Abstract:
An information recording disc has a burst cutting area (BCA) for recording control information for a reproducing apparatus be removing a reflective layer of the disc in a striped shape and a data recording area for recording user data. The burst cutting area includes at least one BCA control information area. The BCA control information area has an application identifier area for identifying applications of control data, a data length area for indication data length of the control data, and an application specific data area data area recording the control data. Also, an information reproducing drive reproduces data from the information recording disc.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an information recording disc for recording control information in a burst cutting area (BCA), an information reproducing drive for reproducing information by using an information recording disc for recording information signals including program data, audio information and video information and an information reproducing system including the information reproducing drive. 
   2. Description of the Prior Art 
   Conventionally, a floppy disk, a hard disk, a compact disc read-only memory (CD-ROM), etc. are known as information storage media for storing program data, audio information and video information. Especially, since the CD-ROM is a portable medium having a storage capacity exceeding 600 MB and can be manufactured at low cost, the CD-ROMs have come into wide use for distributing various software. 
   On the other hand, thanks to recent remarkable improvements of performance of personal computers, it has become possible to handle audio and video (AV) data on the personal computers. For example, applications in which digital moving picture data files employing a video compression method called “Moving Picture Experts Group 1” (MPEG1) are recorded in the CD-ROM or the like and are distributed are on the increase. However, the MPEG1 has high compression ratio but suffers from extraordinary deterioration of video. Therefore, these applications are unsuitable for a case requiring high-quality video such as movies. 
   Thus, an advanced video compression method called “Moving Picture Experts Group 2” (MPEG2) and an optical disc having a capacity as large as 5 GB, i.e., a digital versatile disc (DVD) have been developed in recent years. By combining these two technologies, the DVD is capable of recording high-quality digital AV data for not less than two hours and therefore, is fully expected to serve as a next-generation AV data storage medium. Systems for reproducing the DVD are roughly classified into two groups. One of the systems belongs to a field of consumer electronics and is called a DVD player in which a functional block for reproducing compressed AV data from the DVD and a functional block for expanding the compressed AV data are integrated. The other system belongs to a field of computers and is a computer system which includes a DVD drive and an AV decoding card. The DVD drive has a function of reproducing compressed AV data and control data of contents from the DVD, while the AV decoding card has a function of expanding the compressed AV data. These two devices are independent of each other and are installed into a computer. For example, the DVD drive is provided in an expansion bay of the computer, while the AV decoding card is inserted into an expansion slot of the computer. Through control of the computer, the compressed AV data reproduced by the DVD drive is expanded by the AV decoding card on the basis of the control data reproduced by the DVD drive such that AV data is reproduced. A computer system in which a video CD player, a CD-ROM drive and a MEPEG1 decoder board are incorporated is similar to this configuration. 
   However, since the system in the field of consumer electronics and the system in the field of computers can reproduce the same medium, i.e., the DVD, it is, in fact, difficult to copyright protect, etc. International Publication No. WO97/14147 discloses a technique for copyright protecting and a technique for classifying apparatuses according to applications or regions. In this prior art document, by using an information recording medium in which scrambled (or enciphered) data and key information for descrambling are recorded, descrambling circuits are provided in information reproducing apparatuses and mutual authentication for safely exchanging the key information among the information reproducing apparatuses is performed, whereby an aim of copyright protecting is achieved. Meanwhile, descrambling varying according to applications or regions is performed and the information reproducing apparatuses are classified according to kinds of the descrambling circuits of the information reproducing apparatuses into ones in which descrambling is possible and the remainder in which descrambling is not possible. 
   By classifying the information reproducing apparatuses according to regions, ethical problems can be solved. Ethical ideas depend on climates, customs and religions of countries and therefore, vary according to countries. Hence, such a case may happen that contents which offer no ethical problem in one country pose an ethical problem in another country. In such a case, it is necessary to adopt a measure for preventing reproduction of the ethically undesirable contents in the latter country. 
