JP2005149586A - Information detection method, information detector, and information detection program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for accurately detecting information (for instance, basic information such as an information reproduction condition from a recording medium) from the recording medium even under a deteriorated reproduction condition. <P>SOLUTION: A code word block constituted of an information part, a second correction code for it, and a first correction code for respective sub blocks which are obtained by dividing the information part and the second correction code by a prescribed unit, is repeatedly recorded in the prescribed area of the recording medium. Every time each code word block is read, it is stored in a first storage means, error correction using each first correction code to each sub block is executed, and the sub block which becomes correctable even once is held in a corresponding storage area in a second storage means. In the case that the number of the sub blocks in which an uncorrectable state continues becomes equal to or less than the number based on the correction ability of the second correction code, data stored in the second storage means are corrected by using the second correction code, and the information part is detected from the corrected data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method, apparatus, and program for detecting information recorded on a recording medium. In particular, basic information such as recording / reproducing conditions of an optical disc is repeatedly recorded in a predetermined area of the disc and reproduced. The present invention relates to a method for accurately detecting the basic information even under bad conditions where conditions are not optimally set.

  Optical recording media include CD (Compact disc) and DVD (Digital versatile disc) playback types, CD-R (recordable) and DVD-R write once types, and CD-RW (rewritable). ), DVD-RAM (random access memory), DVD-RW and other rewritable types, etc., but the recording formats are different.

As shown in FIG. 7, the track is formed in a land / groove form for a CD standard write-once optical disk such as CD-R or CD-RW, and the groove 101 and land 102 have a constant frequency (22.05 kHz). It is slightly wobbling left and right.
The wobble is recorded by phase-modulating address information (ATIP) indicating the absolute position of the track. In the optical disc apparatus, a wobble signal is detected from the reflected light of the light spot 103 irradiated on the track from the optical pickup, It is used as a disk rotation control signal and a signal for creating a reference clock when recording / reproducing information.
Also, there are various types of modulation methods for the wobble. For example, in FIG. 8A, a binary value of “0” and “1” is determined depending on whether or not the phase of a 6.5-cycle sine wave wobble is inverted. In FIG. 5B, binary data is similarly represented by adding or subtracting a wave having a frequency twice as high as that of the fundamental wave of the 6-cycle sine wave wobble at a constant rate. Yes.
On the other hand, land / groove type tracks are wobbling on DVD-R, DVD-RAM, etc., but the address information of the disc is created as pits on the land side, and the wobble is used for disc rotation control. The recording is performed in a non-modulation system to provide the clock information (140 KHz).

  Recently, not only the address information as described above, but also basic information such as recording / reproducing conditions peculiar to the optical disc such as reproducing light output, recording light output, and reproducing linear velocity is recorded in the predetermined area by the wobble. The optical disc apparatus is expected to set the optimum conditions in the recording / reproducing mode by reading the basic information in advance by the optical disc apparatus, and to realize compatibility between different optical disc apparatuses. .

By the way, in the signal detection from the wobble, the detection accuracy often deteriorates due to the crosstalk from the adjacent tracks and the formation state of the wobble itself.
For this reason, various proposals have been made to increase information detection accuracy. For example, according to Patent Document 1 below, an error correction having an error correction capability with respect to an address value recorded on a recording medium is available. There has been disclosed a technique for improving operation efficiency by adding a code so that even if there is an error in a detected address value, it can be restored to a correct address value using an error correction code.
In addition, a method of improving detection accuracy by repeatedly recording information collected in a predetermined unit such as the basic information and acquiring information in a good detection state has been implemented.

JP-A-11-31365

Recently, however, the track pitch has become increasingly narrower due to the trend toward higher density recording of optical disks, and the detection conditions for wobble signals have become more severe because the S / N ratio and C / N ratio of detection signals have decreased. Yes.
When the basic information such as the recording / reproducing condition is recorded on the optical disc in the wobble as described above and the information is read in advance, the basic information detected because the optical disc apparatus is not set to the optimum condition. There is a high probability that the information contains errors.
That is, various conditions corresponding to the optical disc cannot be set accurately for the optical disc apparatus, and the quality and reliability of recording and reproduction are impaired.
Therefore, in view of the above-described problems, the present invention provides an information detection method and information detection method that can accurately and accurately detect various information from a recording medium under bad reproduction conditions. It was created for the purpose of providing a device and an information detection program.

