Patent Publication Number: US-6707784-B2

Title: Optical storage medium having two recording areas of different formats

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a data record medium, a data recording method, a data recording apparatus, an accessing method, and an accessing apparatus applied to for example optical discs. 
     2. Description of the Related Art 
     The standard for compact discs (CD), which are common nowadays, is called compact disc audio (CDDA) and based on standard book (referred to as Red Book). Based on the standard book, various formats have been standardized as so-called CD family. As an extended format of CD, the applicant of the present invention has proposed a data record medium having two record areas. The proposed data record medium has an inner record area (referred to as first area) and an outer record area (referred to as second area). The first area has compatibility with CD. However, the second area does not have it. In the second area, audio data that has been compressed and encrypted is recorded. In addition, the record density of the first area is the same as that of conventional CD (namely, single density). On the other hand, the record density of the second area is twice as high as that of conventional CD (namely, double density). 
     As a method for recording data in double density, the track pitch is narrowed and/or the linear velocity is decreased. In the case of a read-only disc such as CD, a master disc is created by a mastering device. In this case, since the track pitch and/or linear velocity differ in the two record areas, it takes a time to switch those parameters. Thus, it is difficult to successively record data to the two record areas. As a result, a non-record portion (gap) takes place between the two record areas. 
     When there is a non-record portion, a problem of how to record addresses takes place. As one method for solving such a problem, addresses may be successively assigned to the first record area and the second record area. In such a case, when the two record areas are successively accessed through the non-record portion, a problem occurs. In other words, the traveling amount of the pickup that accesses the first record area or the second record area differs from that of the pickup that successively accesses the first record area and second record area in the address change amount (difference). 
     As another method, addresses are zero-reset and assigned to the first record area and the second record area. In this case, the same address is redundantly assigned to the two record areas. Thus, when the first record area and the second record area are successively accessed, a problem takes place. In addition, when the first record area and the second record area are accessed, the traveling amount in the radius direction of the disc is detected by counting the number of tracks that the pickup traverses using a track traverse signal. However, in a non-record portion, since there is no track, when the pickup traverses the non-record portion, the traveling amount in the radius direction cannot be accurately detected. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Therefore, an object of the present invention is to provide a data record medium, a data recording method, a data recording apparatus, an accessing method, and an accessing apparatus that allow a problem of which two areas are not successively accessed due to a non-record portion to be solved. 
     To solve the above-described problem, a first aspect of the present invention is a data record medium having at least two record area and a non-record area formed therebetween, wherein assuming that addresses are assigned to the non-record area, addresses are assigned to the record areas. 
     A second aspect of the present invention is a data recording method for recording data to a record medium having at least two record area and a non-record area formed therebetween, wherein assuming that addresses are assigned to the non-record area, addresses are assigned to the record areas. 
     A third aspect of the present invention is a data recording apparatus for recording data to a record medium having at least two record area and a non-record area formed therebetween, comprising a means for recording data to the record areas so that assuming that addresses are assigned to the non-record area, addresses are assigned to the record areas. 
     A fourth aspect of the present invention is an accessing method for accessing a data record medium having at least two record areas and a non-record area formed therebetween, addresses being successively assigned to the record areas, comprising the steps of converting the length of the non-record area into the variation amount of an address, and accessing a desired position corresponding to the converted address. 
     A fifth aspect of the present invention is an accessing apparatus for accessing a data record medium having at least two record areas and a non-record area formed therebetween, addressed being successively assigned to the record areas, comprising a means for converting the length of the non-record area into the variation amount of an address and generating addresses, and a means for accessing a desired position of the data record medium corresponding to the generated addresses. 
     According to the present invention, even if there is a non-record portion between two record areas, since it is assumed that addresses have been assigned to the non-record portion, the two areas can be successively accessed without problem. 
     These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of a best mode embodiment thereof, as illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are schematic diagrams for explaining disc shaped record mediums according to the present invention; 
     FIG. 2 is a schematic diagram for explaining an example of areas of a disc according to the embodiment of the present invention; 
     FIG. 3 is a schematic diagram for explaining the dimensions of the disc according to the embodiment of the present invention; 
     FIG. 4 is a schematic diagram for explaining a non-record portion formed between two areas; 
     FIG. 5 is a block diagram showing the structure of a mastering device according to the embodiment of the present invention; 
     FIG. 6 is a schematic diagram showing an example of the format of a frame according to the embodiment of the present invention; 
     FIG. 7 is a schematic diagram showing an example of the format of Q channel according to the embodiment of the present invention; 
     FIG. 8 is a schematic diagram showing an example of the format of data bits according to the embodiment of the present invention; 
     FIG. 9 is a schematic diagram showing an example of the format of data bits of TOC according to the embodiment of the present invention; 
     FIGS. 10A,  10 B,  10 C, and  10 D are schematic diagrams showing examples of the format of data of CD-ROM according to the present invention; 
     FIGS. 11A and 11B are schematic diagrams showing two examples of the format of a header portion according to the embodiment of the present invention; 
     FIG. 12 is a flow chart for explaining an address generating process according to the embodiment of the present invention; 
     FIG. 13 is a block diagram showing the structure of a reproducing apparatus according to the embodiment of the present invention; and 
     FIG. 14 is a flow chart for explaining the operation of the reproducing apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Next, an embodiment of the present invention will be described. In FIG. 1A, reference numeral  1  represents a record medium such as a disc according to the present invention. On the disc  1 , a program area thereof is divided into two portions in the radius direction. As a result, a first record area (referred to as first part) PA 1  and a second record area (referred to as second part) PA 2  are formed. The first part PA 1  is formed on the inner periphery side, whereas the second part PA 2  is formed on the outer periphery side. In the first part PA 1 , first content data as non-compressed data for example first audio data is recorded. In the second part PA 2 , second content data as compressed data such as second audio data is recorded. Reference numeral  2  represents an opening portion. When necessary, the second audio data is encrypted data. 