   Hereinafter, a conventional method of classifying information reproducing apparatuses according to regions is described.  FIGS. 6 and 7A  to  7 D show the data structure of a known AV data recording disc  400 . In  FIGS. 6 and 7A  to  7 D, the known AV data recording disc  400  is sectioned into information recording units called “sectors” and is divided into a lead-in area  402  for recording control information referred to by the information reproducing apparatuses, a lead-out area  403  and a data recording area  401  for mainly recording user data. Each sector includes a sector header area in which a data identifier (ID) for identifying the sector, etc. are recorded and a user data area in which control information, user data, etc. are recorded.  FIG. 6  shows the known AV data recording disc  400 , while  FIGS. 7A  to  7 D show the lead-in area  402  of the known AV data recording disc  400 . Namely,  FIG. 7A  shows the lead-in area  402  of the known AV data recording disc  400  of  FIG. 6 ,  FIG. 7B  shows a control data area of the lead-in area  402  of  FIG. 7A ,  FIG. 7C  shows physical format information in the control data area of FIG.  7 B and  FIG. 7D  shows disc region information  405  in the physical format information of FIG.  7 C. 
   This known AV data recording disc  400  is characterized in that a sector storing the disc region information  405  exists in a sector header area of the lead-in area  402 . The lead-in area  402  is constituted by blank areas in which “00h” (h=hexadecimal number) is recorded, a reference signal area in which a reference signal for reproduction is recorded and the control data area in which the control information referred to by the information reproducing apparatuses is recorded. In the control data area of  FIG. 7B , identical information is recorded in 192 control data blocks each constituted by 16 sectors. The physical format information is recorded in the first sector of the control data block. In a user data area of the physical format information, physical information such as disc type information indicative of a read-only disc or a rewritable disc and disc size information indicative of a size of 120 mm or 80 mm of the disc is recorded. 
   On the other hand, in the sector header area of the physical format information, the disc region information  405  is recorded together with the data ID and ID error detection (IED) acting as a code for detecting error in the sector header area. The disc region information  405  is constituted by region n flags (n=integer from 0 to 7) which indicate whether or not reproduction in each of eight divided regions is permitted. When a flag corresponding to a region in which the information reproducing apparatus is installed is set to “1”, it means that reproduction in the region is permitted. In order to perform such reproduction control, the information reproducing apparatus should possess information corresponding to the region for its installation and have a function of stopping reproduction in case this information is not coincident with the disc region information  405 . 
   Meanwhile, peripheral devices in the computer market are common throughout the world and are contrary to DVD players, etc. in the consumer electronics market, for which distribution channels are built up in respective regions due to different power source voltages among the regions or different standards for video signals such as “National Television System Committee” (NTSC) and “Phase Alternation by Line” (PAL). Thus, in cost and distribution, apparatuses whose specifications vary according to regions are disadvantageous for users. On the other hand, if regional information of the apparatuses is rewritable from outside, the regional information can be newly changed to illicit regional information any number of times and thus, reproduction control in each of the regions does not function properly. 
   Therefore, in the DVD drive acting as a conventional peripheral device for computers, a scheme is introduced in which the regional information of the apparatuses can be updated only a limited number of times. In this scheme, the disc region information  405  of the AV data recording disc  400  inserted by the user is basically regarded as corresponding to a region for installation of the information reproducing apparatus so as to be stored, as a regional code of the information reproducing apparatus, in a nonvolatile memory and the regional code of the information reproducing apparatus can be changed only an initial predetermined number of times. 
   Hereinafter, a conventional regional information control method is described with reference to  FIGS. 8 and 9 .  FIG. 8  shows a configuration of a conventional information reproducing system  500 . The conventional information reproducing system  500  includes a host computer  510  and a disc reproducing drive  520  which are connected to each other by a device interface bus  550 . The host computer  510  includes a central processing circuit  511 , a main storage  512 , a processor bus  513 , an external bus  515 , an interface control card  516  for performing protocol control with the disc reproducing drive  520 , a magnetic disk unit  517  and an AV data decoding card  518  for converting compressed digital AV data into analog AV signals. 