  In the present invention, a codeword block includes a predetermined information part, a plurality of first correction codes, and a second correction code, and each first correction code includes the information part and the second correction code in a predetermined unit. And the second correction code has error correction capability for the information unit, and the codeword block is recorded on the recording medium. The information detecting method, the information detecting apparatus, and the information detecting program for detecting the information part while reading each codeword block from the recording medium repeatedly and recording the code word block, respectively, have the following configurations: Consists of.

  In the information detection method of the present invention, each time the codeword block is read, the codeword block is stored in the first storage unit, and error correction using each first correction code for each subblock is performed. A subblock that can be corrected at least once by the error correction related to each codeword block is held in a storage area associated with the subblock in the second storage means, and the uncorrectable state continues. The second correction code is used for the data in the second storage means when the number of sub-blocks is counted and the count number is equal to or less than the number based on the error correction capability of the second correction code. Error correction is performed, and the information section is detected from each corrected sub-block.

  The information detection apparatus of the present invention includes a first storage unit that stores a codeword block each time the codeword block is read from the recording medium, and a sub-block of the codeword block stored by the first storage unit. And a first correction unit that performs error correction using the first correction code, and a storage area associated with each sub-block of the codeword block, and the first correction for each codeword block As a result of error correction by the means, second storage means for holding the sub-blocks that can be corrected even once in the corresponding storage area, and counting means for counting the number of sub-blocks in which the uncorrectable state continues , When the count number of the counting means is equal to or less than the number based on the error correction capability of the second correction code, A second correction means for performing error correction using a plus sign, and further comprising a detection means for detecting the information unit from the respective sub-blocks after correction by the second correction means.

  The information detection program of the present invention stores the codeword block in the first storage means each time the codeword block is read, and for each sub-block of the codeword block stored in the first storage means. And performing error correction using each first correction code, and holding a sub-block that can be corrected even once by the error correction in a storage area associated with the sub-block in the second storage means A step of counting the number of sub-blocks in which the uncorrectable state continues, and when the count number is less than or equal to the number based on the error correction capability of the second correction code, Performing error correction on the data using the second correction code, and sub-blocks after error correction using the second correction code. Characterized in that the click to perform the steps in the computer to detect the information unit.

The operation of the present invention will be described below.
First, on the recording medium, a code word block composed of a predetermined information portion, a second correction code, and each first correction code for each sub-block obtained by dividing them by a predetermined unit is repeatedly recorded. Each codeword block is overwritten.
Each time each codeword block is read and stored in the first storage means, each sub-block is subjected to error correction by each first correction code, and can be corrected even once by the error correction. The sub-block is held in the corresponding storage area of the second storage means.
Here, when correction is possible, there is no error in the sub-block and the first correction code, and even if there is an error in the sub-block and the first correction code, the correction can be performed using the first correction code. In other words, the case where correction is impossible is a case where an error exists in the sub-block and / or the first correction code, and the error cannot be corrected even by the first correction code.
It should be noted that the storage area associated with the sub-blocks in which the uncorrectable state is continuous may be stored as arbitrary data having the same number of bits as the sub-block.
By over-reading codeword blocks, the number of sub-blocks in which the uncorrectable state continues is generally reduced.
However, in the present invention, the number of sub-blocks in which the uncorrectable state is continuous does not need to be 0, and the number may be equal to or less than the number based on the error correction capability of the second correction code.
In other words, if the number condition is satisfied, it is possible to correct the error location of the sub-block constituting the information part by the second correction code, and it cannot be corrected no matter how many times the codeword block is read repeatedly. There is no problem even if the sub-block exists, and an error-free information part can be detected.
It does not matter whether each subblock and each subblock correction code are systematically coded or non-systematically coded.

