Title of Invention: Book data service system with data delivery by broadcasting Abstract: A book data service system in which the book data can be delivered by the broadcasting such that the book data can be delivered to any user located at any place promptly and economically, without causing the waste of the resources. A book data service system if formed by at least one data center including: a data center computer for storing and managing book data; and a broadcasting facility for broadcasting the book data stored and managed by the data center computer according to a prescribed communication protocol using a synchronization control and an error correction scheme suitable for data delivery by broadcasting without confirmation from a receiving side; and a plurality of user terminals, each user terminal including: a receiver for receiving the book data broadcasted from the broadcasting facility of the data center; a user terminal computer for storing and managing the book data received by the receiver; and a display for displaying the book data stored and managed by the user terminal computer. Summary of Invention: BACKGROUND OF THE INVENTION &lsqb;0001&rsqb; 1. Field of the Invention &lsqb;0002&rsqb; The present invention relates to a system for presenting data in an image of a book, and more particularly, to a book data service system in which the book data can be delivered by the broadcasting, only the necessary book data can be selectively stored, the service can be charged according to the accesses to the book data actually made, and the feedback from the user to a data center can be supported. &lsqb;0003&rsqb; 2. Description of the Background Art &lsqb;0004&rsqb; In conjunction with the wide spread of the computers, various schemes for making it easier for a user to utilize the computer have been developed, including the so called Book-Metaphor which is an example of a system generally called electronic book in which the data are presented in an image of a book. The Book-Metaphor is a scheme for displaying the data on a computer in an image imitating a visual appearance of a usual book, in which various operation functions associated with the usual book such as a jumping from the table of contents to a desired page, turning pages one by one, etc. are also supported. The software for this Book-Metaphor comprises book data produced in accordance with the prescribed format, and a program for the display of the book data along with the operation functions of a book. &lsqb;0005&rsqb; An exemplary book data display image in the Book-Metaphor is shown in FIG. 1, which incorporates a number of navigation buttons for selectively activating the operation functions of a book supported in the Book-Metaphor arranged below the image of the book. Here, as summarized in FIG. 2, the navigation buttons include (a) a button for commanding a display of the front cover, (b) a button for commanding a display of the back cover, (c) a button for commanding a display of a next page (one page forward shift), (d) a button for commanding the display of a previous page (one page backward shift), (e) a button for commanding a continuously forward shift, (f) a button for commanding a continuously backward shift, (g) a button for commanding an attaching/removing of a slip, (h) a button for commanding a restoring of an original state before the previous operation (undo), and (i) a button for commanding an end of the use of the Book-Metaphor. it is noted that the types and shapes of the navigation buttons are not necessarily limited to those shown in FIGS. 1 and 2 and described here, but the buttons for shifting one page forward and backward are indispensable. In addition, the Book-Metaphor also incorporates a basic function for displaying a page having a table of contents on which any desired chapter or section can be specified, and displaying a page corresponding to the desired chapter or section specified. &lsqb;0006&rsqb; In the exemplary display shown in FIG. 1, the image of the book incorporates a number of tags attached on a side edge of the book, which are shifted when the pages are shifted, and a number of slips attached on an upper edge of the book which can be attached or removed by the navigation button (g) mentioned above. When any of these tags or slips is specified, the page at which the specified tag or slip is attached is opened immediately. &lsqb;0007&rsqb; Using this Book-Metaphor as described, it becomes possible for a user to read a series of data quickly in a manner similar to that of reading a usual book, in addition to the ordinary manners of utilizing the computer such as the processing of the entered data, the retrieval of a desired data from the database, etc. In particular, as the size and weight of the computer are progressively reduced, it is feasible for this Book-Metaphor to replace the conventional books in future. In addition, in this Book-Metaphor, the manner of data access is so intuitive that practically anyone can understand it immediately, so that it is particularly suitable for a case requiring a continuous access to a series of very large data, in contrast to the conventional data access scheme in which it is necessary to narrow down the range of data to be displayed minutely by interactive operations, which is not necessarily intuitive for anyone. &lsqb;0008&rsqb; Conventionally, the available means for entering the book data in such a Book-Metaphor system included the exchangeable memory medium such as floppy disks, CD-ROMs, and IC memory cards. Namely, the data provider must outputs the produced book data to the exchangeable medium once and then offers the exchangeable medium to the user, while the user must use the book data by displaying the stored book data using a book data display program, either directly from the exchangeable medium or by copying them to a large capacity file memory. &lsqb;0009&rsqb; In such a conventional scheme using the exchangeable medium for entering the book data into the system, the medium storing the book data must be sold just