Recording medium, signal recording apparatus thereof, and signal reproducing apparatus thereof

0001The present invention relates to a recording medium such as an optical disc, a signal recording apparatus thereof, and a signal reproducing apparatus thereof.

0002In an optical recording/reproducing system, a modulation system corresponding to optical characteristics is used so as to improve recording density, signal reproducing stability, and so forth. In addition, a data formatting process such as grouping data with a predetermined block is performed so as to prevent a data error due to scratches of a disc or the like from propagating.

0003Fig. 8 shows a sector format of a conventional rewritable optical disc. As shown in Fig. 8, a sector is composed of a header portion and a data portion. In the data portion, real record data (user data) is recorded.

0004In the header portion, an SM (Sector Mark) 1, a VFO 2, an AM (Address Mark) 3, and an address information (ID) 4 have been recorded.

0005The address information (ID) 4 is composed of a track number 9, a sector number 10, and a CRC (Cyclic Redundancy Code) 11.

0006The CRC 11 is a code that is used to detect data errors of track No. 9 and sector No. 10.

0007When data is recorded on an optical disc, a desired sector is detected corresponding to the address information 4 of the header portion, which has been pre-formatted. The data is written to the data portion of the sector.

0008When data is reproduced from the disc, a desired sector is detected corresponding to the address information 4 of the header portion and the data is read from the data portion of the sector.

0009Thus, when data is recorded and reproduced, a desired sector is physically identified corresponding to the address information 4 of the header portion. Consequently, the correct reading of the address information 4 largely affects the reliability of the system. To improve the reliability of the system, the address information 4 is multiply (for example, triply) recorded in the header portion.

0010In recent years, due to the improvement of image compression technologies, optical discs on which digitized images are recorded along with sound have become common. In the system that reproduces data from such optical discs, namely digital video disc system, it is important to record a large amount of image data in a limited area of an optical disc. To do that, the necessity for increasing the recording density has been considered.

0011When a large amount of image data is highly densely recorded in the above-mentioned sector format of the rewritable optical disc, many problems take place. In other words, since the address information 4 is multiply recorded in the header portion in the above-mentioned format, the redundant portion increases, resulting in an obstacle to high density recording. In addition, as the recording density increases, it is predicted that occurrences of data errors increase. However, in such a format, with the address information 4, only an error is detected corresponding to the CRC 11. In other words, in the conventional sector format including the above-described sector format, the high density recording cannot be satisfactorily accomplished.

0012As described above, when the high density recording is performed for a recording medium such as an optical disc, some countermeasures against an error of the address information such as sector number have been required.

0013EP-A-0 420 179 discloses an optical disk comprising sectors, the sectors consisting of a preformat area with addresses and a synchronisation pattern and of a data area with frames comprising resynchronisation patterns. The resynchronisation pattern is not comprise a by the 2-7 modulation rule of the run length code used for the user data. EP-A-0 506 103 shows a sector format for a MO disk comprising a preformat with a sector mark, and addresses and a user data field having resynchronisation signals.

0014The present invention is made to solve the above-described problems. An object of the present invention is to provide a recording medium that allows identification data to be precisely detected and data to be highly densely recorded.

0015Another object of the present invention is to provide a recording apparatus for recording a signal on a recording medium in a sector format that allows the identification data to be precisely detected when data is reproduced.

0016A further object of the present invention is to provide a corresponding reproducing apparatus. The above objects are solved by recording media set out in claims 1 and 7, a recording apparatus set out in claim 2 and reproducing apparatus set out in claims 3 and 8. Thereby the reproducing apparatus serves for reproducing signals from the recording medium.

0017If an error of sector identification data is corrected on the recording medium, when data is reproduced, the detecting accuracy of identification data can be improved and thereby highly dense recording can be accomplished.