     In FIG. 1B, reference numeral  1 ′ represents another example of a disc according to the present invention. On the disc  1 ′, a program area thereof is divided into three portions in the radius direction. As a result, a first part PA 1 , a second part PA 2 , and a third part PA 3  are formed. In the first part PA 1  and the second part PA 2 , first data and second data as non-compressed data are recorded. In the third part PA 3 , third data as compressed data is recorded. The number of program areas formed in the radius direction is not limited to two and three shown in FIGS. 1A and 1B. In other words, the number of program areas can be freely selected. In addition, the first part, the second part, and so forth may be successively arranged from the outer periphery side rather than the inner periphery side. 
     Next, an embodiment of the present invention will be described in detail. According to the embodiment, two program areas are formed as shown in FIG.  1 A. According to the embodiment, the compatibility with conventional CD is considered. FIG. 2 shows areas of the disc  1 . On the outer periphery of a clamping area formed on the innermost periphery, a lead-in area LI 1  is formed. On the outer periphery side of the lead-in area LI 1 , a first part PA 1  is formed. On the outer periphery side of the first part PA 1 , a lead-out area LO 1  is formed. On the outer periphery side of the lead-out area LO 1 , a lead-in area LI 2  is formed. On the outer periphery side of the lead-in area LI 2 , a lead-out area LO 2  is formed. The areas LI 1 , PA 1 , and LO 1  structure a first session. The areas LI 2 , PA 2 , and LO 2  structure a second session. 
     FIG. 3 shows the dimensions of the disc  1 . The dimensions of the disc  1  are the same as those of CD. In FIG. 3, a dot-dash line represents the center position of the disc  1 . As shown in FIG. 3 as an enlarged partial view of the disc  1 , the thickness of the disc  1  is 1.2 mm. On a polycarbonate substrate  3  having a thickness of 1.2 mm, an aluminum reflection layer  4  (40 to 80 nm), a protection layer  5  (10 to 20 μm), and a label  6  are laminated. On the substrate  3 , pits (concave and convex portions) corresponding to data are formed. By radiating a laser beam to the lower side of the substrate  3 , the presence and absence of the pits are read as the light amount difference of the reflected light. 
     The lead-in area LI 1  is formed from 23 mm to 25 mm in the radius direction starting from the center of the disc. In the case of the conventional CD, a program area is formed on the outer periphery side in the range from the center of the disc to 58 mm in the radius direction. A lead-out area is formed on the outer periphery side of the program area in the range from the center of the disc to 58.5 mm in the radius direction. 
     According to the standard of the conventional CD (referred to as Red Book), the track pitch is 1.6 μm±0.1 μm and the linear velocity as CLV (Constant Linear Velocity) is in the range from 1.2 m/s to 1.4 m/s. When the data format of record data complies with the standard, the minimum bit length on CD depends on the linear velocity. When the linear velocity is 1.25 m/s, the minimum time length (the time length of which the number of zeros between ones of record signal is the minimum) Tmin of the EFM modulating system (eight to fourteen modulation: EFM) is 3T. The bit length for 3T is 0.87 μm. The bit length for T is the minimum bit length. The maximum reproduction time (74.7 minutes) is accomplished in the case that the track pitch is 1.6 μm and the linear velocity is 1.2 m/s. 
     According to the embodiment, a digital audio signal is recorded in the same signal format as the conventional CD to the first part PA 1 . In this case, with the lower limit value (1.5 μm) as an allowable value of the track pitch and the lower limit value (1.2 m/s) as an allowable value of the linear velocity according to the CD standard, the audio data is recorded. As a result, in the range from the center of the disc to 56.5 mm in the radius direction (namely, the first part PA 1 ), digital audio data (in the CD format) of the maximum reproduction time (74.7 minutes) is recorded. On the outer periphery side of the first part PA 1 , the range for 0.5 mm in the radius direction is the lead-out area LO 1 . 
     The lead-in area LI 1 , the first part PA 1 , and the lead-out area LO 1  that are recorded in such a manner satisfy the CD standard. Thus, a conventional CD reproducing apparatus can reproduce audio data recorded in the first part PA 1  without a problem. 
     In the range from the center of the disc to 58 mm in the radius direction, on the outer periphery side of the lead-out area LO 1 , there is an area for 1 mm in the radius direction. In the range for 1 mm, the lead-in area LI 2  and the second part PA 2  are formed. In the range for 0.5 mm, on the outer periphery side of the second part PA 2 , the lead-out area LO 2  is formed. As a result, the length from the center of the disc  1  to the lead-out area LO 2  becomes 58.5 mm. Thus, the disc  1  satisfies the dimensions required in the CD standard. The length in the radius direction from the center of the substrate to the outermost periphery is 60 mm (thus, the diameter thereof is 120 mm). 
     The above-described dimensions (LI 2 +PA 2 =1.0 mm; LO 2 =0.5 mm) are a first dimensional example. As a second dimensional example that satisfies the dimensions of the CD standard, dimensions (LI 2 =0.1 mm; PA 2 =1.1 mm; LO 2 =0.3 mm) are available. As a third dimensional example, dimensions (LI 2 =0.1 mm; PA 2 =3.1 mm; LO 2 =0.3 mm) of which the length in the radius direction from the center of the disc to the lead-out area LO 1  is 54.5 mm (narrowed by 2 mm from 56.5 mm) is also available. 
     In brief, audio data in the same format as 25 conventional CD is recorded to the first part PA 1  (since the audio data is non-compressed data, it is referred to as linear PCM). Compressed audio data in single density or double density is recorded to the second part PA 2 . The single density represents the same record density as the conventional CD (track pitch=1.6 μm±0.1 μm; linear velocity=1.2 m/s to 1.4 m/s), whereas the double density represents the record density twice as high as the single density. Audio data recorded in the second part is data to be copyright-protected. The format of data recorded in the second part PA 2  is for example the CD-ROM format. To accomplish the double density for the second part PA 2 , the track pitch is narrowed and/or the linear velocity is decreased. In reality, by narrowing the track pitch to 1.1 μm and decreasing the linear velocity to around 0.9 m/s, the double density can be accomplished. 
