JP4621631B2 - Error correction device - Google Patents

Description

  The present invention relates to an error correction apparatus.

  There are standards such as DVD-RAM and DVD-R / RW for digital versatile discs (hereinafter referred to as DVDs).

  For example, on an optical disc by DVD-R / RW, a guide groove (recording guide) called a groove for guiding the pickup of the optical disc apparatus is pre-formatted. This groove is slightly meandering in the radial direction, so-called wobble. In DVD-R / RW, prepits are preliminarily carved into lands that are protruding portions between grooves.

  In reproduction of such an optical disc, an error occurs in data on the correction block corresponding to the position of the prepit due to the influence of the prepit. For example, in the second correction of the first code string (PI) -second code string (PO), There was a problem that the error could not be corrected and correction of PO-PI-PO had to be performed three times, and the number of correction processes increased and the reproduction performance deteriorated.

The following is a list of literatures that disclose conventional optical disk error correction techniques.
Japanese Patent Laid-Open No. 10-285053

  An object of the present invention is to provide an error correction apparatus that can reduce the number of correction processes and improve reproduction performance.

An error correction apparatus according to an aspect of the present invention records, on a recording unit of an optical disc, first code string data to which an error code is added in the same direction as the order of recording information, and the first code string data on the optical disc. An error correction apparatus for reproducing recorded information from an optical disc on which recording guide information recorded in advance in a state in which the first code string is not erasable as a recording guide for recording, A first position detector that detects a singular point on the physical structure in the recording guide information as a first position, and the first position detected by the first position detector is the position of the first code string data. A second position generation unit that generates the replaced second position; an error detection unit that detects an error in the data at the second position; an error measurement unit that measures the number of errors detected by the error detection unit; error When the number of errors measured portion has a predetermined period measurement satisfies a desired value, the previously granted pointer for erasure correction in the second position in the first code string data to identify the second position, wherein And an error correction unit that forcibly performs erasure correction processing of the first code string data at the second position .

  According to the error correction apparatus of the present invention described above, reproduction performance can be improved without increasing the number of correction processes.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Embodiment 1
FIG. 1 shows the configuration of an optical disk error correction apparatus according to Embodiment 1 of the present invention.

  Information recorded on the optical disk 1 is read out by the pickup 2, and an RF signal, a wobble signal, and a pre-pit signal are obtained and output by the matrix amplifier 3. The RF signal is supplied to the demodulation circuit 4, the wobble signal is supplied to the wobble PLL circuit 12, and the prepit signal is supplied to the prepit decoder 13.

  At the time of reproduction, the RF signal is demodulated by the demodulation circuit 4, and the demodulated RF signal is stored in the correction RAM 6 via the error correction circuit 5. The data stored in the correction RAM 6 is output to the host computer 8 via the data buffer circuit 7.

  At the time of recording, recording data is supplied from the host computer 8 and is supplied to the parity generation circuit 9 via the data buffer circuit 7, and parity is generated and added to the recording data.

  A wobble signal is input to the wobble PLL circuit 12, a wobble clock is generated, and is supplied to the prepit decoder 13 together with the prepit signal. The prepit decoder 13 detects recording guide information (preformat information) in which address information and the like on the optical disc 1 are recorded, generates a recording timing signal, and outputs the recording timing signal to the modulation circuit 10.

  The modulation circuit 10 modulates the recording data to which the parity generated by the parity generation circuit 9 is added based on the recording timing signal, generates a modulation signal, and outputs the modulation signal to the laser control circuit 11. The recording laser of the pickup 2 is driven by the laser control circuit 11 and the recording data is written on the optical disc 1.

  By the way, the DVD employs a product code having an inner code parity (Parity of the Inner code, hereinafter referred to as PI) and an outer code parity (Parity of the Outer code, hereinafter referred to as PO) as elements. In error correction of a product code such as a DVD, “erasure correction can be performed with outer code: PO (inner code: PI) based on error position information of inner code: PI (outer code: PO). ”. When correcting a burst error, which is a continuous error occurring in the same row direction (PI code data arrangement direction) as a continuously reproduced data string, on an optical disc, first, PI code error correction processing is performed. In general, the correction processing of the PO code in the column direction (the direction of the data array of the PO code) is performed next.

  In the DVD-R / RW, in order to record information in the grooves, pits called land pre-pits in which information such as addresses is set in advance in lands between the grooves are formed. This pit is a singular point on the physical structure that is artificially formed in advance in the recording portion (recording area) of the optical disc, and the prepit decoder 13 detects this prepit.

  When scanning and reading the information recorded in the groove with a beam spot, the reflected light component from the prepit acts as noise compared to the amount of reflected light from the prepit, and the groove information is detected with high accuracy. May be difficult.

  Therefore, generally, when a pre-pit signal is present, a reproduction signal from the optical disk is likely to be disturbed. Therefore, in the first embodiment, PI-PO is corrected twice by adding a pointer for erasure correction in advance to the pre-pit position in the correction block, thereby improving reproduction performance. Yes.

  Here, the erasure correction pointer assumes that an error exists regardless of whether or not an error actually exists at a specific position (here, the pre-pit position on the correction block). It is instructed to forcibly perform error correction processing.

  When error correction is performed only within the own code string in a state where the error position is unknown (here, referred to as detection correction), it is possible to correct only the error number that is ½ of the parity number. However, when error positions are given in advance (herein referred to as erasure correction), the same number of errors as the number of parity can be corrected.

Here, between the error number X that can be corrected only within the own code sequence in which the error position is unknown, the error number Y that can be corrected by the erasure correction to which the error position is given, and the parity number Z The following relational expression (1) is established.
2 * X + Y ≦ Z (1)

  By adding such a pointer, it is assumed that there is an error at the pre-pit position where error is likely to occur, and erasure correction is performed to increase the number of correctable errors and reduce the number of correction processes. Performance can be improved.

  The recording data, the wobble signal, and the prepit signal when the prepit (prepit sync) exists in the even sync frame have a relationship as shown in FIG. 2, and the first prepit and the recording data of the prepit exist. The relationship with the sync (32 channel bit length (hereinafter, channel length is referred to as T)) is as shown in FIG.

  Here, as will be described later, there are three types of prepits in the standard, depending on the position and number thereof, prepit sync (Prepit SYNC), prepit data (Prepit data) “1”, and prepit data “0”. .

  Further, one correction block (ECC block) is configured such that PO parity is interleaved as shown in FIG. One sector is composed of 26 sync frames, and one correction block is composed of 16 sectors.

  One symbol consists of 1-byte data, and 1-byte data corresponds to 16 times the channel bit length defined by the recording format when recording information is recorded, that is, 16T. The sync frame has a length of 1488T, and the portion having the length of 32T at the head of one sync frame is used as information for synchronizing each sync frame.

Since the number of errors that can be corrected in the PI code string is 10 symbols for the number of PI parity in one row, the number X that can be corrected only within the own code string where the error position is unknown, and an erasure given the error position The number Y that can be corrected by correction is
2 * X + Y ≦ 10 (2)
The relationship is established.

Since the number of errors that can be corrected in the PO code string is 16 symbols, the number of PO parities in one column is 16 symbols, and the number X that can be corrected only within the own code string where the error position is unknown, and the error position are given. The correctable number Y by the erasure correction
2 * X + Y ≦ 16 (3)
The relationship is established.

  The procedure of the correction operation in this embodiment will be described using the flowchart of FIG.

  In step S11, the correction process by the error correction circuit 5 is started.

  In step S <b> 12, the PI code data is read from the correction RAM 6 by the error correction circuit 5.