as the books or video tapes are sold today. However, except for a case of buying the widely distributed materials such as magazines, the user still have to suffer from the tedious inconvenience of finding an appropriate bookstore first, and then finding a desired book in the bookstore. Also, the data provider may also suffer from the problems of the excessive returned copies or the shortage of the stock copies unless the sales of the book is properly judged beforehand. Moreover, as a physical medium for carrying the data is required for each copy, there is also a problem concerning the waste of resources. &lsqb;0010&rsqb; As for the management of the electronic books, as the medium storing the data of the electronic book has conventionally been sold at the bookstore in a manner similar to the usual book, a large number of such media must be managed by the user in a manner similar to the usual books. In addition, even when the user terminal is equipped with a large capacity files capable of storing a plurality of electronic books, it has been difficult to manage a number of independently acquired book data efficiently. Thus, in the conventional electronic books, only the manner of data access and display on the computer have been changed, without changing the manner of providing data and managing data. &lsqb;0011&rsqb; Also, when the book data of the electronic book contain the questionnaire or the advertisement for the mail-order, the feedback from the user has been relying on the mail or the telephone just as in a case of the usual books. &lsqb;0012&rsqb; As such, compared with the conventional book in paper, the electronic book has advantages related to the possibility of multi-media expression, the powerful data retrieval operation, and the data storage requiring less storage area, but it is still unable to come even close to the conventional book in terms of the beauty of the visual appearance and the easiness of the visual comprehension. Consequently, in order to expect the full-scale spread of the electronic books, it appears necessary to take more advantages of their electronic nature in the aspects related to the manners of providing data, managing data, and supporting the user feedback. &lsqb;0013&rsqb; On the other hand, there has been a system in which the database can be remotely inspected from a data center interactively, or a system which broadcasts the mainly text data repeatedly in short cycles, such that the user at the user terminal can selectively acquire and display the broadcasted data as if the user has interactively communicated with the data center. However, it has been impossible to make accesses to a variety of data freely in such a conventional system because of the severe conditions required for the communication cost and the amount of data that can be delivered within one cycle of the broadcast. In particular, it has been impossible in such a conventional data access scheme to make a continuous access to the very lengthy data without minutely specifying the range of the desired data, as required in dealing with the contents of the books. &lsqb;0014&rsqb; As for the method of access to the data stored in the database, the conventionally available methods included a method using the command or the keyword entered by the user, and a method for selecting from a menu. However, in the method using the user's command input, there is a need for the user to remember the special command, whereas in the method using the user's keyword input, there is a problem that the user must enter the keyword as registered in the database itself. On the other hand, in the method for selecting from a menu, especially when the database is of a very large scale, the database has a complicated data structure which requires many hierarchical levels in menu such that the selection of a desired data becomes difficult especially when the classification made used in the database differs from the classification made by the user. Moreover, in this method for selecting from a menu, the operation of the system is difficult such that a considerable amount of time is required in acquiring sufficient system operation skills. &lsqb;0015&rsqb; As a solution for these problems, the aforementioned Book-Metaphor is also effective, because in the Book-Metaphor, in addition to the data retrieval based on the index or the list display, it is also possible to realize the data retrieval by browsing through the data content of the database in a manner of turning pages one by one, so that it becomes easier to comprehend the data structure and the operation method from the viewpoint of the data retrieval. In other words, it becomes possible to make a necessary access to the data even without knowing the specific keyword for each data. &lsqb;0016&rsqb; Now, in conjunction with the development of the communication technology, the utilization of the database data through the communication network has become fairly common, and it is expected that the utilization of the database data is going to play even more important role in our society in future. As the data plays increasingly more important role, there arises a problem concerning the security of the data. Also, there is a need for a system which provides the data only to the selected users having specific rights assigned, in which the users making access to the data must be charged for the use of the database data. Conventionally, the charging for the utilization of the database data has been realized by carrying out the charging processing on the host computer side at a time of transmitting the data content of the requested data from the database. &lsqb;0017&rsqb; Moreover, as a method for protecting the security of the data, several digital enciphering methods have been developed, and a conventional scheme for protecting the security of the data has been the uniform enciphering of all the data to be transmitted to the user side according a certain enciphering algorithm. However, in such a conventional scheme, because no clue for recognizing the