According to the information detection method, the information detection apparatus, and the information detection program of the present invention, it is possible to accurately detect recorded information while overwriting a codeword block from a recording medium even under poor reproduction conditions.
In particular, even when the optical disc apparatus is not set with favorable playback conditions, basic information such as recording / playback conditions repeatedly recorded on the optical disc with wobbles, land prepits, etc. can be accurately detected. By setting the recording / reproduction conditions based on the basic information, it is possible to always perform high-quality recording / reproduction under the optimum conditions corresponding to the optical disc.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 to 6.
[Embodiment 1]
First, FIG. 1 is a block circuit diagram of an optical disc apparatus to which an information detection apparatus according to the present invention is applied, and mainly shows the configuration of a reproduction signal processing section and an information detection section.
In the figure, reference numeral 1 denotes a groove recording type optical disk to which wobble is applied. A code word block related to basic information such as recording / reproducing conditions is repeatedly recorded as wobbling information in a predetermined area of the optical disk 1. Yes.

The data string of each codeword block has a configuration as shown in FIG. 2A, and the relationship between the information part and the correction code is as shown in FIG.
Here, [DATA (1) to DATA (9)] is an information part corresponding to the basic information, and [ECC (D1) to ECC (D3)] is a first part having a correction capability for the entire information part. 2 correction codes, and each DATA (i) [i = 1 to 9] and ECC (Dj) [j = 1 to 3] are sub-blocks obtained by dividing the basic information and the data of the second correction code by a predetermined unit. It is.
ECC (n) [n = 1 to 12] has a correction capability with respect to each sub-block: DATA (i) [i = 1 to 9] and ECC (Dj) [j = 1 to 3]. 1 correction code.
In the case of FIG. 2 (A), after arranging DATA (i) [i = 1 to 9] and ECC (n) [n = 1 to 9] alternately, ECC (Dj) [j = 1 to 3] and ECC (n) Although the data string configuration of codeword blocks in which [n = 10 to 12] are alternately arranged, when processing is performed in units of codeword blocks, information as shown in FIG. It is composed as a data string in which the part [DATA (1) to DATA (9)] and the correction code: [ECC (D1) to ECC (D3)] and [ECC (1) to ECC (12)] are connected. May be.

  The reproduction signal processing unit 2 of the optical disc apparatus includes an optical pickup 21 that receives the reflected light of the laser beam irradiated on the optical disc 1, a reproduction amplifier 22 that amplifies the light reception read signal of the optical pickup 21, and waveform distortion of the read signal. An equalizer circuit 23 that suppresses intersymbol interference caused by the signal, a waveform shaping circuit 24 that shapes the output signal of the equalizer circuit 23 and converts it into a pulse signal, and a VCO (Voltage Control Oscillator) are used to synchronize with the wobble. A PLL (Phase Locked Loop) circuit 25 that generates a fundamental frequency signal (synchronization signal) and a synchronous detection circuit 26 that samples a wobble signal based on the synchronization signal obtained from the PLL circuit 25. Sampling by the synchronous detection circuit 26 Data is taken into the information detector 3.

The information detection unit 3 is a part that detects the basic information, and includes a data determination unit 30, two memories 31 and 33, a first correction unit 32, a count unit 34, and a reading unit 36.
First, the data determination unit 30 generates binary data based on the correspondence between the signal waveform obtained from the acquired sampling data and “1” or “0” [the relationship as shown in FIGS. 8A and 8B]. The data string of the converted codeword block is saved in the memory 31.

In the first correction unit 32, at the stage where the first codeword block (1) is saved in the memory 31, each sub-block: DATA (i) [i = 1 to 9], ECC (Dj) [j = Error correction is performed using the first correction code: ECC (n) [n = 1 to 12] respectively associated with 1 to 3], and the sub-block in which error correction was possible is saved in the memory 33.
In that case, storage areas corresponding to the sub-blocks: DATA (i) [i = 1 to 9] and ECC (Dj) [j = 1 to 3] are set in the memory 33 in advance, and after error correction. The subblock is saved in the corresponding storage area.
As for the storage area of the memory 33 corresponding to the sub-block that cannot be corrected, any data may be stored if the number of bits is the same as that of each sub-block. In the initial state, all storage areas of the memory 33 are set to a code of only “0” or “1”, and only the storage area related to the uncorrectable sub-block is used as the code data. Can be adopted.