     Next, assuming that the record density of the first part PA 1  is single density and the record density of the second part PA 2  is double density, the data amount that is recorded to the disc  1  will be described. The linear PCM of CD-DA is data sampled at 44.1 kHz and linear-quantized with 16 bits. In stereo, the information amount becomes (2×16×44.1 k≈1.4 Mbps). bps represents bits/second. When the audio data is compressed with a compression rate of {fraction (1/10)} by for example ATRAC3, the information amount becomes 128 kbps. The compression rate of ATRAC used in MD (Mini Disc) is around ⅕. The compression rate of ATRAC3 is higher than that of ATRAC. In the second dimensional example, as with CD-DA, linear PCM for 74.7 minutes can be recoded to the first part PA 1 . ATRAC3 compressed audio data for 74.7 minutes can be recorded to the second part PA 2 . 
     The audio data recorded to the second part PA 2  is not limited to audio data of CD-DA. In other words, besides stereo signals, multi-channel audio data of for example 5.1-channel system can be recorded. In addition, it is not necessary to limit the sampling frequency and the number of quantizing bits to the above-described values. For example, audio data with a sampling frequency of 96 kHz and 24 quantizing bits may be compressed and recorded to the second part. When audio data is compressed corresponding to ATRAC3, the information amount of compressed data becomes 384 kbps. In the second dimensional example (PA 2 =3.1 mm), linear PCM for 68.2 minutes can be recorded to the first part PA 1 , whereas compressed audio data for 68.2 minutes (384 kbps) can be recorded to the second part PA 2 . 
     It is not always necessary to cause the record density of the first part to be different from that of the second part. For example, in the above-described first dimensional example (LI 2 +PA 2 =1.0 mm; LO 2 =0.5 mm), linear PCM for 74.7 minutes is recorded to the first part PA 1 , whereas compressed audio data for 35 minutes (128 kbps) in single density (linear velocity=1.2 m/s; track pitch=1.5 μs) is recorded to the second part PA 2 . 
     In the case of the disc shown in FIG. 3, a lead-out area LO 1  and a lead-in area LI 2  are formed between the first part PA 1  and the second part PA 2 . In reality, due to the structure of a recording apparatus (mastering device) that will be described later, while the record density is switched from one to another, since no data is recorded, a non-record portion as a gap (so-called mirror surface) takes place. 
     On the disc  1  having a plurality of record areas according to the present invention, in addition to the same data as conventional TOC (Table Of Contents) recorded in the lead-in area LI 1  that is initially reproduced upon loaded to the reproducing apparatus, additional information is recorded thereto. The additional information contains an identification that represents a plurality of parts and information of parts. In addition, the additional information contains information that represents whether or not data has been encrypted and information that represents the type of encryption. Moreover, the additional information contains a start address and an end address that represent the start position and end position of the record area of the first part, respectively. 
     According to the embodiment, the addressing system of the first session composed of LI 1 , PA 1 , and LO 1  is different from the addressing system of the second session composed of LI 2 , PA 2 , and LO 2 . However, it should be noted that according to the present invention, it is not always necessary to cause the addressing system of the first session to be different from the addressing system of the second session. As the address notation for the first session, as with the conventional CD, M (minute), S (second), and F (frame) in BCD notation are used. As the address notation for the second session, H (hour), M (minute), S (second), and F (frame) in BCD notation are used. Alternatively, as the address notation for the second session, binary notation may be used. The reason why the addressing system for the second session is different from that for CD is in that data in double density recorded in the second part may cause addresses that exceed the maximum value of the addresses of M (minute), S (second), and F (frame) in BCD notation to take place. 
     Next, with reference to FIG. 5, the recording apparatus for the disc  1  (namely, the mastering device) will be described. In this example, it is assumed that the disc  1  has a first part PA 1  of single density and a second part PA 2  of double density. In FIG. 5, reference numeral  10  represents the overall structure of the mastering device. The mastering device  10  has a laser  11 , an optical modulator  12 , and an optical pickup  13 . The laser  11  is a gas laser (such as Ar ion laser, He—Cd laser, or Kr ion laser) or a semiconductor laser. The optical modulator  12  is an acoustic optical effect type modulator that modulates laser light radiated from the laser  11 . The optical pickup  13  is a recording means that has an objective lens that collects laser light that passes through the optical modulator  12  and radiates the laser light to a photoresist surface of a glass master disc  19  on which a photo-resist as a photosensitive material is coated. 
     The optical modulator  12  modulates laser light radiated from the laser  11  corresponding to a record signal. The mastering device  10  radiates the modulated laser light to the glass master disc  19  so as to create a maser of which data is recorded to each part. In addition, the mastering device  10  has a servo circuit  14  that controls the optical pickup  13  so that the distance between the optical pickup  13  and the glass master disc  19  becomes constant. In addition, the servo circuit  14  controls the rotating and driving operations of a spindle motor  18 . The glass master disc  19  is rotated and driven by the spindle motor  18 . 
     A record signal is supplied from a CD signal generator  20  to the optical modulator  12 . Alternatively, a record signal is supplied from a CD-ROM encoder  23  to the optical modulator  12 . The CD signal generator  20  generates a signal recorded to the first area. The CD-ROM encoder  23  generates a signal recorded to the second area. A linear PCM signal  21  as record data is supplied to the CD signal generator  20  through a switch  15   a . In addition, an address signal is supplied from an address generating portion  22  to the CD signal generator  20  through a switch  15   b . A compressed audio signal  24  as record data is supplied to the CD-ROM encoder  23  through a switch  15   c . In addition, an address signal is supplied from the address generating portion  22  to the CD-ROM encoder  23  through a switch  15   d.    