data contents has been provided, in a case of the retrieval and display of the book data, there arises the problem that the selection of the necessary data cannot be made. For this reason, there has been a proposition of a scheme for deciphering only a part of the data content so as to provide a clue for the retrieval of the data contents. &lsqb;0018&rsqb; However, when the deciphering of the enciphered data at the user terminal side is allowed freely, there arises the problem that the accurate charging processing for the utilization of the data becomes impossible. Moreover, when the enciphered data are transmitted for the purpose of the data retrieval, the data content to be accessed must be enciphered and transmitted once again at the host computer side after the selection of the desired data was made, so that the security of the data cannot be maintained and the amount of communication can also be increased as it is necessary to transmit the same data content twice. &lsqb;0019&rsqb; Also, in a case of measuring the utilization state of the data delivered by the broadcasting, the conventionally employed method has been that in which a recording device given to a specific data user in advance is connected to a receiver device and the utilization state of this specific user is recorded. However, the data user can utilize the broadcasting even when the recording device is disconnected from the receiver device so that there is a possibility for the specific data user to disconnect the recording device, and therefore it has been impossible to make the accurate measurement of the utilization states of all the data users. &lsqb;0020&rsqb; Also, in a case of utilizing the enciphered data delivered by the broadcasting, as the data cannot be utilized unless the data are deciphered, it has been necessary for the data user to connect a decoder for deciphering the enciphered data to the receiver device. However, conventionally, the decoder without the measurement function has been used for this purpose, so that at a time of charging the fee for utilization of the data to the data user, a particular data utilization fee independent of the amount of data utilization has been charged. From a point of view of the user, this implies that the same fee is charged even when the amount of data utilization is small so that the user may very well consider it as unfair, and this has been a reason for may potential users to refrain from subscribing to the use of the data delivered by the broadcasting. &lsqb;0021&rsqb; On the other hand, conventionally, there has been a discussion of a data communication system for carrying out exchanges of the book data among a plurality of systems connected through a network, so as to make it possible for a variety of people to obtain various book data easily. In addition, there has also been a discussion of a manner of displaying the obtained book data to be as easily readable as possible. &lsqb;0022&rsqb; However, as a huge number of data become obtainable by such a data communication system, it rather becomes difficult for each user to smoothly select and store the data which are actually required according to each user's need. &lsqb;0023&rsqb; Now, the usual book in paper often contains a questionnaire, a quiz, or a solicitation for the reader's opinions or impressions, which requires the feedback from the user, and in such a case, the feedback from the reader to the publisher is normally made via mail or facsimile. &lsqb;0024&rsqb; However, in a case of making the feedback to the publisher via mail or facsimile, the reader is required to carry out a work of mailing or facsimile transmitting, which has a qualitatively quite different nature from that of the work of reading, so that it can interrupt the flow of the reading work. Also, because of the reluctance to take a trouble of carrying out the work of qualitatively quite different nature on the user side, the sufficient amount of feedbacks cannot be collected from the users in many cases. From the point of view of the publisher, in a case of computer processing the information obtained from the user feedback, it requires a considerable time and labor to read the contents of the mail or facsimile and entering necessary information into a computer, and it in turn requires a considerable cost and time for this human labor. &lsqb;0025&rsqb; On the other hand, there is a book in a form of a catalogue according to which the user can make an order for items or a reservation for an event. From the point of view of the publisher of this catalogue, there is a work of receiving the orders from the readers, and for the automation of such a work, there has been an order receiving system or a reservation accepting system in which the order data or the reservation data produced by an order slip production tool provided on a personal computer can be transmitted via a personal computer communication network to a center for receiving orders. Also, in the so called videotex, there is provided an order entry system in which the order data, reservation data, or answer data for questionnaire can be entered in a manner of interactive dialogue with the center. &lsqb;0026&rsqb; FIG. 3A shows an example of an order receiving system using a personal computer, which comprises a host computer 1 equipped with a host terminal 2 located at a data center, which is connected with a user terminal provided by a personal computer 3 through a communication network 4. Here, the communication network 4 can be a transparent network such as the telephone network or ISDN, or a value added network. In a case of the value added network, it can either be a network in which the end-to-end dialogue is supported by the protocol conversion that can be carried out in real time at the network, or a network in which the data transmission and reception can be executed for the users by the network which has long time storage function. &lsqb;0027&rsqb; FIG. 3B shows an operation sequence in a case of using either a transparent network or a value added network