0018According to the recording apparatus of the present invention, a signal can be recorded on a recording medium in a sector format where an error of sector identification data may be corrected and the detecting accuracy of the identification data is high when data is reproduced. In addition, the second synchronous pattern may be substituted with a predetermined signal pattern that is present in a signal pattern of user data and that is included in the generating and calculating range of the error correction codes so as to suppress the remainder. Thus, sectors can be composed with a multiple of the period of frames.

0019When necessary, an error of the identification data can be detected corresponding to the error detected data. When an error should be quickly detected as in a search operation, an error of the identification data is detected without need to perform the error correcting process. Thereafter, the identification data may be used for the control process.

0020These and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of best mode embodiments thereof, as illustrated in the accompanying drawings. <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 is a schematic diagram showing a sector format of an optical disc according to an embodiment of the present invention;</li><li>Fig. 2 is a schematic diagram showing the construction of a code conversion table corresponding to 4-9 modulation technique;</li><li>Fig. 3 is a schematic diagram showing binary data of a frame synchronous signal (DCC + SYNC) and a signal pattern in which the binary data has been converted corresponding to NRZI technique;</li><li>Fig. 4 is a schematic diagrams showing binary data of AM (25) and a signal pattern in which the binary data has been converted corresponding to the NRZI technique;</li><li>Fig. 5 is a schematic diagram showing data arrangement in which ECC (error correction code) has been added to user data;</li><li>Fig. 6 is a block diagram showing the construction of a recording apparatus according to the present invention;</li><li>Fig. 7 is a block diagram showing the construction of a reproducing apparatus according to the present invention; and</li><li>Fig. 8 is a schematic diagram showing a sector format of a rewritable optical disc.</li></ul>

0021Next, with reference to the accompanying drawings, embodiments of the present invention will be described.

0022Fig. 1 is a schematic diagram showing a sector format of an optical disc according to an embodiment of the present invention.

0023For the optical disc according to the embodiment, data is encoded corresponding to the 4-9 modulation technique, which is the RLL (Run Length Limited) modulation technique. The 4-9 modulation technique is used to convert 4-bit data into a 9-bit signal pattern. The details of the 4-9 modulation technique are described in for example Japanese Patent Application No. 5-76692.

0024As shown in Fig. 1, one sector is composed of 42 frames. The first frame of the sector is a header portion 21 that is composed of 33 bytes. The rest (41 frames) of the sector other than the first frame is a data portion 22 that is composed of 1353 bytes. One optical disc has a plurality of successive sectors.

0025The header portion 21 is composed of a 2-byte (DCC (23) + SYNC (24)), a 4-byte AM (Address Mark) (25), a 4-byte ID (26), a 2-byte first CRC (27), a 0.5-byte DCC (28), an 8-byte SLD (center Link Data)-1 (29), a 2-byte second CRC (30), a 0.5-byte DCC (31), an 8-byte SLD-2 (32), and a 2-byte third CRC (33). The 2-byte (DCC (23) + SYNC (24)) is a first synchronous pattern. The 4-byte AM (25) is a second synchronous pattern. The 4-byte ID (26) is an address information containing a sector number.

0026The DCCs (23, 28, 31) are cancel codes that are added so as to suppress DC components of signals that have been converted corresponding to the NRZI technique.

0027The SYNC (24) is a synchronous code that is used to generate a timing at which data is extracted, byte by byte, when data is demodulated.

0028The frame synchronous signal, which is composed of the DCC (23) and the SYNC (24), does not correspond to the 4-9 modulation technique. In other words, the frame synchronous signal contains a signal pattern that is not present in the 4-9 modulation code.

0029The AM (25), which is the second synchronous pattern, is data that represents the position of the ID (26) and the delimitation of a sector.

0030The AM (25) is also composed of a signal pattern that is not present in the 4-9 modulation code.

0031The ID (26) is data that represents a sector number, which is address data.

0032The first CRC (27) is an error check code for the ID (26).

0033The SLD-1 (29) and SLD-2 (32) are data that represents data type (for example, image signal, character data, and so forth) of the sectors, subordinate relation of sectors, and so forth.