   Meanwhile, the disc reproducing drive  520  includes an interface control circuit  521  connected to the host computer  510 , a data read-out means  523  for reading various information from the AV data recording disc  400 , a regional information comparing means  524  for deciding whether or not the disc region information  405  of the AV data recording disc  400  is coincident with installation region information of an installation region information memory  526  of the disc reproducing drive  520 , a reproduction control means  522  for effecting changeover between prohibition and permission of delivery of AV data  540  of the AV data recording disc  400  in accordance with the decision of the regional information comparing means  524 , an installation region information updating means  527  for updating the installation region information memory  526  and a regional information setting counter  525  only a limited number of times and a control bus  528 . 
     FIG. 9  shows sequence in which the conventional information reproducing system  500  reproduces the AV data  540  recorded in the AV data recording disc  400 . In response to a request for data reproduction from a user at step S 600 , reproduction application software stored in the main storage  512  issues a command of reproduction of the AV data  540  to the disc reproducing drive  520  via the interface control card  516  at step S 601 . In response to the reproduction command from the interface control circuit  521 , the reproduction control means  522  advances to the regional information comparing means  524  a request for comparison and decision of the regional information. In response to this request from the reproduction control means  522 , the regional information comparing means  524  issues an instruction of read-out of the disc region information  405  to the data read-out means  523  at step S 602 . By comparing the read disc region information  405  and the installation region information of the installation region information memory  526  with each other in the regional information comparing means  524 , a decision is made at step S 603  as to whether or not the disc region information  405  permits reproduction in a region indicated by the installation region information memory  526 . 
   In the case of “YES” at step S 603 , the reproduction control means  522  issues an instruction of read-out of the AV data  540  to the data read-out means  523  at step S 604 . Through the reproduction control means  522  and the interface control circuit  521 , the AV data  540  is converted into analog AV signals by the AV data decoding card  518  in the host computer  510  so as to be outputted at step S 605 . On the other hand, in the case of “NO” at step S 603 , the host computer  510  requests transfer of the disc region information  405 . In response to the request for transfer of the disc region  405 , the reproduction control means  522  transfers the disc region information  405  from the data read-out means  523  to the host computer  510  at step S 607 . Then, at step S 608 , the host computer  510  issues to the disc reproducing drive  520  a request for update of the installation region information so as to make the installation region information of the installation region information memory  526  coincident with the disc region information  405 . 
   In response to the update request from the host computer  510  via the interface control circuit  521 , the installation region information updating means  527  decides whether or not count of the regional information setting counter  525  is zero at step S 609 . In the case of “YES” at step S 609 , a report of error is issued to the host computer  510  at step S 610  by judging that setting has been already performed the permissible limited number of times. In this case, the AV data  540  on the AV data recording disc  400  is not reproduced. On the other hand, in the case of “NO” at step S 609 , the installation region information updating means  527  updates the installation region information of the installation region information memory  526  to the disc region information  405  at step S 611  and count of the regional information setting counter  525  is decremented by 1 at step S 612 . Subsequently, the program flow returns to step S 601 . At this time, since the installation region information of the installation region information memory  526  is coincident with the disc region information  405 , reproduction of the AV data  540  is performed normally. 
   However, in the conventional regional information setting method referred to above, in a case a where a virus program which continuously issues a request for change of the installation region information of the installation region information memory  526  from the host computer  510 , such a problem may arise that since the installation region information has been updated the limited number of times while being set to the regional information irrelevant to the installation region, it is impossible to change the installation region information of the installation region information memory  526 . In such a case, even if the AV data recording disc  400  conforms to the installation region, the user cannot reproduce the AV data recording disc  400 . 
   In order to solve this problem, it is necessary to provide a recovery means which recovers the installation region information from a state where the installation region information cannot be changed while being set to the regional information irrelevant to the installation region and enables new setting of the installation region information. However, if the recovery means is made available for general users, the installation region information can be changed any number of times, so that the original purpose of performing reproduction control in accordance with the installation region cannot be attained. 
