drive  53  by storing the electronic book data D 2  and D 4  on the hard disk drive  53  every time the electronic book data D 2  and D 4  are produced. 
     Then, when the production of the book providing disc  28  is requested by the operator via the operation unit  36  in the state in which the disc-shaped recording medium  118  is mounted on the electronic book producing apparatus  21 , the control unit  30  executes the producing processing of the book providing disc  28 . 
     At this time, the control unit  30  reads the electronic book reproducing program stored in advance from the hard disk drive  53  via the switcher  54 . In addition, the control unit  30  sends the electronic book reproducing program to the drive  120  via the switcher  54 . In so doing, the control unit  30  stores the electronic book reproducing program in the disc-shaped recording medium  118  by the drive  120 . 
     In addition, the control unit  30  reads the book information  65  included in each of a plurality of electronic book data items D 2  and D 4  from the hard disk drive  53  via the switcher  54 . Moreover, the control unit  30  extracts the book title  66 , the book issue date  67 , the book type  71 , and the category  72 , for example, from each of a plurality of book information items  65  and sends them to the graphic engine  38 . 
     The graphic engine  38  produces the book selection screen data, which is for selecting the electronic book, with the use of the book title  66 , the book issued data  67 , the book type  71 , and the category  72  of each of the plurality of electronic books given from the control unit  30 . 
     That is, the graphic engine  38  produces the book selection screen data which is for selecting the electronic book to be provided using the book providing disc  28 , with the use of the book title  66 , the book issue date  67 , the book type  71 , and the category  72  of each of the plurality of electronic books. 
     In addition, the graphic engine  38  sends the book selection screen data to the display unit  40  via the video output unit  39 . In so doing, the graphic engine  38  displays the book selection screen (not shown) based on the book selection screen data on the display unit  40 . 
     In such a case, a list of the book titles  66 , the book issue dates  67 , the book types  71 , and the categories  72  of the plurality of electronic books is displayed in the book selection screen. In addition, a selection button which is for selecting the presence of the recording of the electronic book data D 2  and D 4  on the book providing disc  28  produced at this time is also displayed in the book selection screen. 
     Accordingly, the control unit  30  allows the operator to select one or a plurality of electronic books to be provided is the book providing disc  28  produced at this time, on the book selection screen via the operation unit  36 . In addition, the control unit  30  allows the operator to select the presence of the recording of the electronic book data D 2  and D 4  on the book providing disc  28  produced at this time, on the book selection screen via the operation unit  36 . 
     That is, the control unit  30  allows the operator to select which one of the book providing disc  28  recording the electronic book data D 2  and D 4  and the book providing disc  28  without the electronic book data D 2  and D 4  recorded thereon is to be produced at this time, on the book selection screen. 
     At this time, if the recording of the electronic book data D 2  and D 4  on the book providing disc  28  along with one or a plurality of electronic books is selected, the control unit  30  reads the electronic book data D 2  and D 4  of the selected electronic book from the hard disk drive  53  via the switcher  54 . In addition, the control unit  30  also reads the format conversion information corresponding to the electronic book data D 2  and D 4  of the selected electronic book from the hard disk drive  53  via the switcher  54 . 
     Moreover, the control unit  30  sends the book image data included in the electronic book data D 2  and D 4  to the stream processor  109  along with the format conversion information. Moreover, the control unit  30  converts the book image data in the first or second format into the disc format based on the format conversion information by the stream processor  109 . 
     Then, the control unit  30  sends one or a plurality of electronic book data items D 2  and D 4  including the book image data, for which the first or second format is converted into the disc format, to the drive  120  via the switcher  54 . In so doing, the control unit  30  records one or a plurality of electronic book data D 2  and D 4  on the disc-shaped recording medium  118  by the drive  120 . 
     In addition, when the recording of one or a plurality of electronic book data items D 2  and D 4  on the disc-shaped recording medium  118  is completed, the control unit  30  produces an index table as a list of the book titles of one or a plurality of electronic book data items D 2  and D 4  whose recording has been completed. 
     In addition, the control unit  30  records the index table on the disc-shaped recording medium  118  by the drive  120  by sending the index table to the drive  120  via the switcher  54 . 
     Moreover, the control unit  30  also sends a decoding key information for decoding (breaking the codes) the coded associated data D 7  and the coded audio data D 8  included in one or a plurality of electronic book data D 2  and D 4  whose recording has been completed, to the drive  120  via the switcher  54 . In so doing, the control unit  30  also records the decoding key information on the disc-shaped recording medium  118  by the drive  120 . 
     Furthermore, the control unit  30  stores in advance on the hard disk drive  53  a route certificate as an open key certificate which is issued by a third party and necessary for the electronic book reproducing apparatus  24  to communicate with the history obtaining apparatus  22  via SSL. In addition, SSL is an abbreviation of Secure Sockets Layer Protocol. 
     Accordingly, the control unit  30  reads the route certificate from the hard disk drive  53  via the switcher  54  and sends the read route certificate to the drive  120  via the switcher  54  at this time. In so doing, the control unit  30  also records the route certificate on the disc-shaped recording medium  118  by the drive  120 . 
     In addition to this, the control unit  30  calculates a data verification value to be user for the verification of validity of the electronic data D 2  and D 4  such as a hash with the use of at least a part of the electronic book data D 2  and D 4  for each of the electronic book data D 2  and D 4  whose recording has been completed. In addition, the control unit  30  makes a correspondence relationship between the verification value for each of the electronic book data D 2  and D 4  and the book specifying information  116  of the electronic book data D 2  and D 4 . 
     Moreover, the control unit  30  calculates the certificate verification value to be used for verification of validity of the route certificate such as a hash with the use of at least a part of the route certificate recorded on the disc-shaped recording medium  118 . 
     Then, the control unit  30  organizes the data verification value, the book specifying information  116  corresponded to the data verification value, and the certificate verification value to produce the electronic book certificate and sends the produced electronic book certificate to the drive  120  via the switcher  54 . In so doing, the control unit  30  also records the electronic book certificate on the disc-shaped recording medium  118  by the drive  120 . 
     In so doing, the control unit  30  produces the book providing disc  28  recording the electronic book reproducing program P 2 , one or a plurality of electronic book data D 2  and D 4 , the index table IT, the decoding key information KI, the electronic book certificate EC, and the route certificate RC as shown in  FIG. 13 . 
     In addition, the electronic book data D 2  and D 4  recorded in the book providing disc  28  is constituted by the book image data D 6  in the disc format, the coded associated data D 7 , the coded audio data D 8 , the book information  65 , the page information  85 , and the area information  100 . In addition, the book specifying information  116  is stored on the book information  65  recorded on the book providing disc  28 . 
     By the way, disc specifying information DI with which the disc-shaped recording medium  118  can be individually specified is printed or engraved on the book providing disc  28  at an inner most circumferential part at the time of manufacturing as the original disc-shaped recording medium  118 , for example. In addition, such disc specifying information DI is used for managing the book providing disc  28  purchased by the user as will be described later, for example. 
     In addition, the control unit  30  codes not only the coded associated data D 7  and the coded audio data D 8  included in the electronic book data D 2  and D 4  but also the entire electronic book data D 2  and D 4  in accordance with the presetting, for example. 
     In addition, the control unit  30  can code at least one of the book image data D 6 , the coded associated data D 7 , the coded audio data D 8 , the book information  65 , the page information  85 , and the area information  100  included in the electronic book data D 2  and D 4  in accordance with the presetting. In addition, the control unit  30  can also produce the book providing disc  28  recording the electronic book data D 2  and D 4  in which at least a part is encoded as described above. 
     In addition, when the book providing disc  28  recording the electronic book data D 2  and D 4  in which at least a part is coded is produced as described above, the control unit  30  records the decoding key information which is for decoding the coding, on the book providing disc  28 . 
     On the other hand, if non-recording of the electronic book data D 2  and D 4  along with one or a plurality of electronic books is selected on the book selection screen, the control unit  30  reads the electronic book data D 2  and D 4  of the electronic book selected from the hard disk drive  53  via the switcher  54 . 
     In addition, the control unit  30  produces the index table in the same manner as described above based on the book information  65  included in the electronic book data D 2  and D 4  read from the hard disk drive  53 . Then, the control unit  30  records the index table on the disc-shaped recording medium  118  by the drive  120  by sending the index table to the drive  120  via the switcher  54 . 
     Moreover, the control unit  30  reads the route certificate from the hard disk drive  53  via the switcher  54  and sends the read route certificate to the drive  120  via the switcher  54 . In so doing, the control unit  30  stores the route certificate on the disc-shaped recording medium  118  via the drive  120 . 
     Furthermore, the control unit  30  produces the electronic book certificate in the same manner as described above with the use of the electronic book data D 2  and D 4  of the electronic book selected at this time along with the route certificate and sends the produced electronic book certificate to the drive  120  via the switcher  54 . In so doing, the control unit  30  records the electronic book certificate on the disc-shaped recording medium  118  by the drive  120 . 
     When the non-recording of the electronic book data D 2  and D 4  is selected as described above, the control unit  30  produces the book providing disc  28  (not shown) recording the electronic book reproducing program P 2 , the index table IT, the electronic book certificate EC, and the route certificate RC. 
     In so doing, the control unit  30  can produce the book providing disc  28  recording the electronic book data D 2  and D 4  and produce the book providing disc  28  which does not record the electronic book data D 2  and D 4 . 
     In addition, when a large number of book providing disks  28  with the same recording content are produced, the control unit  30  takes over the entire data to be recorded on the book providing disc  28  to a disc manufacturing factory via a portable recording medium or the network  23 . 
     In addition, when the book providing disc  28  records the electronic book data D 2  and D 4 , the entire data to be recorded on the book providing disc  28  means the electronic book reproducing program P 2 , one or a plurality of electronic book data items D 2  and D 4 , the index table IT, the decoding key information KI, the electronic book certificate EC, and the route certificate RC. 
     In addition, when the book providing disc  28  does not record the electronic book data, the entire data to be recorded on the book providing disc  28  means the electronic book reproducing program  22 , the index table IT, the electronic book certificate EC, and the route certificate RC. 
     According to the electronic book providing system  20 , when the entire data to be recorded on the book providing disc  28  is handed over to the disc manufacturing factory, a stamper for injection molding is manufactured based on the entire data in the disc manufacturing factory, for example. 
     In addition, according to the electronic book providing system  20 , the book providing disc  28  is injection-molded with the use of the stamper in the disc manufacturing factory. In so doing, it is possible to produce a large number of book providing discs  28  with the same recording contents according to the electronic book providing system  20 . 
     1-4. Configuration of Electronic Book Reproducing Apparatus  24   
     [1-4-1. Circuit Configuration of Electronic Book Reproducing Apparatus  24 ] 
     Next, description will be made of the circuit configuration of the electronic book reproducing apparatus  24  with the use of  FIG. 14 . The electronic book reproducing apparatus  24  includes a controller or control unit  130  constituted by a CPU. The control unit  130  reads various programs such as a basic program and/or various application programs stored in advance in a non-transitory computer-readable medium such as the ROM  131 , via the input output bus  132 . 
     In addition, the control unit  130  transfers the various programs to the RAM  134  as a work area of the control unit  130  via the memory bus  133  and executes the various programs thereon. Then, the control unit  30  controls the overall apparatus via the input output bus  132  and the system bus  135  based on the various programs executed on the RAM  134 . In addition, the control unit  130  executes predetermined computation processing based on the various programs. 
     Furthermore, the control unit  130  also executes various kinds of processing in response to the operation command given from the remote control  27  via the external interface unit  136  and the input output bus  132  in this order in response to the operation of the remote control  27  (not shown in  FIG. 14 ) based on the various programs. 
     In so doing, the control unit  130  produces user registration screen request information requesting the user registration screen data when the user registration to the history obtaining apparatus  22  is requested by the user via the remote control  27 , for example. 
     In addition, the control unit  130  transmits the user registration screen request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . As a result, the control unit  130  receives and imports the user registration screen data by the network controller  137  when the user registration screen data is returned from the history obtaining apparatus  22 . 
     In addition, the control unit  130  sends the user registration screen data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order and displays a user registration screen (not shown) based on the user screen data on the display surface of the display apparatus  25 . 
     The control unit  130  stores the user information and produces the user registration request information for requesting the user registration when the user information of the user is input by the user on the user registration screen via the remote control  27  in this state. In addition, the user information includes a user&#39;s name, an address, a credit card number, user specifying information, a password, and the like. 
     Then, the control unit  130  transmits the user registration request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . As a result, the control unit  130  receives and imports the user registration completion notification screen data by the network controller  137  when the user registration is completed and the user registration completion notification screen data for notifying of the completion is returned from the history obtaining apparatus  22 . 
     In addition, the control unit  130  sends the user registration completion notification screen data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order. In so doing, the control unit  130  notifies the user of the completion of the user registration by displaying the user registration completion notification screen (not shown) based on the user registration completion notification screen data on the display surface of the display unit  25 . In addition, the control unit  130  sends the user identification information and the password of the user to a built-in storage unit  140  and stores and keeps the user identification information and the password when the user registration is completed as described above. 
     On the other hand, if the book providing disc  28  is purchased by a user, and a registration of the book providing disk  28  is requested via the remote control  27 , the control unit  130  reads the user specification information and the password from the built-in storage unit  140 . 
     In addition, the control unit  130  stores the user specifying information and the password and produces the authentication processing request information for requesting the user authentication processing. Then, the control unit  130  transmits the authentication processing request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     As a result, when the user authentication processing is performed by the history obtaining apparatus  22  based on the authentication processing request information, the user is authenticated, and the authentication notification information is returned, the control unit  130  receives and imports the authentication notification information by the network controller  137 . 
     When it is detected that the user has been authenticated based on the authentication notification information, the control unit  130  produces disc registration screen request information for requesting the disc registration screen data. Then, the control unit  130  transmits the disc registration screen request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     As a result, when the disc registration screen data is returned from the history obtaining apparatus  22 , the control unit  130  receives and imports the disc registration screen data by the network controller  137 . In addition, the control unit  130  sends the disc registration screen data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order and displays on the display surface of the display apparatus  25  a disc registration screen (not shown) based on the user screen data. 
     When the disc information is input on the disc registration screen by the user via the remote control  27 , the control unit  130  stores the disc information along with the user specifying information and the password and produces the disc registration request information for requesting the disc registration. In addition, the disc information includes disc specifying information of the book providing disc  28  purchased by the user and the book title of the electronic book provided by the book providing disc  28 . 
     Then, the control unit  130  transmits the disc registration request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . As a result, when the disk registration is completed, and the disc registration completion notification screen data for notifying of the completion is returned from the history obtaining apparatus  22 , the control unit  130  receives and imports the disc registration completion notification screen data by the network controller  137 . 
     In addition, the control unit  130  sends the disc registration completion notification screen data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order. In so doing, the control unit  130  displays the disc registration completion notification screen (not shown) based on the disc registration completion notification screen data on the display surface of the display apparatus  25  and notifies the user of the completion of the disc registration. In addition, when the disc registration is completed as described above, the control unit  130  sends the disc specifying information and the book title used for the disc registration to the built-in storage unit  140  and stores and keeps the disc specifying information and the book title. 
     By the way, when the book providing disc  28  is mounted on the electronic book reproducing apparatus  24 , and the reproduction of the electronic book is instructed by the user via the remote control  27 , the control unit  130  accesses the book providing disc  28  via the switcher  141  and the drive  142 . 
     In so doing, the control unit  130  reads the electronic book reproducing program from the book providing disc  28  via the switcher  141  and the drive  142  in this order and transfers the read electronic book reproducing program to the RAM  134  and executes the program thereon. 
     Then, the control unit  130  executes the electronic book reproducing processing based on the electronic book reproducing program along with the aforementioned various programs which have been already executed on the RAM  134 . In such a case, the control unit  130  reads the index table from the book providing disc  28  via the switcher  141  and the drive  142  in this order and sends the index table to the graphic engine  138 . 
     The graphic engine  138  produces the index screen data for list-displaying the book titles of the all (one or a plurality of) electronic books provided via the book providing disc  28  based on the index table given from the control unit  130 . 
     In addition, the graphic engine  138  sends the index screen data to the display apparatus  25  via the video output unit  139  and displays the index screen (not shown) based on the index screen data on the display surface of the display apparatus  25 . 
     In so doing, the control unit  130  notifies the user of the electronic book to be provided by the book providing disc  28  mounted on the electronic book reproducing apparatus  24  at this time as the book title, via the index screen displayed on the display surface of the display apparatus  25 . 
     In addition, when the index screen is displayed on the display surface of the display apparatus  25  as described above, the control unit  130  can allow the user to select, the electronic book to be displayed as the book title on the index screen via the remote control  27 . 
     When the electronic book is selected on the index screen, the control unit  130  detects whether or not the electronic book data D 2  and D 4  of the selected electronic book is stored on the book providing disc  28  via the switcher  141  and the drive  142  in this order. 
     That is, the control unit  130  detects whether or not the book providing disc  28  recording the electronic book data D 2  and D 4  is mounted on the electronic book reproducing apparatus  24  at this time. As a result, if the electronic book data D 2  and D 4  are recorded on the book providing disc  28 , the control unit  130  reads the electronic book data D 2  and D 4  of the selected electronic book from the book providing disc  28  via the switcher  141  and the drive  142  in this order. 
