JP2005285181A - Method and circuit for reproducing, and optical disk reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk reproducing device capable of accurately reproducing data from an optical disk. <P>SOLUTION: In the optical disk reproducing device constructed in such a manner that a recording signal containing the synchronous signal of a fixed cycle read from the optical disk is demodulated into the data of a predetermined format by a demodulation circuit, and error correction is carried out for the demodulated data by an error correction circuit, the error correction circuit executes erasure correction by using an erasure flag generated based on the detection result of the synchronous signal. Especially, the erasure flag is generated when the synchronous signal is not detected from the recording signal or the cycle of the synchronous signal is shifted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reproducing method and a reproducing circuit for performing error correction on data after demodulating a recording signal including a synchronizing signal having a fixed period read from a recording medium into data of a predetermined format, and an optical disc having the reproducing circuit. The present invention relates to a playback device.

  In recent years, an optical disk has been used as a medium for storing a large amount of data such as images and sounds. Among them, a DVD (Digital Versatile Disc) has been widely used.

  In addition to the area for recording normal data, this DVD has an area called BCA (Burst Cutting Area) for recording data for identifying individual recording media around the center hole. In the BCA, barcode data obtained by encoding PE-modulated (Phase Encoding) data by the RZ (Return to Zero) method is recorded.

  The BCA barcode data is converted into BCA data in a data bit format by using a reproduction circuit built in the optical disk reproduction apparatus.

  The bar code data includes a synchronization signal at a constant period, and the subsequent data signal is demodulated with reference to the synchronization signal. Further, a Reed-Solomon code is inserted as an error correction code at a predetermined position in the barcode data, and error correction can be performed during reproduction using this error correction code.

More specifically, as shown in FIG. 6, in the reproducing circuit 101, after the barcode data recorded on the BCA is scanned in the circumferential direction by the optical pickup device, it is converted into a pulsed RZ signal. The RZ signal is demodulated into channel bit format CB data by the RZ-Channel bit demodulator circuit 102, and a synchronization signal of a predetermined period is detected from the CB data using the synchronization detection circuit 103, and this synchronization detection is performed. Only when the synchronization signal is not detected by the circuit 103, the protection circuit 104 inserts a synchronization signal of a predetermined period into the CB data, and then converts the CB data into DB data in the data bit format by the Channel bit-Data bit demodulation circuit 105. The BCA data is generated by demodulating and performing error correction using the error correction circuit 106 using the error correction code included in the DB data.
JP 2002-197665 A

  However, since error correction using a Reed-Solomon code can only correct errors up to half the number of inserted Reed-Solomon codes, it is included in the data read from the optical disk in the conventional optical disk reproducing apparatus. When the number of errors exceeds the number that can be corrected, there is a possibility that the recorded signal recorded on the optical disc cannot be reproduced accurately.

  In particular, in a recording signal that includes a synchronization signal at a fixed period, the subsequent data signal is demodulated with reference to the synchronization signal. If the period is shifted even if it can be detected, the number of errors increases, and there is a possibility that the data signal following the synchronization signal cannot be reproduced.

  Therefore, in the present invention according to claim 1, a recording signal including a synchronization signal having a constant period is read from the recording medium, the recording signal is demodulated into data of a predetermined format, and then error correction is performed on the data. In the reproducing method to be performed, the error correction is performed using an erasure flag generated based on the detection result of the synchronization signal.

  In the present invention according to claim 2, in the present invention according to claim 1, the erasure flag is generated when the synchronization signal is not detected from the recording signal.

  Further, in the present invention according to claim 3, in the present invention according to claim 1 or 2, the erasure flag is generated when the period of the synchronization signal is shifted.

  In the present invention according to claim 4, a demodulating circuit for demodulating a recording signal including a synchronizing signal having a fixed period read from the recording medium into data of a predetermined format, and error correction for the data demodulated by the demodulating circuit The error correction circuit is configured to perform erasure correction using an erasure flag generated based on the detection result of the synchronization signal.

  Further, in the present invention according to claim 5, a recording signal including a synchronizing signal having a fixed period read from the optical disk is demodulated into data of a predetermined format by a demodulation circuit, and an error correction circuit is used to error-demodulate the demodulated data. In the optical disk reproducing apparatus configured to perform correction, the error correction circuit is configured to perform erasure correction using an erasure flag generated based on the detection result of the synchronization signal.