   Consequently, only a limited number of persons such as a manufacturer of the disc reproducing drive or the information reproducing system should be entitled to execute the above mentioned recovery means. Furthermore, instead of a scheme that the recovery means is materialized by only a software program which operates on a host computer and can be copied and distributed easily, it is necessary to adopt a safe scheme including an equipment whose copying is difficult. 
   SUMMARY OF THE INVENTION 
   Accordingly, an essential object of the present invention is to provide, with a view to eliminating the above mentioned drawbacks of the prior art, a safe method of recovering an information reproducing system which cannot be changed while inoperative installation region information is being set in the information reproducing system. 
   In order to accomplish this object of the present invention, an information recording disc according to the present invention has a burst cutting area (BCA) for recording control information for a reproducing apparatus by removing a reflective layer of the disc in a striped shape and a data recording area for recording user data, wherein the burst cutting area includes at least one BCA control information area and the BCA control information area comprises: an application identifier area for identifying applications of control data; a data length area for indicating data length of the control data; and an application specific data area for recording the control data. 
   Meanwhile, an information reproducing drive for reproducing data from a removable information recording medium for recording digital contents having copyright and disc region information indicative of a specific region permitting reproduction of the digital contents, according to the present invention, comprises: an installation region information storage means for storing installation region information for specifying a region in which the information reproducing drive is installed; a regional information setting counter which is updated each time the installation region information storage means is changed by a drive user; a manufacturer initialization counter which is updated each time the regional information setting counter is initialized by a drive manufacturer; a regional comparing means which delivers a regional coincidence signal upon detection through comparison that the disc region information read from the information recording medium is coincident with the installation region information stored in the installation region information storage means; a reproduction control means which reproduces the digital contents from the information recording medium only when the regional comparing means has delivered the regional coincidence signal; an initialization medium decision means for deciding whether or not the loaded information recording medium is a drive manufacturer initialization medium; a regional information updating means which updates, upon receipt of a command of update of the installation region information from the drive user, the installation region information storage means and the regional information setting counter; and a manufacturer initialization means which, upon receipt of a command of drive manufacturer initialization from the drive manufacturer, initializes the regional information setting counter and updates the manufacturer initialization counter only in a case where the initialization medium decision means decides that the loaded information recording medium is the drive manufacturer initialization medium and a count of the manufacturer initialization counter is not an initialization limit value. 
   Furthermore, an information recording method using an information reproducing drive for reproducing data from a removable information recording medium for recording digital contents having copyright and disc region information indicative of a specific region permitting reproduction of the digital contents, according to the present invention, comprises the steps of: storing in an installation region information storage means installation region information for specifying a region in which the information reproducing drive is installed; updating a regional information setting counter each time the installation region information storage means is changed by a drive user; updating a manufacturer initialization counter each time the regional information setting counter is initialized by a drive manufacturer; delivering from a regional comparing means a regional coincidence signal upon detection through comparison that the disc region information read from the information recording medium is coincident with the installation region information stored in the installation region information storage means; reproducing the digital contents from the information recording medium only when the regional comparing means has delivered the regional coincidence signal; deciding whether or not the loaded information recording medium is a drive manufacturer initialization medium; updating, upon receipt of a command of update of the installation region information from the drive user, the installation region information storage means and the regional information setting counter; and initializing the regional information setting counter and updating the manufacturer initialization counter upon receipt of a command of drive manufacturer initialization from the drive manufacturer only in a case where the decision step decides that the loaded information recording medium is the drive manufacturer initialization medium and a count of the manufacturer initialization counter is not an initialization limit value. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This object and features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings in which: 
       FIGS. 1A ,  1 B and  2 A to  2 C are views showing data layout of a manufacturer initialization disc according to one embodiment of the present invention; 
       FIGS. 3A and 3B  are views explanatory of a recording method of a burst cutting area (BCA) of the manufacturer initialization disc of  FIG. 1A ; 
       FIG. 4  is a block diagram showing a configuration of an information reproducing system according to one embodiment of the present invention; 
       FIG. 5  is a flowchart showing a sequence of reinitialization of regional setting information in the information reproducing system of  FIG. 4 ; 
       FIGS. 6 and 7A  to  7 D are views showing data layout of a prior art AV data recording disc; 
       FIG. 8  is a block diagram showing a configuration of a prior art information reproducing system; and 
       FIG. 9  is a flowchart showing sequence of data reproduction of the prior art information reproducing system of FIG.  8 . 