supporting the dialogue type communication. From the point of view of the dialogue between the terminals, there is no difference among these networks. In the operation sequence of FIG. 3B, in a case the user makes an order, the ordering software is activated at the user terminal personal computer 3, and the order slip is produced by the dialogue between the user and the personal computer 3. Then, the communication software is activated from the ordering software, and the communication path is set up with respect to the host computer 1 through the communication network 4. Here, the host computer 1 is in a state of waiting for communication all the times, and the communication path is set up in response to the call from the user terminal. When the communication path is set up, the order slip data are transmitted collectively, and the host computer 1 which receives the order slip data then carries out the admission processing while returning the admission notice to the user terminal. When there are other order slip data to be transmitted, the user terminal repeats the similar operations for the other order slip data. After the admission notices for all the order slip data are received, the communication path is leased and the communication software and the ordering software are terminated. &lsqb;0028&rsqb; In this operation sequence, the contents of the admission processing and the admission notice depend on the required conditions of the system. For instance, it is possible to have a case of immediately making an inventory check and a notification, a case of making an inventory check later on and a notification is made later on by the transmission from the data center side, or a case in which the notification based on the inventory check is omitted as the stock is large enough to eliminate any possibility for the shortage of the stock. In a case of involving the lot drawing as in a case of the ticket reservation, the winners are going to be notified afterwards. &lsqb;0029&rsqb; FIG. 4A shows an example of the order entry system in the videotex, in which the videotex terminal 5 replaces the personal computer 4 in FIG. 3A as the user terminal. The similar remarks as mentioned above for the network 4 in FIG. 3A also apply in this case. In the videotex of FIG. 4A, unlike the order receiving system of FIG. 3A, all the screen displays at the videotex terminal 5 are transmitted from the data center in response to the requests made from the videotex terminal 5. Therefore, the production of the order slip is also carried out by the dialogue with the data center. &lsqb;0030&rsqb; FIG. 4B shows an operation sequence in this videotex of FIG. 4A, in which the videotex terminal 5 is activated first, and then the communication path is set up with respect to the host computer 1. In response, the initial display is transmitted from the host computer 1, and then using the ordering display transmitted from the host computer 1 in response to the ordering display retrieval request, the order data are entered and the accordingly updated ordering display is transmitted from the host computer 1. Then, the host computer 1 which receives the order data then carries out the admission processing while transmitting the admission notice. After the admission notice is received, the communication path is leased and the videotex terminal 5 is terminated. &lsqb;0031&rsqb; By comparing these cases of FIG. 3B and FIG. 4B, the ordering software is required on the user terminal side in a case of FIG. 3B, but the appropriate ordering software may be different according to the conditions of the data center side for receiving the orders, so that the burden on the user can be heavy in a case of dealing with many order receivers. In addition, there is a need to modify the software at the user terminal side in a case of changing the ordering item or the ordering number. In contrast, in a case of FIG. 4B, the function required on the user terminal side is a simple screen display alone, so that the number of order receivers is of no concern as long as a standard protocol is used. &lsqb;0032&rsqb; However, in this case, the communication path is maintained even during the production of the order slip, so that when the use of the communication network 4 costs the communication fee, the fee can be higher. Moreover, in a case of using the packet communication network, it can be inconvenient to have such a large amount of data transmission from the data center. SUMMARY OF THE INVENTION &lsqb;0033&rsqb; It is therefore an object of the present invention to provide a book data service system in which the book data can be delivered by the broadcasting and managed by a centralized management, only the necessary book data can be selectively stored at each user terminal, the service can be charged according to the accesses to the book data actually made, and the feedback from the user to a data center can be made by simply entering the feedback content into the displayed book data. &lsqb;0034&rsqb; More specifically, it is an object of the present invention to provide a book data service system in which the book data can be delivered to any user located at any place promptly and economically, without causing the waste of the resources. &lsqb;0035&rsqb; It is another object of the present invention to provide a book data service system in which the accurate charging for the use of the book data can be made without requiring the transmission of the same data content twice. &lsqb;0036&rsqb; It is another object of the present invention to provide a book data service system capable of measuring the amount of utilization of the data delivered by the broadcasting by each user. &lsqb;0037&rsqb; It is another object of the present invention to provide a book data service system in which the user is allowed to make a selection of a desired data efficiently according to the advertisement for the book data, so as to improve the easiness in handling of the system using the data delivery by the broadcasting. &lsqb;0038&rsqb; It is another object