     In addition, the control unit  130  reads the electronic book certificate and the route certificate from the book providing disc  28  via the switcher  141  and the drive  142  in this order. Moreover, the control unit  130  calculates the data verification value with the use of at least a part of the electronic book data D 2  and D 4  read from the book providing disc  28 . Furthermore, the control unit  130  calculates the certificate verification value with the use of at least a part of the route certificate. 
     Then, the control unit  130  checks the validity of the electronic book data D 2  and D 4  (that is, whether the data has been falsified) read from the book providing disc  28  at this time, based on the electronic book certificate, the calculated data verification value, and the certificate verification value. If it is confirmed as a result that the electronic book data D 2  and D 4  are valid, the control unit  130  sends the book cover image data included in the electronic book data D 2  and D 4  to the graphic engine  138 . 
     When the book over image data is given from the control unit  130 , the graphic engine  138  sends the book cover image data to the display apparatus  25  via the video output unit  139  after performing display processing on the book cover image data. In so doing, the graphic engine  138  displays the book cover image based on the book cover image data over the entire surface of the display surface of the display apparatus  25 . 
     If the page sending is instructed by the user via the remote control  27  in this state, the control unit  130  sends the book page image data of the top facing pages to the graphic engine  138  from among the book page image data included in the electronic book data D 2  and D 4 . 
     Then, when the top book page image data is given from the control unit  130 , the graphic engine  138  sends the book page image data to the display apparatus  25  via the video output unit  139  after performing display processing on the book page image data in the same manner as described above. In so doing, the graphic engine  138  displays the book page images of the top facing pages on the entire surface of the display surface of the display apparatus  25  instead of the book cover image which have been displayed until then. 
     In addition, if the page sending is instructed by the user via the remote control  27  in the state in which the book page image is displayed on the display apparatus  25 , the control unit  130  sends the book image data of the facing pages in accordance with the instruction to the graphic engine  138 . 
     Then, when the new book page image data is given from the control unit  130 , the graphic engine  138  sends the book page image data to the display apparatus  25  via the video output unit  139  after performing display processing on the book page image data in the same manner as described above. 
     In so doing, the graphic engine  138  displays the book page images of the next facing pages over the entire surface of the display surface of the display apparatus  25  instead of the book page images of the facing pages which have been displayed until then. 
     Furthermore, when the page return is instructed by the user via the remote control  27  in the state in which the book page image is displayed on the display apparatus  25 , the control unit  130  sends the book page image data of the facing pages in accordance with the instruction to the graphic engine  138 . 
     Then, when the new book page image data is given from the control unit  130 , the graphic engine  138  sends the book page image data to the display apparatus  25  via the video output unit  139  after performing display processing on the book page image data in the same manner as described above. In so doing, the graphic engine  138  displays the book page images of the previous facing pages over the entire surface of the display surface of the display apparatus  25  instead of the book page images of the facing pages which have been displayed until then. 
     As described above, the control unit  130  displays the book page image  47  of the electronic book over the entire surface of the display surface of the display apparatus  25  connected to the electronic book reproducing apparatus  24  and appropriately switches the book page images  47  to be displayed over the entire surface of the display surface, as shown in  FIG. 15 . 
     In addition, when the index display of the book page image is instructed by the user is the remote control  2 /during the display of the book page image  47 , the control unit  130  sends a plurality of thumbnail image data items included in the electronic book data D 2  and D 4  to the graphic engine  138 . 
     When a plurality of thumbnail image data items are given from the control unit  130 , the graphic engine  138  synthesizes the plurality of thumbnail image data items with the book page image data of the book page image  47  displayed at this time and performs display processing. 
     Then, the graphic engine  138  sends the book page image data with which the thumbnail image data has been synthesized to the display apparatus  25  via the video output unit  139 . In so doing, the graphic engine  138  continuously displays the book page image  47  which has been displayed until then and displays a plurality of thumbnail images  143  arranged in a line in the horizontal direction of the screen on the book page image  47 , in the display surface of the display apparatus  25  as shown in  FIG. 16 . 
     When the index display of the book page image is instructed, the control unit  130  shows a plurality of book page images of the electronic book as thumbnail images  143  on the book page image  47 . 
     At this time, if the scrolling of the thumbnail images  143  is instructed by the user via the remote control  27 , the control unit  130  controls the graphic engine  138  to scroll the plurality of thumbnail images  143  in the horizontal direction of the screen on the book page image  47 . 
     Then, when a desired thumbnail image  143  is selected by the user via the remote control  27  on the book page image  47 , the control unit  130  sends the book page image data corresponding to the selected thumbnail image  143  to the graphic engine  138 . 
     When the book page image data is given from the control unit  130 , the graphic engine  138  performs the same processing as described above. In so doing, the graphic engine  138  displays the book page image of the facing pages corresponding to the selected thumbnail image  143  over the entire surface of the display surface of the display apparatus  25  instead of the book page image  47  and the plurality of thumbnail images  143  which have been displayed until then. 
     The control unit  130  can also switch the book page images  47  to be displayed on the display surface of the display apparatus  25  as if a plurality of pages are skipped regardless of the order of the pages as described above. 
     As described above, the control unit  130  can allow the user to read the electronic book by appropriately switching and displaying the book page images  45  to  48  of the electronic book on the display surface of the display apparatus  25  after the book cover image of the electronic book. 
     By the way, when the book cover image is displayed on the display surface of the display apparatus  25 , the control unit  130  specifies the common audio data included in the electronic book data D 2  and D 4  based on the audio specifying information stored on the book information  65  and sends the common audio data to the stream processor  144 . In addition, the control unit  130  reads the decoding key information from the book providing disc  28  via the switcher  141  and the drive  142  in this order and sends the decoding key information to the stream processor  144  at this time. 
     If the decoding key information is given from the control unit  130  along with the coded common audio data, the stream processor  144  decodes (breaks the code) of the coded common audio data based on the decoding key information and produces the common audio data. Then, the stream processor  144  sends the common audio data to the audio processor  145 . 
     When the common audio data is given from the stream processor  144 , the audio processor  145  sends the common audio data to the display apparatus  25  via the audio output unit  146  after decoding the common audio data. In so doing, the audio processor  145  causes the speaker provided in the display apparatus  25  to output the audio based on the common audio data. 
     When the display of the book cover image is started, the control unit  130  starts the reproduction of the common audio data as described above. Then, the control unit  130  continues the reproduction of the common audio data and allows the user to listen to the audio based on the common audio data while the book cover image is displayed. 
     In addition, when the book page image  47  is displayed on the display apparatus  25  instead of the book cover image, the control unit  130  refers to the page information  85  corresponding to the book page image  47 . Then, if the audio specifying information is store in the referred page information  85 , the control unit  130  sends the audio data for the page specified by the audio specifying information included in the electronic book data D 2  and D 4  to the stream processor  144  instead of the common audio data. 
     When the coded audio data for the page is given from the control unit  130  instead of the common audio data, the stream processor  144  decodes (breaks the code) the coded audio data for the page based on the decoding key information and produces the page audio data. Then, the stream processor  144  sends the page audio data to the audio processor  145 . 
     When the audio data for the page is given from the stream processor  144  instead of the common audio data, the audio processor  145  sends the audio data for the page to the display apparatus  25  via the audio output unit  146  after decoding the audio data for the page. In so doing, the audio processor  145  causes the speaker provided in the display apparatus  25  to output the audio based on the audio data for the page instead of the audio based on the common audio data. 
     When the display of the book page image is started, the control unit  130  starts the reproduction of the audio data for the page instead of the common audio data as described above. Then, the control unit  130  continues the reproduction of the audio data for the page and allows the user to listen to the audio based on the audio data for the page while the written page image is displayed. 
     On the other hand, if the audio specifying information is not stored on the referred page information  85 , the control unit  130  continuously sends the common audio data to the stream processor  144 . Therefore, the stream processor  144  continuously sends the common audio data to the audio processor  145  after decoding (breaking the code) the coded common audio data based on the decoding key information. 
     Then, the audio processor  145  also sends the common audio data to the display apparatus  25  via the audio output unit  146  after decoding the common audio data. In so doing, the audio processor  145  causes the speaker provided in the display apparatus  25  to continuously output the audio based on the common audio data. 
     If setting is made such that the common audio data is reproduced while the book page image  47  is displayed, the control unit  130  allows the user to continuously listen to the audio based on the common audio data during the display of the book page image  47 . 
     Moreover, when the book page image displayed on the display apparatus  25  is switched, the control unit  130  refers to the page information  85  corresponding to the book page image before switching and the page information  85  corresponding to the book page image after switching and compares therebetween. 
     As a result, if setting is made such that different audio data is produced for the book page images before switching and after switching, the control unit  130  stops sending the common audio data or the audio data for the pages which have been sent to the stream processor  144  until then. 
     Then, the control unit  130  sends the audio data for the page and the common audio data set to be reproduced during the display of the book page image after switching to the stream processor  144 . At this time, the stream processor  144  performs processing on the audio data for the page or the common audio data in the same manner as described above. In addition, the audio processor  145  also performs processing on the audio data for the page or the common audio data in the same manner as described above. 
     In so doing, the audio processor  145  causes the speaker of the display apparatus  25  to output via the audio output unit  146  the audio based on the audio data for the page or the common audio data, which is different from the previous data, instead of the audio which has been output until then. 
     In so doing, if setting is made such that different audio data is reproduced for the book page images before switching and after switching, the control unit  130  switches the audio to be listened to by the user in accordance with the switching of the display of the book page images. 
     On the other hand, if setting is made such that the same audio data is reproduced for the book page images before switching and after switching, the control unit  130  continuously sends the common audio data or the audio data for the pages which have been sent to the stream processor  144  until then. 
     At this time, the stream processor  144  continuously performs processing on the same audio data for the page or the common audio data in the same manner. In addition, the audio processor  145  also continuously performs processing on the same audio data for the page or the common audio data in the same manner. In so doing, the audio processor  145  causes the speaker of the display apparatus  25  to continuously output the audio which have been output until then, via the audio output unit  146 . 
     When setting is made such that the same audio data is reproduced for the book page images before switching and after switching, the control unit  130  allows the user to listen to the same audio even if the displayed book page images are switched. 
     In addition, when an associated part is designated on the book page image  47  displayed on the display surface of the display apparatus  25  by the user via the remote control  27 , the control unit  130  refers to the associating information for the designated associated part included in the page information  85 . 
     If the association specifying information for reproduction is stored on the associating information as a result, the control unit  130  sends the associated data for reproduction specified by the association specifying information for reproduction included in the electronic book data D 2  and D 4  to the stream processor  144 . 
     In addition, the control unit  130  reads the decoding key information from the book providing disc  28  via the switcher  141  and the drive  142  in this order and sends the decoding key information to the stream processor  144  at this time. When the decoding key information is given from the control unit  130  along with the coded associated data for reproduction, the stream processor  144  decodes (breaks the code) the coded associated data for reproduction based on the decoding key information. 
     Then, if the associated data for reproduction decoded at this time is audio data or includes audio data, the stream processor  144  sends the audio data to the audio processor  145 . In addition, if the associated data for reproduction decoded at this time is still image data or includes moving image data, the stream processor  144  sends the still image data or the moving image data to the video decoder  147 . 
     At this time, when the audio data is given from the stream processor  144 , the audio processor  145  sends the audio data to the display apparatus  25  via the audio output unit  146  after decoding the audio data. In so doing, the audio processor  145  causes the speaker of the display apparatus  25  to output the audio based on the audio data. 
     In addition, when the still image data or the moving image data is given from the stream processor  144 , the video decoder  147  decodes the still image data or the moving image data. Then, the video decoder  147  sends the decoded still image data or the moving image data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order. 
     In so doing, the video decoder  147  displays the still image or the moving image based on the still image data or the moving image data instead of the book page image  47  or so as to be overlapped with at least a part of the book page image  47  on the display surface of the display apparatus  25 . 
     The control unit  130  can allow the used to view the still image, the movie, or the like associated with the associated part by reproducing the associated data for reproduction when the associated part associated with the associated data for reproduction is designated on the book page image  47  as described above. 
     On the other hand, if an associated is stored on the referred associating information, the control unit  130  accesses the associated address on the network  23  via the network controller  137 . Accordingly, the control unit  130  receives and imports the associated data for provision, which is associated with the associated part designated by the user, by the network controller  137  from the providing source of the associated data for provision represented by the associated address. 
     Then, if audio data is included in the associated data for provision, the control unit  130  sends the audio data to the audio processor  145 . In addition, if still image data or moving image data is included in the associated data for provision, the control unit  130  sends the still image data or the moving image data to the video decoder  147 . 
     When the audio data is given from the control unit  130  at this time, the audio processor  145  decodes the audio data in the same manner as described above and sends the audio data to the display apparatus  25  via the audio output unit  146 . In so doing, the audio processor  145  causes the speaker of the display apparatus  25  to output the sound based on the audio data. 
     In addition, when the still image data or the moving image data is given form the control unit  130 , the video decoder  147  decodes the still image data or the moving image data in the same manner as described above. Then, the video decoder  147  sends the decoded still image data or the moving image data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order. 
     In so doing, the video decoder  147  displays the still image or the moving image based on the still image data or the moving image data instead of the book page image  47  so as to be overlapped with at least a part of the book page image  47  on the display surface of the display apparatus  25 . 
     In so doing, the control unit  130  can allow the user to watch the movie or the like or view the homepages associated with the associated part by reproducing the associated data for provision when the associated part associated with the associated data for provision is designated on the book page image  47 . 
     In addition, if the associated book title is stored on the referred associating information, the control unit  130  determines whether or not the electronic book data D 2  and D 4  with the associated book title is recorder on the book providing disc  28  via the switcher  141  and the drive  142  in this order. 
     If the electronic book data D 2  and P 4  with the associated book title is recorded in the book providing disc  28  as a result, the control unit  130  reads the electronic book data D 2  and D 4  from the book providing disc  28  via the switcher  141  and the drive  142  in this order. 
     Then, the control unit  130  sends the book page image data to which the associated page number stored on the associating information is added to the graphic engine  138  from among the book page image data included in the electronic book data D 2  and D 4 . 
     When the book page image data is given form the control unit  130 , the graphic engine  138  sends the book page image data to the display apparatus  25  via the video output unit  139  after performing display processing on the book page image data in the same manner as described above. In so doing, the graphic engine  138  displays the associated page image instead of the book page image  47  which has been displayed until then or so as to be overlapped with at least a part of the book page image  47  on the display surface of the display apparatus  25 . 
     On the other hand, if the electronic book data D 2  and D 4  with the associated book title is not recorded in the book providing disc  28 , the control unit  130  reads the user specifying information and the password from the built-in storage unit  140 . In addition, the control unit  130  produces authentication processing request information storing the user specifying information and the password. Then, the control unit  130  transmits the authentication processing request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     if the user authentication processing is executed used on the authentication processing request information, the user is authenticated, and the authentication notification information is returned from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports the authentication notification information by the network controller  137 . 
     When it is detected that the user has been authenticated based on the authentication notification information, the control unit  130  stores the associated book title and the associated book number and produces image request information for requesting the book page image data to which the associated page number is added. 
     Then, the control unit  130  transmits the image request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . When the book page image data to which the associated page number is added is returned from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports the book page image data by the network controller  137 . Then, the control unit  130  sends the book page image data to the graphic engine  138 . 
     When the book page image data is given from the control unit  130 , the graphic engine  138  sends the book page image data to the display apparatus  25  via the video output unit  139  after performing display processing on the hook page image data in the same manner as described above. 
     In so doing, the graphic engine  138  displays the associated page image instead of the book page image  47  which has been displayed until then or so as to be overlapped with at least a part of the book page image  47 , on the display surface of the display apparatus  25 . 
     As described above, the control unit  130  can show the user the associated page image by reproducing the associated data for provision when the associated part associated with the associated page image is designated on the book page image  47 . 
     In addition, the control unit  130  controls the graphic engine  138  and the video decoder  147  if the display return is instructed via the remote control  27  in the state in which movie, a still image, or the like is output via the display apparatus  25  in response to the designation of the associated part by the user. 
     In so doing, the control unit  130  stops the output of the movie, the still image, or the like associated with the associated part via the display apparatus  25  and displays only the book page image  47  which has been displayed before the movie, the still image, or the like is output in the display apparatus  25 . 
     Accordingly, the control unit  130  can easily return to the display of the book page image  47  before output and allow the user to read the electronic book again even if the movie, the still image, or the like associated with the associated part is output via the display apparatus  25 . 
     By the way, if showing of the enlargement target area is instructed by the user is the remote control  27  in the state in which the book page image is displayed, the control unit  130  determines whether or not the enlargement target area is present in the book page image  47  based on the area information  100 . 
     If it is detected that the enlargement target area is not present in the book page image being currently displayed as a result, the control unit  130  controls the graphic engine  138 , for example. At this time, the graphic engine  138  produces synthesis image data by synthesizing message image data for notifying of that the enlargement target area is not present in the book page image with the book page image data of the book page image being currently displayed. 
