JPS61144777A - Optical disk device - Google Patents

Abstract

PURPOSE:To evade cases in which data can not be restored by calculating the frequency of data error occurrence of every sector and deciding on the failure degree of a sector. CONSTITUTION:When a central processor informs an optical disk limiting circuit 1 of the reading of data, the circuit 1 sets a target address in a sector address detecting circuit 6 and allows a driving circuit 5 to drive and start a read/write control circuit 4. Data outputted from the circuit 4 is applied to an error composing circuit 8 through a demodulating circuit 7 to perform error processing, so that corrected data CD is outputted to the circuit 1. A correction flag from the circuit 8 is counted by a flag counter 9, and when its counted value exceeds a specific value N, an overerror flag OF is set and the circuit 1 is informed that the sector is a defective sector. The circuit 1 outputs the data CD to an external bus line EBD and outputs a defective sector signal BS to the central processor to let an operator know that.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical disk device used as an auxiliary storage device in a computer system.

[Prior Art] In recent years, there has been a proposal to use an optical disk device that uses a disk-shaped optical disk made of a photoreactive recording material as a storage medium as an auxiliary storage device for a computer system.

This optical disk has a spiral track formed on the surface with a track pinch of about 1.5 μm, and pits with a diameter of about 1 μm are formed on this track depending on the information to be stored, and pits with a micro diameter of about 1 μm are formed on this track. Written directly by a focused laser spot. Further, for example, an optical director having a diameter of 30 cm can store data of about 1011 to 1012 bits per sheet.

In this way, optical disk devices have a large storage capacity,
Furthermore, since the data tS is written directly onto the optical disk, it is advantageous in terms of storage of stored data compared to a storage device using a magnetic storage medium.

On the other hand, since the storage density is very high, the influence of data errors due to scratches formed on the surface of the optical disk or minute dust attached to the surface is large, and the data error rate is relatively high (about 10-5).

Therefore, optical disk devices are equipped with an error correction processing device that detects and corrects data errors occurring in read data, reducing the data error rate to about 1o-15, thereby eliminating practical problems. I've lost it.

However, on the other hand, it is unavoidable that the number of bit errors increases as the optical disk ages and the scratches on the surface of the optical disk increase over time.As a result, at some point the amount of data errors becomes excessive and the error correction processing However, there was a risk that the data could not be completely recovered.

[Objective] The present invention has been made to solve the above-mentioned disadvantages of the prior art, and an object of the present invention is to provide an optical disk device that can prevent 10,000 situations in which data cannot be recovered.

[Configuration] In order to achieve the above-mentioned object, the present invention counts the frequency of data errors in each sector and determines the degree of defectiveness of that sector, thereby alerting you to a defective sector, and furthermore, detecting a defective sector. Information is being rewritten to a spare sector.

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

FIG. 1 illustrates a data recording format of an optical disc in an optical disc device according to an embodiment of the present invention.

On the track TR of the optical disc, sectors SC are consecutively arranged via gaps GP, and each sector SC includes a preformat part PF consisting of a preamble, a sector synchronization signal, and a sector address signal, and a set of 256 data frames DF. It is composed of a data part DM consisting of.

This preformat part PF is formed on the master disc of the optical disc, and the preformat part PF is formed on the master disc of the optical disc.
are formed simultaneously.

The data frame DF also includes a preamble, a frame synchronization signal, 8 data words, and 2 sets of parity words p1. Q I IP 2 IQ 2 (
(described later) consists of a 12-word recording data section. It should be noted that each word of the recording data section is composed of 8 bits long.

In this way, 256 data frames I and DF are consecutively recorded in one sector SC, and 2048 words are recorded.
In this embodiment, in order to suppress the influence of burst errors, the original recorded data (hereinafter referred to as original data) is interleaved to form the recorded data of the data frame DF.

That is, first, the original data of 2048 words is divided into 256 groups of 8 words each in the order of arrangement, and parity words P and Q of b-adjacent codes are added to each group.

Then, the data word of the Ath group in the original data is interleaved so as to be placed in the word Wk of the first frame. However, B is the following formula (
1).

B=A+14X (k-1) ...(
I) Also, the parity words P and O of the A-th group are.

Parity word P of the (A+112)th frame, respectively.
2. It is placed in the parity word Q2 of the (^+126)th frame.

Note that if B exceeds 256, the value obtained by subtracting 256 from b is used as n, and this interleaving is performed on sector S.
I try to complete it within C. Furthermore, the positions of parity words P and Q are also similar.

Therefore, for example, the first word of the first group becomes the word WI of the first frame, the second word becomes the word W2 of the 15th frame, the third word becomes the word W3 of the 29th frame, and the fourth word becomes the word W3 of the 43rd frame. The 5th word goes to word W5 of the 57th frame, the 6th word goes to word W6 of the 71st frame, the 7th word goes to word W7 of the 85th frame, and the 8th word goes to word W7 of the 99th frame. In word W8, parity word P is in parity word P2 of the 113th frame, and parity word Q is in the first
They are allocated to parity words Q2 of 27 frames.