  In step S13, the system controller 14 determines whether the optical disc 1 is a DVD-R / RW. As a result, the presence or absence of pre-pits on the standard becomes clear.

  If the optical disc 1 is not a DVD-R / RW, there is no pre-pit. Therefore, in step S18, the error correction by the PI code alone, that is, the correction of the error location only within the own code string without being given from the outside. Detection and correction that can be performed is performed by the error correction circuit 5, and the process proceeds to step S20.

  When the optical disk 1 is a DVD-R / RW, the process proceeds to step S14, and the prepit position information is updated. Thereby, the position of the pre-pit in the current correction block is recognized by the error correction circuit 5.

  In step S15, whether or not a condition for adding a pointer for erasure correction of a prepit position to be described later is satisfied is determined using prepit position error detection measurement information. For example, if it is found that there are many errors in the prepit position in the optical disc 1 by the correction processing of the previous correction block or a plurality of consecutive correction blocks one or more previous, the prepit from the beginning. Since it is possible to increase the number of errors that can be corrected by performing erasure correction on the assumption that there is an error, an erasure correction pointer is added in advance.

  This determination is made by the system controller 14 or an external controller not shown in FIG. If not, error correction is performed with the PI code alone in step S17.

  Here, as described above, the detection correction with the PI code alone can be up to 5 per column of the PI code data shown in FIG. 4, and the detection correction cannot be performed when there are 6 or more. This step is terminated when it is unknown whether any of the columns contain errors.

  If the conditions for erasure correction are satisfied, in step S16, the error correction process using only the PI code is performed, that is, detection correction that exists at random other than the pre-pit position, and error correction at the pre-pit position using the pre-pit position information. Forced erasure correction is performed.

  In step S20, the error correction circuit 5 corrects the information data stored in the correction RAM 6, and further, PI code error position information relating to the position of the error existing in the PI code string is generated.

  In step S21, it is determined whether or not the PI code string correction process has been completed. If not, the process returns to step S12. If completed, the process proceeds to step S22.

  In step S <b> 22, the PO code data is read from the correction RAM 6 by the error correction circuit 5.

  In step S23, the error correction circuit 5 performs erasure correction using the error position information of the generated PI code, together with detection correction using the PO code alone without being provided with information on the position where the error exists.

  In step S24, it is determined whether or not the PO code string correction process has been completed. If not, the process returns to step S22. If completed, the correction process is terminated in step S25.

  Next, a routine for generating pre-pit position error detection and measurement information used when determining whether or not the pre-pit position erasure correction condition is satisfied will be described.

  In step S101, the system controller controls error detection and measurement start of the prepit position.

  In step S102, the error detection measurement result Q at the pre-pit position is initialized (Qn = “L”, Qn−1 = “L”, Qn−2 = “L”).

  In step S103, pre-pit position error detection and measurement processing is started.

  In step S104, data of one code string (PI code string) is read, and a pre-pit position and an error position are detected.

  In step S105, the prepit position is based on the prepit position information generated by the prepit position information generation circuit, and the erroneous position detection is performed based on the correction processing information of the error correction circuit for one code string.

  In step S106, if the error position is the pre-pit position, in step S107, the fact that pre-pit position erasure correction is permitted is set in the error detection measurement result of the pre-pit position (Qn = “H”).

  If the error position is not the pre-pit position, in step S108, the fact that pre-pit position erasure correction is not permitted is set in the pre-pit position error detection measurement result (Qn = "L").

  If the condition for adding an erasure correction pointer to the pre-pit position is satisfied in step S109 (when erasure correction of the pre-pit position is permitted in two consecutive PI code strings (Qn-1Qn = "HH")), step In S112, pre-pit position error detection measurement information for executing erasure correction on the pre-pit position is generated.

  In step S110, when the condition for deleting the pointer for erasure correction at the prepit position is satisfied (when erasure correction of the prepit position is not permitted in three consecutive PI code strings (Qn-2Qn-1Qn = "LLL") In step S113, pre-pit position error detection measurement information indicating that erasure correction is not performed on the pre-pit position is generated.

  If neither the condition for adding the erasure correction pointer to the prepit position nor the condition for deleting the erasure correction pointer at the prepit position is satisfied, the previous state of erasure correction at the prepit position is maintained as step S111. The error detection measurement information of the pre-pit position is generated.

  In step S114, if the measurement end condition set by the system controller 14 is satisfied, the measurement is ended in step S115. If not satisfied, the process returns to step S104 to start the measurement process.

  The above routine is processing for error detection and measurement at one prepit position, but the same processing is performed for other prepit positions.

  In the first embodiment, the error detection and measurement start of the prepit position are controlled from the system controller 14, but they may be linked with the correction processing of the error correction circuit 5.

  In the first embodiment, error position detection is based on information of correction processing of the error correction circuit 5 for one code string, but a dedicated circuit may be provided for error position detection.

  FIG. 6 shows the error occurrence status for each correction processing block, the presence / absence of a pointer for erasure correction at the prepit error position, the error information measurement result at the prepit error position, the data after correction processing, and the erasure correction for one correction block. Examples of pointer addition conditions, pointer addition conditions for erasure correction in a plurality of consecutive correction blocks, pointer deletion conditions for erasure correction in one correction block, and pointer deletion conditions for erasure correction in a plurality of consecutive correction blocks are shown.

  The code “n−2, n−1, n, n + 1,...” Is applied to the correction block that performs processing for deleting the pointer for erasure correction, and “m” is applied to the correction block that performs processing for adding the pointer for erasure correction. -2, m-1, m, m + 1, ... ".

  As the error occurrence status, “E-1” is a situation where an error as shown in FIG. 7 has occurred, “E-2” is a situation where an error is shown as shown in FIG. 8, and “E-3” is a figure. As shown in FIG. 9, the situation where no error has occurred is shown.

  In the figure, “present” in “presence / absence of pointer at prepit error position” indicates addition of a pointer for erasure correction, and “absence” indicates deletion of the pointer for erasure correction.

  “Data after correction processing” indicates the presence or absence of an error included after two corrections of PI-PO.

  “◯” in “addition condition in one correction block” or “deletion condition in one correction block” indicates that the block satisfies the addition condition or deletion condition in one correction block, and “×” indicates a block that does not satisfy the condition Indicates that

  In the “pointer addition condition” or “pointer deletion condition”, “◯” indicates that each condition is satisfied, and “x” indicates that the condition is not satisfied.

  The errors shown in FIG. 7 are continuously generated in the longitudinal (PO row) direction due to pre-pits.

  In the figure, “◯” indicates one symbol error due to pre-pit sync, “Δ” indicates one symbol error due to pre-pit data “1”, and “x” indicates a randomly generated error.

  PI columns -1 to 16 are the positions of the prepit sync, that is, the positions of PO column-1 and PO column-2, and the positions of the prepit sync, that is, the positions of PO column-3 and PO column-4. An error occurs in the symbol, and errors occur in two other random locations, indicating that a total of six symbols are in error.

  In PI column-17, an error occurs in the symbol of the position of the prepit data, that is, the position of PO column-2, and the adjacent position, that is, the position of PO column-4. This shows a state where an error has occurred and a total of 6 symbol errors have occurred.

  When the number of error occurrences in one PI sequence is 5 or less, PI correction can be performed only within the own code sequence without giving error position information. When the number exceeds five, PI correction only within the own code string cannot be performed at all.

  In the error shown in FIG. 8, no error occurs at all due to pre-pits, and only a random error occurs.