     Then, the graphic engine  138  sends the synthesis data to the display apparatus  25  via the video output unit  139 . In so doing, the graphic engine  138  displays the message image so as to be overlapped with the book page image being displayed on the display surface of the display apparatus  25 . 
     When the enlargement target area is not present in the book page image  47  even if the showing of the enlargement target area is instructed, the control unit  130  notifies the user of the fact as described above. 
     On the other hand, if it is detected that the enlargement target area is present in the book page image  47 , the control unit  130  extracts any one of the area position information items  103  corresponding to the page number of the book page image  47  being currently displayed from the area information  100 . Then, the control unit  130  sends the area position information  103  to the graphic engine  138 . 
     When the area position information  103  is given from the control unit  130 , the graphic engine  138  processes the book page image data of the book page image  47  being currently displayed based on the area position information  103 . 
     In addition, the graphic engine  138  sends the processed book page image data to the display apparatus  25  via the video output unit  139 . In so doing, the graphic engine  138  displays a frame image  93  surrounding any one of the enlargement target areas  92  so as to be overlapped with the book page image  47  being displayed on the display surface of the display apparatus  25  as shown in  FIG. 17 . 
     In addition, if the moving of the frame image  93  is instructed by the user via the remote control  27  in the state in which the frame image  93  is displayed on the book page image  47 , the control unit  130  determines whether or not another enlargement target area is present in the book page image  47  based on the area information  100 . 
     If it is detected that another enlargement target area is not present in the book page image  47  being currently displayed as a result, the control unit  130  controls the graphic engine  138 , for example. At this time, the graphic engine  138  synthesizes message image data for notifying of that only one enlargement target area is present in the book page image  47  with the book page image data of the book page image  47  being currently displayed and produces synthesis image data. 
     Then, the graphic engine  138  sends the synthesis image data to the display apparatus  25  via the video output unit  139 . In so doing, the graphic engine  138  displays the message image so as to be overlapped with the book page image  47  being displayed on the display surface of the display apparatus  25 . 
     When only one enlargement target area is present in the book page image  47 , the control unit  130  notifies the user of that the frame image  93  cannot be moved, via the message image even if the movement of the frame image  93  for the enlargement target area is instructed. 
     On the other hand, if it is detected that another enlargement target area is present in the book page image  47 , the control unit  130  extracts another area position information item  103  corresponding to the page number of the book page image  47  being currently displayed from the area information  100 . Then, the control unit  130  sends the area position information  103  to the graphic engine  138 . 
     When the area position information  103  is given from the control unit  130 , the graphic engine  138  processes the book page image data based on the area position information  103  in the same manner as described above and sends the book page image data to the display apparatus  25  via the video output unit  139 . 
     In so doing, the graphic engine  138  moves and displays the frame image  93 , which has been displayed so as to surround any one of the enlargement target areas  92  until then, so as to surround another enlargement target area on the book page image  47  being displayed on the display surface of the display apparatus  25 . 
     As described above, the control unit  130  can notify of whether or not enlargement target area  92  is present in the book page image  47  by display of the frame image  93  and the message image in response to the instruction of showing the enlargement target area. In addition, if only one enlargement target area  92  is present in the book page image  47 , the control unit  130  can notify of the fact by the message image. 
     Moreover, if a plurality of enlargement target areas  92  is present in the book page image  47 , the control unit  130  can allow the user to check the plurality of enlargement target areas  92  in turns by sequentially moving the frame image  93  in response to the instruction of the movement of the frame image  93 . 
     In addition, if one or a plurality of enlargement target areas  92  is present in the book page image  47 , the control unit  130  can allow the user to designate a desired enlargement target area  92  by surrounding the enlargement target area  92  with the frame image  93 . 
     That is, if selection is instructed by the user via the remote control  27  in the state in which any one of the enlargement target areas  92  in the book page image  47  is surrounded by the frame image  93 , the control unit  130  recognizes that the enlargement target area  92  surrounded by the frame image  93  at this time is selected. 
     At this time, the control unit  130  detects area specifying information for the designated enlargement target area  93  in the area information  100 . In addition, the control unit  130  sends the area enlargement image data to which the detected area specifying information is added to the graphic engine  138  from among one or a plurality of area enlargement image data items included in the electronic book data D 2  and D 4 . 
     When the area enlargement image data is given from the control unit  130 , the graphic engine  138  synthesizes the area enlargement image data with the book page image data of the book page image  47  being currently displayed and produces synthesis image data. 
     Then, the graphic engine  138  sends the synthesis image data to the display apparatus  25  via the video output unit  139 . In so doing, the graphic engine  138  displays the area enlargement image  150  based on the area enlargement image data so as to be overlapped with the book page image  47  being displayed on the display surface of the display apparatus  25 , as shown in  FIG. 18 . 
     If a desired enlargement target area  92  is designated on the book page image  47  being displayed on the display surface of the display apparatus  25 , the control unit  130  can enlarge and display the designated enlargement target area  92  as the area enlargement image  150  on the book page image  47 . 
     Accordingly, the control unit  130  can enhance the visibility and show the enlargement target area  92  enlarged and displayed on the display surface of the display apparatus  25 . Particularly, when text is included in the enlargement target area  92 , the control unit  130  can enlarge the text so as to be easily read. 
     In addition, if return of the display is instructed by the user via the remote control  27  in the state in which the enlargement target area  92  is enlarged and displayed as the area enlargement image  150 , the control unit  130  controls the graphic engine  138 , the video decoder  147 , and the like. 
     In so doing, the control unit  130  deletes only the area enlargement image  150  while the display of the book page image  47  and the frame image  93  is left as it is on the display surface of the display apparatus  25 . That is, the control unit  130  recovers the display contents on the display surface of the display apparatus  25  to the state immediately before enlarging and displaying the enlargement target area  92  (that is, immediately before displaying the area enlargement image  150 ). Accordingly, the control unit  130  can allow the user to check and appropriately designate the enlargement target area  92  again with the frame image  93  by deleting the area enlargement image  150  from the display surface of the display apparatus  25 . 
     In addition, if return of the display is instructed by the user via the remote control  27  in the state in which the frame image  93  is displayed so as to be overlapped with the book page image  47 , the control unit  130  controls the graphic engine  138 , the video decoder  147 , and the like. 
     In so doing, the control unit  130  deletes the frame image  93  from the book page image  47  on the display surface of the display apparatus  25 . That is, the control unit  130  recovers the display contents on the display surface of the display apparatus  25  to the state immediately before displaying the frame image  93 . Accordingly, the control unit  130  can allow the user to read the electronic book by deleting the frame image  93  from the display surface of the display apparatus  25  and switching the book page images to be displayed again and the like. 
     By the way, if display of the index screen is requested by the user via the remote control  27  in the state in which the book cover image, the book page image  47 , and the like are output via the display apparatus  25 , the control unit  130  produces the index screen data in the same manner as described above. 
     Then, when the index screen is displayed on the display surface of the display apparatus  25 , and a new electronic book is selected, the control unit  130  displays the book cover image of the selected electronic book on the display surface of the display apparatus  25  in the same manner as described above. 
     In addition, the control unit  130  displays the book page image, the enlargement target area, and the like of the selected electronic book on the display surface of the display apparatus  25  in response to the operation of the remote control  27  by the user in the same manner as described above after displaying the book cover image on the display surface of the display apparatus  25 . 
     On the other hand, if completion of the display of the electronic book is instructed by the user via the remote control  27  in the state in which the book cover image, the book page image  47 , and the like are output via the display apparatus  25 , the control unit  130  completes the electronic book reproducing processing in response to this. 
     That is, the control unit  130  stops the output of the book cover image, the book page image, and the movie and the like associated with the associated part via the display apparatus  25  and completes the reproduction of the electronic book. In so doing, the control unit  130  can allow the user to read one or a plurality of electronic books and watch and view various kinds of information associated with the associated part in the electronic book while the electronic book reproduction processing is executed. 
     By the way, if the electronic book data D 2  and D 4  of the electronic book selected on the index screen is not recorded on the book providing disc  28  when the electronic book reproduction processing is started, the control unit  130  is provided with the electronic book from the history obtaining apparatus  22 . 
     That is, if it is detected that the book providing disc  28  in which the electronic book data D 2  and D 4  is not recorded is mounted on the electronic book reproducing apparatus  24 , the control unit  130  reads the user specifying information and the password from the built-in storage unit  140 . 
     In addition, the control unit  130  produces the authentication processing request information storing the user specifying information and the password. Then, the control unit  130  transmits the authentication processing request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     If the user authentication processing is executed based on the authentication processing request information, the user is authenticated, and the authentication notification information is returned from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports the authentication notification information by the network controller  137 . 
     When it is detected that the user is authenticated based on the authentication notification information, the control unit  130  stores the book specifying information  116  of the electronic book selected on the index screen by the user and produces the electronic book obtaining request information for requesting the obtaining of the electronic book. 
     Then, the control unit  130  transmits the electronic book obtaining request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . In so doing, when the electronic book data D 2  and D 4  of the electronic book selected by the user is returned from the history obtaining apparatus  22 , the control unit  130  receives and imports the electronic book data D 2  and D 4  by the network controller  137 , 
     In so doing, when the electronic book data D 2  and D 4  is obtained from the history obtaining apparatus  22 , the control unit  130  reads the electronic book certificate and the route certificate from the book providing disc  28  via the switcher  141  and the drive  142  in this order. 
     In addition, the control unit  130  calculates the data verification value with the use of at least a part of the electronic book data D 2  and D 4  obtained from the history obtaining apparatus  22 . Moreover, the control unit  130  calculates the certificate verification value with the use of at least a part of the route certificate. 
     Then, the control unit  130  checks the validity of the electronic book data D 2  and D 4  (that is, whether the data has been falsified) obtained from the history obtaining apparatus  22  at this time based on the electronic book certificate, the calculated data verification value, and the certificate verification value. If it is confirmed that the electronic book data D 2  and D 4  is valid as a result, the control unit sends the book cover image data included in the electronic book data D 2  and D 4  to the graphic engine  138 . 
     When the book over image data is given from the control unit  130 , the graphic engine  138  performs processing in the same manner as described above and displays the book cover image over the entire surface of the display surface of the display apparatus  25  via the video output unit  139 . 
     As described above, even when the electronic book data D 2  and D 4  are obtained from the history obtaining apparatus  22 , the control unit  130  displays the book page image, the enlargement target area, and the like on the display surface of the display apparatus  25  in response to the operation of the remote control  27  by the user in the same manner as described above after this. 
     Then, when display of the index screen is requested by the user via the remote control  27  in the state in which the book cover image, the book page image  47 , and the like are output via the display apparatus  25 , the control unit  130  produces the index screen data in the same manner as described above. 
     When the index screen is displayed on the display surface of the display apparatus  25 , and a new electronic book is selected at this time, the control unit  130  obtains the electronic book data D 2  and D 4  of the selected electronic book from the history obtaining apparatus  22  in the same manner as described above. 
     Accordingly, the control unit  130  performs the processing again in the same manner as described above and displays the book cover image, the book page image, the enlargement target area, and the like of the new electronic book on the display surface of the display apparatus  25 . Even in such a case, if the completion of the display of the electronic book is instructed by the user via the remote control  27  in the state in which the book cover image, the book page image  47 , and the like are output via the display apparatus  25 , the control unit  130  completes the electronic book reproduction processing in response to this. 
     As described above, the control unit  130  can allow the user to read one or a plurality of electronic books even when the electronic book reproduction processing is executed in the state in which the book providing disc  28  in which the electronic data D 2  and D 4  is not recorded is mounted on the electronic book reproducing apparatus  24 . In addition, the control unit  130  can allow the user to watch and view various kinds of information associated with the associated part in the electronic book in the same manner as described above. 
     By the way, when obtaining of the electronic book introducing screen data for introducing the electronic book to be provided on the network  23  is requested by the user via the remote control  27 , the control unit  130  reads the user specifying information and the password from the built-in storage unit  140 . 
     In addition, the control unit  130  produces the authentication processing request information storing the usr specifying information and the password. Then, the control unit  130  transmits the authentication request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     If the user authentication processing is executed based on the authentication processing request information, the user is authenticated, and the authentication notification information is returned from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports the authentication notification information by the network controller  137 . 
     When it is detected that the user has been authenticated based on the authentication notification information, the control unit  130  produces the introducing screen obtaining request information for requesting the obtaining of the electronic book introducing screen data. Then, the control unit  130  transmits the introducing screen obtaining request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     When the electronic book introducing screen data is returned from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports the electronic book introducing screen data by the network controller  137 . In addition, the control unit  130  sends the electronic book introducing screen data to the display apparatus  25  via the graphic engine  138  and the video output unit  139  in this order. In so doing, the control unit  130  displays the electronic book introducing screen (not shown) based on the electronic book introducing screen data on the display surface of the display apparatus  25 . 
     In addition, book titles, book issue dates, book types, categories, and the like of the electronic books which can be provided by the history obtaining apparatus  22  are displayed on the electronic book introducing screen. In addition, the book specifying information  116  of the electronic books are embedded so as to correspond to the book titles of the electronic books displayed on the electronic book introducing screen in the electronic book introducing screen data. 
     If one or a plurality of desired electronic books are selected as the book titles on the electronic book introducing screen by the user via the remote control  27  in this state, the control unit  130  extracts the book specifying information  116  of each selected electronic book from the electronic book introducing screen data. 
     Moreover, the control unit  130  stores one or a plurality of book specifying information items  116  extracted from the electronic book introducing screen data along with the user specifying information and the password and produces electronic book purchasing request information for requesting the purchase of one or a plurality of electronic books selected by the user. 
     Then, the control unit  130  transmits the electronic book purchasing request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . If the electronic book data D 2  and D 4  of one or a plurality of electronic book data is returned after performing purchasing processing of one or a plurality of electronic books whose purchase is requested from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports them by the network controller  137 . 
     In addition, the control unit  130  also receives and imports the electronic book reproducing program and the index table returned along with one or a plurality of electronic book data items D 2  and D 4  from the history obtaining apparatus  22  at this time by the network controller  137 . 
     Moreover, the control unit  130  also receives and imports the decoding key information, the electronic book certificate, and the route certificate returned along with one or a plurality of electronic book data items D 2  and P 4  from the history obtaining apparatus  22  at this time by the network controller  137 . 
     Then, the control unit  130  sends one or a plurality of electronic book data items D 2  and D 4 , the electronic book reproducing program, the index table, the decoding key information, the electronic book certificate, and the route certificate to the hard disk drive  152  via the switcher  141 . 
     In so doing, the control unit  130  associates and stores one or a plurality of electronic book data items D 2  and D 4  purchased at this time with the index table, the decoding key information, the electronic book certificate, and the route information on the hard disk drive  152 . In addition, the control unit  130  also stores the electronic book reproducing program on the hard disk drive  152 . 
     If reproduction of the electronic book in the hard disk drive  152  is instructed by the user via the remote control  27  in this state, the control unit  130  reads the electronic book reproducing program from the hard disk drive  152  via the switcher  141 . 
     In addition, the control unit  130  transfers the electronic book reproducing program to the RAM  134  and executes the program thereon. In so doing, the control unit  130  executes the electronic book reproduction processing based on the electronic book reproducing program along with the aforementioned various programs which have been already executed on the RAM  134 . In such a case, the control unit  130  reads the index table from the hard disk drive  152  via the switcher  141  and sends the index table to the graphic engine  138 . 
     The graphic engine  138  produces index screen data for list-displaying the book titles of all (one or a plurality of) electronic books to be provided via the book providing disc  28  based on the index table given from the control unit  130 . 
     In addition, the graphic engine  138  sends the index screen data to the display apparatus  25  via the video output unit  139  and displays the index screen (not shown) based on the index screen data on the display surface of the display apparatus  25 . 
     In so doing, the control unit  130  notifies the user of the electronic books to be provided by the book providing disc  28  mounted on the electronic book reproducing apparatus  24  at this time as the book titles via the index screen displayed on the display surface of the display apparatus  25 . 
     Then, when the index screen is displayed on the display surface of the display apparatus  25  as described above, the control unit  130  can allow the user to select the electronic book to be displayed as the book title on the index screen via the remote control  27  in the same manner as described above. 
     When the electronic book is selected on the index screen, the control unit  130  reads the electronic book data D 2  and D 4  of the selected electronic book from the hard disk drive  152  via the switcher  141 . 
     In addition, the control unit  130  reads the electronic book certificate and the route certificate from the hard disk drive  152  via the switcher  141 . Moreover, the control unit  130  calculates the data verification value with the use of at least a part of the electronic book data D 2  and D 4  read from the hard disk drive  152 . Furthermore, the control unit  130  also calculates the certificate verification value with the use of at least a part of the route certificate. 
     Then, the control unit  130  checks the validity of the electronic book data D 2  and D 4  (that is, whether the data has been falsified) read from the book providing disc  28  at this time based on the electronic book certificate, the calculated data verification value, and the certificate verification value if it is confirmed that the electronic book data D 2  and D 4  is valid as a result, the control unit  130  sends the book cover image data included in the electronic book data D 2  and D 4  to the graphic engine  138 . 