of the present invention to provide a book data service system in which the feedback to the data center side can be made without interrupting the book data reading operation of the user, the computer input operation for the collected feedback content is unnecessary at the data center side, and the flexible data input from the user terminal to the data center can be realized by requiring only a low communication cost to each user. &lsqb;0039&rsqb; According to one aspect of the present invention there is provided a book data service system, comprising: at least one data center including: data center computer for storing and managing book data; and broadcasting means for broadcasting the book data stored and managed by the data center computer according to a prescribed communication protocol using a synchronization control and an error correction scheme suitable for data delivery by broadcasting without confirmation from a receiving side; and a plurality of user terminals, each user terminal including: receiver means for receiving the book data broadcasted from the broadcasting means of the data center; user terminal computer for storing and managing the book data received by the receiver means; and display means for displaying the book data stored and managed by the user terminal computer. &lsqb;0040&rsqb; According to another aspect of the present invention there is provided a method for providing a book data service, comprising the steps of: storing and managing book data on a data center side by a data center computer of a data center; broadcasting the book data stored and managed by the data center computer according to a prescribed communication protocol using a synchronization control and an error correction scheme suitable for data delivery by broadcasting without confirmation from a receiving side; receiving the book data broadcasted from the data center at each user terminal; storing and managing the book data on a user terminal side by a user terminal computer of the user terminal; and displaying the book data stored and managed by the user terminal computer on a display in an image of a book. Detailed Description: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS &lsqb;0095&rsqb; First, the main features of the book data service system according to the present invention will be summarized briefly. &lsqb;0096&rsqb; In the book data service system according to the present invention, the book data are presented in an image of a book, and delivered to each user terminal by the broadcasting. Here, the user terminal is permanently equipped with means for managing the book data and means for displaying the book data which are common to all the user terminals, and only the book data produced according to the prescribed rules are delivered. In this manner, it becomes possible to reduce the amount of data to be delivered, while the display mode and the operation scheme are standardized from the point of view of a user such that the handling of the system becomes easier for the user. &lsqb;0097&rsqb; Of course, the degrees of freedom for the manner of expression and the manner of operation depending on the type of the book should be retained, but the identical display and operations are to be used for the same purpose. For example, it is normally preferable to use the expression in an image of a double sided book as shown in FIG. 1, but the expression in an image of a single sided book may also be required in a case involving many wide figures and tables. These different types of expressions are to be controlled by the same program for the same operations to realize the functions such as the page turning and the index search. &lsqb;0098&rsqb; Also, all the books including those which utilize only the basic function of still image display, as well as those which contains the speeches or dynamic images are handled by the same program, with the only difference concerning whether or not to provide call up buttons for the speeches or dynamic images on the book data display, such that the functions common to various books such as the page turning and the index search can be realized by the same operations. In addition, the management data format and menu configuration for enabling the search and selection of the book data are set to be uniform. &lsqb;0099&rsqb; The protocol for the book data broadcasting is that which is capable of automatic pull in at the terminal side and using the error correction codes, as it is impossible to make a response or a re-transmission request from the terminal side. Also, in order to explicitly indicate the start and end of each book data, identifiers for indicating the top, middle, and bottom of the book data are provided at prescribed positions among the synchronization codes. In addition, the book codes or field codes, the book title, the author name, the publisher name, etc. which are necessary for the management of the book data are also provided at prescribed positions in the book data. &lsqb;0100&rsqb; As the goal of the present invention is to make a large amount of book data freely accessible to the user, the book data broadcasting from the data center is not repeated in short period of time, and the re-broadcasting is limited to those which are absolutely necessary as the measure against the uncorrectable burst errors, and those of the popular book data after some period of time since the initial broadcasting, while the terminal is equipped with a large capacity file memory such that a large number of book data can be stored and managed. Here, it is preferable to make at least one re-broadcasting of each book data, but any further re-broadcasting is to be carried out according to the aerial state at a time of the broadcasting or a number of requests from the users. &lsqb;0101&rsqb; In conjunction with the deliver the book data by the broadcasting, the following two problems arise. One is a problem of how to charge the user, which is relevant in a case of providing the book data in exchange to the fee. The other is a problem that the