When the processing for the first codeword block (1) is completed, the counting unit 34 counts the number of sub-blocks stored in the memory 33.
When the count number of the count unit 34 is larger than the number related to the correction capability of the second correction code [ECC (D1) to ECC (D3)] for the entire information unit, the first correction unit 32 saves in the memory 31. Error correction using the first correction code: ECC (n) [n = 1 to 12] is executed for each sub-block of the second codeword block (2).
In this case, since the sub-block that can be corrected in the first codeword block (1) has already been saved in the corresponding storage area of the memory 33, the storage area related to such sub-block is newly stored in the storage area. Only the sub-block that can be corrected for the first time is saved in the corresponding storage area.
Of course, all the sub-blocks that can be corrected may be written in an overwriting manner in the corresponding storage area of the memory 33.

Therefore, the sub-blocks that can be corrected in either one of the codeword blocks (1) and (2) are saved in the corresponding storage area of the memory 33. When the count number is larger than the number related to the correction capability of the second correction code [ECC (D1) to ECC (D3)], the first correction unit 32 performs the next code as described above. Correction is performed for each sub-block of word block (3).
The above procedure is repeatedly executed until the count number of the counting unit 34 satisfies the above condition, and when the condition is satisfied, the second correction unit 35 applies the second correction code: ECC ( Dj) Perform error correction using [j = 1 to 3].
In that case, the second correction code: ECC (Dj) [j = 1 to 3] is also a sub-block, and there is a possibility that there is an uncorrectable one in the sub-block. In other words, the sub-block which has become uncorrectable is corrected to the original data recorded on the recording medium 1 by the second correction unit 35.

FIG. 3 shows the correction result for each codeword block (k) by the first correction unit 32 and the sub-blocks for each storage area of the memory 33: DATA (i) [i = 1 to 9], ECC (Dj). The save state of [j = 1 to 3] is shown as a specific example. However, “NUL” in the figure is a code composed of “0” or “1” having the same number of bits as the sub-block.
Further, the second correction code: ECC (Dj) [j = 1 to 3] in this specific example is an error correction that can correct errors when there are two or less sub-blocks. It shall have the ability.
First, at the stage where the first correction unit 32 performs error correction using the first correction code: ECC (n) [n = 1 to 12] for each subblock of the codeword block (1), the subblock DATA ( 1), DATA (4), DATA (6), DATA (7), and ECC (D2) can be corrected, and other sub-blocks cannot be corrected. The save state is as shown in FIG.
In this case, since there are 7 (> 2) sub-blocks that could not be corrected, the 5 sub-blocks that could be corrected were saved and the sub-block of the next codeword block (2) was saved. Correction processing is performed.

If the correction result for the codeword block (2) is as shown in FIG. 3B, the saved state and error correction state of the memory 33 rewritten based on the result are as shown in FIG. 3C. .
That is, in the correction result of the codeword block (2), the sub-blocks that can be corrected for the first time are DATA (8), DATA (9), and ECC (D1). Those sub-blocks are newly added.
Here, the number of sub-blocks that remain in the uncorrectable state through the codeword blocks (1) and (2) is four as can be confirmed in FIG. 3 (C), and the condition of two or less is not yet satisfied. Further, correction processing is performed on the sub-block of the codeword block (3).

If the correction result for the codeword block (3) is as shown in FIG. 3D, the saved state and error correction state of the memory 33 rewritten based on the result are as shown in FIG. become.
In this case, the sub-blocks that can be corrected for the first time are DATA (2) and ECC (D3). By adding these sub-blocks to the save state in FIG. There are two sub-blocks, DATA (3) and DATA (4).
Accordingly, at this stage, the condition of the error correction capability based on the second correction code: ECC (Dj) [j = 1 to 3] is satisfied, and the second correction unit 35 converts the data saved in the memory 33 into data. On the other hand, correction using the second correction code is performed to restore DATA (3) and DATA (4) to obtain all sub-blocks.