     When the book cover image data is given from the control unit  130 , the graphic engine  138  performs processing in the same manner as described above and displays the book cover image over the entire surface of the display screen of the display apparatus  25  via the video output unit  139 . 
     In so doing, the control unit  130  displays the book page image, the enlargement target area, and the like on the display surface of the display apparatus  25  in response to the operation of the remote control  27  by the user in the same manner as described above after this even when the electronic book data D 2  and D 4  is purchased from the history obtaining apparatus  22 . 
     In addition, if the display of the index screen is requested by the user via the remote control  27  in the state in which the book cover image, the book page image  47 , and the like are output via the display apparatus  25 , the control unit  130  produces the index screen data again in the same manner as described above. 
     If the index screen is displayed on the display surface of the display apparatus  25 , and a new electronic book is selected at this time, the control unit  130  reads the electronic book data D 2  and D 4  of the selected electronic book from the hard disk drive  152  in the same manner as described above. 
     Accordingly, the control unit  130  performs processing again in the same manner as described above and displays the book cover image, the book page image, the enlargement target area, and the like of the new electronic book on the display surface of the display apparatus  25 . Even in such a case, if completion of the display of the electronic book is instructed by the user via the remote control  27  in the state in which the book cover image, the book page image  47 , and the like are output via the display apparatus  25 , the control unit  130  completes the electronic book reproduction processing in response to this. 
     As described above, the control unit  130  reproduces the electronic book data D 2  and D 4  with the use of the hard disc drive  152  instead of the book providing disc  28  when the electronic book data D 2  and D 4  are purchased from the history obtaining apparatus  22 . 
     However, the control unit  130  basically executes the same electronic book reproduction processing as that in the case of using the book providing disc  28  even when the hard disk drive  152  is used instead of the book providing disc  28  and reproduces the electronic book data D 2  and D 4 . 
     Accordingly, the control unit  130  can allow the user to read one or a plurality of electronic books in the same manner as in the case of using the book providing disc  28  even when the electronic book data D 2  and D 4  are reproduced with the use of the hard disk drive  152 . In addition, the control unit  130  can also allow the user to watch and view various kinds of information associated with the associated part in the electronic book. 
     By the way, the control unit  130  extracts the book specifying information  116  of the electronic book from the book information  65  when the display of the book cover image on the display surface of the display apparatus  25  is started in response to the selection of the electronic book while the electronic hook reproduction processing is executed. In addition, the control unit  130  checks the current time by a time which is not shown in the drawing and detects the time at the time point at which the display of the book cover image is started. 
     Moreover, the control unit  130  makes a correspondence relationship between the book specifying information  116  extracted from the book information  65  and the time information indicating the time at the display start time point of the detected book cover image as a display history of the electronic book displayed in response to the user operation. Then, the control unit  130  sends and stores the display history to the built-in storage unit  140 . 
     In addition, when the display of the book page image  47  on the display surface of the display apparatus  25  is started in response to the page sending instruction, the control unit  130  extracts the page number  86  of the book page image  47  from the page information  85 . 
     Moreover, the control unit  130  detects the time at the time point at which the display of the book page image  47  is started based on the current time shown by the timer. Then, the control unit  130  associates and sends the page number  86  extracted from the page information  85  with the time information indicating the time at the display start time point of the detected book page image  47  to the built-in storage unit  140 . 
     In so doing, the control unit  130  stores the associated page number  86  and the time information to be added to the display history in the built-in storage unit  140  and updates the display history in the built-in storage unit  140 . 
     Moreover, when the enlargement target area  92  is enlarged and displayed as the area enlargement image  150  on the display surface of the display apparatus  25  in response to the designation of the enlargement target area  92 , the control unit  130  extracts the area specifying information  101  of the enlargement target area  92  from the area information  100 . 
     In addition, the control unit  130  detects the time at the time point at which the enlargement and display of the enlargement target area  92  is started based on the current time shown by the timer. Then, the control unit  130  associates and sends the area specifying information  101  extracted from the area information  100  with the time information indication the time at the enlargement and display start time point of the detected enlargement target area  92  to the built-in storage unit  140 . 
     In so doing, the control unit  130  stores the associated area specifying information  101  and the time information to be added to the display history in the built-in storage unit  140  and updates the display history in the built-in storage unit  140 . 
     As described above, the control unit  130  updates the display history such that the book specifying information  116 , the page number  86 , and the area specifying information  101  are stored on the built-in storage unit  140  along with the time information every time the book cover image, the book page image  47 , and the area enlargement image  150 . 
     Then, the control unit  130  detects the time at the time point at which the reproduction of the electronic book is completed based on the current time shown by the time when the reproduction of the electronic book is completed in response to the instruction by the user. 
     In addition, the control unit  130  sends the time information indicating the time at the reproduction completion time point of the detected electronic book to the built-in storage unit  140 . In so doing, the control unit  130  stores the time information at the reproduction completion time point of the electronic book so as to be added to the display history which has been already stored in the built-in storage unit  140  and finally updates the display history in the built-in storage unit  140 . 
     As described above, the control unit  130  produces the display history IH in which the book specifying information  116 , the page number  86 , and the area specifying information  101  are arranged in a time-series manner along with the time information  151  in the built-in storage unit  140  while the electronic book reproduction processing is executed as shown in  FIG. 19 . 
     That is, the control unit  130  produces the display history IH specifically showing the electronic book whose display is started in response to the user operation and the book page image  47  and the enlargement target area  92 , which have been actually displayed, in the electronic book, while the electronic book reproduction processing is executed. 
     When the production of the display history IH in the built-in storage unit  140  is completed in accordance with the completion of the reproduction of the electronic book, the control unit  130  reads the display history IH, whose production is completed, from the built-in storage unit  140 . In addition, the control unit  130  also reads the user specifying information and the password from the built-in storage unit  140 . 
     Furthermore, the control unit  130  stores the user specifying information and the password and produces the authentication processing request information for requesting the user authentication processing. Then, the control unit  130  transmits the authentication processing request information to the history obtaining apparatus  22  from the network controller  137  via the network  23 . 
     If the usr authentication processing is executed based on the authentication processing request information, the user is authenticated, and the authentication notification information is returned from the history obtaining apparatus  22  as a result, the control unit  130  receives and imports the authentication notification information by the network controller  137 . When it is detected that the user is authenticated based on the authentication notification information, the control unit  130  produces the display history notification data storing the user specifying information and the password along with the display history IH. 
     Then, the control unit  130  transmits the display history notification data to the history obtaining apparatus  22  from the network controller  137  via the network  23 . In so doing, the control unit  130  can notify the history obtaining apparatus  22  of the book page image  47  and the enlargement target area  92  of the electronic book read by the user by the display history IH stored on the display history notification data. 
     [1-4-2. Configuration of Program Module Mounted on Electronic Book Reproducing Apparatus  24 ] 
     Next, description will be made of various program modules as the aforementioned various programs mounted on a non-transitory computer-readable medium within the electronic book reproducing apparatus  24  (for example, stored in advance on the ROM  131 ) with the use of  FIG. 20 . 
     The various program modules mounted on the electronic book reproducing apparatus  24  are configured to be operated on a basic program  160  such as an operation system. In addition, the basic program  160  manages the resources of various program modules in the higher order. In addition, the basic program  160  also manages input and output of the hardware in the electronic book reproducing apparatus  24  via the driver  161 . 
     The file management module  162  which manages a data file existing on the basic program  160  is positioned in the higher order of the basic program  160 . In addition, a title management module  163  which manages the electronic book data D 2  and D 4  stored on the book providing disc  28  and the electronic book data D 2  and D 4  stored on the hard disk drive  152  is positioned in the higher order of the file management module  162 . In addition, the title management module  163  is for operating the data file existing on the basic program  160  via the file management module  162 . 
     Moreover, a network management module  164  which performs the control at the time of using the network  23  is positioned in the higher order of the basic program  160 . In addition, a reproducing program execution management module  165  is positioned in the higher order of the title management module  163  and the network management module  164 . 
     The reproducing program execution module  165  is provided by the book providing disc  28  and manages the communication between the electronic book reproducing program P 2  provided by the history obtaining apparatus  22  and the other program modules mounted on the electronic book reproducing apparatus  24 . 
     Furthermore, a screen display control module  166  is positioned in the higher order of the basic program  160 , and a text module display module  167  and a title reproduction module  168  which controls the reproduction of the electronic book data D 2  and D 4  are positioned in the higher order of the screen display control module  165 . Furthermore, a built-in application  169  is positioned in the higher order of the text display module  167  and the title reproduction module  158 . 
     The built-in application  169  provides a graphic user interface to the electronic book reproducing apparatus  24 . In addition, the text display module  167  instructs the drawing of book cover image, the book page image, and the like of the selected electronic book via the graphic user interface provided by the built-in application  169 . 
     In addition, the screen display control module  166  decides how to draw the book cover image, the book page image, and the like based on the instruction of the text display module  167  and performs drawing as decided. 
     In addition, when the book providing disc  28  is a BD, for example, in this embodiment, a BD-Java (registered trademark) program is recorded on the book providing disc  28  as the electronic book reproducing program  92 . 
     In addition, when the electronic book data D 2  and D 4  recorded on the book providing disc  28 , which is a BD, is reproduced in the electronic book reproducing apparatus  24 , Java Virtual Machine (Java (registered trademark) VM) (registered trademark) is used as the reproducing program execution management module  165 . 
     1-5. Circuit Configuration of History Obtaining Apparatus  22   
     Next, description will be made of the circuit configuration of the history obtaining apparatus  22  with the use of  FIG. 21 . The history obtaining apparatus  22  includes a control unit  180  constituted by a CPU. The control unit  180  reads various programs such as a basic program, a history obtaining program, and the like which are stored in advance in a non-transitory computer readable medium such as the ROM  181 , for example, via the input output bus  182 . 
     In addition, the control unit  180  transfers the various programs to the RAM  184  as a work area of the control unit  180  via the memory bus  183  and executes the programs thereon. Then, the control unit  180  controls the entire apparatus via the input output bus  182  and the system bus  185  based on the various programs executed on the RAM  184 . In addition, the control unit  180  executes predetermined computation processing based on the various programs. 
     Moreover, the control unit  180  also executes various kinds of processing in response to an operation command given from the operation unit  186  via the external interface unit  187  and the input output bus  182  in this order in response to the operation of the operation unit  186  constituted by a keyboard, a mouse, or the like based on the various programs. 
     In so doing, when user registration screen request information is transmitted from the electronic book reproducing apparatus  24  via the network  23 , the control unit  180  receives and imports the user registration screen request information by the network controller  188 . 
     When the user registration screen request information is imported as described above, the control unit  180  reads user registration screen data stored in advance from the hard disk drive  189 . Then, the control unit  180  transmits the user registration screen data to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . 
     When user information input on the user registration screen is transmitted from the electronic book reproducing apparatus  24  via the network  23  as a result, the control unit  180  receives and imports the user information by the network controller  188 . 
     Here, the control unit  180  constitutes database for registering a user in the hard disk drive  189 . In addition, the database for registering a user will also be referred to as user database in the following description. 
     Accordingly, the control unit  180  sends the user information to the and disk drive  189  at this time. In so doing, the control unit  189  stores the user information on the hard disk drive  180  and registers the user information in the user database. 
     When the user information is registered in the user database, and the user registration for a user of the electronic book reproducing apparatus  24  is completed as described above, the control unit  180  reads user registration completion notification screen data stored in advance from the hard disk drive  189 . 
     Then, the control unit  180  transmits the user registration completion notification screen data to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . In so doing, the control unit  180  notifies the user of the electronic book reproducing apparatus  24  of that the user registration has been completed. 
     In addition, when authentication processing request information is transmitted from the electronic book reproducing apparatus  24  via the network  23 , the control unit  180  sends the authentication processing request information to the authentication processing unit  190  after receiving and importing the authentication processing request information by the network controller  188 . 
     At this time, the authentication processing unit  190  extracts the use specifying information and the password from the authentication processing request information and executes user authentication processing based on the user specifying information and the password. In such a case, the authentication processing unit  190  detects whether or not the usr specifying information and the password extracted from the authentication processing request information have already been registered in the user database of the hard disk drive  189 . 
     If the user specifying information and the password extracted from the authentication processing request information has already been registered in the user database as a result, the authentication processing unit  190  authenticates the user of the electronic book reproducing apparatus  24 , who has accessed the history obtaining apparatus  22  at this time, as a normal user. Then, when the user is authenticated as described above, the authentication processing unit  190  notifies the control unit  180  of this. 
     When the control unit  180  is notified by the authentication processing unit  190  of that the user has been authenticated, the control unit  180  transmits authentication notification information for notifying of that the user has been authenticated to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . In so doing, the control unit notifies the electronic book reproducing apparatus  24  of that the user has been authenticated. 
     On the other hand, if the user specifying information and the password extracted from the authentication processing request information have not been registered in the user database, the authentication processing unit  190  does not authenticate the user of the electronic book reproducing apparatus  24 , who has accessed the history obtaining apparatus  22  at this time, as a normal user. Then, the authentication processing unit  190  notifies the control unit  180  of that the user is not authenticated. 
     If the control unit  180  is notified by the authentication processing unit  190  of that the user is not authenticated, the control unit  180  transmits authentication error information for notifying of that the user is not authenticated to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . In so doing, the control unit  180  notifies the electronic book reproducing apparatus  24  that the user is not authenticated. 
     By the way, when disc registration screen request information is transmitted from the electronic book reproducing apparatus  24  as a result of transmitting the authentication notification information to the electronic book reproducing apparatus  24 , the control unit  180  receives and imports the disc registration screen request information by the network controller  188 . 
     When the disc registration screen request information is imported as described above, the control unit  180  reads disc registration screen data stored in advance from the hard disk drive  189  in response to this. Then, the control unit  180  transmits the disc registration screen data to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . 
     When disc registration request information in which the disc information input on the disc registration screen is stored is transmitted from the electronic book reproducing apparatus  24  as a result, the control unit  180  receives and imports the disc registration request information by the network controller  188 . 
     At this time, the control unit  180  extracts the user specifying information and the password from the disc registration request information along with the disc information. In addition, the control unit  180  specifies the user information including the user specifying information and the password in the user database of the hard disk drive  189  based on the user specifying information and the password. 
     Then, the control unit  180  sends the disc information to the hard disk drive  189 . In so doing, the control unit  180  stores the disc information on the hard disk drive  189  and associates and registered the disc information with the specified user information in the user database. 
     When the disc information is registered as described above, the control unit  180  reads disc registration completion notification screen data stored in advance from the hard disk drive  189 . Then, the control unit  180  transmits the disc registration completion notification screen data to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . In so doing, the control unit  180  notifies the user of the electronic book reproducing apparatus  24  of that the disc registration has been completed. 
     By the way, when the electronic book data D 2  and D 4  is transmitted from the electronic book reproducing apparatus  21  via the network  23  along with the specification request information, the control unit  180  receives and imports the electronic book data D 2  and D 4  and the specification request information by the network controller  188 . 
     At this time, the book specifying information  116  with which the electronic book which is received at this time and is based on the electronic book D 2  and D 4  is issued in accordance with the control unit  180  and the specification request information. Then, the control unit  180  transmits the book specifying information  116  to the electronic book producing apparatus  21  from the network controller  188  via the network  23 . 
     Here, the control unit  180  constitutes a database for registering the electronic book (that is, for registering the electronic book data D 2  and D 4  produced in the electronic book producing apparatus  21 ) in the hard disk drive  189 . In addition, the database for registering the electronic book will also be referred to as a book database in the following description. 
     Accordingly, the control unit  180  stores the issued book specifying information  116  on the book information  65  included in the electronic book data D 2  and D 4  received at this time. Then, the control unit  180  sends the book information  65  storing the book specifying information  116  to the hard disk drive  189  along with the book specifying information  116 . 
     In so doing, the control unit  180  stores the book information  55  and the book specifying information  116  on the hard disk drive  189  and associates and registers the book information  65  with the book specifying information  116  in the book database. 
     In addition, the control unit  180  sends the page information  85  included in the electronic book data D 2  and D 4  received at this time to the hard disk drive  189 . In so doing, the control unit  180  stores the page information  85  on the hard disk drive  189  and associates and registers the page information  85  with the book specifying information  115  in the book database. 
     Moreover, the control unit  180  sends the area information  100  included in the electronic book data D 2  and D 4  received at this time to the hard disk drive  189 . In so doing, the control unit  180  stores the area information  100  on the hard disk drive  189  and associates and registers the area information  100  with the book specifying information  116  in the book database. 
     Then, when the electronic book data D 2  and D 4  is designated as a provision target using the network  23  by the operator via the operation unit  186 , the control unit  180  sends the book image data D 6  included in the electronic book data D 2  and D 4  to the hard disk drive  189 . 
     In addition, the control unit  180  also sends the coded associated data D 7  and the coded audio data D 8  included in the electronic book data D 2  and D 4  to the hard disk drive  189 . In so doing, the control unit  180  stores the book image data D 6  on the hard disk drive  189  and associates and registers the book image data D 6  with the book specifying information  116  in the book database. 
     In addition, the control unit  180  stores the coded associated data D 7  and the coded audio data D 8  on the hard disk drive  189  and associates and registers the coded associated data D 7  and the coded audio data D 8  with the book specifying information  116  in the book database. 