shortage of the file memory capacity can be caused easily if all the broadcasted book data are to be stored, as an enormous amount of book data are to be delivered day and night. &lsqb;0102&rsqb; As a solution to the problem of charging, it is possible to consider the scheme for charging a uniform fee per month from all the subscribers regardless of the amount of accesses actually made, but the charging according to the amount of accesses actually made is more reasonable for the users as well as more rewarding for the author. As a scheme for charging an access to the book data delivered by the broadcasting, there is a scheme in which the book data are enciphered and a deciphering key request is transmitted automatically from the terminal to the data center whenever the user calls up the book data in response to which the deciphering key is returned while charging the fee, and a scheme in which the record of the deciphering operations carried out is inspected by the regular inspection by an inspection worker or the remote inspection from the data center. Here, in a case of providing means for communicating feedbacks from the users to the data center as will be described below, the end-to-end communication through a public communication network between each terminal and the data center is necessary, and such communication means can also be utilized for the supply of the deciphering key or the remote inspection described above, so that the investment required for the purpose of the charging can be reduced. &lsqb;0103&rsqb; As the solution to the problem of the book data amount, there is a scheme for selectively storing only those book data whose storing has been reserved by the user in accordance with the broadcast schedule delivered in advance. Here, unlike the reservation by specifying time as in the conventional VTR recording reservation, the reservation is to be made by specifying a book code assigned to each book data such that those book data having the book codes coinciding with reserved book codes are stored. &lsqb;0104&rsqb; This reservation scheme is adopted because the reservation by time is less reliable in view of its accuracy as the book data of a normal size can be broadcasted in a very short period of time when one TV broadcasting channel is exclusively used for the transmission of the book data for example, and because the book code is necessary even when the reservation by time is adopted as it is necessary to store the book data with some margins before and after the significant portion and take out the significant portion from the stored data afterwards. &lsqb;0105&rsqb; In addition, the reservation by the book code has an advantage in that it is possible to deal with the change of the broadcasting time due to the aerial state or the convenience of the data center. It is also useful in preventing the redundant storage of the already stored book data in a case of the re-broadcasting. Of course, it is also possible to limit the reception time range along with the reservation by the book code from a point of view of saving the power. It is to be noted here that there is no need for the user to be conscious about the book code itself, and the reservation by the book code is made automatically as the user specifies the desired books on the broadcast schedule delivered to the user. &lsqb;0106&rsqb; Furthermore, the book data service system according to the present invention also provides means for communicating feedbacks from the user terminal to the data center. More specifically, the user entry spaces or the choice indicating columns are provided in the book data, and the data entered or selected by the user at these user entry spaces or the choice indicating columns are automatically edited in the prescribed format and transmitted to the data center as soon as the data transmission is specified by the user after the entry or the selection of the data. Here, more than one data centers may be involved, so that the subscribed network type or number of the data center to which the feedback is to be transmitted is registered in the book data by the prescribed format, and the connection of the data center and the user terminal is automatically made according to the registered information. In response to the feedback received, the data center at least returns the receipt notice immediately, such that the receipt result can be displayed at the user terminal side. In a case of returning the result of the processing at the data center, it is returned along with the receipt notice immediately if possible, or it is returned separately by the call initiated by the data center as in a case of the ticket reservation involving the drawing in which it is impossible to return it immediately. &lsqb;0107&rsqb; Among these features of the book data service system according to the present invention, the book data delivery using the broadcasting is a feature common to all the embodiments described below, while the features concerning the charging, the storing reservation, and the feedback communication are mutually compatible with each other, so that it is possible to construct the system incorporating all of these features simultaneously. &lsqb;0108&rsqb; Now, the first embodiment of the book data service system according to the present invention will be described in detail. &lsqb;0109&rsqb; In this first embodiment, the book data service system has a system configuration as shown in FIG. 5, which comprises: a data center 50 equipped with a computer 51 containing a book data storage unit 52 for storing the book data and a book data broadcast management unit 53 for managing the mroadcasting of the book data, and a broadcasting facility 54 for executing the broadcasting of the book data; and a plurality of user terminals 55, each containing a computer 56 for manipulating the book data and a broadcast recevier 57 for receiving the broadcast from the data center 50. Here, it is also possible to provide more than one data centers 50 in which case the broadcast receiver 57 of the user