0034The second CRC (30) is an error check code for the SLD-1 (29).

0035The third CRC (33) is an error check code for the SLD-2 (32).

0036Each (data portion 22) of the second to 42nd frames of the sectors is composed of a 2-byte frame synchronous signal (DCC (41) + SYNC (42)), 10-byte user data (43), a 0.5-byte DCC (44), 10-byte user data (45), a 0.5-byte DCC (46), and 10-byte user data (47).

0037As with the frame synchronous signal of the first frame (header portion 21), the frame synchronous signal (DCC (41) + SYNC (42)) is composed of a signal pattern that is not present in the 4-9 modulation code. The user data (43, 45, 47) contains an ECC (Error Correction Code).

0038Fig. 2 is a schematic diagram showing the construction of a code conversion table for the 4-9 modulation system. In Fig. 2, D_n is a value of which an input binary data sequence is divided by every four bits and represented in hexadecimal (HEX) notation.

0039T_n is a binary bit pattern in which the input D_n is converted into 9 bits and at least three "0s" are present between two bit "1s". Due to the relation between D_n and D_n+1, two or three T_n patterns are provided. Depending on the value of D_n+1, the pattern of T_n is determined. When D_n = 5, T_n is either "000000100" or "000010001". When D_n+1 is 6, 7, 8, D, or F, T_n is "000010001". Otherwise, T_n is "000000100". When T_n is "000000100", depending on D_n+1, D_n+2 also corresponds to the table of case (1). As a practical example, when D is 5, 6, or 7, "000010001", "000000000", or "100001000" can be obtained, respectively.

0040The minimum code inversion length (Tmin) and the maximum code inversion length (Tmax) in the 4-9 modulation code are 4T and 18T, respectively.

0041Next, the signal pattern of the frame synchronous signal (DCC + SYNC) in each frame and the signal pattern of the AM (25) in the first frame will be described.

0042Fig. 3 is a schematic diagram showing binary data of the frame synchronous signal (DCC + SYNC) and a signal pattern in which the binary data has been converted corresponding to the NRZI technique.

0043In Fig. 3, "*" is "1" or "0". The DCC depends on the value of "*". In other words, the 4-9 modulation code of the DCC is "000001000" or "010001000" whichever the value of DSV (Digital Sum Value) is smaller.

0044When the frame synchronous signal is converted corresponding to the NRZI technique, a signal pattern in which a sequence of the maximum code inversion length (Tmax) for 18T of the 4-9 modulation code is followed by a sequence of a code inversion length for 7T is obtained. The signal pattern in which the maximum code inversion length for 18T is followed by the code inversion length for 7T is not present in the 4-9 modulation code. Thus, the frame synchronous signal is uniquely distinguished from other signal patterns. Consequently, the frame synchronous signal can be easily and accurately detected.

0045Fig. 4 is a schematic diagram showing binary data of the AM (25) and a signal pattern in which the binary data has been converted corresponding to the NRZI technique. When the AM (25) is converted corresponding to the NRZI technique, as shown in Fig. 4, 14 sequences of a code inversion length for 4T are followed by a sequence of a code inversion length for 8T, followed by a code inversion length for 8T or more in which 4T is the minimum code inversion length (Tmin) of the 4-9 modulation code. The signal pattern in which 14 sequences of a code inversion length for 4T take place is not present in the 4-9 modulation code. Since the 4-9 modulation code is not present in the signal pattern that represents the AM (25) and the signal pattern contains 14 sequences of a code inversion length for 4T, the AM (25) can be uniquely distinguished from other signal patterns and thereby easily and accurately detected.

0046Fig. 5 is a schematic diagram showing a data arrangement in the case that an ECC (Error Correction Code) has been added to user data. In this example, six sectors compose one ECC group in which there are two error correction codes C1 and C2 as product codes. The error correction code C1 and the error correction code C2 are Reed Solomon codes that are expressed as a primitive polynomial P(x) = x⁸ + x⁴ + x³ + x² + 1 such as (90, 84, 7) and (84, 78, 7), respectively.