     On the other hand, if the operator instructs to exclude the electronic book data D 2  and D 4  from the provision target using the network  23  via the operation unit  186 , the control unit  180  discards the book image data D 6  included in the electronic book data D 2  and D 4 . In addition, the control unit  180  also discards the coded associated data D 7  and the coded audio data D 8  included in the electronic book data D 2  and D 4 . 
     That is, if the provision of an electronic book, which is produced based on a publication, with the use of the network  23  is permitted by a publisher of the publication, for example, the control unit  180  registers the entire electronic book data D 2  and D 4  of the electronic book in the book database. 
     In so doing, the control unit  180  maintains and manages the electronic book data D 2  and D 4  for the electronic book whose provision with the use of the network  23  is permitted and makes it possible to provide the electronic book with the use of the network  23 . 
     On the other hand, if the provision of the electronic book with the use of the network  23  is not permitted by the publisher, the control unit  180  registers only the book information  65 , the page information  85 , and the area information  100  included in the electronic book data D 2  and D 4  of the electronic book. 
     Then, the control unit  180  discards the book image data D 6 , the coded associated data D 7 , and the coded audio data D 8  included in the electronic book data D 2  and D 4 . In so doing, the control unit  180  makes it impossible to provide the electronic book whose provision with the use of the network  23  is not permitted in practice by discarding the book image data D 6  while managing the data by the book database. 
     By the way, the control unit  180  receives and imports the authentication processing request information, which provides the electronic book and the associated page images to the electronic book reproducing apparatus  24  and has been firstly transmitted from the electronic book reproducing apparatus  24  via the network  23 , by the network controller  188 . 
     When the authentication processing request information is imported as described above, the control unit  180  sends the authentication processing request information to the authentication processing unit  190  and causes the authentication processing unit  190  to execute the same user authentication processing as that described above. In addition, the control unit  180  transmits the authentication notification information or the authentication error information to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23  in accordance with the execution result of the user authentication processing by the authentication processing unit  190 . 
     Then, when the authentication notification information is transmitted to the electronic book reproducing apparatus  24 , the control unit  180  sequentially receives the obtaining and the purchasing of the electronic book and requests for the associated page images from the electronic book reproducing apparatus  24 . 
     When the electronic book obtaining request information is actually transmitted from the electronic book reproducing apparatus  24 , which has received the authentication notification information, via the network  23 , the control unit  180  receives and imports the electronic book request information by the network controller  188 . 
     At this time, the control unit  180  extracts from the electronic book obtaining request information the book specifying information  116  for one or a plurality of electronic books selected on the index screen by the user in the electronic book reproducing apparatus  24 . 
     Then, the control unit  180  reads the book information  65  associated with the book specifying information  116 , the page information  85 , and the area information  100  from the hard disk drive  189  based on the book specifying information  116  extracted from the electronic book obtaining request information. 
     In addition, the control unit  180  also reads the book image data D 6  associated with the book specifying information  116  from the hard disk drive  189  based on the book specifying information  116  extracted from the electronic book obtaining request information. 
     Moreover, the control unit  180  also reads the coded associated data D 7  and the coded audio data D 8  associated with the book specifying information  116  from the hard disk drive  189  based on the book specifying information  116  extracted from the electronic book obtaining request information. 
     Then, the control unit  180  organizes the book information  65 , the page information  85 , the area information  100 , the book image data D 6 , the coded associated data D 7 , and the coded audio data D 8 , which are read from the hard disk drive  189 , to produce the electronic book data D 2  and D 4 . 
     As described above, the control unit  180  produces the electronic book data D 2  and D 4  for each of one or a plurality of electronic books selected by the user in the electronic book reproducing apparatus  24 . Then, the control unit  180  transmits one or a plurality of produced electronic book data items D 2  and D 4  to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . 
     In so doing, when the electronic book data D 2  and D 4  are reproduced with the use of the book providing disc  28  in which the electronic book data D 2  and D 4  are not recorder, the control unit  180  can provide the electronic book data D 2  and D 4  to the electronic book reproducing apparatus  24 . 
     In addition, when the introducing screen obtaining request information is transmitted from the electronic book reproducing apparatus  24 , which has received the authentication notification information, via the network  23 , the control unit  180  receives and imports the introducing screen obtaining request information by the network controller  188 . 
     At this time, the control unit  180  reads from the hard disk drive  189  the electronic book introducing screen data stored thereon. In addition, the control unit  180  transmits the electronic book introducing screen data to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . In so doing, the control unit  180  can introduce the electronic books to be provided on the network  23 , via the electronic book introducing screen in the electronic book reproducing apparatus  24  to the user. 
     Then, if the electronic book purchasing request information is continuously transmitted from the electronic book reproducing apparatus  24 , which has received the electronic book introducing screen data, via the network  23 , the control unit  180  receives and imports the electronic book purchasing request information by the network controller  188 . 
     At this time, the control unit  180  extracts the book specifying information  116  for one or a plurality of electronic books selected by the user to be purchased on the electronic book introducing screen in the electronic book reproducing apparatus  24 , from the electronic book purchasing request information. In addition, the control unit  180  also extracts the user specifying information and the password from the electronic book purchasing request information. 
     Then, the control unit  180  firstly executes purchasing processing of the electronic book, whose purchasing has been requested, for the user. In such a case, the control unit  180  specifies the user information including the user specifying information and the password from the hard disk drive  189  based on the user specifying information and the password. 
     In addition, the control unit  180  reads the user&#39;s name and the credit card number, for example, included in the user information from the hard disk drive  189 . Moreover, the control unit  180  produces charging data for electronically making settlement of the charge of the electronic book, whose purchasing has been requested by the user, based on the name, the credit card number, and one or a plurality of book specifying information items extracted from the electronic book purchasing request information. Then, the control unit  180  transmits the charging data to the settlement server  26  from the network controller  188  via the network  23 . 
     In so doing, when the purchasing of the electronic book is requested by the user, the control unit  180  allows the user to electronically make settlement to pay the charge of the electronic book by the settlement server  26  by executing the purchasing processing. 
     When the purchasing processing is completed, the control unit  180  reads the book information  65  associated with the book specifying information  116 , the page information  85 , and the area information  100  from the hard disk drive  189  based on the book specifying information  116  extracted from the electronic book obtaining request information. 
     In addition, the control unit  180  also reads the book image data D 6  associated with the book specifying information  116  from the hard disk drive  189  based on the book specifying information  115  extracted from the electronic book obtaining request information. 
     Moreover, the control unit  180  also reads the coded associated data D 7  and the coded audio data D 8  associated with the book specifying information  116  from the hard disk drive  189  based on the book specifying information  116  extracted from the electronic book obtaining request information. 
     Then, the control unit  180  organizes the book information  65 , the page information  85 , the area information  100 , the book image data D 6 , the coded associated data D 7 , and the coded audio data D 8 , which are read from the hard disk drive  189 , to produce the electronic book data D 2  and D 4 . In so doing, the control unit  180  produces the electronic book data D 2  and D 4  for each of one or a plurality of electronic books selected by the user to be purchased in the electronic book reproducing apparatus  24 . 
     In addition to this, when one or a plurality of electronic book data D 2  and D 4  are produced, the control unit  180  reads the electronic book reproducing program, which is stored in advance for reproducing the electronic book data D 2  and D 4 , from the hard disk drive  189 . 
     In addition, the control unit  180  reads the decoding key information which has been previously obtained from the electronic book producing apparatus  21  and stored on the hard disk drive  189  for decoding the coded associated data D 7  and the coded audio data D 8 , for example. 
     Moreover, the control unit  180  reads the route certificate, which is stored in advance, from the hard disk drive  189 . Then, the control unit  180  produces the electronic book certificate with the use of the electronic book data D 2  and D 4  along with the route certificate by the same method as the aforementioned method by the electronic book producing apparatus  21 . 
     Furthermore, the control unit  180  produces an index table as a list of the book titles of one or a plurality of produced electronic book data items D 2  and D 4 . Then, the control unit  180  transmits one or a plurality of produced electronic book data items D 2  and D 4  to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23  along with the electronic book reproducing program and the index table. 
     The control unit  180  also sends the decoding key information, the electronic book certificate, and the route certificate to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23  at this time. In so doing, when the purchasing of one or a plurality of electronic books is requested, the control unit  180  can provide the electronic book data D 2  and D 4  for one of a plurality of electronic books to the electronic book reproducing apparatus  24 . 
     Moreover, when the image request information is transmitted from the electronic book reproducing apparatus  24 , which has received the authentication notification information, via the network  23 , the control unit  180  receives and imports the image request information by the network controller  188 . 
     At this time, the control unit  180  extracts the associated book title and the associated page number corresponding to the associated part designated by the user in the electronic book reproducing apparatus  24 , from the image request information. In addition, the control unit  180  reads the book page image data to which the associated page number is added from among a plurality of book page image data items for the electronic book with the associated book title from the hard disk drive  189  based on the associated book title and the associated page number. 
     Then, the control unit  180  transmits the book page image data to the electronic book reproducing apparatus  24  from the network controller  188  via the network  23 . In so doing, when an associated part associated with another associated page image is designated on the book page image, the control unit  180  provides the book page image data for the associated page image to the electronic book reproducing apparatus  24 . 
     Moreover, when history notification data is transmitted from the electronic book reproducing apparatus  24 , which has received the authentication notification information, via the network  23 , the control unit  180  receives and imports the history notification data by the network controller  188 . 
     At this time, the control unit  180  extracts the user specifying information and the password from the history notification data along with the display history IH. In addition, the control unit  180  specifies the user information including the user specifying information and the password in the user database of the hard disk drive  139  based on the user specifying information and the password. 
     Then, the control unit  180  sends the display history IH to the hard disk drive  189 . In so doing, the control unit  180  stores the display history IH on the hard disk drive  189  and associates and registers the display history IH with the specified user information in the user database. 
     Here, the page number  86  of the book page image  47  displayed in the electronic book reproducing apparatus  24  is included in the display history IH, and the book specifying information  116  of the electronic book including the book page image  47  is also stored thereon. Therefore, the control unit  180  can determine the book page image  47  including the articles and the like read by the user in the electronic book reproducing apparatus  24  based on the display history IH. 
     In addition, the book page image data to which the page number  86  is added is associated with the book specifying information  116  as described above and registered in the book database of the hard disk drive  189 . 
     Accordingly, the control unit  180  can easily specify the contents of the book page image, which has been actually displayed, as the book page image data along with the electronic book selected to be displayed in the electronic book reproducing apparatus  24  with the use of the book database based on the display history IH. 
     By the way, when the book page image  47  is displayed, the enlargement target area  92  is made to be purposely designated in the book page image  47  to be enlarged and displayed. That is, the enlarged and displayed enlargement target area  92  is designated for enlargement and display just because the user is interested in the enlargement target area  92 . Accordingly, it is considered that the contents of the enlarged and displayed enlargement target area  92  have been substantially surely checked (that is, read) by the user. 
     In addition, the area specifying information  101  of the enlargement target area  92  enlarged and displayed in the electronic book reproducing apparatus  24  is included in the display history IH, and the book specifying information  116  for the electronic book including the book page image  47  in which the enlargement target area  92  is present is also stored thereon. 
     Accordingly, the control unit ISO can specifically determine a part, which has been actually read by the user by the electronic book reproducing apparatus  24 , in the book page image  47  as the enlargement target area  92  based on the display history IH. 
     Moreover, the enlargement target image data added to the area specifying information  101  is associated with the book specifying information  116  as described above and registered in the book database of the hard disk drive  189 . 
     Accordingly, the control unit  180  can easily specify the contents of the enlargement target area  92 , which has been actually enlarged and displayed by the electronic book reproducing apparatus  24 , as the area enlargement image data with the use of the book database based on the display history IH. 
     In addition, the control unit  180  can allow an advertising company and a manufacturing company of the electronic book to use the book page images and the contents of the enlargement target area in order to manufacture the electronic book advertisement or a new electronic book by providing the book page image data and the area enlargement image data specified as described above to the advertising company and the manufacturing company of the electronic book. 
     That is, the control unit  180  can specifically determine not only the book page image  47 , which is read by the user, in the electronic book but also a part, which has been actually read, in the book page image  47  as the enlargement target area  92  based on the display history IH. Accordingly, the control unit  180  can allow the advertising company and the manufacturing company to more effectively use the display history IH for advertising the electronic book and manufacturing a new electronic book. 
     By the way, the control unit  180  sends the display history IH to the preference extraction unit  191  at this time. When the display history IH is given from the control unit  180 , the preference extraction unit  191  extracts the book specifying information  116 , the page number  86 , and the area specifying information  101  along with the corresponding time information  151  from the display history IH. 
     In addition, the preference extraction unit  191  specifies the book information  65  of the electronic book associated with the book specifying information (that is, the book information  65  including the book specifying information  116 ) in the book database of the hard disk drive  189  based on the book specifying information  116 . 
     in so doing, the preference extraction unit  191  reads the category  72  as specific book attribute information for preference extraction from among the book attribute information included in the specified book information  65  from the hard disk drive  189 . 
     Moreover, the preference extraction unit  191  specifies the page information  85  including the page number  86  from among the page information  85  associated with the book specifying information  116  in the book database of the hard disk drive  189  based on the book specifying information  116  and the page number  86 . 
     In so doing, the preference extraction unit  191  reads the in-page text  88 , the keyword  89 , and the category  90  as the page attribute information for preference extraction from among the page attribute information included in the specified page information  85  from the hard disk drive  189 . 
     Moreover, the preference extraction unit  191  specifies the area information  100  including the area specifying information  101  from among the area information  100  associated with the book specifying information  116  in the book database of the hard disk drive  189  based on the book specifying information  116  and the area specifying information  101 . 
     In so doing, the preference extraction unit  191  reads the in-page text  105 , the keyword  106 , and the category  107  as specific area attribute information for preference extraction from among the area attribute information included in the specified area information  100  from the hard disk drive  189 . 
     Then, the preference extraction unit  191  extracts the user preference based on the book attribute information, the page attribute information, and the area attribute information, which are read from the hard disk drive  189 , and the time information  151  extracted from the display history IH. 
     In such a case, the preference extraction unit  191  selects the specific book attribute information for preference extraction read from the hard disk drive  189  to be used as it is for preference extraction since the specific book attribute information for preference extraction is related to the electronic book which the user is interested in and selects to actually read. 
     In addition, since the enlargement target area  92  is made to be purposely designated in the book page image  47  to be enlarged and displayed when the book page image  47  is displayed as described above, and it is considered that the contents thereof is substantially surely checked by the user when the enlargement target area  92  when the enlargement target area  92  is enlarged and displayed. Therefore, the preference extraction unit  191  selects all specific area attribute information for preference extraction read from the hard disk drive  189  so as to be used as it is for preference extraction. 
     However, the book page image  47  may be temporarily displayed in response to the instruction of sending and returning of the page for searching for a desired book page image  47 , and the articles and the like in the book page image  47  is not actually read in some cases. 
     Therefore, the preference extraction unit  191  performs subtraction processing with the use of time information  151  at the display start time point of the book page image  47  (that is, corresponding to the page number  86 ) and the time information  151  indicating the next time after the time indicated by the former time information  151  in a time series manner from among the time information  151 . 
     In so doing, the preference extraction unit  191  calculates the display time of the book page image  47  (that is, the time during which the display is continued) displayed in response to the user operation indicated by the display history IH. In addition, the preference extraction unit  191  compares the calculated display time with a predetermined threshold value which is chosen in advance in order to determine whether or not the articles and the like in the book page image  47  has been read. 
     The preference extraction unit  191  selects specific page attribute information corresponding to the book page image  47 , whose articles and the like have been determined to be read, from among the specific page attribute information read from the hard disk drive  189  based on the comparison result so as to be used for preference extraction. 
     In addition to this, the preference extraction unit  191  executes natural language processing for the in-area text  105  as the specific area attribute information and the in-page text  88  as the specific page information selected to be used for preference extraction. 
     In such a case, the preference extraction unit  191  reads morpheme dictionary data and semantic dictionary data stored in advance from the hard disk drive  189 . In addition, the morpheme dictionary data is produced by associating a plurality of morphemes of various word classes such as nouns verbs, particles, adverbs, and the like with the reading, the word classes, and the like of the morphemes. 
     In addition, the morpheme is a minimum unit of a language with a meaning, and some constitute words by themselves, others constitute words in combination with another morpheme, and others do not constitute any word by themselves and even in combination with another morpheme. 
     In addition, the semantic dictionary data represents specific words of word classes such as nouns and verbs and represents the meanings of the words with the broader concept in a hierarchical manner. When the specific words are nouns “ramen” and “udon”, for example, the semantic dictionary data shows the meaning “cooking: noodles” with the broader concept as the meaning of the words. 
     When the morpheme dictionary data and the semantic dictionary data are read from the hard disk drive  189 , the preference extraction unit  191  performs morpheme analysis on the in-area text  105  based on the morpheme dictionary data. In so doing, the preference extraction unit  191  specifies each of the word classes of a plurality of morphemes by sectioning the in-area text  105  into the plurality of morphemes. 