In addition, the interleaving of each word in other groups is shown in Table 1 below.

In addition, each numerical value in the table indicates the corresponding frame number, and P (2) and Q (2) of word printing are: Parity words P and Q for each group and parity word P2 of each data frame. ．． It's raining Q2.

(Left below) Table J In this way, the original data of 2048 words is recorded in one sector SC by adding parity words P and Q based on the b-adjacent code every 8 words and interleaving every 14 frames. Ru.

Furthermore, the data in one sector SC formed in this way is selected (that is, interleaved) in a direction different from the data recording direction and the alignment direction of the original data to form a C+ correction sequence, and a parity word with b-adjacent codes is formed. P
+, Q+ are added. Note that for this (, + correction series, in the following, one-dimensional data and parity words P, Q
The sequence (P 2 . Q 2 ) is called a C2 correction sequence.

For example, the C+ correction sequence is interleaved every 11 frames to select words W1 to W8 and parity words P2. Q2, and parity words PI and Q+ added as b-adjacent codes to these 10 words.9, parity words P1. The positions of C1+ are set 11 frames and 22 frames after parity word Q2, respectively.

Further, this CI correction sequence is also formed by connecting the 256th frame and the first frame so that it is completed within one sector SC.

As shown in Figures 2 and 3, the arrangement of the C1 correction series and C2 correction series described above shows that two correction series (C+ correction series, C2 correction series) are arranged in different directions intersecting the data recording. is set.

In the above example, the 01 correction sequence is formed by interleaving every 11 frames, and the C2 correction sequence is formed by interleaving every 14 frames, but the interleaving interval is not limited to this. . The interleaving interval of the CI correction sequence may be larger than the interleaving interval of the C2 correction sequence.

Furthermore, although the C2 correction series and the original data are arranged in the same direction, they do not need to be in the same direction. for example,
Make the alignment direction of the original data the same as the data recording direction,
Parity word P2. A C2 correction sequence may be used as the additional direction of Q2.

Now, parity words P, Q (P +
.

Q+, P2. Q2) is generated in a first-order manner.

The number of words constituting the correction series is n (n for C+correction series)
-10,02 correction series (row 8), parity words P and Ω are calculated by the following equations (II) and (m), respectively. In addition, in the following, data word Di (1≦
1≦n) indicates the words forming each correction sequence.

P=ΣDi...(old i=TsutaX=+ Here, D is when the word length (number of bits) is b
It is a square matrix consisting of a primitive polynomial G(X) having elements of +1) terms. In this example, since one word is 8 bits, the primitive polynomial G(X) and the square matrix T are determined, for example, as follows.

G (X) =X"+X'+X' +X4+ 1
(IV) (Hereinafter in the margin) According to this b-adjacent code, it is possible to correct 17-tot errors (single-error correction) in a correction sequence, and this will be explained first.

That is, when the recorded data is read out, it is assumed that the data word Di and parity words P and Q that make up the correction sequence contain errors, and each error pattern is expressed as Ei.
, E p , E Q , the erroneous data food Di and parity words P', Q' are expressed by the following formula % However, the operator ■ performs modulo 2 addition.

Here, the syndrome Sp is defined by a linear equation.

Think about SO.

That is, the syndrome Sp consists of each data word Di' and parity word P of the correction series related to the read data.
′ is the result of adding all modulo 2.

The syndrome SQ is the result of adding each term of each data word Di' weighted by a square matrix T and the parity word Q', all modulo 2.

Now, considering the case where the data word Di' and the property words P' and Q' in the correction sequence are all error-free, Di' = D1. P' = P+ Q
' ``Since Q, the syndrome Sp, So by definition
are both 0.

Therefore, if the values of syndromes Sp and So are both 0, it can be determined that there is no error in this correction series.

Next, consider the case where an error Ek occurs in the data word Dk' of the data word Di'.
The syndromes SP and SQ in this case are as follows.

5p=Ek (XI) By eliminating Ek from the above two equations, the position k of the error word can be found in a first-order manner.

That is, according to this equation (XI[I), at this time, the error pattern Ek appears in the syndrome Sp, so that the data word Dk' can be corrected as shown in the following equation.

Dk = Dk'■Ek...(Xr
V) In addition, when an error occurs in each of the parity words P' and Q', the following formula holds true6: In other words, if one of the syndromes is 0, an error occurs in the other syndrome, and the error The patterns are the values of each syndrome.

In this way, one word errors within the correction sequence can be corrected.

Therefore, considering the CI correction series, the data words that make up this CI correction series are interleaved every 11 frames, so even if a continuous burst error occurs within 11 frames, the error will be C.I.
From the perspective of the correction sequence, this is only an 1-word error, so the error can be corrected by the procedure described above. Further, similar error correction processing can be performed with the C2 correction series.

Note that C+, C=frame interval of each word of the correction sequence (
If the interleave interval (interleaving interval) is lengthened, the burst error correction ability can be increased proportionally, but if the frame interval of each word is lengthened, burst errors occurring at multiple locations will be This increases the probability that more than one error will be mixed in, increasing the possibility that error correction will not be possible.