  PI columns 1 to 17 include the positions of the prepit sync, that is, the positions of PO column-1 and PO column-2, and the positions of the prepit sync, that is, the positions of PO column-3 and PO column-4. In addition, four symbols indicate an error.

  In the correction block shown in FIG. 9, from PI columns -1 to 17, prepit sync positions, that is, PO column-1 and PO column-2 positions, and adjacent to the prepit sync positions, that is, PO column- It indicates that no error has occurred at the positions of 3 and PO column-4, and at other positions.

  Next, as data reproduced from the optical disc 1, the correction block A is shown in FIG. 10, the correction block B is shown in FIG. 11, and the correction block C is shown in FIG.

  In correction block A in FIG. 10, PI columns 1-1-1 to 11 have prepit sync positions, that is, PO column-1 and PO column-2 positions, and adjacent to the prepit sync positions, that is, PO columns. In addition to the positions of column-3 and PO column-4, four symbols indicate errors.

  In PI columns -1-12 to 16, errors occur in four symbols at the position of the prepit sync and next to the position of the prepit sync, and errors occur in two symbols at other positions. An error has occurred in a total of 6 symbols.

  In the correction block B in FIG. 11, in PI columns 2-1 to 8, 10, and 12-16, an error occurs in a prepit sync position and a symbol adjacent to the prepit sync position, and other positions. In FIG. 2, an error occurs in two symbols, and a total of six symbols are in error.

  In PI row-2-9, an error occurs in two symbols at the prepit sync position (PO row-2 position) and next to the prepit sync position (PO row-4 position). No error has occurred at the pit sync position (position PO-1) and the position adjacent to the pre-pit sync (position PO-3). An error has occurred in a total of two symbols.

  In PI column 2-11, an error occurs in two symbols at the position of the prepit sync (position of PO column-2) and next to the position of the prepit sync (position of PO column-4). No error occurred at the position of the prepit sync (position of the PO row-1) and the position of the prepit sync (position of the PO row-3). An error has occurred in two symbols at a position other than the position of the prepit sync and the position adjacent to the prepit sync, and errors of a total of four symbols have occurred.

  In PI column-2-17 to 33, an error occurs in two symbols adjacent to the position of the prepit data and the position of the prepit data, and errors occur in four symbols in other positions. An error has occurred in six symbols.

  In the correction block C in FIG. 12, an error occurs in the pre-pit sync position and the four symbols adjacent to the pre-pit sync position in the PI columns 3-1 and 2, and two in other positions. This indicates that an error has occurred in these symbols and that a total of six symbols are in error.

  In PI columns 3-3 to 16, errors occur in four symbols at a position other than the position of the prepit sync and the position adjacent to the prepit sync.

  In FIG. 13, when a prepit is detected, a pulse is generated at that position, and a prepit detection signal for detecting one of the three types of prepits, and a symbol position on a correction block of recorded data recorded in accordance with the standard, The relationship is shown.

  The recording data recorded on the optical disc 1 is normally recorded in accordance with a standard. For this reason, the position of the second pre-pit in the even-numbered (Even) position of the pre-pit sync on the correction block is such that the 11th symbol from the beginning of the PI code string is the PO string in the correction blocks A to C as shown in FIG. The position of the PO string-2 on the correction blocks A to C of the third prepit sync and the second prepit of the prepit data “1” is the 23rd symbol from the beginning of the PI code string. It corresponds to.

  When recording is performed in conformity with the standard, prepit sync exists on the first line of the sector, and prepit data exists on the second to thirteenth lines.

  The pre-pit position information generation circuit 15 shown in FIG. 1 includes PI columns 1-1-1 to 16 in the correction block A, PI columns 2-1 to 16 in the correction block B, and PI column -3 in the correction block C. Prepit position information is generated by using the positions of the PO row-1 of -1 to 16 and the position of the PO row-2 in the correction blocks A to C as prepit positions, and output to the prepit position error measuring circuit 16.

  The prepit position error measurement circuit 16 detects the presence or absence of a prepit position error from the correction status of the PI code string of the prepit position generated by the prepit position information generation circuit 15.

  Here, the correction status is information relating to the presence / absence of an error in the PI code string or PO code string, correctability / impossibility, error position, number of errors, and the like.

  FIG. 14 shows the relationship between the presence / absence of an error in the PO sequence-1, which is the pre-pit position of the correction blocks A to C, and the order of the PI code sequence reproduced from the optical disc 1. Note that the position of the prepit error a corresponds to PO row-1.

  In PI columns -1-8 to 11, 2-9, 2-11, 3-3 to 9, no error has occurred at the position of the prepit error a, and PI columns -1-12 to 16, 2- In 1-8, 2-10, 2-12-16, and 3-1-2, an error has occurred at the position of the prepit error a.

  As a condition for adding an erasure correction pointer to a pre-pit position, for example, when an error occurs in a pre-pit position in two consecutive PI code strings in which a pre-pit exists, there is a high probability that an error exists in the pre-pit position. Since it is considered that the processing efficiency is improved if correction is made on the premise that there is a certain point, an erasure correction pointer is added to the pre-pit position. If no error occurs in the prepit position in three consecutive PI code strings in which prepits exist, it is considered that there is a high probability that no error exists in the prepit position. If the erasure correction is not performed, the number of errors that can be corrected at other random positions can be increased. Therefore, the erasure correction pointer at the pre-pit position is deleted. Hereinafter, such a condition is referred to as a condition α.

  In the PI correction shown in FIG. 14, an error occurs at the position of the prepit error a in two consecutive rows in PI columns -1-12 and 13. In this case, since the condition α is satisfied, a signal to the effect that a pointer for erasure correction is added to the prepit position is transmitted from the error measurement circuit 16 for the prepit position to the system controller 14.

  After PI row 3-3, no error has occurred at the position of the prepit error a. In PI column -3-5, three columns in which no error has occurred at the position of the prepit error a are consecutive, and the condition α is satisfied. Therefore, a signal to delete the erasure correction pointer added to the pre-pit position is transmitted from the pre-pit position error measurement circuit 16 to the system controller 14.

  Such error detection and measurement at the position of the PO row-1, that is, the position of the prepit error a, is performed in the same manner for the other prepit positions, that is, the PO rows-2 to 4.

  When the error correction circuit 5 receives a signal indicating that an erasure correction pointer is added to the prepit position from the system controller 14, the error correction circuit 5 adds the erasure correction pointer to the prepit position and performs PI correction. When a signal to delete the erasure correction pointer at the pre-pit position is received from the system controller 14, the error correction circuit 5 does not add the erasure correction pointer to the pre-pit position, and corrects the error with the PI code alone. Do.

  Taking the correction block A shown in FIG. 10 as an example, in the PI columns 1-1-1 to 11, the pointer for erasure correction is not added to the pre-pit positions of the PO columns-1 to 4, and the PI code alone is corrected. Done. Therefore, errors in the PI strings 1-1-1 to 11 are corrected by PI correction.

  In the PI columns -1-12 and 13, the erasure correction pointer is not added to the pre-pit positions of the PO columns -1 to 4, so that the PI code alone is corrected. Errors in the PI columns 1-12 and 13 cannot be corrected by PI correction, but are corrected by PO correction.

  In the PI columns -1-14 to 16, the erasure correction pointer is added to the prepit positions of the PO columns -1 to 4. Therefore, at this pre-pit position, erasure correction of the pre-pit position is performed together with detection and correction of the PI code alone for random errors other than the pre-pit position. Errors in the PI string-1-14 to 16-16 are corrected only by PI correction.