terminal 55 is required to have a function for selecting the frequency or other characteristic of the broadcasting radio waves from each data center 50. Also, the broadcasting is not necessarily limited to the radio broadcasting, and can be a wire broadcasting in a manner of the cable TV. &lsqb;0110&rsqb; The user terminal 55 has a detailed configuration as shown in FIG. 6, where the broadcast receiver 57 includes a channel selection and demodulation circuit 67 connected with an antenna or a CATV connector for removing a broadcasting carrier from the received signals to obtain demodulated signals, a data signal separation circuit 68 for separating the error correction encoded data from the demodulated signals, and an error correction circuit 69 for applying an error correction to the error correction encoded data to obtain the error corrected data representing the received book data. On the other hand, the computer 56 includes a book data storage unit 61, a book data management unit 62, and a book data display unit 63, while the computer 56 is also equipped with peripheral devices such as a large capacity file memory 64, an operation input unit 65, and a display unit 66, which are utilized in storing and displaying the book data. &lsqb;0111&rsqb; Here, the large capacity file memory 64 is usually realized by a hard disk device, but it can be realized by the other memory device as long as sufficient memory capacity and memory access performance can be provided. The operation input unit 65 usually incorporates a keyboard and a mouse, but it may also incorporate the other input device such as a pen input device, or a touch panel display to be provided integrally with the display unit 66. It is also noted that these peripheral devices can be provided within the main body of the computer 56 if desired. &lsqb;0112&rsqb; This system shown in FIG. 5 and FIG. 6 operates as follows. First, the data delivery from the data center 50 is achieved by supplying the book data stored in the book data storage unit 52 of the computer 51 to the broadcasting facility 54 in accordance with the broadcast schedule registered in advance in the book data broadcast management unit 53, and then sequentially broadcasting the supplied book data from the broadcasting facility 54. At this point, the broadcasted signals are those in which the digital data are divided into appropriate sizes, the error correction codes and the synchronization codes are added, and then superposed onto the broadcast carrier, as in a case of the multi-channel character broadcasting. &lsqb;0113&rsqb; At the user terminal 55, the broadcasted signals are received by the broadcast receiver 57, and the error corrected data are supplied to the computer 56 as described above. In the computer 56, the main body of the book data is taken out from the received data by separating the management data, and stored into the large capacity file memory 64 by the book data storage unit 61, while at the same time, the management data such as the book title, author name, field name, etc. are taken out and and supplied to the book data management unit 62 along with a file name of the stored book data, in response to which the book data management unit 62 updates the book management data. The book management data are also stored in the large capacity file memory 64. &lsqb;0114&rsqb; The presentation of the stored book data is made in such a manner that, in response to an access to the book data management unit 62 made by the user by using the operation input unit 65, the book data management unit 62 reads out the book management data from the large capacity file memory 64, and then produces and displays the book menu on the display unit 66. In this display of the book menu, the selection of the book data can be made easier by narrowing the books listed on the menu by specifying the author name, the field of the book, etc. as the key data. Then, as the desired book is selected by the user on the book menu, the book data management unit 62 supplies the file name of the selected book data to the book data display unit 63, and the book data display unit 63 reads out the corresponding book data from the large capacity file memory 64 and displays the front cover of the read out book data on the display unit 66. Thereafter, the display of the book data in accordance with the usual operations and display functions of the Book-Metaphor is going to be carried out. &lsqb;0115&rsqb; Here, the broadcasting facility 54 of the data center 50 broadcasts the book data according to the prescribed communication protocol suitable for the data delivery by the broadcasting, in which the synchroinization control and the error correction can be made without the confirmation signal from the user terminal 55, by adding the control data and the error correction codes, and appropriately modulating the book data. In correspondence, the broadcast receiver 57 of the user terminal 55 receives the broadcasting signals of the radio broadcasting or the wire broadcasting, and extracts the data to be supplied to the computer 56 according to the prescribed communication protocol. In a case of the radio broadcasting, the communication protocol having a sufficient redundancy level such as that of the multi-channel character broadcasting as mentioned above. &lsqb;0116&rsqb; It is also to be noted that the book data storage unit 52 of the computer 51 may not necessarily be provided in the same building as the broadcasting facility 54, but the book data broadcast management unit 53 should be provided in a vicinity of the broadcasting facility 54, and the book data storage unit 52 and the book data broadcast management unit 53 can be connected either by the communication line or by transportation of the data storing medium. &lsqb;0117&rsqb; FIG. 7 shows an alternative system configuration for this first embodiment, in which the CATV is utilized for the deliver of the book data. In this case, the data center is equipped with a CATV broadcasting facility 71 connected with the broadcast receiver 57 of