The sub-block is composed of DATA (i) [i = 1 to 9] corresponding to the information part and the second correction part: ECC (Dj) [j = 1 to 3], which is required here. It is only DATA (i) [i = 1 to 9] in the information part.
Therefore, when the correction processing by the second correction unit 35 is completed, the reading unit 36 reads the corrected DATA (i) [i = 1 to 9] saved in the memory 33 and transfers it to the system control unit 41. To do.
The system control unit 41 confirms basic information (recording / reproducing conditions) of the optical disc 1 included in DATA (i) [i = 1 to 9], and the reproducing light output, recording light output, and reproducing linear velocity of this optical disc apparatus. Etc. are set to optimum values.
That is, according to this optical disc apparatus, when the optical disc 1 is set, the basic information repeatedly recorded as wobbling information in a predetermined area is accurately detected, and the optimum recording / reproducing condition corresponding to the optical disc 1 is determined. Can be set.

In the above explanation, DATA (i) [i = 1 to 9] is obtained by fetching a plurality of blocks of codeword blocks (k) recorded repeatedly in a predetermined area of the optical disc 1. If the sub-blocks: DATA (i) [i = 1 to 9] and ECC (Dj) [j = 1 to 3] that can be corrected by only the word block (1) are obtained, the correction processing by the second correction unit 35 is performed. The reading unit 36 only reads DATA (i) [i = 1 to 9] from the memory 36 without passing through.
Further, in this embodiment, the wobbling information of the optical disc 1 related to the basic information is composed of a data string as shown in FIG. 2, but as shown in FIG. 4, the sub-block: DATA (i in each codeword block (k) ) [I = 1 to 9], ECC (Dj) [j = 1 to 3] and the first correction code: ECC (n) [n = 1 to 12] may be non-systematic encoded. DATA (i) + α (i) ”[i = 1 to 9] and“ ECC (Dj) + α (Dj) ”[j = 1 to 3] each represent a non-systematic code.

[Embodiment 2]
This embodiment relates to a case where the information detection unit 3 in the first embodiment is configured by a microcomputer circuit (hereinafter referred to as “microcomputer circuit”) and the same function is executed by software.
First, FIG. 5 is a block circuit diagram of an optical disk apparatus having the configuration. As is clear from the comparison with FIG. 1, only the information detection unit 50 is a microcomputer circuit, and other parts are the same as those in the first embodiment. It is.
Therefore, description of the optical disc 1, the reproduction signal processing unit 2, and the system control unit 41 is omitted here, and the operation procedure of the information detection unit 50 will be mainly described.

The information detection unit 50 has a configuration as a normal microcomputer circuit including a CPU 51, a ROM 52, a RAM 53, and an I / O port 54.
The ROM 52 stores an information detection program. When the CPU 51 executes the program, the wobbling signal sampling data is fetched from the reproduction signal processing unit 2 and the basic information of the optical disc 1 given as wobble information is obtained. Detect information.

Hereinafter, the operation of the information detection unit 50 will be described with reference to the flowchart of FIG.
First, in this embodiment, the RAM 53 stores a codeword block storage area and storage areas [A (1)] of sub-blocks: DATA (i) [i = 1 to 9], ECC (Dj) [j = 1 to 3]. ... (A (12)] are configured separately, and the CPU 51 initializes each of the above-described areas before the optical disk 1 is set and the wobble signal is read (S1). However, each sub-block storage area [A (1) to A (12)] is set as code data consisting of only “0” or “1” having the same number of bits as the sub-block.

Here, when the data fetch of the codeword block (1) is started, the CPU 51 saves it in the codeword block storage area (S2 to S4).
Then, error correction using the first correction code: ECC (i) is performed on DATA (i) of the information part, and if the error correction is impossible, the next DATA (i + 1) Shift to error correction using the first correction code: ECC (i + 1) (S6, S7 → S9, S10), but if error correction is possible, the corrected DATA (i) Save in the sub-block storage area A (i) (S7, S8).
The procedure is executed for 9 sets of DATA (i) and ECC (i) (S6 to S9 → S10 → S6 to S9).
Further, the same procedure as described above is executed for the three sets of the second correction code: ECC (Dj) and the first correction code: ECC (j + 9), and if error correction is possible, the correction is performed. The later ECC (Dj) is saved in the sub-block storage area A (j + 9) (S12 to S16).