  Taking the correction block B shown in FIG. 11 as an example, in the PI columns 2-1 to 16, pointers for erasure correction are added to the pre-pit positions of the PO columns -1 to 4. For this reason, the erasure correction of the prepit position is performed together with the correction of the PI code alone. Errors in the PI columns 2-1 to 16 are corrected only by PI correction.

  In the PI column-2-17 to 33, an erasure correction pointer is added to the pre-pit positions of the PO column-2 and 4. For this reason, the erasure correction of the prepit position is performed together with the correction of the PI code alone. Errors in the PI string-2-17 to 33 are corrected only by PI correction.

  Taking the correction block C shown in FIG. 12 as an example, in the PI columns 3-1 and 2, pointers for erasure correction are added to the pre-pit positions of the PO columns -1 to 4. For this reason, the erasure correction of the prepit position is performed together with the correction of the PI code alone. Errors in PI columns 3-1 and 2 are corrected only by PI correction.

  In PI columns 3-3 to 5, pointers for erasure correction are added to the pre-pit positions of PO columns -1 to 4. For this reason, the erasure correction of the prepit position is performed together with the correction of the PI code alone. The errors in the PI column 3-3 to 5 cannot be corrected only by the PI correction, but all errors can be corrected by the subsequent PO correction.

  According to the first embodiment, when an error as shown in the correction blocks A, B, and C occurs, the error can be corrected by performing the PI-PO correction twice, so that the reproduction performance is improved.

  By the way, regarding the error detection of the pre-pit position, when the correction result of the PI code string becomes uncorrectable, “presence of error” may be set at the pre-pit position regardless of the presence or absence of the symbol error at the pre-pit position, or “No error” may be used.

  In the first embodiment, the condition α is set based on the number of errors in which errors continuously occur at the position of the prepit error a. However, even when errors occur discontinuously at the position of the prepit error a, if the total number of errors occurring at the position of the prepit error a satisfies a predetermined number, the erasure is performed at the position of the prepit error a. A condition may be set so that a correction pointer is added.

  As an example of this case, FIG. 15 shows a flow when pre-pit position error detection and measurement is performed for 208 PI code sequences. Here, steps S11 to S25 in FIG. 15 are the same as those in the first embodiment, and the description thereof is omitted.

  In step S101, the system controller 14 controls pre-pit position error detection and measurement start.

  In step S103, pre-pit position error detection and measurement processing is started.

  In step S151, the pre-pit position error detection result measurement number N is initialized.

  In step S104, data of one code string (PI code string) is read, and in step S105, a pre-pit position and an error position are detected.

  Pre-pit position detection is performed based on pre-pit position information generated by the pre-pit position information generation circuit 15, and error position detection is performed based on correction processing information of the error correction circuit 5 for one code string.

  If the error position is a pre-pit position in step S106, the error detection result of the pre-pit position is measured in step S152 (N = N + 1).

  If the error position is not the pre-pit position, the process proceeds to step S153 without measuring the pre-pit position error detection result.

  In step S153, if the correction process for all the PI code sequences has been completed, the process for determining the error detection result of the pre-pit position is performed. If the process has not been completed, the process for the next column is performed.

  In step S154, when the number N of prepit position error detection result measurements satisfies the condition for adding an erasure correction pointer to the prepit position, prepit position error detection measurement information indicating that erasure correction is performed on the prepit position in step S112. Is generated.

  If the number of pre-pit position error detection results measurement number N does not satisfy the condition for adding an erasure correction pointer to the pre-pit position, step S113 generates pre-pit position error detection measurement information indicating that erasure correction is not performed. To do.

  If the measurement end condition is satisfied in step S114, the measurement ends in step S1115. If not satisfied, the process returns to step S151 to perform measurement processing.

  Further, under condition α, the number of PI columns for adding an erasure correction pointer may be set to an arbitrary number of columns.

  In the first embodiment, when an erasure correction pointer is added to the pre-pit position, a signal to that effect is transmitted to the error correction circuit 5 via the system controller 14. However, the present invention is not limited to this, and information indicating that the pointer for erasure correction is added to the pre-pit position is held in a memory or register such as the correction RAM 6, and the error correction circuit 5 determines the pointer position for erasure correction based on the information. Then, erasure correction may be performed.

  Prepit position error measurement may be performed by sequentially measuring the presence or absence of errors in the prepit position of each detected code string, or after detecting and holding the presence or absence of errors in the prepit position of each code string. It may be done by doing.

(2) Embodiment 2
An optical disk error correction apparatus according to Embodiment 2 of the present invention will be described. The circuit configuration is as shown in FIG. 1 as in the first embodiment, and the processing procedure is as shown in FIG. Here, the processing from step S11 to step S42 to step S11 to S25 is the same as that in the first embodiment, and the description thereof is omitted.

  A routine for generating pre-pit position error detection and measurement information used when determining whether or not the condition for erasure correction of the pre-pit position is satisfied in step S15 will be described below.

  In step S101, the system controller 14 controls prepit position error detection and measurement start.

  In step S102, the pre-pit position error detection measurement result Q is initialized.

  In step S103, pre-pit position error detection and measurement processing is started.

  In step S201, the pre-pit position error detection result measurement number N is initialized.

  In step S104, data of one code string (PI code string) is read, and in step S105, a pre-pit position and an error position are detected.

  Pre-pit position detection is performed based on pre-pit position information generated by the pre-pit position information generation circuit 15, and error position detection is performed based on correction processing information of the error correction circuit 5 for one code string.

  If the error position is a pre-pit position in step S106, the error detection result of the pre-pit position is measured in step S202 (N = N + 1).

  If the error position is not the pre-pit position, the process proceeds to step S203 without measuring the pre-pit position error detection result.

  In step S203, when the correction process for all the PI code sequences has been completed, the process proceeds to the determination process for the error detection result of the prepit position in step S204, and in the case where the correction process has not been completed in step S204, the process returns to step S104. The next code string is processed.

  In step S204, when the number N of pre-pit position error detection result measurement satisfies the condition for adding a pointer for erasure correction of the pre-pit position (N ≧ 16), in step S107, the pre-pit position error detection measurement result is included in the pre-pit position error detection measurement result. Is set to permit the erasure correction of Q1 (Qn = "H").

  If the pre-pit position error detection result measurement number N satisfies the condition for deleting the pointer for erasure correction of the pre-pit position (N <16), the pre-pit position erasure correction is added to the pre-pit position error detection measurement result in step S108. Set not to permit (Qn = "L").

  In step S207, when the condition for adding an erasure correction pointer to the pre-pit position is satisfied (when erasure correction of the pre-pit position is permitted in three consecutive correction blocks (Qn-2Qn-1Qn = "HHH")), In step S112, pre-pit position error detection measurement information for executing erasure correction on the pre-pit position is generated.

  In step S208, when the condition for deleting the pointer for erasure correction at the prepit position is satisfied (when erasure correction of the prepit position is not permitted in three consecutive correction blocks (Qn-2Qn-1Qn = "LLL")) In step S113, error detection measurement information on the prepit position is generated to the effect that erasure correction is not performed on the prepit position.

  If neither the condition for adding the erasure correction pointer to the pre-pit position nor the condition for deleting the erasure correction pointer at the pre-pit position is satisfied, the previous state of erasure correction at the pre-pit position is maintained in step S111. The error detection measurement information of the pre-pit position is generated.

  If the measurement end condition is satisfied in step S114, the measurement ends in step S115. If not satisfied, the process returns to step S201, and the measurement process is started again.

  The above is processing for error detection and measurement at one prepit position, but the same processing is performed for each of the other prepit positions.