     The switches  15   a  to  15   d  compose a selector  15 . The selector  15  is controlled with a selection signal supplied from an area selecting circuit  17  that is controlled by a controller  16 . In other words, when data is recorded to the first part PA 1 , lead-in area LI 1 , and lead-out area LO 1 , the switches  15   a  and  15   b  are turned on. When data is recorded to the second part PA 2 , lead-in area LI 2 , and lead-out area LO 2 , the switches  15   c  and  15   d  are turned on. In addition, the area selecting circuit  17  generates a selection signal corresponding to a non-record portion formed between the lead-out area LO 1  and the lead-in area LI 2 . The length of the non-record portion is pre-set. In the non-record portion, all the switches  15   a  to  15   d  are turned off. In the non-record portion, required switching operations for example track pitch and linear velocity are performed. 
     The address generating portion  22  generates addresses for both the two areas. A selection signal is supplied from the area selecting circuit  17  to the address generating portion  22 . As the area is switched, the type of generated addresses is switched. In addition, the controller  16  controls the servo circuit  14  as the-area is switched so as to control the track pitch and the linear velocity of each area. Moreover, the controller  16  controls the overall operations of the mastering device  10 . 
     To switch the record density between the two record areas, it is necessary to control the track pitch and/or linear velocity. For example, at the switching position, the recording operation is temporarily stopped and then the track pitch and/or linear velocity (the rotation of the spindle motor  18 ) is changed. In this case, a non-record area (so-called mirror surface) takes place between the two areas. 
     The CD signal generator  20  converts the linear PCM signal  21  and sub-code (supplied from the address generating portion  22 ) into CD format data. In other words, 16 bits of one sample or one word are divided into a high order eight-bit portion and a low order eight-bit portion. Each of the high order eight-bit portion and the low order eight-bit portion is treated as a symbol. In the unit of a symbol, an error correction encoding process (for adding parity data and so forth for correcting an error corresponding to for example CIRC (Cross Interleave Reed-Solomon Code) and a scrambling process are performed and then modulated corresponding to EFM (Eight to Fourteen Modulation). In addition to TOC data of CD-DA, the address generating portion  22  generates additional information that contains information of the parts as data that is recorded to the lead-in area LI 1 . When necessary, the mastering device  10  also has an encrypting circuit (not shown) that encrypts the additional information. 
     The CD-ROM encoder  23  converts the format of data that is recorded to the second part into the data format of CD-ROM (the data format of CD-ROM will be described later). As an example of the compression-encoding method, AAC (Advanced Audio Coding) of MPEG2 (Moving Picture Experts Group Phase 2), MP3 (MPEG1 Audio Layer III), ATRAC (Adaptive Transform Acoustic Coding), ATRAC3, or the like can be used. ATRAC3 is a modification of ATRAC used in MD and accomplishes a higher compression rate (around {fraction (1/10)}) than ATRAC. 
     The glass master disc  19  recorded by the mastering device  10  is developed and electrically formed. As a result, a metal master is created. With the metal master, a mother disc is created. Thereafter, with the mother disc, a stamper is created. With the stamper, CDs are created by compression molding method, injection molding method, or the like. 
     Next, signals that are recorded to the each part will be described. FIG. 6 shows the data structure of one frame of a CD signal. In CD, with a total of 12 samples (24 symbols) of two channels of digital audio data, parity Q and parity P are generated. Each of parity Q and parity P is composed of four symbols. 33 symbols of which one symbol of sub-code is added to 32 symbols (namely, 264 data bits) are treated as one block. In other words, one frame that has been modulated corresponding to EFM contains a total of 33 symbols that are sub-code of one symbol, data of 24 symbols, Q parity of four symbols, and P parity of four symbols. 
     When the EFM-modulation is performed, each symbol (eight data bits) is converted into 14 channel bits. A connection bit portion of three bits is formed between adjacent 14-channel bit portions. In addition, a frame sync pattern is added at the beginning of each frame. The frame sync pattern is composed of sequences  11 T,  11 T, and  2 T (where T is a period of a channel bit). Since such a pattern does not take place in the EFM modulation rule, a frame sync is detected with such a special pattern. One frame is composed of a total of 588 channel bits. 
     With 98 frames, a sub-code frame is formed. A sub-code frame of which 98 frames are successively arranged in the vertical direction is composed of a frame synchronous portion, a sub-code portion, a data portion, and a parity portion. The frame synchronous portion identifies the beginning of the sub-code frame. A sub-code frame is equivalent to {fraction (1/75)} seconds of reproduction time of conventional CD. 
     Sub-code generated by the address generating portion  22  is recorded to the sub-code portion. The sub-code portion is composed of 98 frames. Two frames at the beginning of the sub-code portion serve for both a synchronous pattern of a sub-code frame and an out-of-rule pattern of EFM. In addition, the individual bits of the sub-code portion form P, Q, R, S, T, U, V, and W channels, respectively. 
     R to W channels are used for a special purpose for a still picture such as Karaoke&#39;s subtitle. P and Q channels are used for the track position controlling operation for the pickup in reproducing digital data recorded on the disc. 
     In the lead-in area of the inner periphery portion of the disc, P channel is used to record a signal whose level is “0”. In the lead-out area of the outer periphery portion of the disc, P channel is used to record a signal whose level changes between “0” and “1” at a predetermined period. In the program area formed between the lead-in area and the lead-out area of the disc, P channel is used to record a signal whose level is “1” between music programs and whose level is “0” in each program. P channel is used to detect the beginning of each music program in reproducing digital audio data recorded on CD. 
     Q channel is used to precisely control the reproducing operation of digital audio data recorded on CD. As shown in FIG. 7, one sub-code frame of Q channel is composed of a synchronous bit portion  51 , a control bit portion  52 , an address bit portion  53 , a data bit portion  54 , and a CRC bit portion  55 . 