That is, an error using the first correction code: ECC (i) [i = 1 to 12] for each sub-block: DATA (i) [i = 1 to 9] and ECC (Dj) [j = 1 to 3] Correction is performed, and the sub-blocks that can be corrected are saved in the storage area A (i) associated in advance.
In that case, each subblock: DATA (i) [i = 1 to 9], ECC (Dj) [j = 1 to 3] and the first correction code: ECC (i) [i = 1 to 12], respectively. However, in any case, as a result, the sub-block that can be corrected is saved.

When the processing for the codeword block (1) is completed, the CPU 51 keeps the initial state in each sub-block storage area [A (1) to A (12)] (area where the sub-block is not saved). Is counted (S17).
If the number is larger than 2, the same processing as described above is executed for the codeword block (2) fetched next (S17 → S18 → S3 to S17).
However, in the processing stage of the second codeword block (2), there is also a subblock storage area in which the subblock that can be corrected in the first codeword block (1) is saved. In such a storage area, only overwriting is performed (S8, S14).
Therefore, in the subblock storage area, in addition to the subblock that can be corrected by the processing of the codeword block (1), the subblock storage area can be newly corrected by the processing of the codeword block (2) by other subblocks. Subblocks will be saved.

When the processing for the codeword block (2) is completed, the number of storage areas in which the sub-block is not saved is counted in the same manner as described above, and if the number is larger than 2, the next codeword block (3) Then, the same processing operation is repeated until the number becomes 2 or less (S3 to S17 → S18 → S3 to S17).
If the number of codeword blocks (1) and (2) is 2 or less, it is natural to complete the processing operation at that stage.

In this way, when the number of subblock storage areas in which subblocks are not saved becomes 2 or less, A (10) is applied to the data saved in A (1) to A (12) of the subblock storage areas. ) To A (12), the error correction process is executed using the second correction code saved in (S17 → S18).
In this case, as described in the first embodiment, an uncorrectable error occurs in the sub-block to be saved in the storage area A (10) to A (12), and the sub-block related to the second correction code: ECC Even if not all of (Dj) [j = 1 to 3] are satisfied, all sub-blocks: DATA (i) [i = 1 to 9], ECC (Dj) [j = 1 to 3] can be restored.

  Then, the CPU 51 changes the subblock storage area restored subblocks: DATA (i) [i = 1 to 9], ECC (Dj) [j = 1 to 3] to the information section (basic information of the optical disc 1). Reading only the corresponding DATA (i) [i = 1 to 9] and transferring it to the system control unit 41 is the same as in the first embodiment (S20).

As described above, in each of the above-described embodiments, the case where the codeword block (basic information of the optical disk) is repeatedly recorded as wobbling information in the predetermined area on the optical disc 1 has been described. It is natural that the method can be applied to those recorded with or without pits.
Further, as disclosed in Japanese Patent Application Laid-Open No. 2002-279732, main information is modulated by a modulation method that satisfies the RLL (d, k) rule with run length restriction, and the restriction of k is performed at a predetermined interval. By switching, the present invention can also be applied to an optical disc that is recorded in such a manner that the codeword block as sub-information is superimposed on the main information.