  The system controller 14 adds pointers for erasure correction to the PO column-1 and the PO column-3 adjacent thereto, the PO column-2, and the PO column-4 adjacent thereto shown in FIG. Perform PI correction.

  In FIG. 7, PO column-1 is the position of prepit error 1, adjacent PO column-3 is the position of prepit error 3, PO column-2 is the position of prepit error 2, and it is adjacent to this. PO row-4 is set as the position of the pre-pit error 4.

  An operation in which the prepit position error measurement circuit 16 measures the number of occurrences of prepit position errors and adds or deletes a PI correction erasure correction pointer to the prepit position will be described.

  First, the operation of adding a pointer for erasure correction for PI correction to the prepit position will be described by taking the case where it is performed at the position of prepit error 1 as an example.

  In one correction block, the number of occurrences of errors at the position of pre-pit error 1 is measured based on the correction status of PI correction, and the occurrence of errors in the column of pre-pit error 1 based on the correction status of PO correction Measure the number.

  The occurrence of an error at the position of prepit error 1 in the correction block based on the measurement result of the number of errors occurring at the position of prepit error 1 and the measurement result of the number of occurrences of errors in the prepit error 1 row Generate information indicating the situation.

  When the information on the occurrence status of the error at the position of the prepit error 1 in the correction block satisfies a condition for adding a pointer for erasure correction of the position of the prepit error 1 (hereinafter referred to as condition 1), Information indicating that the condition 1 is satisfied is generated.

  Similarly, in each of the other correction blocks that are sequentially reproduced, the number of occurrences of the error at the position of prepit error 1 in each correction block is measured, and if condition 1 is satisfied, information indicating that is generated To do.

  Then, for each reproduced correction block, the number of correction blocks satisfying the condition 1 is measured, and a pointer for erasure-correcting the position of the prepit error 1 over one or more reproduced correction blocks. Is satisfied, the pre-pit position error measurement circuit 16 adds the position of the pre-pit error 1 to the system controller 14 as a pointer for erasure correction for PI correction. Send that the conditions are met.

  When the system controller 14 receives that the position of the prepit error 1 satisfies this condition, the system controller 14 adds a pointer for erasure correction in the PI correction after the next correction block to the prepit position information generation circuit 15. It transmits to the error correction circuit 5.

  An operation of adding a pointer for erasure correction for PI correction to the pre-pit position will be described by taking as an example a case where data reproduced from the optical disc 1 is a correction block as shown in FIG.

  Here, condition 1 is a case where there are 16 or more errors at the position of prepit error 1 in one correction block, and condition 2 is that correction blocks satisfying condition 1 are consecutive in three correction blocks from the start of measurement. If it occurs.

  In the correction block n in FIG. 6, the number of occurrences of the error at the position of the prepit error 1 is measured, and information indicating that the condition 1 is satisfied is generated and stored. Similarly, also in the correction blocks n + 1 and n + 2 of FIG. 6, the number of occurrences of the error at the position of the prepit error 1 is measured, and information indicating that the condition 1 is satisfied is generated.

  Further, since the correction block satisfying the condition 1 in the correction block n + 2 is continuous with three correction blocks, the condition 2 is satisfied. As a result, the system controller 14 is notified that the position of the pre-pit error 1 satisfies the condition for adding as a pointer for erasure correction for PI correction.

  When the system controller 14 receives that the condition for adding the position of the prepit error 1 as a pointer for erasure correction for PI correction is satisfied, the system controller 14 serves as a pointer for erasure correction in the PI correction after the next correction block. The addition is transmitted to the pre-pit position information generation circuit 15 and the error correction circuit 5.

  Similarly, the number of occurrences of errors is measured for pre-pit errors 2, 3, and 4. In order to satisfy Condition 1 and Condition 2, processing for adding a pointer for erasure correction for PI correction to the pre-pit position is performed.

  In the correction block n + 2 in FIG. 6, in order to satisfy the condition for adding the erasure correction pointer for PI correction at the prepit position, the erasure correction pointer for PI correction is added to the prepit position in the correction block n + 3.

  The number of occurrences of errors in the pre-pit position is measured, and if the measurement result satisfies the condition for adding a pointer for erasure correction for PI correction to the pre-pit position, a pointer for erasure correction for PI correction is added to the pre-pit position. In many cases, the PI-PO can be corrected twice, thereby improving the reproduction performance.

  The operation of deleting the erasure correction pointer for PI correction of the pre-pit position will be described taking the case of the position of the pre-pit error 1 as an example.

  In one correction block, the number of occurrences of errors at the position of pre-pit error 1 is measured based on the correction status of PI correction, and the occurrence of errors in the column of pre-pit error 1 based on the correction status of PO correction Measure the number.

  Based on the measurement result of the number of error occurrences at the prepit error 1 position and the measurement result of the number of error occurrences in the prepit error 1 column, the error occurrence status at the position of the prepit error 1 in the correction block Generate information about.

  When the information regarding the occurrence status of the error at the position of the prepit error 1 in the correction block satisfies a condition for deleting the pointer for erasure correction of the position of the prepit error 1 (hereinafter referred to as condition 3), Information indicating that the condition 3 is satisfied is generated.

  Similarly, in each correction block that is sequentially reproduced, the number of occurrences of the error at the position of the prepit error 1 in each correction block is measured, and information indicating that the condition 3 is satisfied is generated.

  For each reproduced correction block, the number of correction blocks indicating that the condition 3 is satisfied is measured, and the position of the pre-pit error 1 is erasure-corrected over one or more reproduced correction blocks. When the condition for deleting the pointer (hereinafter referred to as condition 4) is satisfied, the system controller 14 is notified that the position of the prepit error 1 satisfies the condition for deleting the pointer for erasure correction for PI correction. To do.

  Here, the condition 3 may be a case where the condition 1 is not satisfied, and the condition 4 may be a case where the condition 2 is not satisfied.

  When the system controller 14 receives that the condition for deleting the pointer for erasure correction for PI correction at the position of the pre-pit error 1 is satisfied, the system controller 14 sets the pointer for erasure correction for PI correction after the next correction block. The deletion is transmitted to the pre-pit position information generation circuit 15 and the error correction circuit 5.

  The operation of deleting the erasure correction pointer for PI correction at the pre-pit position will be described by taking as an example a case where the data reproduced from the optical disc 1 is a correction block as shown in FIG.

  Here, condition 3 is a case where the number of errors is less than 16 at the position of prepit error 1 in the one correction block, and condition 4 is a case where correction blocks satisfying condition 3 are consecutive in three correction blocks from the start of measurement. If this occurs.

  In the correction block m in FIG. 6, the number of error occurrences at the position of the prepit error 1 is measured, and information indicating that the condition 3 is satisfied is generated and stored. Similarly, also in the correction blocks m + 1 and m + 2 in FIG. 6, the number of error occurrences at the position of the prepit error 1 is measured, and information indicating that the condition 3 is satisfied is generated.

  In the correction block m + 2 in FIG. 6, the correction block satisfying the condition 3 is continued by three correction blocks, and therefore the condition 4 is satisfied. Therefore, the system controller 14 is notified that the position of the pre-pit error 1 satisfies the condition for deleting the pointer for erasure correction for PI correction.

  When the system controller 14 receives that the condition for deleting the pointer for erasure correction for PI correction at the position of the pre-pit error 1 is satisfied, the system controller 14 sets the pointer for erasure correction for PI correction after the next correction block. The deletion is transmitted to the pre-pit position information generation circuit 15 and the error correction circuit 15.