     The synchronous bit portion  51  is composed of data of two bits. A part of the above-described synchronous pattern is recorded to the synchronous bit portion  51 . The control bit portion  52  is composed of data of four bits. Data that represents the number of audio channels and identifications for emphasis, digital data, and so forth is recorded to the control bit portion  52 . When the data of four bits of the control bit portion  52  is “0000”, the data represents that 2-channel audio without pre-emphasis. When the data of four bits of the control bit portion  52  is “1000”, the data represents 4-channel audio without pre-emphasis. When the data of four bits of the control bit portion  52  is “0001”, the data represents 2-channel audio with pre-emphasis. When the data of four bits of the control bit portion  52  is “1001”, the data represents 4-channel audio with pre-emphasis. When the data of four bits of the control bit portion  52  is “0100”, the data represents non-audio data track. The address bit portion  53  is composed of data of four bits. A control signal that represents the format and type of data stored in the data bit portion  54  is recorded to the address bit portion  53 . The CRC bit portion  55  is composed of data of 16 bits. Data for detecting an error of cyclic redundancy check code (CRC) is recorded to the CRC bit portion  55 . 
     The data bit portion  54  is composed of data of 72 bits. When the data of four bits of the address bit portion  53  is “0001”, as shown in FIG. 8, the data bit portion  54  is composed of a track number portion (TNO)  61 , an index portion (INDEX)  62 , an elapsed time minute component portion (MIN)  63 , an elapsed time second component portion (SEC)  64 , an elapsed time frame number portion (FRAME)  65 , a zero portion (ZERO)  66 , an absolute time minute component portion (AMIN)  67 , an absolute time second component portion (ASEC)  68 , and an absolute time frame number portion (AFRAME)  69 . Each portion of the data bit portion  54  is composed of data of eight bits. 
     The track number portion (TNO)  61  is represented in two-digit binary coded decimal (BCD) notation. When the track number portion (TNO)  61  is “00”, it represents a lead-in track number of a track from which data reading operation starts. When the track number portion (TNO)  61  is “01” to “99”, it represents a track number corresponding to a music program number, a movement number, or the like. When the track number portion (TNO)  61  is “AA” in hexadecimal notation, it represents a lead-out track number of a track at which the data reading operation stops. 
     The index portion (INDEX)  62  is represented in 2-digit BCD notation. When the index portion (INDEX)  62  is “00”, it represents pause. When the index portion (INDEX)  62  is “01” to “99”, it represents a sub-track number of a music program, a movement, or the like. 
     Each of the elapsed time minute component portion (MIN)  63 , the elapsed time second component portion (SEC)  64 , and the elapsed time frame number portion (FRAME)  65  is represented in 2-digit BCD notation. The elapsed time minute component portion (MIN)  63 , the elapsed time second component portion (SEC)  64 , and the elapsed time frame number portion (FRAME)  65  represent elapsed time (TIME) of each music program or each movement with a total of six digits. Eight bits of the zero portion (ZERO)  66  are all “0s”. 
     Each of the absolute time minute component portion (AMIN)  67 , the absolute time second component portion (ASEC)  68 , and the absolute time frame number portion (AFRAME)  69  is denoted in 2-digit BCD notation. The absolute time minute component portion (AMIN)  67 , the absolute time second component portion (ASEC)  68 , and the absolute time frame number portion (AFRAME)  69  represent the elapsed time (ATIME) starting from the first music program with a total of six digits. 
     As shown in FIG. 9, the data bit portion  54  of TOC (Table Of Contents) of the lead-in area of the disc is composed of a track number portion (TNO)  71 , a point portion (POINT)  72 , an elapsed time minute component portion (MIN)  73 , an elapsed time second component portion (SEC)  74 , an elapsed time frame number portion (FRAME)  75 , a zero portion (ZERO)  76 , an absolute time minute component portion (PMIN)  77 , an absolute time second component portion (PSEC)  78 , and an absolute time frame number portion (PFRAME)  79 . Each of the portions of the data bit portion  54  is composed of data of eight bits. 
     Each of the track number portion (TNO)  71 , the elapsed time minute component portion (MIN)  73 , the elapsed time second component portion (SEC)  74 , and the elapsed time frame number portion (FRAME)  75  is fixed to “00” in hexadecimal notation. As with the abovedescribed zero portion (ZERO)  66 , all the eight bits of the zero portion (ZERO)  76  are “0s”. 
     When the point portion (POINT)  72  is “A0” in hexadecimal notation, the absolute time minute component portion (PMIN)  77  represents the first music program number or the first movement number. When the point portion (POINT)  72  is “A1” in hexadecimal notation, the absolute time minute component portion (PMIN)  77  represents the first music program number or the first movement number. When the point portion (POINT)  72  is “A2” in hexadecimal notation, the absolute time minute component portion (PMIN)  77 , the absolute time second component portion (PSEC)  78 , and the absolute time frame number portion (PFRAME)  79  represent the absolute time (PTIME) at which the lead-out area starts. When the point portion (POINT)  72  is represented in  2 -digit BCD notation, each of the absolute time minute component portion (PMIN)  77 , the absolute time second component portion (PSEC)  78 , and the absolute time frame number portion (PFRAME)  79  represents an address at which each music program or each movement starts as absolute time (PTIME). 
     Thus, although in Q channel, the format in the program area of the disc is slightly different from the format in the lead-in area thereof, time information of 24 bits is recorded to Q channel. 
     Next, CD-ROM data format (referred to as Yellow Book) applied for data recorded to the second part PA 2  will be described. In CD-ROM, 2,352 bytes of data contained in 98 frames of one period of sub-code are used as an access unit. The access unit is also referred to as block or sector. The length of each frame is {fraction (1/75)} seconds that are the same as a sub-code frame. The CD-ROM data format has mode 0, mode 1, mode 2 (form 1), and mode 2 (form 2). As shown in FIG. 10, the CD-ROM data format slightly differs in each mode. 