0047In the two error correction codes, the C1 error correction code is generated and the error correcting process thereof is performed with a row of 90 bytes in the X (horizontal) direction of Fig. 5. On the other hand, the C2 error correction code is generated and the error correcting process thereof is preformed with a sequence of 84 bytes in the Z (diagonal) direction of Fig. 5.

0048The SYNC and the DCC in the sector format shown in Fig. 1 are not included in the generating and error correcting range of the error correction codes C1 and C2. In other words, the AM (25), the ID (26), the first CRC (27), the SLD-1 (29), the second CRC (30), the SLD-2 (32), and the third CRC (33) of the header portion 21 are included in the generating and error correcting range of the generation of the error correction codes C1 and C2.

0049However, since the AM (25) is composed of a special signal pattern that does not correspond to the modulation rule, it cannot be included in the calculating range of the error correction codes C1 and C2. Thus, before the error correction codes C1 and C2 are generated and calculated on the recording apparatus side, the AM (25) is substituted with fixed data corresponding to the modulation rule. Thereafter, the error correction codes C1 and C2 are generated for the AM (25).

0050On the other hand, in the data portion 22, all the user data other than the DCC and the SYNC are included in the generating range of the error correction codes C1 and C2 and the error correcting process.

0051Next, a recording apparatus that records a signal on an optical disc according to an embodiment of the present invention will be described.

0052Fig. 6 is a block diagram showing the construction of the recording apparatus. Referring to Fig. 6, the recording apparatus comprises a memory 61, a fixed data generating circuit 62, a first selecting circuit 63, a parity generating circuit 64, a 4-9 modulating circuit 65, a formatting circuit 66, an AM generating circuit 67, a second selecting circuit 68, and an NRZI modulating circuit 69. Next, the operation of the recording apparatus will be described.

0053Data to be recorded on an optical disc is stored in the memory 61. The data stored in the memory 61 is user data such as image data, and sound data, ID, CRC, and SLD. Data is read from the memory 61 corresponding to the error correction codes C1 and C2 of the parity generating circuit 64. The data is supplied to the parity generating circuit 64 through the first selecting circuit 63. At this point, for the AM data area, the first selecting circuit 63 selects 4-byte fixed data (such as "00", "00", "00", "00") from the fixed data generating circuit 62 and supplies the fixed data to the parity generating circuit 64.

0054The parity generating circuit 64 calculates the error correction codes C1 and C2, adds them to the record data, and supplies the resultant data to the 4-9 modulating circuit 65.

0055The 4-9 modulating circuit 65 converts the input data sequence into a 4-9 modulation code and supplies the 4-9 modulation code to the formatting circuit 66.

0056The formatting circuit 66 adds a predetermined signal pattern of the SYNC and the DCC to a data sequence of the 4-9 modulated data so as to form sector data composed of sectors.

0057Thereafter, the formatting circuit 66 supplies the sector data to the NRZI modulating circuit 69. The NRZI modulating circuit 69 performs the NRZI modulation for the sector data. At this point, for the AM data area, the second selecting circuit 68 selects the predetermined signal pattern shown in Fig. 4 from the AM generating circuit 67 and supplies the signal pattern to the NRZI modulating circuit 69. Thereafter, a record processing portion (not shown) records the NRZI-modulated sector data on the optical disc.

0058As described above, according to the embodiment, since AM (25) is substituted with fixed data and included in the generating and calculating range of the error correction codes, sectors with a multiple of periods of frames can be composed. In addition, since the fixed data of the AM is restored to the original signal pattern of the AM just before the NRZI-modulation has been performed, the function of the AM can be securely performed.

0059Next, a reproducing apparatus that reproduces a signal from the optical disc on which the signal has been recorded in the above-described manner will be described.

0060Fig. 7 is a block diagram showing the construction of the reproducing apparatus.