  Similarly, the number of occurrences of errors is measured for pre-pit errors 2, 3, and 4. In order to satisfy the conditions 3 and 4, the pointer for erasure correction for PI correction of the prepit position is deleted.

  In the correction block m + 2 shown in FIG. 6, the condition for deleting the erasure correction pointer for PI correction of the prepit position is satisfied. Therefore, the erasure correction pointer for PI correction of the prepit position is deleted from the correction block m + 3.

  If an error as shown in FIG. 8 has occurred, if the erasure correction pointer is not added to the pre-pit position, error correction of the pre-pit position is not forcibly performed. It is possible to correct all errors by detecting and correcting the code string. If all errors have been corrected in the first PI correction, error correction processing does not occur in the subsequent PO correction step.

  When error correction execution processing does not occur in the last PO correction, there is no error in output data that occurs due to an error correction or data update in the memory in the last PO correction. Therefore, it is not necessary to correct the PO-PI-PO three times, and the correction can be performed by correcting the PI-PO twice.

  In the second embodiment, the condition 2 is determined based on whether or not the number of correction blocks satisfying the condition 1 continuously satisfies a predetermined number. However, the present invention is not limited to this, and it may be based on whether or not the correction blocks satisfying the condition 1 satisfy a predetermined number regardless of continuous or discontinuous.

  Similarly, in the second embodiment, the condition 4 is based on whether or not correction blocks satisfying the condition 3 continuously satisfy a predetermined number. However, it may be determined whether or not the number of correction blocks satisfying the condition 3 satisfies a predetermined number regardless of continuous or discontinuous.

  As described above, according to the second embodiment, the number of occurrences of errors at the prepit position is measured, and the measurement result satisfies the condition for adding or deleting the erasure correction pointer for PI correction at the prepit position. By adding or deleting an erasure correction pointer for PI correction of the pre-pit position, in many cases, error correction can be performed twice with PI-PO, and reproduction performance is improved.

(3) Embodiment 3
FIG. 17 shows the configuration of an optical disk error correction apparatus according to the third embodiment of the present invention. In the third embodiment, unlike the first and second embodiments having the configuration shown in FIG. 1, PI code string symbol position information is generated from the demodulation circuit 4 and output to the prepit position information generation circuit 15. In addition, a prepit detection pulse is generated from the prepit decoder 13 and output to the prepit position information generation circuit 15.

  Unlike the first and second embodiments, the erasure correction pointer is added or deleted corresponding to the pre-pit position in the even position or the odd position.

  The correction process according to the third embodiment will be described taking an example in which an error as shown in FIG. 18 occurs.

  In the third embodiment, it is assumed that the recording data is recorded on the recording disk in a state where it deviates from the state based on the standard for some reason when it is recorded on the recordable disk.

  In FIG. 18, an error occurs in the first half of one correction block due to the pre-pits in the even positions, and an error occurs in the second half due to the pre-pits in the odd positions.

  The PI code sequence from PI sequence -1 to PI sequence 8 is the position of the pre-pit sync at even positions, that is, the position of PO sequence-1 and PO sequence-2, and the adjacent position, that is, PO sequence-3 and PO sequence- An error occurs in the symbol at position 4, and an error occurs in two other random locations. A total of six symbols are in error.

  In the PI code sequence from PI sequence -9 to 16, an error occurs in the symbol of the odd-numbered position of the pre-pit sync, that is, the position of the PO sequence -5, and the adjacent position, that is, the position of the PO sequence -7. In addition, an error of four symbols has occurred, and a total of six symbol errors have occurred.

  In the PI code sequence from PI sequence -17 to 25, an error occurs in the symbols of the odd-numbered positions of the prepit data, that is, the position of the PO sequence -6 and the adjacent position, that is, the position of the PO sequence -8. In addition, an error of four symbols has occurred, and a total of six symbol errors have occurred.

  In the PI code string of PI string -26, four errors occur in symbols other than the position of the prepit sync and the position of the prepit data.

  Here, as a condition for adding an erasure correction pointer to the prepit position of the PI code string in which the prepit exists, if there is one column in which an error exists in the prepit position, an erasure correction pointer is added, It is assumed that the pointer for erasure correction is deleted when there is one column in which no error exists at the prepit position of the PI code sequence in which the prepit exists (hereinafter referred to as condition β).

  The prepit decoder 13 generates PI code string symbol position information corresponding to a counter value as shown in FIG. 19 and a prepit detection pulse when reproducing the PI strings -1 to 8 in FIG. In an even position sync frame, pre-pit detection pulses are output at the start time and at the (j + 1) -th symbol and the (k + 1) -th symbol corresponding to the pre-pit position on the correction block.

  Here, FIG. 20 shows the pre-pit positions of the (j + 1) th symbol and the (k + 1) th symbol in one correction block.

  Similarly, when the PI trains -9 to 16 in FIG. 18 are reproduced, as shown in FIG. 21, the pre-pit detection pulse is output at the start time at the odd position and at the (m + 1) th symbol. Further, when the PI trains 17 to 25 are reproduced, as shown in FIG. 22, the pre-pit detection pulse is output at the start time at the odd position and at the (n + 1) th symbol.

  The pre-pit position information generation circuit 15 receives from the demodulation circuit 4 a signal indicating the PI code string symbol position and a signal indicating a delimiter such as a correction block unit or a sector unit as shown in FIGS. . Then, prepit position information in the PI code string direction on the correction block is generated from the signal indicating the PI code string symbol position.

  Taking the pre-pit position information of the correction block shown in FIG. 18 as an example, the columns of PI columns -1 to 8 correspond to the position of PO column -1 in the j + 1 symbol shown in FIG. 19 and FIG. The position of -2 corresponds to the (k + 1) th symbol. In the columns PI columns -9 to 16, the PO column-5 is positioned at the (m + 1) th symbol shown in FIGS. 21 and 23, and the columns PI columns -17 to 25 are positioned in the PO column -6 in FIGS. This corresponds to the (n + 1) th symbol shown.

  Further, the prepit position information generation circuit 15 determines whether the received prepit detection pulse is a sector head line (the first line of the sector, prepit sync exists) from a signal indicating a delimiter such as a correction block unit or a sector unit, or Pre-pit position information in the PO code string direction for the second to thirteenth lines (prepit data exists) of the sector is generated.

  Hereinafter, the position of the PO row-1 is the position of the prepit error 21, the position of the PO row-2 is the position of the prepit error 22, the position of the PO row-3 is the position of the prepit error 23, and the position of the PO row-4 , The position of the prepit error 24, the position of the PO row-5 is the position of the prepit error 25, the position of the PO row-6 is the position of the prepit error 26, the position of the PO row-7 is the position of the prepit error 27, The position of the PO row -8 is the position of the prepit error 28.

  FIG. 24 shows a flow of correction processing in the third embodiment. In particular, it differs from the first embodiment shown in FIG. 5 in that step 13 a is added after step 13.

  In step 13a, prepit position information is generated based on the generated prepit detection pulse. This pre-pit position information indicates that the detected pre-pit position is the position of the pre-pit sync at the even position in the first line of the sector, the position of the pre-pit sync at the odd position, the position of the pre-pit data “1” at the even position, and the odd position. One of the positions of the pre-pit data “1” is indicated. In the next step 14, the position of the pre-pit is newly recognized based on this information. The description regarding the same steps as those in the first embodiment is omitted.

  FIG. 25 shows the erasure correction at the position of the pre-pit sync at the even position, the position of the pre-pit data “1” at the even position, the position of the pre-pit sync at the odd position, and the position of the pre-pit data “1” at the odd position. The schematic diagram of addition determination of a pointer is shown.