each user terminal 55 through a CATV cable 72. The rest is similar to the system configuration of FIG. 5. In this case, the communication protocol of the multi-channel character broadcasting is also suitable because of the affinity with the CATV broadcasting mechanism. However, in this case, the reliability of the data transmission is high because of the wire broadcasting, so that the more efficient communication protocol with the lower redundancy level may be used if desired. &lsqb;0118&rsqb; Here, as a communication scheme similar to the wire broadcasting, the off-talk communication utilizing the subscriber lines of the telephone or ISDN may also be used, in which case the book data can be transmitted instead of the usual facsimile data within the communication protocol of the off-talk facsimile communication. Also, by using the digital off-talk communication, it becomes possible to make the data transmission at a higher speed. It is to be noted however that, by using the telephone subscriber lines or the digital subscriber lines of 64 kb/s, the transmission of the book data for one book can take as long as several minutes to several tens of minutes, so that the use of these transmission lines may be limited for the special purposes until the higher speed ISDN becomes widely available. &lsqb;0119&rsqb; The user terminal 55 shown in FIG. 6 can have a more specific configuration as shown in FIG. 8, in which the radio antenna or the CATV wire connector is not explicitly shown. In the broadcast receiver 57, the channel selection and demodulation circuit 67 selects and demodulates the channel such as that of the multi-channel character broadcasting for example, and the data signal separation circuit 68 extracts the significant data. In a case of the multi-channel character broadcasting, the character signals can be separated from the signal waveform of the vertical interval signals. Then, the error correction circuit 69 carries out the error correction using the error correction codes of the received data, and the obtained data are supplied to the computer 56. &lsqb;0120&rsqb; The computer 56 comprises a processor (CPU) 81, a ROM 82 and a RAM 83 for storing programs, etc., a broadcast receiving interface 84 for receiving received data from the broadcast receiver 57, a display controller 85 for controlling the display on the display unit 66, a hard disk (HD) controller 86 for controlling-data input/output of the hard disk device 64A, a floppy disk (FD) controller 87 for controlling data input/output of the floppy disk device 64B, a keyboard interface 88 for controlling input from the keyboard 65A, and a mouse interface 89 for controlling input from the mouse 65B. &lsqb;0121&rsqb; When the book data receiving function of the book data display program for realizing the operation of the book data display unit 63 of FIG. 6 is active on the computer 56, the book code of the received data is checked, and the received data are written into the hard disk device 64A if the received data are new data, while updating the list of the books accordingly. When the book data reception becomes abnormal in a middle, the received data are discarded and the incoming data are ignored until the next new book data arrive. &lsqb;0122&rsqb; Here, the book with a large data amount has a higher chance of encountering the radio obstruction in a middle, so that it is possible to carry out the storing in units of chapters or pages, such that the normally received chapters or pages can be stored even after the book data reception is interrupted in a middle as parts of the incompletely received book, and the missing parts can be supplemented afterwards by the book data reception of the re-broadcasting. In this case, it is necessary to define in advance the data structure in which the storing units such as chapters or pages can be re-arranged on the memory. &lsqb;0123&rsqb; In this case, the book data reception processing at the computer 56 including the data supplementing can be carried out according to the flow chart of FIG. 9 as follows. &lsqb;0124&rsqb; Namely, the book code is received (step S1), and the list of the already received books is searched through (step S2) to judge whether the received book data is the newly received book or not (step S3). In a case of the newly received book, the book data is received and stored (step S4), while judging if there is any missing data or not (step S5). If there is no missing data, the received book data is classified as the completely received book data (step S6), and the book list is updated to add the entry for this book data (step S7). If there is some missing data, the received book data is classified as the incompletely received book data (step S8), and then the re-broadcasting is awaited as an opportunity for supplementing the book data. &lsqb;0125&rsqb; When the received book data is not the newly received book, whether it is the already received book which is classified as the incompletely received or not is judged (step S9). If it is not the incompletely received book data, it implies that it is the already received book, so that the received book data is discarded (step S10). If it is the incompletely received book data, the book data is received and stored (step S11), while judging if there is any missing data or not (step S12). If there is no missing data, the received book data is classified as the completely received book data (step S13), and the book list is updated to add the entry for this book data (step S14). &lsqb;0126&rsqb; If there is some missing data, whether it is possible to supplement the missing data from the already received data or not is judged (step S15). If it is possible, the missing data of the book data is suppledmented by the already received data (step S16), and the received book data is classified as the completely received book
{'app_number': '09944610', 'application_number': None, 'doc_number': '20020034296', 'publication_number': None, 'source_file': './application/2002/pa020321.xml', 'source_data': 'USPTO-Application'}