  And in this invention, there exists an effect described below.

  In other words, in the present invention, the erasure flag is generated based on the detection result of the synchronization signal included in the recording signal at a constant period, and the erasure correction is performed using this erasure flag. And the recording signal can be accurately reproduced from the recording medium.

  In particular, since the erasure flag is generated based on the detection result of the synchronization signal, it is possible to correct an error included in the data following the synchronization signal having a fixed period, and to reproduce the data accurately.

  Further, in the present invention, since the erasure flag is generated when the sync signal is not detected from the recording signal or when the cycle of the sync signal is deviated, an area that is likely to contain an error is concentrated. Thus, the error can be corrected and the recording signal can be reproduced more accurately from the recording medium.

  The optical disk reproducing apparatus according to the present invention reads, for example, a recording signal including a synchronizing signal recorded in a BCA or NBCA of a DVD from an optical disk using an optical pickup device, and the recording signal is read by a reproducing circuit. It is designed to be reproduced as format data.

  In addition, the reproduction circuit includes a demodulation circuit that demodulates the recording signal read from the recording medium into data of a predetermined format, and an error correction circuit that performs error correction on the data demodulated by the demodulation circuit. In the error correction circuit, an erasure flag is generated based on the detection result of the synchronization signal, and erasure correction is performed using the erasure flag.

  As described above, in the reproduction circuit built in the optical disk reproduction apparatus according to the present invention, the erasure flag is generated based on the detection result of the synchronization signal included in the recording signal at a constant period, and the erasure correction is performed using the erasure flag. Therefore, the number of data that can be error-corrected can be increased, and the recording signal can be accurately reproduced from the recording medium.

  Hereinafter, a specific configuration of a reproduction circuit built in the optical disk reproduction apparatus according to the present invention will be described with reference to the drawings. In the following description, the playback circuit built in the optical disc playback apparatus for playing back the barcode data recorded on the BCA of the DVD to the BCA data is described, but the present invention is not limited to this. The present invention can also be applied to an optical disc recording / reproducing apparatus that incorporates a recording circuit as well as a reproducing circuit.

  The reproduction circuit 1 uses the RZ-Channel bit demodulation circuit 2 to convert the pulsed RZ signal S1 detected by scanning the barcode data recorded in the BCA in the circumferential direction with the optical pickup device into the CB in the channel bit format. The data is demodulated into data S2, and a synchronization signal S3 having a predetermined period is detected from the CB data S2 using the synchronization detection circuit 3. Only when the synchronization signal S3 is not detected by the synchronization detection circuit 3, the protection circuit 4 determines the predetermined value. The CB data S4 is newly generated by inserting the period synchronization signal S3 into the CB data S2, and then the CB data S4 is demodulated into DB data S5 in the data bit format by the channel bit-data bit demodulation circuit 5, By using the error correction code included in the DB data S5, the error correction circuit 6 performs error correction on the DB data S5 to generate BCA data S6.

  In this error correction circuit 6, the erasure flag generation circuit 7 generates an erasure flag S8 based on the detection signal S7 representing the detection result of the synchronization signal S3 in the synchronization detection circuit 3, and the erasure flag S8 is used to generate DB data S5. And erasure correction.

  The erasure flag generation circuit 7 generates the erasure flag S8 as described below.

  As shown in FIG. 2, the DB data S5 has a data format in which a 1-byte (16-bit) synchronization signal S3 and a 4-byte data signal S9 are alternately continued over a plurality of rows. The synchronization signal S3 is shown in FIG. As shown, the data signal S9 is composed of a fixed pattern and a synchronization number. On the other hand, the data signal S9 includes a 4-byte “00h” preamble (Preamble), 16 · n−4 bytes of information (Information), and 4 bytes of EDC ( It consists of a 16-byte ECC (Error Correction Code), a 4-byte “55h” postamble (Postamble), and a vertical direction (for example, I0, I4,..., I16n-8, EDC0 direction) can be corrected using 4-byte ECC (for example, C0,0, C0,1, C0,2, C0,3) ing.

  Then, the erasure flag generation circuit 7 performs the processing shown in FIG. 4 on all the rows of the DB data S5.