   

   Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, one embodiment of the present invention is described with reference to the drawings.  FIGS. 1A ,  1 B and  2 A to  2 C show data layout of a manufacturer initialization disc  101  of the present invention, which is used for operation for enabling a manufacturer to reset installation region information (hereinafter, referred to as “manufacturer initialization”).  FIG. 1A  shows data layout of the manufacturer initialization disc  101  which is roughly divided sequentially radially outwardly into a burst cutting area (BCA)  102 , a lead-in area  103 , a data recording area  104  and a lead-out area  105 . 
   A construction of the BCA  102  is shown in  FIGS. 3A and 3B .  FIG. 3A  is a disc sectional view explanatory of the principle of the BCA  102 . The manufacturer initialization disc  101  has a construction in which one set of a substrate  711  and a reflective layer  712  are bonded to another set of the substrate  711  and the reflective layer  712  by a bonding layer  713 . By irradiating a high-output laser  710  to the reflective layer  712 , the reflective layer  712  can be removed partially. Therefore, by controlling output of the high-output laser  710 , an arbitrary pattern can be formed in the reflective layer  712 .  FIG. 3B  is a conceptual view explanatory of reproduction of the disc subjected to BCA working. Amplitude of the quantity of reflected light during reproduction is large in a region in which the reflective layer remains but is small in a region in which the reflective layer has been removed. By utilizing this principle, information is recorded in the BCA  102 . 
     FIG. 1B  shows data structure of the BCA  102 . The BCA  102  includes a BCA application identifier area  106 , a BCA version area  107 , a BCA data length area  108  and a BCA application specific (AS) data area  109 . The BCA application identifier area  106  is located at a starting position of the BCA  102 . A unique code indicative of purpose of use of data of the BCA application specific data area  109  is recorded in the BCA application identifier area  106 . In the case of the manufacturer initialization disc  101 , “0001h” (h=hexadecimal number indicative of region setting information is recorded in an application identified. A version of rules followed by the data structure recorded in the BCA application specific data area  109  is recorded in the BCA version area  107 . Data length of the BCA application specific data area  109  is designated by the BCA data length area  108 . A medium identifier code is recorded in the BCA application specific data area  109  of the manufacturer initialization disc  101 . It is to be noted here that the medium identifier code is an intrinsic code allotted to each of the manufacturer initialization discs  101 . 
     FIG. 2A  shows data structure of the lead-in area  103 . The lead-in area  103  includes a reference signal area and a control data area and each of the reference signal area and the control data area is interposed between blank areas in each of which data of “00h” is recorded. A reference signal which an apparatus for reproducing the manufacturer initialization disc  101  refers to as a reference is recorded in the reference signal area. Meanwhile, physical information required for the reproducing apparatus, for example, physical shape and recording density of the manufacturer initialization disc  101  is recorded in the control data area. 
     FIG. 2B  shows data layout of the control data area. The control data area is constituted by  192  control data blocks from a control data block  0  to a control data block  191 . Identical information is recorded in each of the 192 control data blocks. Furthermore, each of the control data blocks is constituted by 16 sectors from a sector  0  to a sector  15 . Physical format information is recorded in the sector  0 , while the remaining sectors  1  to  15  are reserved for future extension and each store data of “00h”. 
     FIG. 2C  shows data structure of the physical format information. The physical format information is recorded in an area of one sector. The sector includes a sector header area of 12 bytes (1 byte=8 bits), a user data area of 2048 bytes and an error detection code (EDC) area of 4 bytes. The sector header area has a configuration similar to that of the prior art shown in FIG.  7 C and thus, records disc region information, etc. On the other hand, error detection codes of the sector header area and the user data area are recorded in the EDC. 