  Errors in PI columns -2 to 8, 10 to 16, and 18 are corrected by PI correction, and errors in PI columns-1, 9, and 17 are corrected by PO correction.

  When the pointer for erasure correction is added to the position of pre-pit errors 21 to 24 of all PI code strings, it is corrected by adding or not adding the pointer for erasure correction according to the error of the pre-pit position. The processing efficiency is improved, and in many cases, PO-PI-PO is not corrected three times, so that the reproduction performance is improved.

(4) Embodiment 4
The configuration of an optical disk error correction apparatus according to Embodiment 4 of the present invention is shown in FIG.

  Compared with the first to third embodiments shown in FIG. 1, the fourth embodiment is different in that prepit presence / absence information is output from the prepit decoder 13 to the prepit position information generation circuit 15. The prepit decoder 13 transmits prepit presence / absence information indicating whether the bit pattern of the prepit reproduced from the optical disc 1 is prepit sync or prepit data “1” to the prepit position generation circuit 15.

  Here, since no prepit exists in the data writing area, the prepit data “0” is excluded without causing an error in reading due to the prepit.

  The processing procedure in the fourth embodiment is shown in the flowchart of FIG. Compared to the processing procedure in the first embodiment shown in FIG. 5, the difference is that step S15A and step S15B are added between step S15 and step S16.

  In step S15, it is determined whether a condition for erasure correction of the prepit position is satisfied.

  When this condition is satisfied, the process proceeds to step S15A, and it is determined whether or not the pre-pit sync or pre-pit data is “1”.

  If it is pre-pit sync or pre-pit data “1”, the process proceeds to the same step S16 as in the first embodiment, and if different, the process proceeds to step S15B.

  In the case of pre-pit sync, the pre-pit position is the j + 1-th symbol and the k + 1-th symbol shown in FIGS. 19 and 20, and the m + 1-th symbol shown in FIGS.

  In the case of pre-pit data “1”, the pre-pit position is the (k + 1) th symbol shown in FIGS. 19 and 20 and the (n + 1) th symbol in FIGS. 22 and 23.

  In step S15B, detection correction is performed with the PI code alone, and the process proceeds to step S19.

  The prepit position information generation circuit 15 generates prepit position information for each PI code string on the correction block.

  Based on the correction status of the error correction circuit 5, the pre-pit position error measurement circuit 16 pre-pit positions of the PI code string where the pre-pit sync or pre-pit data “1” exists, that is, the j + 1-th symbol, the k + 1-th symbol, and the m + 1-th symbol. For each of the symbols and the (n + 1) th symbol, detection and measurement such as the position of the prepit error a shown in FIG. 14 is performed as in the first embodiment, and the erasure is performed when the condition α is satisfied. A signal to add a correction pointer is transmitted to the system controller 14.

  The error correction circuit 5 receives a signal indicating that an erasure correction pointer is added to the prepit position from the system controller 14 and corrects the PI code string in which prepit sync or prepit data “1” exists In addition, an error correction pointer is added to the pre-pit position to perform error correction.

  If the PI code string to be corrected has a pre-pit sync at an even position, erasure correction pointers are added to the j + 1 and k + 1 symbols of the PI code string to perform erasure correction. When the pre-pit does not exist in the PI code string to be corrected, the PI code alone is detected and corrected.

  When an error such as the correction block B shown in FIG. 11 occurs, a pointer for erasure correction is added to the positions of the PO columns 1 to 4 for the PI columns 2-1 to 16, and the PI code alone The erasure correction is performed together with the correction.

  For PI columns-2-17 to 33, erasure correction pointers are added to the positions of PO column 2 and PO column 4, and erasure correction is performed together with correction of the PI code alone. For PI columns other than the above, correction is performed using the PI code alone. Thereby, since all errors can be corrected only by PI correction, it is not necessary to perform three corrections of PO-PI-PO, and the reproduction performance is improved.

  In the fourth embodiment, when the pre-pit position on the correction block is the pre-pit sync, the j + 1-th symbol, the k + 1-th symbol, and the m + 1-th symbol are set. If the pre-pit position on the correction block is pre-pit data “1”, the k + 1-th symbol and the n + 1-th symbol are used. However, the present invention is not limited to this, and these positions may be positions according to the standard, and may be controlled by the system controller 14.

  In the fourth embodiment, the pre-pit position on the correction block is usually only the even position because there is a tendency for the pre-pits to be more in the even position. However, the pre-pit position on the correction block may be only an odd position, or may be both an even position and an odd position.

(5) Embodiment 5
The configuration of the optical disk error correction apparatus according to the fifth embodiment of the present invention is as shown in FIG. 26 as in the fourth embodiment, and the processing procedure is shown in FIG.

  Compared with the processing procedure in the fourth embodiment shown in FIG. 27, the processing in step S15AA is different. That is, the pre-pit decoder 13 is configured so that the pre-pit bit pattern reproduced from the optical disc 1 has an even-position pre-pit sync, an even-position pre-pit data “1”, an odd-position pre-pit sync, and an odd-position pre-pit data. Pre-pit presence / absence information indicating whether it is “1” is generated and transmitted to the pre-pit position information generation circuit 15.

  The prepit position information generation circuit 15 generates prepit position information for each PI code string on the correction block. When the reproduced pit pattern is a prepit sync, the positions of the prepits are the j + 1th symbol, the k + 1th symbol, and the m + 1th symbol.

  When the pit pattern of the prepit is prepit data “1”, the prepit position is the (k + 1) th symbol and the (n + 1) th symbol.

  Based on the correction status of the error correction circuit 5, the pre-pit position error measurement circuit 16 pre-pit positions of the PI code string where the pre-pit sync or pre-pit data “1” exists, that is, the j + 1-th symbol, the k + 1-th symbol, and the m + 1-th symbol. For each symbol and n + 1th symbol, detection and measurement such as the position of the prepit error a shown in FIG. 14 is performed, and a pointer for erasure correction is added when the condition α is satisfied. A signal is transmitted to the system controller 14.

  The error correction circuit 5 receives a signal indicating that an erasure correction pointer is added to the prepit position from the system controller 14 and corrects the PI code string in which prepit sync or prepit data “1” exists Further, error correction is performed by adding a pointer for erasure correction to the pre-pit position of either the even position or the odd position where pre-pit sync or pre-pit data “1” exists.

  If the PI code string to be corrected has a pre-pit sync at an even position, erasure correction pointers are added to the j + 1 and k + 1 symbols of the PI code string to perform erasure correction. If there is no pre-pit in the PI code string to be corrected, the PI code alone is used for correction.

  When an error as shown in FIG. 18 occurs, an erasure correction pointer is added to the positions of the PO columns 1 to 4 in the PI columns -1 to 8 and erasure correction is performed together with correction of the PI code alone.

  In the PI columns -9 to 16, erasure correction pointers are added to the positions of the PO columns 5 and 7, and erasure correction is performed together with correction of the PI code alone.

  In PI columns -17 to 25, erasure correction pointers are added to the positions of the PO columns 6 and 8, and erasure correction is performed together with correction of the PI code alone. For other PI sequences, correction is performed using the PI code alone.

  As a result, according to the fifth embodiment, an error caused by the effect of the pre-pit is obtained by adding or deleting a PI correction erasure correction pointer to the pre-pit position in accordance with the occurrence state of the pre-pit position error. Playback performance is improved because it is possible to flexibly respond to the occurrence status of

  According to the first to fifth embodiments described above, preformat information recorded in a state that cannot be erased in advance when data recorded on a recordable disc such as a DVD-R / RW is reproduced. When an error occurs in the recording data due to the effect of the prepit, the PI correction is performed twice by adding or deleting the PI correction erasure correction pointer to the prepit position according to the prepit position error occurrence state. And improve playback performance.