1 is a block circuit diagram of an optical disc apparatus to which an information detection apparatus according to Embodiment 1 is applied. (A) is a data string configuration diagram of a codeword block recorded as wobble on an optical disc, and (B) is an information part: DATA (i) [i = 1 to 9] and a second correction code: ECC (Dj) [j = 1 to 3] and the first correction code corresponding to each sub-block: ECC (i) [i = 1 to 12], (C) is an information part: DATA ( i) [i = 1 to 9] and correction code part: ECC (Dj) [j = 1 to 3], ECC (i) [i = 1 to 12] It is a data sequence block diagram. FIG. 4 is a time series diagram showing, as a specific example, a correction result for each codeword block by a first correction unit and a save state of each sub-block for each storage area of the memory 33; It is a data string block diagram of the codeword block at the time of comprising each subblock as a non-systematic code. 6 is a block circuit diagram of an optical disc apparatus to which an information detection apparatus according to Embodiment 2 is applied. FIG. 6 is a flowchart illustrating an operation procedure of the information detection apparatus according to the second embodiment. It is a perspective view which shows the formation aspect of the wobbling in an optical disk. It is a graph which shows the expression system of "0" and "1" by a wobble signal, (A) is a phase inversion system, (B) is a 2nd harmonic addition / subtraction system with respect to a fundamental wave.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Reproduction signal processing part, 3 ... Information detection part, 21 ... Optical pick-up, 22 ... Reproduction amplifier, 23 ... Equalizer circuit, 24 ... Waveform shaping circuit, 25 ... PLL circuit, 26 ... Synchronous detection circuit, 30 Data determination unit 31, 33 ... Memory 32 ... First correction unit 34 ... Counting unit 35 ... Second correction unit 36 ... Reading unit 41 ... System control unit 50 ... Microcomputer circuit 51 ... CPU, 52 ... ROM, 53 ... RAM, 54 ... I / O port, 101 ... groove, 102 ... land, 103 ... light spot, DATA (i) [i = 1 to 9] ... information part (basic information of optical disk), ECC (i) [i = 1-12]... First correction code, ECC (Dj) [j = 1-3].

Claims (3)

The codeword block includes a predetermined information part, a plurality of first correction codes, and a second correction code, and each first correction code is obtained by dividing the information part and the second correction code by a predetermined unit. Each of the obtained sub-blocks has an error correction capability, and the second correction code has an error correction capability for the information section, and the code word block is placed in a predetermined area of the recording medium. An information detection method for repeatedly recording and detecting the information part while reading each codeword block from the recording medium,
Each time the codeword block is read, the codeword block is stored in the first storage means,
Performing error correction using each first correction code for each sub-block;
By causing the error correction related to each codeword block to be held in a storage area associated with the subblock in the second storage means, which can be corrected even once,
Count the number of sub-blocks that are continuously in an uncorrectable state,
When the count number becomes equal to or less than the number based on the error correction capability of the second correction code, error correction using the second correction code is performed on the data in the second storage means,
An information detection method comprising: detecting the information part from each corrected sub-block. The codeword block includes a predetermined information part, a plurality of first correction codes, and a second correction code. Each first correction code is obtained by dividing the information part and the second correction code by a predetermined unit. Each of the obtained sub-blocks has an error correction capability, and the second correction code has an error correction capability for the information section, and the code word block is placed in a predetermined area of the recording medium. An information detection device that repeatedly records and detects the information part while reading each codeword block from the recording medium,
First storage means for storing the codeword block each time the codeword block is read from the recording medium;
First correction means for performing error correction using the first correction code for each sub-block of the codeword block stored in the first storage means;
A storage area associated with each sub-block of the codeword block, corresponding to a sub-block that can be corrected at least once as a result of error correction by the first correction means for each codeword block; Second storage means stored in the storage area;
Counting means for counting the number of sub-blocks in which the uncorrectable state continues,
When the count number of the counting means is equal to or less than the number based on the error correction capability of the second correction code, error correction using the second correction code is performed on the data in the second storage means. 2 correction means,
An information detecting apparatus comprising: detecting means for detecting an information part from each sub-block corrected by the second correcting means. The codeword block includes a predetermined information part, a plurality of first correction codes, and a second correction code. Each first correction code is obtained by dividing the information part and the second correction code by a predetermined unit. Each of the obtained sub-blocks has an error correction capability, and the second correction code has an error correction capability for the information section, and the code word block is placed in a predetermined area of the recording medium. An information detection program for repeatedly recording and detecting the information part while reading each codeword block from the recording medium,
Storing the codeword block in the first storage means each time the codeword block is read;
Performing error correction using each first correction code for each sub-block of the codeword block stored in the first storage means;
Holding a sub-block that can be corrected even once by the error correction in a storage area associated with the sub-block in the second storage means;
Counting the number of sub-blocks in which the uncorrectable state continues,
Performing error correction using the second correction code on the data in the second storage means when the count number is less than or equal to the number based on the error correction capability of the second correction code;
An information detection program causing a computer to execute the step of detecting the information section from each sub-block after error correction using the second correction code.

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