   Information on physical characteristics of the manufacturer initialization disc  101  is recorded in the user data area. The user data area includes a disc type information area, a disc size information area, a read-out rate information area, a disc structure information area, a recording density information area, a data area allocation information area, a BCA existence information area, a BCA application identifier area  110  and a BCA version area  111 . Information for specifying a standard for reference is recorded in the disc type information area. In the case of the manufacturer initialization disc  101 , information indicative of digital versatile disc read-only memory (DVD-ROM) standard is recorded in the disc type information area. Information indicating that the disc has a diameter of 120 mm is recorded in the disc size information area. Data read-out rate of the disc is recorded in the read-out rate information area. Information for discriminating whether or not the disc is a two-layer disc characteristic of the DVD is recorded in the disc structure information area. Information indicative of a single-layer disc is recorded in the disc structure information area of the manufacturer initialization disc  101 . Information on recording data of data is recorded in the recording density information area. Positional information (data identifier (ID)) of a starting sector and a last sector of an area in which data is actually recorded is recorded in the data area allocation information area. Information for discriminating whether or not the disc includes the BCA is recorded in the BCA existence information area. In the manufacturer initialization disc  101 , since a manufacture initialization medium identifier, the medium identifier code, etc. are recorded in the BCA, information indicative of existence of the BCA is recorded in the BCA existence information area. 
   The BCA application identifier area  10  for recording application of data recorded in the BCA  102  is effective for a case in which the BCA existence information indicates that the BCA exists. In the case of the manufacturer initialization disc  101 , the manufacturer initialization medium identifier of “0001h” identical with that of the BCA application identifier area  106  of the BCA  102  is recorded in the BCA application identifier area  110 . Version information of data recorded in the BCA application specific data area  109  of the BCA  102  is recorded in the BCA version area  111 . 
   Then, a configuration of an information reproducing system  200  in which regional information setting is initialized by using the manufacturer initialization disc  101  is described with reference to FIG.  4 . The information reproducing system  200  includes a host computer  210  and a disc reproducing drive  220  which are connected to each other by a device interface bus  250 . The host computer  210  includes a central processing circuit  211  for performing processing in accordance with a software program, a main storage  212  for storing programs and data, a processor bus  213  for connecting the central processing circuit  211  and the main storage  212 , a bus bridge circuit  214  for connecting the processor bus  213  and an external bus  215 , an interface control card  216  for controlling interface protocol with peripheral devices such as the disc reproducing drive  220  in accordance with “Small Computer System Interface” (SCSI) standard, a magnetic disk unit  217  formed by a nonvolatile memory for storing programs and data and an AV data decoding card  218  for decoding and converting compressed digital AV data into analog AV signals, with the above elements  216  to  218  being connected to the external bus  215 . 
   The disc reproducing drive  220  includes an interface control circuit  221  for transmitting to and receiving from the host computer  210  control information and data in accordance with SCSI protocol, an installation region information memory  226  formed by an nonvolatile memory for storing installation region information of the information reproducing system  200 , a regional information setting counter  225  formed by a nonvolatile memory which is decremented by 1 from a maximum permissible updating number each time the installation region information of the installation region information memory  226  is updated, a manufacturer initialization counter  229  formed by a nonvolatile memory which is decremented by 1 from a maximum initialization number each time a manufacturer of the disc reproducing drive  220  or the information reproducing system  200  initializes the regional information setting counter  225 , an initialization medium identifier code memory  230  formed by a nonvolatile memory for storing history information of a reinitialization medium identifier code of a manufacturer initialization disc used during reinitialization of the regional information setting counter  225  performed by the manufacturer, an installation region updating means  227  for updating the installation region information of the installation region information memory  226  in response to a request from the host computer  210 , a manufacturer initialization means  231  for reinitializing the regional information setting counter  225  in response to a request from the host computer  210 , a data read-out means  223  for reading data from a loaded disc (manufacturer initialization disc  101  in FIG.  4 ), a manufacturer initialization medium decision means  232  for deciding whether or not the loaded disc is the manufacturer initialization disc  101 , a regional information comparing means  224  for deciding whether or not the disc region information set in the loaded disc is coincident with the installation region information of the installation region information memory  226 , a reproduction control means  222  which transfers AV data to the host computer  210  through the interface control circuit  221  only when the decision of the regional information comparing means  224  indicates coincidence of the disc region information and the installation region information, and a control bus  228  for transmitting control information among the constituent elements. 