1 is a block diagram showing a configuration of an optical disk error correction device according to a first embodiment of the present invention. Explanatory drawing which shows recording data, a wobble signal, and a prepit signal when a prepit exists in an even-numbered sync frame. Explanatory drawing which shows the relationship between the 1st prepit when a prepit exists, and the sync of recording data. Explanatory drawing which shows the structure of 1 correction block. 6 is a flowchart showing a procedure of correction processing in the error correction method for an optical disc according to the first embodiment. 6 is a flowchart showing a procedure of correction processing in the error correction method for an optical disc according to the first embodiment. FIG. 3 is an explanatory diagram showing an error occurrence status of a correction block reproduced from an optical disc, presence / absence of a pointer for erasure correction at a prepit position, and the like. FIG. 3 is an explanatory diagram illustrating an error occurrence state on a correction block when an error of 2 symbols generated due to the influence of a pre-pit and other errors occur. Explanatory drawing which shows the generation | occurrence | production condition of the error on a correction block when an error generate | occur | produces other than the position of a prepit. Explanatory drawing which shows the correction block when the error has not occurred. Explanatory drawing which shows the generation | occurrence | production condition of the error on the correction block A when the error of 2 symbols generate | occur | produces by the influence of a prepit (even position), and another error generate | occur | produces. Explanatory drawing which shows the generation | occurrence | production situation of the error on the correction block B when the error of 2 symbols generate | occur | produces by the influence of a prepit (even position), and another error generate | occur | produces. Explanatory drawing which shows the generation | occurrence | production condition of the error on the correction block C when the error of 2 symbols generate | occur | produces by the influence of a prepit (even number position), and another error generate | occur | produces. Explanatory drawing which showed the relationship between the position of the data in a correction block, and the position of a prepit. 3 is an explanatory diagram showing a positional relationship between a PI code string reproduced from an optical disc and a prepit error. FIG. The flowchart which shows the procedure in the case of performing error detection and measurement of a prepit position with respect to the PI code series 208 columns. The flowchart which shows the procedure in the case of performing error detection and measurement of a prepit position with respect to the PI code series 208 columns. 9 is a flowchart showing a correction processing procedure in an optical disk error correction method according to a second embodiment of the present invention. 9 is a flowchart showing a correction processing procedure in an optical disk error correction method according to a second embodiment of the present invention. 9 is a flowchart showing a correction processing procedure in an optical disk error correction method according to a second embodiment of the present invention. The block diagram which shows the structure of the error correction apparatus of the optical disk by Embodiment 3 of this invention. Explanatory drawing which shows the generation | occurrence | production situation of the error on a correction block when the error of 2 symbols and other errors generate | occur | produced by the influence of a prepit (even position and odd position). Explanatory drawing which showed the method in which the prepit information generation circuit produces | generates the signal which detects the prepit position in the even position of a correction block. Explanatory drawing which showed the positional relationship of the prepit detection signal and correction block data in the even position of a correction block. Explanatory drawing which showed the method in which the prepit information generation circuit produces | generates the signal which detects the prepit position in the odd-numbered position of a correction block. Explanatory drawing which showed the method in which the prepit information generation circuit produces | generates the signal which detects the prepit position in the odd-numbered position of a correction block. Explanatory drawing which showed the positional relationship of the prepit detection signal and correction block data in the odd-numbered position of a correction block. 10 is a flowchart showing a correction processing procedure in the optical disk error correction method according to the third embodiment. 10 is a flowchart showing a correction processing procedure in the optical disk error correction method according to the third embodiment. Explanatory drawing which shows the generation | occurrence | production condition of the error when the error of 2 symbols and others generate | occur | produce by the influence of the prepit in the even position and odd position of a correction block. The block diagram which shows the structure of the error correction apparatus of the optical disk by Embodiment 4 and 5 of this invention. 9 is a flowchart showing a processing procedure in an optical disc error correction method according to the fourth embodiment. 9 is a flowchart showing a processing procedure in an optical disc error correction method according to the fourth embodiment. 10 is a flowchart showing a processing procedure in an error correction method for an optical disc according to the fifth embodiment. 10 is a flowchart showing a processing procedure in an optical disk error correction method according to the fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Pickup 3 Matrix amplifier 4 Demodulation circuit 5 Error correction circuit 6 Correction RAM
7 Data buffer circuit 8 Host computer 9 Parity generation circuit 10 Modulation circuit 11 Laser control circuit 12 Wobble PLL circuit 13 Prepit decoder 14 System controller 15 Prepit position information generation circuit 16 Prepit position error measurement circuit

Claims (6)

First code string data in which an error code is added to the recording unit of the optical disk in the same direction as the order of recording information, and the first code string as a recording guide for recording the first code string data on the optical disk An error correction device for reproducing recorded information from an optical disc on which recording guide information is recorded in advance in a state where it cannot be erased before being recorded,
A first position detector that detects a singular point on the physical structure in the recording guide information as a first position;
A second position generation unit that generates a second position by replacing the first position detected by the first position detection unit with the position of the first code string data;
An error detector for detecting an error in the data at the second position;
An error measuring unit for measuring the number of errors detected by the error detecting unit;
When the number of errors measured by the error measurement unit for a predetermined period satisfies a desired value, an erasure correction pointer is assigned in advance to the second position in the first code string data to identify the second position. An error correction unit that forcibly performs erasure correction processing of the first code string data at the second position;
It is characterized by providing .   The error correction apparatus according to claim 1, wherein the error detection unit that detects an error in the data at the second position detects an error position from the first code string data.   The error detection unit for detecting an error in the data at the second position detects an error position from the second code string data to which an error code is added in a direction different from the first code string. The error correction device according to 1. The optical disc is a DVD-R or DVD-RW disc;
4. The method according to claim 1, wherein the second position generation unit generates the second position based on information on whether the first detection unit has detected the singular point . 5. The error correction apparatus according to one item. The first detection unit has means for identifying a bit pattern of the singular point ,
The second position generator is
When the bit pattern of the singular point detected by the first detector is a prepit sync, the first predetermined position (J) and the second predetermined position (K) are set as the second position (where J <K ),
5. The error correction apparatus according to claim 4, wherein when the bit pattern of the singular point is pre-pit data 1, the second predetermined position (K) is set as the second position. The first detection unit includes:
Means for identifying a bit pattern of the singular points ;
The singular point detected by the first detection unit is an even sync frame of the first code string data;
Means for identifying which frame of the odd sync frame is present,
The second position generator is
When the singular point detected by the first detection unit exists in the even sync frame of the first code string data, and the bit pattern of the singular point detected by the first detection unit is a pre-pit sync, The first predetermined position (J) and the second pre-pit position (K) are set as the second position,
When the singular point detected by the first detection unit exists in an even sync frame of the first code string data, and the bit pattern of the singular point detected by the first detection unit is prepit data 1 , The second predetermined position (K) as the second position,
When the singular point detected by the first detection unit exists in an odd sync frame of the first code string data, and the bit pattern of the singular point detected by the first detection unit is a pre-pit sync, The third predetermined position (L) is the second position,
When the singular point detected by the first detection unit exists in an odd sync frame of the first code string data, and the bit pattern of the singular point detected by the first detection unit is prepit data 1 5. The error correction apparatus according to claim 4, wherein the fourth predetermined position (M) is the second position (where J <K <L <M).

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