     In addition, the preference extraction unit  191  determines one or a plurality of morphemes constituting specific words of word classes such as nouns and verbs from among the plurality of morphemes based on the result of the morpheme analysis and the semantic dictionary data. Moreover, the preference extraction unit  191  specifies the meanings of a word constituted by one or a plurality of determined morphemes. 
     Then, the preference extraction unit  191  performs syntax analysis on the in-area text  105  based on such a result of the morpheme analysis and the word meaning specification result obtained for the in-area text  105 . In so doing, the preference extracting unit  191  specifies the grammatical roles of the morphemes included in the in-area text  105  and specifies the modification relationship and the like between the morphemes in the in-area text  105 . 
     As described above, the preference extraction unit  191  obtains the processing result of the natural language processing (that is, the result of the morpheme analysis, the word meaning specification result, and the result of the syntax analysis) for the in-area text  105 . The preference extraction unit  191  detects a keyword, which is important to understand the contents of the in-area text  105 , from the in-area text  105  based on the processing result of the natural language processing for the in-area text  105 . 
     That is, the preference extraction unit  191  maintains a list (hereinafter, this will also be referred to as a word class list) of morphemes of predetermined word classes such as particles and adverbs, which have been detected in advance by learning with the use of various texts, for example, and do not contribute to understanding of the contents of the text. 
     In addition, the preference extraction unit  191  also maintains a list of words with predetermined meanings, which have been detected in advance by learning with the use of various texts, for example, and do not contribute to understanding of the contents of the text. 
     Accordingly, the preference extraction unit  191  excludes from the candidates of keywords the morphemes of the word classes registered in the word class list as the morphemes which are not important to understand the contents of the in-area text  105 , from among a plurality of morphemes included in the in-area text  105 . 
     In addition, the preference extraction unit  191  also excludes from the candidates of keywords one or a plurality of morphemes constituting words with meanings registered in the meaning list as the morphemes which are not important to understand the contents of the in-area text  105 , from among a plurality of words included in the in-area text  105 . 
     Moreover, the preference extraction unit  191  specifies morphemes which are not important in the context to understand the contents of the in-area text  105  from among a plurality of morphemes in the in-area text  105  based on the grammatical roles, modification relationships, and the like of the plurality of morphemes included in the in-area text  105 . Then, the preference extraction unit  191  excludes the specified morphemes from the candidates of keywords. 
     As described above, the preference extraction unit  191  detects the words such as nouns and verbs constituted by one or a plurality of morphemes, which are not excluded and remain from among a plurality of morphemes in the in-area text  105 , as the keywords which are important to understand the contents of the in-area text  105 . 
     In addition, the preference extraction unit  191  also performs natural language processing on the in-page text  88  selected to be used for preference extraction in the same manner as in the case of the in-area text  105  and detects keywords, which are important to understand the contents of the in-page text  88 , based on the processing result. 
     Then, the preference extraction unit  191  gathers the categories  72 ,  90 , and  107  selected to be used for preference extraction. That is, the preference extraction unit  191  sets the number of the categories to one if the category is different from any one of the other categories  72 ,  50 , and  107 , and the preference extraction unit  191  sets the number of categories to the number which is two or greater as a whole if the two or more same categories are present. 
     Moreover, the preference extraction unit  191  gathers the keywords  89 , and  106  selected to be used for preference extraction with the keywords detected from the in-area text  105  and the in-page text  88 . That is, the preference extraction unit  191  sets the number of the categories to one if the category is different from any one of the other categories, and the preference extraction unit  191  sets the number of categories to the number which is two or greater as a whole if the two or more same categories are present. 
     In so doing, the preference extraction unit  191  extracts a predetermined number or greater of the categories as categories of items, in which the user is interested, from among a plurality of categories based on the gathering result, for example. In addition, the preference extraction unit  191  extracts a predetermined number or greater of keywords as keywords which representing the features of the items, in which the user is interested, from among a plurality of keywords based on the gathering result, for example. 
     As described above, the preference extracting unit  191  extracts categories of the items and keywords representing the items, in which the user is interested, as user preference (that is, as information representing user preference). In addition, the categories and the keywords extracted by the preference extracting unit  191  as the information representing user preference as described above will also be referred to as preference information in the following description. Then, the preference extracting unit  191  sends the preference information to the control unit  180 . 
     When the preference information is give from the preference extraction unit  191 , the control unit  180  sends the preference information to the hard disk drive  189 . In so doing, the control unit  180  stores the preference information on the hard disk drive  189  and associates and registers the preference information with the previously specified (that is, specified for registering the display history IH) user information. 
     1-6. Procedure of Image Data Producing Processing for Electronic Book 
     Next, description will be made of a procedure RT 1  of image data producing processing for an electronic book, in which the control unit  30  of the electronic book producing apparatus  21  produces book cover image data and the book page image data in the electronic book producing process executed based on the electronic book producing program, with the use of  FIG. 22 . 
     The control unit  30  of the electronic book producing apparatus  21  starts the procedure RT 1  of image data producing processing for an electronic book shown in  FIG. 22  based on the electronic book producing program when the start of the electronic book producing processing is instructed by an operator via the operation unit  36 , for example. 
     When the procedure RT 1  of image data producing processing for an electronic book is started, the control unit  30  imports original document data in the first or second format from the outside in Step SP 1  and moves on to the next Step SP 2 . 
     In Step SP 2 , the control unit  30  prompts the operator to input the format conversion information via the display unit  40 , for example, and waits for the input of the format conversion information by the operator via the operation unit  36 . When the format conversion information is input, the control unit  30  then moves on to the next Step SP 3 . 
     In Step SP 3 , the control unit  30  determines whether or not the format of the original document data imported from the outside at this time is the second format. If a positive result is obtained in this Step SP 3 , this means that the original document data in the second format, which has been produced by scanning a publication, is imported from the outside at this time. If such a positive result is obtained in Step SP 3 , the control unit  30  moves on to the next Step SP 4 . 
     In Step SP 4 , the control unit  30  adds page numbers to the image data for one or a plurality of facing pages included in the original document data and moves on to the next Step SP 5 . In Step SP 5 , the control unit  30  respectively performs size conversion processing on the image data for the cover and the image data of one or a plurality of facing pages of the publication included in the original document data. 
     In so doing, the control unit  30  produces the book cover image data and the book page image data with image sizes of HDTV standard, moves on to the next Step SP 6 , and completes such a procedure RT 1  of image data producing processing for an electronic book. 
     In addition, if a negative result is obtained in the aforementioned Step SP 3 , this means that the original document data in the first format, which has been produced for manufacturing a publication, is imported from the outside at this time. If such a negative result is obtained in Step SP 3 , the control unit  30  moves on to Step SP 7 . 
     In Step SP 7 , the control unit  30  cuts the original data into image data for the cover of the publication and image data for each facing page of the publication after decoding the original document and moves on to Step SP 5 . 
     Accordingly, the control unit  30  respectively performs the size conversion processing on the image data for the cover cut from the original data and the image data for one or a plurality of facing pages in Step SP 5  in such a case. In so doing, the control unit  30  produces the book cover image data and the book page image data with the image sizes of HDTV standard, moves on to the next Step SP 6 , and completes such a procedure RT 1  of image data producing processing for an electronic book. 
     1-7. Procedure of Electronic Book Data Producing Processing 
     Next, description will be made of the procedure RT 2  of electronic book data producing processing, in which the control unit  30  of the electronic book producing apparatus  21  produces electronic book data in the electronic book producing processing executed based on the electronic book producing program, with the use of  FIGS. 23 and 24 . 
     For example, when the procedure RT 1  of image data producing processing for an electronic book is completed, the control unit  30  of the electronic book producing apparatus  21  starts the procedure RT 2  of electronic book data producing processing shown in  FIGS. 23 and 24  based on the electronic book producing program. 
     When the procedure RT 2  of electronic book data producing processing is started, the control unit  30  displays the electronic book producing screen  42 A on the display unit  40  based on the book display image data and the book page image data in Step SP 11  and moves on to the next Step SP 12 . 
     In Step SP 12 , the control unit  30  waits for the input of the book attribute information on the book attribute input image  49  of the electronic book producing screen  42 A by the operator via the operation unit  36 . When the book attribute information is input on the book attribute input image  49 , the control unit  30  then moves on to the next Step SP 13 . 
     In Step SP 13 , the control unit  30  organizes the book attribute information in the book attribute input image  49  with the total page number to produce book information  65  and moves on to the next Step SP 14 . In Step SP 14 , the control unit  30  determines whether or not the book page images  45  to  48  are selected on the image list display unit  43  on the electronic book producing screen  42 A by the operator via the operation unit  36 . 
     If a positive result is obtained in this Step SP 14 , this means that the book page images  45  to  48  have been selected for inputting the page attribute information by the operator. When such a positive result is obtained in Step S 214 , the control unit  30  updates the electronic book producing screen  42 A displayed on the display unit  40  to the electronic book producing screen  42 B including the page attribute input image  75  and moves on to the next Step SP 15 . 
     In Step SP 15 , the control unit  30  waits for the input of the page attribute information on the page attribute input image  75  in the electronic book producing screen  42 B by the operator via the operation unit  36 . When the page attribute information is input on the page attribute input image  75 , the control unit  30  then moves on to the next Step SP 16 . 
     In Step SP 16 , the control unit  30  associates the page attribute information in the page attribute input image  75  with the page number of the book page image  47  selected at this time to produce the individual book page information and moves on to the next Step SP 17 . 
     In Step SP 17 , the control unit  30  performs downsize processing on the book page image data for the book page image  47  selected at this time and produces a thumbnail image data for the thumbnail image as an index of the book page image  47 . In addition, the control unit  30  adds the page number of the original book page image  47  to the thumbnail image data and moves on to the next Step SP 18 . 
     In Step SP 18 , the control unit  30  determines whether or not the enlargement target area  92  has been chosen in the book page image  47 , which has been enlarged and displayed on the electronic book producing screen  42 A, by the operator via the operation unit  36 . If a positive result is obtained in this Step SP 18 , this means that the enlargement target area  92  which can be enlarged and displayed has been chosen on the book page image  47  by the operator when the electronic book is displayed by the user. 
     If such a positive result is obtained in Step SP 18 , the control unit  30  issues area specifying information  101  of the chosen enlargement target area  92 . Then, the control unit  30  updates the electronic book producing screen  42 A displayed on the display unit  40  to the electronic book producing screen  42 V including the area attribute input image  94  and moves on to the next Step SP 19 . 
     In Step SP 19 , the control unit  30  waits for the input of the area attribute information on the area attribute input image  94  in the electronic book producing screen  42 C by the operator via the operation unit  36 . If the area attribute information is input on the area attribute input image  94 , the control unit  30  then moves on to the next Step SP 20 . 
     In Step SP 20 , the control unit  30  associates the area attribute information in the area attribute input image  94  with area position information association representing the position of the enlargement target area  92  chosen at this time. In addition, the control unit  30  also associates the area attribute information in the area attribute input image  94  with the page number of the book page image  47  including the enlargement target area  92  chosen at this time to produce the area individual information and moves on to the next Step SP 21 . 
     In Step SP 21 , the control unit  30  cuts a part of the enlargement target area  92  chosen at this time as area data from among the book page image data for the book page image  47 . In addition, the control unit  30  adds the area specifying information  101  of the original enlargement target area  92  to produce the area enlargement image data after performing enlargement processing on the area data and then moves on to the next Step SP 22 . 
     In Step SP 22 , the control unit  30  determines whether or not the production of the book page information and the area individual information has been completed. If a negative result is obtained in Step SP 22 , this means that book page images  45  to  48  which have not been selected for the input of the page attribute information are present or that completion of choosing has not been instructed by the operator for choosing the enlargement target area  92 . If such a negative result is obtained in Step SP 22 , the control unit  30  returns to Step SP 14 . 
     In addition, if a negative result is obtained in the aforementioned Step SP 14 , this means that the contents of the book page image  47  enlarged and displayed in the electronic book producing screen  42 B is being checked by the operator, for example. 
     That is, such a negative result means that the book page images  45  to  48  have not been selected by the operator for input of the page attribute information and there is a possibility in that the enlargement target area  92  is chosen. If such a negative result is obtained in Step SP 14 , the control unit  30  moves on to Step SP 19 . 
     Furthermore, if a negative result is obtained in Step SP 18 , this means that there is a possibility in that new book page image  45  to  48  is selected by the operator, who has completed the input of the page attribute information, for input of the page attribute information, for example. If such a negative result is obtained in Step SP 18 , the control unit  30  moves on to Step SP 22 . 
     In so doing, the control unit  30  allows the operator to select the book page images  45  to  48  and input the page attribute information thereafter by repeatedly and cyclically executing the processing from Step SP 14  to Step SP 22  until a positive result is obtained in Step SP 22 . In addition, the control unit  30  allows the operator to choose an enlargement target area and input the area attribute information by repeatedly and cyclically executing the processing from Step SP 14  to Step SP 22 . 
     Then, if a positive result is obtained in Step SP 22 , this means that the page attribute information has been input for all book page images  45  to  48  by the operator and the production of the book page individual information for all book page images  45  to  48  has been completed. 
     In addition, such a positive result means that completion of the choosing of the enlargement target area  92  is instructed by the operator and the production of the area individual information has been completed for all enlargement target areas chosen by the operator. If such a positive result is obtained in Step SP 22 , the control unit  30  moves on to the next Step SP 23 . 
     In Step SP 23 , the control unit  30  produces the page information  85  with the use of all individual book page information and moves on to the next Step SP 24 . In Step SP 24 , the control unit  30  produces the area information  100  with the use of all area individual information and moves on to the next Step SP 25 . 
     Then, in Step SP 25 , the control unit  30  moves on to the next Step SP 26  after organizing the book image data, the book information  65 , the page information  85 , the area information  100 , the coded audio data, and the coded associated data, which are produced at this time, to produce the electronic book data D 2  and D 4 . In so doing, the control unit  30  completes such a procedure RT 2  of electronic book data producing processing in Step SP 26 . 
     1-8. Procedure of Electronic Book Registration Processing 
     Next, description will be made of a procedure RT 3  of electronic book registration processing, in which the control unit  180  of the history obtaining apparatus  22  registers the electronic book produced by the electronic book producing apparatus  21  based on a registration program stored in advance on the ROM  181 , for example, with the use of  FIG. 25 . 
     When the electronic book data D 2  and  54  transmitted from the electronic book producing apparatus  21  is received, the control unit  180  of the history obtaining apparatus  22  starts the procedure RT 3  of electronic book registration processing shown in  FIG. 25  based on the registration program. When the procedure RT 3  of electronic book registration processing is started, the control unit  180  issues book specifying information  116  of the electronic book based on the electronic book data D 2  and  54  received at this time in Step SP 31  and moves on to the next Step SP 32 . 
     In Step SP 32 , the control unit  180  stores the book specifying information  116  on the book information  65  included in the electronic book data D 2  and D 4 , transmits the book specifying information  116  to the electronic book producing apparatus  21  via the network  23 , and moves on to the next Step SP 33 . 
     In Step SP 33 , the control unit  180  stores the book information  65  storing the book specifying information  116  and the book specifying information  116  on the hard disk drive  189 , associates therebetween, registers them in the honk database, and then moves on to the next Step SP 34 . 
     In Step SP 34 , the control unit  180  stores the page information included in the electronic hook data D 2  and D 4  on the hard disk drive  189 , associates and registers the page information  85  with the book specifying information  116  in the hook database, and then moves on to the next Step SP 35 . 
     In Step SP 35 , the control unit  180  stores the area information  100  included in the electronic book data D 2  and D 4  on the hard disk drive  189 , associates and registers the area information  100  with the book specifying information  116 , and then moves on to the next Step SP 36 . 
     In Step SP 36 , the control unit  180  determines whether or not the electronic book data D 2  and D 4  received at this time is electronic book data D 2  and D 4  which can be provided via the network  23 . If a positive result is obtained in Step SP 36 , this means that the electronic book data D 2  and D 4  received at this time is electronic book data D 2  and D 4  whose providing with the use of the network  23  is permitted. If such a positive result is obtained in Step SP 36 , the control unit  180  moves on to the next Step SP 37 . 
     In Step SP 37 , the control unit  180  stores the book image data D 4  included in the electronic book data D 2  and D 4  on the hard disk drive  189  and associates and registers the book image data D 6  with the book specifying information  116  in the book database. 
     In addition, the control unit  180  stores the coded associated data D 7  and the coded audio data D 8  included in the electronic book data D 2  and D 4  on the hard disk drive  188 , associates and registers the coded associated data D 7  and the coded audio data D 8  with the book specifying information  116  in the book database, and then moves on to the next Step SP 38 . In so doing, the control unit  180  completes the procedure RT 3  of electronic book registration processing in Step SP 38 . 
     On the other hand, if a negative result is obtained in the aforementioned Step SP 36 , this means that the electronic book data D 2  and D 4  received at this time is electronic book data D 2  and D 4  whose providing with the use of the network  23  is not permitted. If such a negative result is obtained in Step SP 36 , the control unit  180  moves on to Step SP 38  without executing the processing in Step SP 37  and completes such a procedure RT 3  of electronic book registration processing. 