   The manufacturer initialization disc  101  is shown in  FIGS. 1A ,  1 B and  2 A to  2 C. The manufacturer initialization medium identifier is recorded in the BCA application identifier area  110  of the lead-in area  103 , while the manufacturer initialization medium identifier and the medium identifier code are, respectively, recorded in the BCA application identifier area  106  and the BCA application specific data area  109  of the BCA  102 . The device interface bus  250  is an SCSI bus for connection of the peripheral devices. 
   Then, a sequence of initialization of the regional information setting counter  225  of the information reproducing system  200  is described. It is supposed that the regional information setting counter  225  had been originally set to a number enabling update of the installation region information. Thereafter, the regional information setting counter  225  was decremented by 1 each time the installation region information of the installation region information memory  226  was updated. After the installation region information of the installation region information memory  226  was updated an update permissible number of update times, the regional information setting counter  225  is supposed to have a count of 0 at this time. Meanwhile, it is supposed that the manufacturer initialization counter  229  is set to a predetermined permissible number as an initial value and is decremented by 1 each time manufacturer initialization is performed. 
   Meanwhile, manufacturer initialization to be described below is not performed by a user, but is performed by a person who possesses the manufacturer initialization disc  101 . In the actual market, it is supposed that manufacturer initialization is performed at, for example, a service center for maintenance of products, which is operated by a manufacturer of the information reproducing system  200 . Meanwhile, it is assumed that prior to manufacturer initialization, the manufacturer initialization disc  101  has been loaded into the information reproducing system  200 . 
   Hereinafter, a processing sequence of manufacturer initialization of the information reproducing system  200  is described with reference to FIG.  5 . Initially, the host computer  210  issues to the disc reproducing drive  220  via the interface control card  216  a command of manufacturer initialization at step S 301 . This command of manufacturer initialization is received by the interface control circuit  221  of the disc reproducing drive  220  and is delivered to the manufacturer initialization means  231 . The manufacturer initialization means  231  advances to the manufacturer initialization medium decision means  232  a request for deciding whether or not the currently loaded disc is the manufacturer initialization disc  101 . Thus, tie manufacturer initialization medium decision means  232  issues to the data read-out means  223  a request for read-out of the lead-in area  103  and receives information of the lead-in area  103  of the manufacturer installation disc  101  at step S 302 . 
   Subsequently, at step S 303 , the manufacturer initialization medium decision means  232  decides whether or not the manufacturer initialization medium identifier of the read BCA application identifier area  110  is “00011h”. In the case of “NO” at step S 303 , the manufacturer initialization medium decision means  232  informs the manufacturer initialization means  231  of the decision that the manufacturer initialization disc  101  is not loaded into the information reproducing system  200  at this time. Then, the manufacturer initialization means  231  informs, through the interface control circuit  221 , the host computer  210  of the error, thereby resulting in erroneous end of manufacturer initialization. 
   On the other hand, in the case of “YES” at step S 303 , the manufacturer initialization medium decision means  232  requests the data read-out means  223  to read data of the BCA  102 . Thus, at step S 304 , the data read-out means  223  reads the BCA  102  of the manufacturer initialization disc  101  and transfers the read data to the manufacturer initialization medium decision means  232 . Thereafter, at step S 305 , the manufacturer initialization medium decision means  232  decides whether or not the manufacturer initialization medium identifier of the BCA application identifier area  106  of the received data of the BCA is “0001h”. In the case of “NO” at step S 305 , the manufacturer initialization medium decision means  232  informs the manufacturer initialization means  231  of the decision that the manufacturer initialization disc  101  is not loaded into the information reproducing system  200  at this time. Then, the manufacturer initialization means  231  informs, through the interface control circuit  221 , the host computer  210  of the error, thereby resulting in erroneous end of manufacturer initialization. 