  The processing for each row will be described. First, the erasure flag generation circuit 7 reads the detection signal S7 sent from the synchronization detection circuit 3 (F1).

  Next, it is determined whether the fixed pattern of the synchronization signal S3 is detected by the synchronization detection circuit 3 based on the detection signal S7 (F2).

  When the synchronization detection circuit 3 cannot detect the fixed pattern of the synchronization signal S3, as schematically shown in FIG. 5B, the row and the data of the row one row before the row are obtained. An error flag is added (F3).

  On the other hand, when the synchronization detection circuit 3 can detect the fixed pattern of the synchronization signal S3, the synchronization detection circuit 3 uses the detection signal S7 to shift the fixed pattern of the synchronization signal S3 from a fixed period (here, every 80 bits). It is determined whether or not (F4).

  When the fixed pattern of the synchronization signal S3 deviates from a certain period, as shown schematically in FIG. 5C, a shift flag is added to the data in the previous row (see FIG. 5C). F5).

  On the other hand, when the fixed pattern of the synchronization signal S3 is not deviated from a certain period, neither an error flag nor a deviation flag is added as schematically shown in FIG.

  Then, the erasure flag generation circuit 7 generates an erasure flag S8 by combining the error flag and the deviation flag (F6), and then outputs the erasure flag S8 to the error correction circuit 6 (F7).

  As described above, the error correction circuit 6 generates the erasure flag S8 before and after the synchronization signal S3 when the synchronization detection circuit 3 does not detect the fixed pattern of the synchronization signal S3 from the CB data S2. When the period of the fixed pattern of the synchronization signal S3 detected in step S1 deviates from a predetermined period, an erasure flag S8 is generated before the synchronization signal S3, and erasure correction is performed using the erasure flag S8.

  Therefore, in the reproduction circuit 1, the number of data that can be corrected by the error correction circuit 6 increases, and BCA data can be reproduced accurately.

  In particular, since the erasure flag S8 is generated when the synchronization signal S3 is not detected or when the cycle of the synchronization signal S3 is shifted, the error correction circuit 6 concentrates on a region likely to contain an error. Error correction, and BCA data can be reproduced more accurately.

1 is a circuit diagram showing a reproducing circuit according to the present invention. Explanatory drawing which shows the format of BCA data. Explanatory drawing which shows the synchronizing signal of BCA data. The flowchart which shows the production | generation method of an erasure flag. The schematic diagram which shows the production | generation method of an erasure flag. The circuit diagram which shows the conventional reproduction circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reproduction | regeneration circuit 2 RZ-Channel bit demodulation circuit 3 Synchronization detection circuit 4 Protection circuit 5 Channel bit-Data bit demodulation circuit 6 Error correction circuit 7 Erasure flag generation circuit
S1 RZ signal
S2 CB data
S3 Sync signal
S4 CB data
S5 DB data
S6 BCA data
S7 detection signal
S8 erasure flag

Claims (5)

In a reproduction method of reading a recording signal including a synchronization signal having a fixed period from a recording medium, demodulating the recording signal into data of a predetermined format, and then performing error correction on the data,
The error correction is performed by performing erasure correction using an erasure flag generated based on the detection result of the synchronization signal.   2. The reproducing method according to claim 1, wherein the erasure flag is generated when the synchronization signal is not detected from the recording signal.   The reproduction method according to claim 1 or 2, wherein the erasure flag is generated when a period of the synchronization signal is shifted. In a reproduction circuit having a demodulation circuit that demodulates a recording signal including a synchronization signal having a fixed period read from a recording medium into data of a predetermined format, and an error correction circuit that performs error correction on the data demodulated by the demodulation circuit ,
The reproduction circuit according to claim 1, wherein the error correction circuit is configured to perform erasure correction using an erasure flag generated based on the detection result of the synchronization signal. In an optical disk reproducing apparatus configured to demodulate a recording signal including a synchronization signal of a fixed period read from an optical disk into data of a predetermined format by a demodulation circuit, and to perform error correction on the demodulated data by an error correction circuit ,
The optical disk reproducing apparatus, wherein the error correction circuit is configured to perform erasure correction using an erasure flag generated based on the detection result of the synchronization signal.

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