0061Referring to Fig. 7, the reproducing apparatus comprises a SYNC detecting circuit 71, a frame synchronizing circuit 72, an AM detecting circuit 73, a sector synchronizing circuit 74, a timing circuit 75, a 4-9 demodulating circuit 76, a selecting circuit 77, a fixed data generating circuit 78, a memory 79, an error correcting circuit 80, and a CRC checking circuit 81.

0062A reproduction processing portion (not shown) reads a signal from an optical disc and supplies the signal to the SYNC detecting circuit 71 and the AM detecting circuit 73.

0063The SYNC detecting circuit 71 detects a SYNC pattern from the input disc reproduced signal. Thereafter, the frame synchronous circuit 72 synchronizes with frames corresponding to the SYNC detected signal received from the SYNC detecting circuit 71. At this point, synchronous protection is performed so that out-of-synchronism does not takes place even if a few SYNCs are lost.

0064On the other hand, the AM detecting circuit 73 extracts an AM pattern whenever every 42 SYNCs take place.

0065The sector synchronizing circuit 74 synchronizes with sectors corresponding to the AM detected signal received from the AM detecting circuit 73. At this point, as with the frame synchronizing circuit 72, the sector synchronizing circuit 74 protects synchronism of sectors so as to prevent out-of-synchronism of sectors from taking place even if the AM pattern is lost.

0066The timing circuit 75 receives the synchronous signals from the frame synchronizing circuit 72 and the sector synchronizing circuit 74, generates a demodulating timing signal and a write address signal, and supplies the demodulating timing signal to the 4-9 demodulating circuit 76 and the write address signal to the memory 79.

0067Although the 4-9 demodulated data is supplied to the memory 79, for the AM area, the selecting circuit 77 selects fixed data received from the fixed data generating circuit 78 and supplies the fixed data to the memory 79. The fixed data is the same as the fixed data generated by the fixed data generating circuit 62 of the recording apparatus. In other words, the fixed data is for example "00", "00", "00", "00".

0068Thereafter, data is read from the memory 79. The data is supplied to the error correcting circuit 80 that performs an error correcting process. The error correcting circuit 80 corrects errors of ID (26), CRC (27), SLD-1 (29), CRC (30), SLD-2 (32), and CRC (33) of the header portion 21 as well as the user data. Even if an error takes place in these portions, when it is in the error correctable range, it can be corrected to correct data.

0069In the reproducing apparatus, when necessary, the 4-9 modulated data is supplied to the CRC checking circuit 81 that detects errors of ID (26), SLD-1 (29), and SLD-2 (32) of the header portion 21 without need to perform the error correcting process. The detected result of the CRC checking circuit 81 is supplied to a control circuit. The control circuit performs a predetermined control process corresponding to a situation.

0070For example, to precisely detect and correct an error as in the conventional reproducing operation, the error correcting process is performed. To quickly detect and correct an error as in the search operation or the like, the CRC checking circuit 81 is activated so as to detect an error of the header portion 21 and perform control process for the header portion 21.

0071As described above, since an error of sector identification data may be corrected, when data is reproduced, the detecting accuracy of identification data can be improved and thereby highly dense recording on the recording medium can be accomplished.

0072According to the recording apparatus of the present invention, a signal can be recorded on a recording medium in a sector format where an error of sector identification data may be corrected and the detecting accuracy of the identification data is high when data is reproduced. In addition, the second synchronous pattern may be substituted with a predetermined signal pattern that is present in a signal pattern of user data and that is included in the generating and calculating range of the error correction codes so as to suppress the remainder. Thus, sectors can be composed with a multiple of the period of frames.

0073According to the reproducing apparatus of the present invention, an error sector identification data may be corrected. When necessary, an error of the identification data can be detected corresponding to the error detected data. When an error should be quickly detected as in a search operation, an error of the identification data may be detected without need to perform the error correcting process. Thereafter, the identification data is used for the control process.