     1-9. Procedure of Electronic Book Reproduction Processing 
     Next, description will be made of the procedure RT 4  of electronic book reproduction processing, in which the control unit  130  of the electronic book reproducing apparatus  24  reproduces the electronic book data D 2  and D 4  based on the electronic book reproducing program P 2 , with the use of  FIG. 26 . 
     When the reproduction of the electronic book is instructed by the user, the control unit  130  of the electronic book reproducing apparatus  24  starts the procedure RT 4  of the electronic book reproduction processing shown in  FIG. 26  based on the electronic book reproducing program P 2  read from the book providing disc  28  or the hard disk drive  152 . 
     When the procedure RT 4  of the electronic book reproduction processing is started, the control unit  130  displays the index screen on the display apparatus  25  in Step SP 41  and waits for the user&#39;s selection of an electronic book to be reproduced. When the electronic book to be reproduced is selected on the index screen by the user, the control unit  130  then moves on to the next Step SP 42 . 
     In Step SP 42 , the control unit  130  reproduces the book cover image data included in the electronic book data D 2  and D 4  for the electronic book selected by the user, displays the book cover image based on the book cover image data on the display apparatus  25 , and moves on to the next Step SP 43 . 
     In Step SP 43 , the control unit  130  associates and stores the book specifying information  116  of the electronic book selected by the user with the time information at the display start time point of the book cover display on the built-in storage unit  140  as the display history IH and moves on to the next Step SP 44 . 
     In Step SP 44 , the control unit  130  determines whether or not the displayed book page images  45  to  48  have been selected by the user. If a positive result is obtained in Step SP 44 , this means that the book page images  45  to  48  displayed on the display apparatus  25  have been selected by the instruction of sending or returning of the page or the selection of a thumbnail image by the user. If such a positive result is obtained in Step SP  44 , the control unit  130  moves on to the next Step SP 45 . 
     In Step SP 45 , the control unit  130  reproduces the book page image data in accordance with the user operation (instruction or selection), displays the book page image based on the book page image data on the display apparatus  25 , and moves on to the next Step SP 46 . 
     In Step SP 46 , the control unit  130  associates and stores the page number  86  of the displayed book page images  45  to  48  with the time information at the display start time point in the built-in storage unit  140 , updates the display history IH, and then moves on to the next Step SP 47 . 
     In Step SP 47 , the control unit  130  determines whether or not the enlargement target area  92  has been designated in the book page images  45  to  48  being displayed by the user. If a positive result is obtained in Step SP 47 , this means that the enlargement target area  92  whose enlargement and display are desired has been designated in the book page images  45  to  48  being displayed by the user. If such a positive result is obtained in Step SP 47 , the control unit  130  moves on to the next Step SP 48 . 
     In Step SP 4 , the control unit  130  reproduces the area enlargement image data corresponding to the enlargement target area  92  designated by the user, enlarges and displays the enlargement target area  92  as the area enlargement image  150  on the display apparatus  25 , and moves on to the next Step SP 49 . 
     In Step SP 49 , the control unit  130  associates and stores the area specifying information  101  of the enlarged and displayed enlargement target area  92  with the time information at the enlargement and display start point in the built-in storage unit  140 , updates the display history IH, and the moves on to the next Step SP 50 . 
     In Step SP 50 , the control unit  130  determines whether or not another electronic book has been selected for reproduction by the user. If a negative result is obtained in Step SP 50 , this means that there is a possibility in that the user instructs to display the book page images  45  to  48  of the previously selected electronic book and to enlarge and display the enlargement target area  92 . If such a negative result is obtained in Step SP 50 , the control unit  130  moves on to the next Step SP 51 . 
     In Step SP 51 , the control unit  130  determines whether or not the reproduction of the electronic book is completed. If a negative result is obtained in Step SP 51 , this means that the electronic book is being read by the user and completion of the reproduction of the electronic book has not been instructed yet. If such a negative result is obtained in Step SP 51 , the control unit  130  returns to Step SP 44 . 
     By the way, if a negative result is obtained in the aforementioned Step SP 44 , this means that the articles and the like in the book page images  45  to  40  being displayed at this time is being read or the enlargement target area  92  to be enlarged and displayed is being selected by the user. If such a negative result is obtained in Step SP 44 , the control unit  130  moves on to Step SP 47  without executing the processing in Step SP 45  and Step SP 46 . 
     In addition, if a negative result is obtained in the aforementioned Step SP 47 , this means that the book page images  45  to  40  being displayed at this time or the articles and the like in the enlargement target area  92  being enlarged and displayed are being read by the user. If such a negative result is obtained in Step SP 47 , the control unit  130  moves on to Step SP 50  without executing the processing in Step SP 48  and Step SP 49 . 
     Moreover, if a positive result is obtained in the aforementioned Step SP 50 , this means that the index screen has been displayed again in response to the user&#39;s instruction and an electronic book to be subsequently reproduced has been selected on the displayed index screen. If such a positive result is obtained in Step SP 50 , the control unit  130  returns to Step SP 42 . 
     In so doing, the control unit  130  repeatedly and cyclically executes the processing in Step SP 42  to Step SP 50  thereafter until a positive result is obtained in Step SP 51 . Accordingly, the control unit  130  can allow the user to read the articles in the book page images  45  to  40  and the enlargement target area  92  by sequentially displaying the book page images  45  to  48  of one or a plurality of electronic books or sequentially enlarging and displaying the enlargement target area  92 . 
     Then, if a positive result is obtained in Step SP 51 , this means that completion of the reproduction of the electronic book has been instructed by the user. If such a positive result is obtained in Step SP 51 , the control unit  130  moves on to the next Step SP 52  and completes the procedure RT 4  of the electronic book reproduction processing. 
     1-10. Procedure of Display History Providing and Obtaining Processing 
     Next, description will be made of a procedure of history providing and obtaining processing, which is executed by the control unit  130  of the electronic book reproducing apparatus  24  and the control unit  180  of the history obtaining apparatus  22 , with the use of  FIG. 27 . When completion of the reproduction of the electronic book is instructed by the user, the control unit  130  of the electronic book reproducing apparatus  24  starts the procedure RT 5  of the display history providing processing shown in  FIG. 27(A)  based on the electronic book reproducing program P 2  read from the book providing disc  28  or the hard disk drive  152 . 
     That is, when completion of the reproduction of the electronic book is instructed by the user, the control unit  130  of the electronic book reproducing apparatus  24  starts the procedure RT 5  of the display history providing processing as part of the aforementioned electronic book reproducing processing. When the procedure RT 5  of the display history providing processing is started, the control unit  130  completes the production of the display history IH in the built-in storage unit  140  in Step SP 61 . Then, the control unit  130  completes the production, reads the display history IH from the built-in storage unit  140 , and moves on to the next Step SP 62 . 
     In Step SP 62 , the control unit  130  accesses the history obtaining apparatus  22  via the network  23 , communicates with the history obtaining apparatus  22 , and moves on to the next Step SP 63 . Then, in Step SP 63 , the control unit  130  produces the authentication processing request information, transmits the authentication processing request information to the history obtaining apparatus  22  via the network  23 , and moves on to the next Step SP 64 . 
     At this time, the control unit  180  of the history obtaining apparatus  22  starts the procedure RT 6  of the display history obtaining processing shown in  FIG. 27(B)  based on the history obtaining program stored in advance on the ROM  181 , for example, in response to the communication with the electronic book reproducing apparatus  24 . 
     When the procedure RT 6  of the display history obtaining processing is started, the control unit  180  waits for the transmission of the authentication processing request information from the electronic book reproducing apparatus  24  in Step SP 71 . Then, when the authentication processing request information transmitted from the electronic book reproducing program  24  is received, the control unit  180  moves on to the next Step SP 72 . 
     In Step SP 72 , the control unit  180  causes the authentication processing unit  190  to executes the user authentication processing based on the authentication processing request information and moves on to the next Step SP 73 . In Step SP 73 , the control unit  180  determines whether or not the user has been authenticated as a result of the user authentication processing. If a positive result is obtained in Step SP 73 , this means that the history obtaining apparatus  22  has been accessed by the electronic book reproducing apparatus  24  of a user, who has already completed the user registration, at this time. If such a positive result is obtained in Step SP 73 , the control unit  180  moves on to the next Step SP 74 . Accordingly, the control unit  180  transmits the authentication notification information to the electronic book reproducing apparatus  24  at this time in Step SP 74  and moves on to the next Step SP 75 . 
     On the other hand, if a negative result is obtained in Step SP 73 , this means that the history obtaining apparatus  22  has been accessed by the electronic hook reproducing apparatus  24  of a user, who has not completed the user registration yet, at this time. If such a negative result is obtained in Step SP 73 , the control unit  180  transmits the authentication error information to the electronic book reproducing apparatus  24 , then moves on to Step SP 77 , and completes such a procedure RT 6  of the display history obtaining processing. 
     By the way, the control unit  130  of the electronic book reproducing apparatus  24  waits for the notification of the processing result of the user authentication processing from the history obtaining apparatus  22  (that is, the transmission of the authentication notification information or the authentication error information) in Step SP 64 . 
     Then, when the control unit  130  is notified of the processing result of the user authentication processing by the history obtaining apparatus  22 , the control unit  130  determines whether or not the user has been authenticated. If a positive result is obtained in Step SP 64 , this means that the user who owns this apparatus has completed the user registration. If such a positive result is obtained in Step SP 64 , the control unit  130  moves on to the next Step SP 65 . 
     Accordingly, the control unit  130  produces the display history notification data to provide the display history transmits the display history notification data to the history obtaining apparatus  22 , moves on to the next Step SP 66 , and completes such a procedure RT 5  of the display history obtaining processing in Step SP 65 . 
     In addition, if a negative result is obtained in Step SP 64 , this means that the user who owns this apparatus has not completed the user registration yet. If such a negative result is obtained in Step SP 64 , the control unit  130  moves on to Step SP Step SP 66  without executing the processing in Step SP 65  and completes such a procedure RT 5  of the display history providing processing. 
     By the way, when the control unit  180  of the history obtaining apparatus  22  transmits the authentication notification information to the electronic book reproducing apparatus  24  and moves on to Step SP 75 , the control unit  180  of the history obtaining apparatus  22  waits for the transmission of the display history notification data from the electronic book reproducing apparatus  24 . Then, when the display history notification data transmitted from the electronic book reproducing apparatus  24  is received, the control unit  180  moves on to the next Step SP 78 . 
     In Step SP 78 , the control unit  180  extracts the display history IH from the display history notification data. Then, the control unit  180  stores the display history IH on the hard disk drive  180 , associates and registers the display history IH with the user information of the user of the electronic book reproducing apparatus  24  in the user database, and moves on to the next Step SP 79 . 
     In Step SP 79 , the control unit  180  reads specific book attribute information, page attribute information, and area attribute information for preference extraction from the hard disk drive  189  based on the display history IH by the preference extraction unit  191  and moves on to the next Step SP 80 . 
     In Step SP 80 , the control unit  180  causes the preference extraction unit  191  to extract user preference based on specific book attribute information, page attribute information, and area attribute information for preference extraction and moves on to the next Step SP 81 . 
     In Step SP 81 , the control unit  180  stores the user preference extracted by the preference extraction unit  191  as the preference information on the hard disk drive  189  and associates and registers the user information of the user in the user database. Then, when the registration of the preference information has been completed, the control unit  180  moves on to Step SP 77  and completes such a procedure RT 6  of the display history obtaining processing. 
     1-11. Operations and Effects of Embodiments 
     In the above configuration, the electronic book producing apparatus  21  in the electronic book providing system  20  imports the original document data from the outside. In addition, the electronic book producing apparatus  21  produces the book cover image data and one or a plurality of book page image data items based on the original document data. 
     Moreover, the electronic book producing apparatus  21  produces the electronic book data for the electronic book including book cover image data and one or a plurality of book page image data in which one or a plurality of parts selected in the book page image are set as enlargement target areas which can be individually enlarged and displayed. 
     In addition, the electronic book reproducing apparatus  24  in the electronic book providing system  20  performs reproducing processing on the electronic book data produced by the electronic book producing apparatus  21  and displays the book cover image and the book page image on the display apparatus  25 . 
     If an enlargement target area in the book page image displayed on the display apparatus  25  is designated by the user via the remote control  27 , the electronic book reproducing apparatus  24  enlarges and displays the designated enlargement target area on the display apparatus  25  as an area enlargement image. 
     Furthermore, when the reproduction processing is performed on the electronic book data as describe above, the electronic book reproducing apparatus  24  produces a display history showing enlargement target area enlarged and displayed on the display apparatus  25 . Then, when the reproduction of the electronic book is completed, the electronic book reproducing apparatus  24  transmits the display history to the history obtaining apparatus  22  via the network  23 . 
     Furthermore, when the display history is transmitted from the electronic book reproducing apparatus  24  in accordance with the completion of the reproduction of the electronic book, the history obtaining apparatus  22  in the electronic book providing system  20  receives the display history and associates and stores the display history with the user information of the user of the electronic book reproducing apparatus  24 . 
     Accordingly, the electronic book providing system  20  can specifically determine which part, that is, which enlargement target area has been actually read by the user in the book page image of the electronic book, based on the display history by the history obtaining apparatus  22 . 
     According to the above configuration, configuration is made in the electronic book system  20  such that when the electronic book producing apparatus  21  produces electronic book data of an electronic book, which has one or a plurality of book page image data items based on original document data imported from the outside, in which one or a plurality of parts selected in a book page image based on the book page image data are set to enlargement target areas which can be individually enlarged and displayed, and the electronic book reproducing apparatus  24  performs reproduction processing on the electronic book data, displays the book images on the display apparatus  25 , causes the display apparatus  25  to enlarge and display the designated enlargement target area when the enlargement target area in the book page image is designated by the user, produces the display history showing the enlargement target area enlarged and displayed on the display apparatus  25  when the reproduction processing is performed on the electronic book data as described above, and transmits the produced display history to the history obtaining apparatus  22 , and the history obtaining apparatus  22  receives the display history and associates and stores the display history with the user information of the user of the electronic book reproducing apparatus  24 . In so doing, the electronic book providing system  20  can specifically determine which part in the book page image of the electronic book has been actually read by the user based on the display history by the history obtaining apparatus  22 . Accordingly, the electronic book providing system  20  can more effectively use the display history of the electronic book displayed by the electronic book reproducing apparatus  24  for advertising of the electronic book, manufacturing of a new electronic book, and extracting of user preference and the like. 
     In addition, the history obtaining apparatus  22  in the electronic book providing system  20  determines the enlargement target area enlarged and displayed by the electronic book reproducing apparatus  24  based on the display history provided from the electronic book reproducing apparatus  24 . Then, the history obtaining apparatus  22  is configured to extract user preference based on a keyword and a category in accordance with the contents of the determined enlargement target area. 
     Accordingly, the electronic book providing system  20  can accurately extract user preference based on a part, which has been substantially surely checked (read) by the user, in the book page image. That is, the electronic book providing system  20  can precisely extract user preference while avoiding using even a part, which has not been actually checked (read) in the book page image including articles of various contents, for example, for the user preference extraction to the maximum extent. 
     Moreover, when the enlarged and displayed enlargement target area is determined based on the display history, the history obtaining apparatus  22  in the electronic book providing system  20  performs natural language processing on texts in the enlargement target area and detects keywords in accordance with the contents of the enlargement target area based on the processing result. Then, the history obtaining apparatus  22  is configured to extract user preference with the use of the detected keywords. 
     Accordingly, even when the keywords for the enlargement target area have not been input by the operator at the time of producing the electronic book data, the electronic book providing system  20  can accurately extract user preference. 
     Furthermore, when the reproduction processing is performed on the electronic book data, the electronic book reproducing apparatus  24  in the electronic book providing system  20  produces a display history representing the book page image displayed on the display apparatus  25  along with the enlargement target area enlarged and displayed on the display apparatus  25 . Then, when the reproduction of the electronic book is completed, the electronic book reproducing apparatus  24  is configured to transmit the display history to the history obtaining apparatus  22  via the network  23 . 
     In addition, the history obtaining apparatus  22  in the electronic book providing system  20  also determines the book page image displayed by the electronic book reproducing apparatus  24  along with the enlargement target area enlarged and displayed by the electronic book reproducing apparatus  24  based on the display history. 
     Then, the history obtaining apparatus  22  is configured to extract user preference based on the keywords and the category in accordance with the contents of the determined enlargement target area and the contents of the specified book page image. Accordingly, when the entire contents of the book page image has been checked by the user, the electronic book providing system  20  can extracts the user preference even with the use of the contents. 
     Furthermore, when the reproduction processing is performed on the electronic book data, the electronic book reproducing apparatus  24  in the electronic book providing system  20  shows the enlarged and displayed enlargement target area on the display apparatus  25  along with the time at the start time point of enlargement and display and produces the display history showing the book page image displayed on the display apparatus  25  along with the time at the display start time point. Then, when the reproduction of the electronic book is completed, the electronic book reproducing apparatus  24  is configured to transmit the display history to the history obtaining apparatus  22  via the network  23 . 