     The data format of mode 0 is composed of a data portion of 2336 bytes that are all zeros. Mode 0 is used for a dummy block that causes the structure of the lead-in area and the lead-out area of the second part PA 2  to be the same as the structure of CD-ROM. 
     As shown in FIG. 10A, the data format in mode 1 is composed of a sync portion of 12 bytes, a header portion of four bytes, a user data portion of 2048 bytes (2 kbytes), and an auxiliary data portion of 288 bytes. The sync portion contains a signal that identifies a frame. The user data portion contains objective information. The auxiliary data portion contains error detection/correction code. In mode 1, the auxiliary data portion improves the error correction performance. The data format of mode 1 is suitable for recording data with reliability such as character code or computer data. 
     As shown in FIG. 10B, the data format of mode 2 is composed of a sync portion of 12 bytes, a header portion of four bytes, and a user data portion of 2336 bytes. The sync portion contains a signal that identifies a frame. The user data portion contains objective information. In mode 2, an area preceded by the header portion can be used as a user data area although additional error correction code is not used. The data format of mode 2 is suitable for data that can be error-corrected by interpolating process. 
     As shown in FIG. 10C, the data format of mode 2 (form 1) is composed of a sync portion of 12 bytes, a header portion of four bytes, a sub-header portion of eight bytes, a user data portion of 2336 bytes, and an auxiliary data portion of 280 bytes. The sync portion contains a signal that identifies a frame. The user data portion contains objective information. 
     As shown in FIG. 10D, the data format of mode 2 (form 2) is composed of a sync portion of 12 bytes, a header portion of four bytes, a sub-header portion of eight bytes, a user data portion of 2324 bytes, and an EDC (Error Detection Code) portion of four bytes. The sync portion contains a signal that identifies a frame. The user data portion contains objective information. 
     The sub-header portion of each of mode 2 (form 1) and mode 2 (form 2) is composed of a file number, a channel number, a sub mode, coding information, a file number, a channel number, a sub mode, and coding information, each of which is composed of one byte. 
     According to the embodiment of the present invention, data recorded in the second part PA 2  has the CD-ROM format. In this case, as the CD-ROM format, any mode of FIGS. 10A to  10 D can be used. Since audio data is recorded, for example, the format of mode 1 (see FIG. 10A) is used. The data transfer rate of CD-ROM is 150 kbytes/sec. 
     The header portion of the conventional CD-ROM has the structure as shown in FIG. 11A regardless of the mode. In other words, the header portion is composed of an absolute address portion (ADDRESS) and a mode portion (MODE). The absolute address portion (ADDRESS) represents the absolute address of a frame with 24 bits of time information of minute (MIN), second (SEC), and frame number (FRAME). The mode portion (MODE) represents a mode with eight bits. The address structure of the header portion is the same as the address structure of sub-code. 
     The absolute address portion (ADDRESS) is composed of an absolute address minute component portion (MIN), an absolute address second component portion (SEC), and an absolute address frame number component portion (FRAME), each of which is composed of eight bits. The absolute address portion (ADDRESS) is equivalent to (just corresponds to) time information of Q channel of sub-code of the above-described CD-DA. Each of the absolute address minute component portion (MIN), the absolute address second component portion (SEC), and the absolute address frame number component portion (FRAME) is represented in 2-digit BCD notation. 
     On CD-ROM, the above-described sub-code portion (not shown) is additionally formed. An absolute address represented with the above-described “MIN”, “SEC”, and “FRAME” is recorded to Q channel. 
     According to the embodiment, the addressing system (address notation method) for the header of the CD-ROM format of data recorded to the second part is binary notation shown in FIG. 11B rather than BCD notation shown in FIG.  11 A. In binary notation, all of “MIN”, “SEC”, and “FRAME” of the header portion are represented in 24-bit binary notation. When addresses are represented in 24-bit binary notation, since 2 24 =16777216, assuming that the data amount of one frame (one sector) is 2 kbytes, data of up to around 33 Gbytes can be represented. Thus, data can be recorded in high density. When data is recorded to the second part in double density, it is preferred to use the binary notation. 
     In addition, with a predetermined number of bits of 24 bits, address information represented in BCD notation can be distinguished from an address represented in binary notation. For example, the most significant bit of 24 bits can be used to distinguish them. Besides the most significant bit, they can be distinguished using at least one predetermined bit. In addition, due to the fact that the address change state of time information is different from that of binary number, they can be distinguished. By distinguishing the address representations, the disc type can be determined. 
     The time information of Q channel of sub-code of CD-ROM data may be the same as that of the CD format. However, when the time information of sub-code is partly modified, longer time information can be represented than before. In other words, the time information of sub-code contains the zero portion (ZERO)  66  and the zero portion (ZERO)  76  whose bits are all zeros. With the zero portion (ZERO)  66  and the zero portion (ZERO)  76 , the time information can be extended. For example, each of the zero portion (ZERO)  66  and the zero portion (ZERO)  76  is divided into a high order four bit portion and a low order four bit portion and assigned “HOUR” and “AHOUR” thereto. Information of hour (HOUR) is recorded to these portions. Alternatively, all eight bits or the low order four bits of each of the zero portion (ZERO)  66  and the zero portion (ZERO)  76  are used to represent the digit of 100 minutes. In this case, the time information of sub-code can be represented corresponding to high density mode. 