   On the other hand, in the case of “YES” at step S 305 , the manufacturer initialization medium decision means  232  sends to the manufacturer initialization means  231  the decision that die loaded disc is the manufacturer initialization disc  101  and the medium identifier code obtained from the BCA application specific data area  109  of the BCA  102 . Upon reception of the decision that the loaded disc is the manufacturer initialization disc  101 , the manufacturer initialization means  231  decides whether or not count of the manufacturer initialization counter  229  is zero at step S 306 . In the case of “YES” at step S 306 , the manufacturer initialization means  231  judges that manufacturer initialization has been already performed a permissible number of times and informs, via the interface control circuit  221 , the host computer  210  of the error, thus resulting in erroneous end of manufacturer initialization. 
   On the other hand, in the case of “NO” at step S 306 , the manufacturer initialization means  231  sets the regional information setting counter  225  to an initial value at step S 307  such that the installation region information can be again set a predetermined number of times. Then, at step S 308 , the manufacturer initialization means  231  decrements the manufacturer initialization counter  229  by 1. Subsequently, at step S 309 , the medium identifier code of the BCA application specific data area  109  of the manufacturer initialization disc  101 , which has been received from the manufacturer initialization medium decision means  232 , is stored as an initialization medium identifier code in the initialization medium identifier code memory  230  by the manufacturer initialization means  231 . After the above described processing has been completed, the manufacturer initialization means  231  informs, through the interface control circuit  221 , the host computer  210  of a normal end. 
   Meanwhile, in this embodiment of the present invention, reproduction of an AV data recording disc is performed in the same manner as the prior art referred to earlier and therefore, the description is abbreviated for the sake of brevity. 
   Meanwhile, in this embodiment of the present invention, the manufacturer initialization counter  229 , the regional information setting counter  225 , the installation region information memory  226  and the initialization medium identifier code memory  230  are provided separately but are formed by nonvolatile memories, respectively. Therefore, it is needless to say that these elements may also be formed by a single nonvolatile memory. 
   Moreover, it goes without saying that each means of the disc reproducing drive  220  may not be formed by hardware but may be obtained by executing a software program by a microprocessor. 
   Thus, description of the embodiment of the present invention has been finished. 
   As will be seen from the foregoing description, the following effects can be achieved in the present invention. Firstly, in the present invention, loading of the disc in which the manufacturer initialization medium identifier is stored in the BCA subjected to special working is essential for reinitialization of regional information setting. Accordingly, it is possible to positively eliminate such a risk that the installation region information is updated any number of times due to propagation of software for reinitialization of regional information setting or the like. 
   Meanwhile, in the present invention, since the manufacturer initialization medium identifier identical with that of the BCA is provided also in the lead-in area, it is possible to prevent such a phenomenon that the information reproducing system malfunctions even if a disc in which a value identical with the manufacturer initialization medium identifier is accidentally recorded in the BCA is placed on the market. Accordingly, safety for preventing a person other than the manufacturer from illegally reinitializing regional information setting is upgraded. 
   Furthermore, in the present invention, the information reproducing system stores in the nonvolatile memory the initialization medium identifier code of the manufacturer initialization disc in use during manufacturer initialization. Accordingly, even if it is revealed that regional information setting has been reinitialized illegally due to propagation of the manufacturer initialization discs to the market in general and users, it is possible to control such illegal reinitialization of regional information setting by performing follow-up survey from the initialization medium identifier code stored in the nonvolatile memory of the information reproducing system. 
   In addition, in the present invention, the manufacturer initialization counter  229  is provided. Accordingly, even if such an incident should happen that manufacturer initialization is performed by general users, the initialization can be restricted to a limited number of times by confirming that count of the manufacturer initialization counter  229  is not zero.