     In addition, when the book page image displayed by the electronic book reproducing apparatus  24  is determined based on the display history, the history obtaining apparatus  22  in the electronic book providing system  20  determines whether or not the contents of the book page image has been actually checked, based on the time information included in the display history. 
     Then, the history obtaining apparatus  22  is configured to extract user preference based on the keywords and the category in accordance with the contents of the determined enlargement target area and the contents of the book page image, which is determined to have been actually checked. Accordingly, it is possible to avoid extracting the user preference with the use of the book page image, which is temporarily displayed by the electronic book reproducing apparatus  24  for page shifting or the like, whose contents have not been checked, according to the electronic book providing system  20 . 
     2. MODIFIED EXAMPLES 
     2-1. Modified Example 1 
     In addition, in the aforementioned embodiment, the electronic book reproducing apparatus  24  produces the display history showing the electronic book selected for reproduction, the book page image displayed on the display apparatus  25 , and the enlargement target area enlarged and displayed on the display apparatus  25  and transmits display history to the history obtaining apparatus  22 . In addition, the description was made of a case in which the history obtaining apparatus  22  was configured to extract user preference with the use of the display history. 
     However, the present invention is not limited thereto, and the electronic book reproducing apparatus  24  produces the display history showing only the enlargement target area enlarged and displayed on the display apparatus  25  and transmits the display history to the history obtaining apparatus  22 . In addition, the history obtaining apparatus  22  may be configured to extract user preference based only on the contents of the enlargement target area shown by the display history. 
     In addition, the present invention may be configured such that the electronic book reproducing apparatus  24  shows book page image displayed for a predetermined time period or longer from among the displayed book page images along with the enlarged and displayed enlargement target area, produces a display history which does not particularly include the time information, and transmits the display history to the history obtaining apparatus  22 . 
     With such a configuration, it is not necessary to determine the book page image, whose contents have been actually checked, when the user preference is extracted by the history obtaining apparatus  22 , and it is possible to simplify the preference extraction processing for extracting the preference and reduce the processing load of the processing, according to the present invention. 
     2-2 Modified Example 2 
     In the aforementioned embodiment, description was made of the case in which the electronic book producing apparatus  21  produced the electronic book data including the page information storing the in-page text and the area information storing the in-area text and the history obtaining apparatus  22  stored the electronic book data. 
     However, the present invention is not limited thereto, the electronic book producing apparatus  21  may produce the electronic book data including the page information which does not store the in-page text and the area information which does not store the in-area text, and the history obtaining apparatus  22  may store the electronic book data. 
     In addition, the present invention may be configured such that when the user preference is extracted by the history obtaining apparatus  22 , the book page image displayed by the electronic book reproducing apparatus  24 , the in-page text and the in-area text in the enlarged and displayed enlargement target area may be extracted from the book page image data and the area enlargement image data included in the electronic book data stored on the history obtaining apparatus  22  itself. 
     In addition, the present invention may be configured such that the in-page text and the in-area text are extracted from the book page image data, or such that the in-page text is extracted from the book page image data while the in-area text is extracted from the area enlargement image data. 
     Furthermore, the present invention may be configured such that when the user preference is extracted by the history obtaining apparatus  22 , the in-page text and the in-area text in the book page image displayed by the electronic book reproducing apparatus  24  and in the enlarged and displayed enlargement target area are obtained from the electronic book producing apparatus  21  and the electronic book reproducing apparatus  24 . 
     Furthermore, the present invention may be configured such that the electronic book reproducing apparatus  24  produces a display history including the in-page text and the in-area text in the displayed book page image and the enlarged and displayed enlargement target area and transmits the display history to the history obtaining apparatus  22 . 
     Furthermore, keywords are extracted from the in-page text and the in-area text when the user preference is extracted by the history obtaining apparatus  22  as described above, according to the present invention. Therefore, the electronic book producing apparatus  21  may produce the electronic book data including page information which does not store keywords (and categories as well) and the area information which does not keywords (and categories as well) in the same manner, and the history obtaining apparatus  22  may store the electronic book data. 
     2-3 Modified Example 3 
     Furthermore, in the aforementioned embodiment, description was made of a case in which the history obtaining apparatus  22  was configured to execute the user authentication processing with the use of the user specifying information and the password. However, the present invention is not limited thereto, and the history obtaining apparatus  22  may execute the user authentication processing with the use of the disc specifying information DI of the book providing disc  28  when the electronic book data is reproduced by the electronic book reproducing apparatus  24  with the use of the book providing disc  28 . 
     2-4 Modified Example 4 
     Furthermore, in the aforementioned embodiment, description was made of a case in which the electronic book providing system according to the present invention was applied to the electronic book providing systems  1  and  20  described above with  FIGS. 1 to 27 . 
     However, the present invention is not limited thereto and can be applied to other electronic book providing systems with various configurations such as an electronic book providing system or the like including a PDA (Personal Digital Assistance), a personal computer, a mobile phone, or a videogames machine, which include the same functions as those of the electronic book reproducing apparatuses  3  and  24 , instead of the stationary type electronic book reproducing apparatuses  3  and  24 . 
     2-5 Modified Example 5 
     Furthermore, in the aforementioned embodiment, the electronic book reproducing program according to the present invention is applied to the electronic book producing program to be provided to the electronic book reproducing apparatus  24  via the book providing disc  28  and the network  23  described above with  FIGS. 1 to 27 . 
     In addition, the description was made of a case in which the control unit  130  of the electronic book reproducing apparatus  24  executed the procedure RT 4  of the electronic book reproducing processing described above with  FIG. 26  based on the electronic book reproducing program and the procedure RT 5  of the display history providing processing described above with  FIG. 27 . 
     However, the present invention is not limited thereto, and the electronic book reproducing apparatus  24  may install the electronic book reproducing program with a semiconductor memory magnetic disk storing the electronic book reproducing program. In addition, the control unit  130  may execute the procedure RT 4  of the electronic book reproducing processing and the procedure RT 5  of the display history providing processing based on the installed electronic book reproducing program. 
     2-6 Modified Example 6 
     Furthermore, in the aforementioned embodiment, the history obtaining program according to the present invention is applied to the history obtaining program stored in advance on the ROM  181  of the history obtaining apparatus  22  described above with  FIGS. 1 to 27 . 
     In addition, the description was made of a case in which the control unit  180  of the history obtaining apparatus  22  executed the procedure RT 6  of the display history obtaining processing described above with  FIG. 27  based on the history obtaining program. However, the present invention is not limited thereto, and the history obtaining apparatus  22  may install the history obtaining program by a computer-readable storage medium storing the history obtaining program. In addition, the control unit  180  may execute the procedure RT 6  of the display history obtaining processing based on the installed history obtaining program. 
     In addition, the history obtaining apparatus  22  may install the history obtaining program from the outside with the use of a wired or wireless communication medium such as a local area network, the Internet, digital satellite broadcasting, or the like. In addition, the computer-readable storage medium to install the history obtaining program in the history obtaining apparatus  22  so as to be in an executable state may be realized by a package medium such as a CD-ROM (Compact Disc-Read Only Memory) or a DVD. Furthermore, such a computer-readable storage medium may be realized not only by a package medium but also by a semiconductor memory, a magnetic disk, or the like on which various programs are temporarily or permanently stored. 
     In addition, as a means for storing the history obtaining program on the computer-readable storage medium, a wired or wireless communication medium such as a local area network, the Internet, digital satellite broadcasting, or the like may be used. Furthermore, the history obtaining program may be stored on the computer-readable storage medium via various communication interfaces such as a router, a modem, and the like. 
     2-7 Modified Example 7 
     Furthermore, in the aforementioned embodiment, the electronic book producing program according to the present invention is applied to the electronic book producing program stored in advance on the ROM  31  of the electronic book producing apparatus  21  described above with  FIGS. 1 to 27 . 
     In addition, the description was made of a case in which the control unit  30  of the electronic book producing apparatus  21  executed the procedure RT 1  of the image data producing processing for the electronic book described above with  FIG. 22  based on the electronic book producing program and the electronic book data producing processing RT 2  described above with  FIGS. 23 and 24 . 
     However, the present invention is not limited thereto, and the electronic book producing apparatus  21  may install the electronic book producing program with a computer-readable storage medium on which the electronic book producing program is stored. In addition, the control unit  30  may execute the procedure RT 1  of the image data producing processing for the electronic book and the electronic book data producing processing RT 2  based on the installed electronic book producing program. 
     In addition, the electronic book producing apparatus  21  may install the electronic book producing program from the outside with the use of a wired or wireless communication medium such as a local area network, the Internet, digital satellite broadcasting, or the like. In addition, the computer-readable storage medium to install the electronic book producing program in the electronic book producing apparatus  21  so as to be in an executable state may be realized by a package medium such as a flexible disk. 
     In addition, the computer-readable storage medium to install the electronic book producing program in the electronic book producing apparatus  21  so as to be in an executable state may be realized by a package medium such as a CD-ROM or a DVD. Furthermore, such a computer-readable storage medium may be realized not only by a package medium but also by a semiconductor memory, a magnetic disk, or the like on which various programs are temporarily or permanently stored. 
     In addition, as a means for storing the history obtaining program on the computer-readable storage medium, a wired or wireless communication medium such as a local area network, the Internet, digital satellite broadcasting, or the like may be used. Furthermore, the history obtaining program may be stored on the computer-readable storage medium via various communication interfaces such as a router, a modem, and the like. 
     2-8 Modified Example 8 
     Furthermore, in the aforementioned embodiment, the description was made of a case in which the reproducing unit  12  and the graphic engine  138  described above with  FIGS. 1 to 27  were applied as the reproducing unit which displayed the book page image on the display unit by performing reproducing processing on the electronic book data, which includes one or a plurality of book page images, in which one or a plurality parts in the book page images were set to enlargement target area which could be individually enlarged and displayed. 
     However, the present invention is not limited thereto, and it is possible to widely apply reproducing units with other various configurations such as a reproducing circuit with a hardware circuit configuration, a microprocessor, DSP (Digital Signal Processor) or the like which displays the book page image on the display unit by performing reproducing processing on the electronic book data, which includes one or a plurality of book page images, in which one or a plurality parts in the book page images are set to enlargement target areas which can be individually enlarged and displayed. 
     2-4 Modified Example 9 
     Furthermore, in the aforementioned embodiment, the description was made of a case in which the display unit  13  and the display apparatus  25  constituted by a television receiver, which were described above with  FIGS. 1 to 27 , were applied as the display unit which displays the book page image. However, the present invention is not limited thereto, and it is possible to widely apply display units with other various configurations such as a liquid crystal display, an organic EL display, and the like. 
     2-10 Modified Example 10 
     Furthermore, in the above embodiment, the description was made of a case in which the operation unit  14  and the remote control  27  described above with  FIGS. 1 to 27  were applied as the operation unit to be used for arbitrarily designating the enlargement target area in the book page image displayed on the display unit. 
     However, the present invention is not limited thereto, and it is possible to widely apply other various operation units such as a mouse, a joy stick, a pointing device such as a touch panel, a keyboard, and the like. 
     2-11 Modified Example 11 
     Furthermore, in the above embodiment, the description was made of a case in which the control unit  15  and the control unit  130  constituted by a CPU, which were described above with  FIGS. 1 to 27 , were applied to the control unit which controls the reproducing unit such that the designated enlargement target area was enlarged and displayed on the display unit when the enlargement target area in the book page image was designated via the operation unit. However, the present invention is not limited thereto, and control units with other various configurations such as a microprocessor, DSP, and the like can be widely applied. 
     2-12 Modified Example 12 
     Furthermore, in the above embodiment, the description was made of a case in which the transmission unit  16  and the network controller  137 , which are described above with  FIGS. 1 to 27 , are applied to the transmission unit which transmits the display history of the electronic book showing the enlargement target areas enlarged and displayed on the display unit. However, the present invention is not limited thereto, and it is possible to widely apply various transmission units in accordance with a wireless or wired communication scheme. 
     2-13 Modified Example 13 
     Furthermore, in the above embodiment, the description was made of a case in which the receiving unit  17  and the network controller  188 , which were described above with  FIGS. 1 to 27 , were applied to the receiving unit which receives the display history when the designated enlargement target area was enlarged and displayed on the display unit in response to the designation of the enlargement target area in the book page image displayed on the display unit by the electronic book reproducing apparatus which displayed a book page image on the display unit by performing reproducing processing on the electronic book data for the electronic book, which includes one or a plurality of book page images, in which one or a plurality of parts in the book page image were set to enlargement target areas which could be individually enlarged and displayed, and when the display history of the electronic book representing the enlarged and displayed enlargement target areas was then transmitted. It is possible to widely apply various receiving units in accordance with a wireless or a wired communication scheme. 
     2-14 Modified Example 14 
     Furthermore, in the above embodiment, the description was made of a case in which the storage unit  10  and the hard disk drive  189 , which were described above with  FIGS. 1 to 27 , were applied to the storage unit which stores the display history received by the receiving unit. However, the present invention is not limited thereto, and it is possible to widely apply storage units with other various configurations such as a semiconductor memory, an optical disc, and the like. 
     2-15 Modified Example 15 
     Furthermore, in the above embodiment, the description was made of a case in which the preference extraction unit  191  described above with  FIGS. 1 to 27  was applied to the preference extraction unit which extracts the user preference based on the enlargement target areas represented by the display history. 
     However, the present invention is not limited thereto, and it is possible to widely apply preference extraction units with other various configurations such as a reference extraction circuit with a hardware circuit configuration, a microprocessor, a DSP, and the like which extract user preference based on the enlargement target areas represented by the display history. 
     2-16 Modified Example 16 
     Furthermore, in the above embodiment, the description was made of a case in which the importing unit  10  and the external interface unit  37 , which were described above with  FIGS. 1 to 27 , were applied to the importing unit which imports the original document data including images for one or a plurality of pages. However, the present invention is not limited thereto, and it is possible to widely apply various importing units in accordance with the communication scheme with the outside. 
     2-17 Modified Example 17 
     Furthermore, in the above embodiment, the description was made of a case in which the producing unit  11  and the control unit  30 , which were described above with  FIGS. 1 to 27 , were applied to the producing unit which produces the electronic book data for the electronic book, which includes one or a plurality of book page images, in which one or a plurality of parts chosen in the book page image were set to enlargement target areas which could be individually enlarged and displayed, based on the original document data imported by the importing unit. 
     However, the present invention is not limited thereto, and it is possible to widely apply producing units with other various configurations such as a producing circuit with a hardware circuit configuration, a microprocessor, a DSP, and the like which produce electronic book data for the electronic book, which includes one or a plurality of book page images, in which one or a plurality of parts chosen in the book page image were set to enlargement target areas which could be individually enlarged and displayed, based on the original document data imported by the importing unit. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be used for an electronic book providing system constituted by an electronic book reproducing apparatus such as a mobile terminal, a personal computer, a mobile phone, or the like, a history obtaining apparatus with a server configuration, and an electronic book producing apparatus such as a personal computer or the like. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 ,  20  ELECTRONIC BOOK PROVIDING SYSTEM 
               2 ,  21  ELECTRONIC BOOK PRODUCING APPARATUS 
               3 ,  24  ELECTRONIC BOOK REPRODUCING APPARATUS 
               4 ,  22  HISTORY OBTAINING APPARATUS 
               10  IMPORTING UNIT 
               11  PRODUCING UNIT 
               12  REPRODUCING UNIT 
               13  DISPLAY UNIT 
               14  OPERATION UNIT 
               15 ,  30 ,  130  CONTROL UNIT 
               16  TRANSMISSION UNIT 
               17  RECEIVING UNIT 
               18  STORAGE UNIT 
               25  DISPLAY APPARATUS 
               27  REMOTE CONTROL 
               28  BOOK PROVIDING DISC 
               37  EXTERNAL INTERFACE UNIT 
               45  TO  48  BOOK PAGE IMAGE 
               65  BOOK INFORMATION 
               85  PAGE INFORMATION 
               92  ENLARGEMENT TARGET AREA 
               100  AREA INFORMATION 
               101  AREA SPECIFYING INFORMATION 
               138  GRAPHIC ENGINE 
               137 ,  188  NETWORK CONTROLLER 
               150  AREA ENLARGEMENT IMAGE 
               189  HARD DISK DRIVE 
               191  PREFERENCE EXTRACTION UNIT 
             D 1 , D 3  ORIGINAL DOCUMENT DATA 
             D 2 , D 4  ELECTRONIC BOOK DATA 
             IH DISPLAY HISTORY 
             P 1  ELECTRONIC BOOK PRODUCING PROGRAM 
             P 2  ELECTRONIC BOOK REPRODUCING PROGRAM 
             RT 1  PROCEDURE OF IMAGE DATA PRODUCING PROCESSING FOR ELECTRONIC BOOK 
             RT 2  PROCEDURE OF ELECTRONIC BOOK DATA PRODUCING PROCESSING 
             RT 3  PROCEDURE OF ELECTRONIC BOOK REGISTRATION PROCESSING 
             RT 4  PROCEDURE OF ELECTRONIC BOOK REPRODUCING PROCESSING 
             RT 5  PROCEDURE OF DISPLAY HISTORY PROVIDING PROCESSING 
             RT 6  PROCEDURE OF DISPLAY HISTORY OBTAINING PROCESSING