     In addition, according to the embodiment, a non-record portion (in reality, a gap) is accessed assuming that it contains data of the first session (or the second session). Thus, an operation for successively accessing two areas can be smoothly performed. For example, it is assumed that an area from the center to 50 mm in the radius direction is a first session and an area from a gap to 58 mm in the radius direction is a second session. When the gap is 30 μm and the track pitch is 1.5 μm, the gap is equivalent to 20 tracks. In this case, when the linear velocity is 1.2 m/s, the gap is equivalent to an address value of around 5 seconds and 18 frames. Thus, assuming that the gap is assigned addresses, it is necessary to process “+5 seconds and 18 frames” for the gap. When the length in the radius direction of the non-record portion is converted into an address value, it is assumed that the record density is single density or double density. In the above-described example, the gap is equivalent to “393” in binary notation. 
     An example of addresses that have continuity between the first area represented in MSF notation and the second area represented in binary notation will be described. When the end address of the lead-out area LO 1  is “70 minutes, 10 seconds, 25 frames”, the value of the start address of the lead-in area LI 2  becomes “1 hour, 10 minutes, 10 seconds, 26 frames+5 seconds, 18 frames=1 hours, 10 minutes, 15 seconds, 44 frames”. 
     Next, the case that the first area is represented in MSF notation and the second area is represented in binary notation will be described. As with the above-described example, when the end address of the lead-out area LO 1  is “70 minutes, 10 seconds, 25 frames”, the start address of the lead-in area LI 2  is “315,776+393” (frames or sectors). “315,776” is equivalent to “70 minutes, 10 seconds, 26 frames” in MSF notation. 
     However, when there is a non-record portion, the end address of the first area and the start address of the second area may be successive. In this case, when the first area and the second area are successfully accessed through the non-record portion, the CPU of the drive adds a value of which the length of the non-record portion is converted into the number of tracks to the track count value (traverse count). As a simple example, the case that the end address of the first area is 10 minutes, 20 seconds, 0 frame, that the start address of the second area is 10 minutes, 20 seconds, 1 frame, and that the non-record portion is equivalent to 1 minute is considered. In the example, a command for accessing “10 minutes, 20 seconds, 1 frame” is construed as a command for accessing “11 minutes, 20 seconds, 1 frame”. 
     In the recording apparatus shown in FIG. 5, the address generating portion  22  is controlled by the area selecting circuit  17 . The address generating portion  22  generates addresses of the first session (the same addresses as CD). When the record position moves from the first session to the second session through the non-record area, the address generating portion  22  starts generating addresses of the second session from the start address. For example, the address generating portion  22  generates first addresses and second addresses in parallel and selectively outputs the first addresses or second addresses corresponding to the selection signal supplied from the area selecting circuit  17 . 
     FIG. 12 is a flow chart showing an address generating process performed by the address generating portion  22 . First of all, at step S 1 , the address generating portion  22  determines whether or not the area selection signal represents the first session. When the area selection signal represents the first session, the address generating portion  22  generates normal addresses (at step S 2 ). The normal addresses are addresses represented in BCD notation and start with 0 minute, 0 second, 0 frame same as CD. When the determined result at step S 1  represents that the area selection signal does not represent the first session, the flow advances to step S 3 . 
     At step S 3 , the address generating portion  22  calculates the gap length corresponding to the end address of the first session. For example, the address generating portion  22  resets the end address to zero. Until the second session starts, the address generating portion  22  generates addresses as the gap length. At step S 4 , the address generating portion  22  generates the start address of the second session with (end address+gap length). At step S 5 , the address generating portion  22  determines whether or not the second session has ended. Unless the second session ends, the address generating portion  22  continues to generate second addresses. After the second session ends, the address generating portion  22  stops generating addresses. 
     Next, with reference to FIG. 13, a disc reproducing apparatus will be described. The disc reproducing apparatus reproduces data from the disc  1 . The disc  1  is created corresponding to a master recorded by the mastering device  10 . On the disc  1 , linear PCM has been recorded to the first part PA 1  in CD format and compression-encoded audio data has been recorded to the second part PA 2  in CD-ROM format. 
     In FIG. 13, reference numeral  81  represents a spindle motor that rotates and drives the disc  1 . Reference numeral  82  is an optical pickup that reproduces a signal recorded on the disc  1 . The optical pickup  82  comprises a semiconductor laser, an optical system, a detector, and a focus and tracking mechanism. The semiconductor laser radiates laser light to the disc  1 . The optical system is for example an objective lens. The detector receives the reflected light of the disc  1 . The optical pickup  82  is traveled in the radius direction of the disc  1  by a thread mechanism  84 . 
     Output signals of for example a four-divided detector of the optical pickup  82  are supplied to an RF amplifier  83 . The RF amplifier  83  calculates the output signals of the detector members of the four-divided detector and generates a reproduction (RF) signal, a focus error signal, and a tracking error signal. The reproduction signal is supplied to a selector  85 . Lead-in data that is read from the lead-in area LI 1  is supplied to a lead-in data extracting portion  86 . The focus error signal and the tracking error signal are supplied to a servo circuit  87 . The servo circuit  87  controls the rotation of the spindle motor  81  corresponding to a reproduction clock of the RF signal. In addition, the servo circuit  87  controls the focus servo and tracking servo of the optical pickup  82 . 
     The lead-in data extracting portion  86  decodes the lead-in data of the lead-in area LI 1  and supplies the decoded data to a CPU  88 . The CPU  88  has a function as a system controller that controls the overall operations of the reproducing apparatus. In association with the CPU  88 , an operating portion  89  and a displaying portion  90  are disposed. The operating portion  89  has the same operation keys as a conventional CD reproducing apparatus. In addition, the operating portion  89  has a key or the like that designates the reproduction of the first part/second part. The CPU  88  controls the servo circuit  87  so as to control the operation of the reproducing apparatus and the access operation to the disc  1 . In addition, the CPU  88  generates information displayed on the displaying portion  90  corresponding to information of sub-code. 
     The selector  85  is controlled by the CPU  88 . The selector  85  outputs the reproduction data of the first session (LI 1 , PA 1 , and LO 1 ) to an output terminal a. In addition, the selector  85  outputs the reproduction data of the second session (LI 1 , PA 1 , and LO 1 ) to an output terminal b. The selector  85  selects a terminal c for a non-record portion. A first part demodulating portion  91  is connected to the output terminal a. A second part demodulating portion  92  is connected to the output terminal b. 
     The first part demodulating portion  91  performs the same signal process as a reproduction signal process of CD-DA. In other words, the first part demodulating portion  91  EFM-demodulates the reproduction signal, separates sub-code from the demodulated signal, and outputs sub-code. The sub-code is decoded by a decoder. The decoded sub-code (including address information) is supplied to the servo circuit  87  and the CPU  88 . Data that has been EFM-demodulated is supplied to an error correcting portion  97 . The error correcting portion  97  performs an error correction corresponding to CIRC. An output of the error correcting portion  97  is supplied to an D/A (Digital/Analog) converting portion  98 . An analog output of the D/A converting portion  98  is extracted from an output terminal  99 . An error that cannot be corrected by the error correcting portion  97  is interpolated (not shown). 
     The second part demodulating portion  92  performs the same signal process as the first part demodulating portion  91 . Sub-code (including address information) and header information that are output from the second part demodulating portion  92  are supplied to the servo circuit  87  and the CPU  88 . Data that has been EFM-demodulated is supplied to an error correcting portion  101 . A CD-ROM decoder  102  is connected to the error correcting portion  101 . The CDROM decoder  102  performs a disassembling process for the CD-ROM format and extracts data recorded as user data. The extracted data is supplied to a decompressing portion  103 . The decompressing portion  103  decompresses the user data. An output of the decompressing portion  103  is supplied to a D/A converting portion  104 . An analog signal supplied from the D/A converting portion  104  is extracted from an output terminal  105 . 
     When encrypted data is recorded in the second part, an encrypting circuit is disposed on the recording apparatus side and a decrypting circuit is disposed on the reproducing apparatus side. 
     When the disc  1  is loaded, additional information recorded in the lead-in area LI 1  is read to the CPU  88  by the lead-in data extracting portion  86 . The user inputs predetermined data with the operating portion  89 . The CPU  88  generates a signal for controlling the selector  85  with reference to the read information. Thus, data of one of the first part and the second part is selectively reproduced. 
     When the reproducing apparatus reproduces data of the first part PA 1 , the CPU  88  controls the selector  85  so that it selects the output terminal a. When the reproducing apparatus reproduces data from the second part PA 2 , the CPU  88  controls the selector  85  so that it selects the output terminal b. 
     FIG. 14 is a flow chart for explaining an outline of a reproducing operation according to the embodiment. First of all, at step S 11 , the disc  1  is loaded to the reproducing apparatus. Thereafter, at step S 12 , information recorded in the lead-in area LI 1  is read to the memory of the CPU  88 . In other words, both TOC that is the same as a conventional CD and additional information are read to the CPU  88 . In addition, while the disc  1  is loaded to the reproducing apparatus, when the power of the reproducing apparatus is turned on, the flow advances to step S 12 . 
     At step S 13 , it is determined whether or not data of the first part PA 1  is reproduced. For example, when the user operates the operating portion  89 , the reproduction for data of the first part or the second part is designated. When the determined result at step S 13  represents that the reproduction for data of the first part has been designated, the flow advances to step S 14 . At step S 14 , the reproducing operation for data of the first part is performed. The reproducing operation for data of the first part is the same as that of a conventional CD reproducing apparatus. Thus, the detail description will be omitted. At step S 16 , it is determined whether or not the reproducing operation has been completed. When the reproducing operation has not been completed, the flow returns to step S 13 . When the reproducing operation has been completed, the process is completed. 
     When the determined result at step S 13  represents that the reproducing operation for data of the first part has not been designated, the flow advances to step S 15 . At step S 15 , the reproducing operation for data of the second part PA 2  is performed. At step S 16 , it is determined whether or not the reproducing operation for data of the second part has been completed. When the reproducing operation has not been completed, the flow returns to step S 13 . When the reproducing operation has been completed, the process is completed. 
     The CPU  88  controls the access operation in the reproducing mode. As was described above, addresses are assigned assuming that the addresses are recorded in a non-record area. Thus, CPU  88  controls the access operation corresponding to the reproduced address. As a result, the two sections can be successively and smoothly accessed. 
     Since the disc  1  satisfies the CD standard, besides the reproducing apparatus according to the embodiment, the disc  1  can be reproduced by a conventional CD reproducing apparatus. However, in this case, audio data of only the first part PA 1  is reproduced. 
     According to the embodiment, the two parts are applied for the data formats of CD and CD-ROM. However, the present invention is not limited to such an example. In other words, as data formats of the two parts, combinations of single density CD and double density CD, CD and DVD, DVD and DVD-ROM, and so forth are available. 
     In addition, the present invention can be applied to recordable disc-shaped record mediums such as CD-RW, CD-R, DVD-RW, and DVD-R. CD-RW is a phase change type disc of which data is recorded with laser light and data is reproduced by detecting a light amount difference. CD-R is a write once type record medium using an organic coloring matter as a record material. In addition, the present invention can be applied to a disc-shaped record medium having a recordable area and a read-only area. In the case of the recordable disc-shaped record medium, wobbled track guide grooves are formed and addresses as wobbling information are recorded. This system is referred to as ATIP. Alternatively, address areas can be discretely formed on tracks so as to record addresses. According to the present invention, any system can be used. In addition, when the present invention is applied to a data record medium other than a discshaped record medium, the same effect can be achieved. 
     According to the above-described embodiment, although audio contents were mainly explained, the present invention can be applied to contents of video data, still picture data, character data, computer graphic data, game software, and computer programs other than audio. 
     As was described above, according to the present invention, when there is a non-record portion between two record areas, since it is assumed that addresses have been assigned to the non-record portion, the access operation can be smoothly performed. 
     Although the present invention has been shown and described with respect to a best mode embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the present invention.