It is necessary to set the frame interval of each word in consideration of both.

An example of the control section of an optical disk device including the above-mentioned error correction processing section is shown in FIG.
When data is to be stored on the optical disc from the optical disc, the central processing unit first raises the selection signal SL to a logic H level. On the other hand, if the optical disk control circuit 1 is in an operable state, it responds to the central processing unit by raising the status signal SS to the logic H level.

As a result, the central processing unit outputs the sector address SA of the sector in which data is to be written onto the external data bus FDB, and then raises the sector address latch signal AL to a logic H level to send the sector address SA to the optical disc control circuit 1.
A is stored, and the read/write control signal RW is lowered to the logic L level that prevents data writing.
One sector worth of write data is sequentially output onto the external data bus EDB.

When the optical disk control circuit 1 stores the sector address SA, it sets it in the sector address detection circuit 6. After that, when the read/write control signal RW becomes a logic L level and write data is added from the external data bus EDB,
This is outputted to the error encoding circuit 2, and the read/write control signal RW is set to logic L level to set the read/write control circuit 4 to the read state, and a start signal ST is output to start the operation of the optical disk drive circuit 5. let

As a result, the write data is interleaved by the error encoding circuit 2 as described above, and the parity words PI, QllP2 . With Q2 added,
The data read from the optical disk is stored and held in the error encoding circuit 2 as recording data WD for l sectors, and at the same time, the data read from the optical disk is applied from the read l write control circuit 4 to the sector address detection circuit 6 to detect the target sector. Detection begins.

The sector address detection circuit 6 determines the sector address recorded in the preformat part PF of the optical disc from the data applied from the read/write control circuit 4, and the determined sector address is the sector address to which the optical disc control circuit 1 adds the sector address. It compares it with SA and if the two match, it outputs a sector discovery signal SF to the optical disc control circuit 1.

As a result, the optical disk control circuit 1 sets the read/write control signal WR to the logic H level, puts the read/write control circuit 4 into the data writing state, and also sets the data output signal D.
E is output to the error encoding circuit 2 to cause the error encoding circuit 2 to output recording data WD. This recorded data WD is
After being modulated in a predetermined manner by the modulation circuit 3, it is output to the optical disk drive circuit 5 via the read/write control circuit 4, whereby data is recorded in the sector specified by the central processing unit.

When the central processing unit reads data from an optical disk,
First, the central processing unit specifies the sector to be read in the same manner as described above, and also sets the read/write control signal RW to the logic H level to notify the optical disc control circuit 1 of reading data.

The optical disc control circuit 1 sets a target sector address in the sector address detection circuit 6 in the same manner as described above, and causes the read/write control circuit 4 to start driving the optical disc drive circuit 5.

Furthermore, the data output from the read/write control circuit 4 is demodulated by the demodulation circuit 7.

The data is added to the error decoding circuit 8 as read data RD, subjected to the above-described error correction process, dinterleaved with the original data, and outputted to the optical disc control circuit 1 as corrected data CD. At the same time, the error decoding circuit 8
When both are non-zero and the error position is in the data portion, a correction flag EF is output, and this correction flag EF is counted by a correction flag counter 9.

The correction flag counter 9 stores a correction flag EF for each sector.
When the counted value exceeds a predetermined value N, an over error flag OF is raised, and the optical disc control circuit 1 is notified that the sector in question is a bad sector.

As a result, the optical disc control circuit 1 receives the corrected data CD output from the error decoding circuit 8 after the sector address detection circuit 6 outputs the sector discovery signal SF as the data read from the optical disc and sends it to the external path line E.
Immediately after outputting one sector of the corrected data CD to the DB, if the over error flag OF is raised, the bad sector signal O5 is output to the central processing unit and the sector is Alerts you that it is a bad sector.

The central processing unit notifies the operator when this bad sector signal BS is output. Therefore, since the operator can identify a bad sector, some action can be taken on the data stored before the sector becomes completely unusable, thereby making it possible to protect the data. For example, an operator can move the data to an alternate storage device or alternate sector.

FIG. 5 shows a specific example of the error decoding circuit 8.

In the figure, reproduced data RD input from the demodulation circuit 7 via the input register 31 is sent to the dinterleave memory 32 designated by the memory write address counter 33.
are sequentially stored in the storage area via the data bus DDB.

When one sector worth of reproduction data RD is stored in the dinterleave memory 32, the lob code address counter 35
An address for reading a data word from C+ correction series is generated from dinterleave memory 32 and C
1 decoder 37 via address bus ADB.

As a result, the data read from the dinterleave memory 32 is sequentially applied to the C+ decoder 37, and the above-mentioned single-error correction is executed. At this time, the corrected data word is returned to the dinterleave memory 32 and its contents are rewritten.

For a correction sequence in which both syndromes SP and SQ are non-zero and the error position is in the data part, a correction flag EFI is output every time such a correction sequence is detected.

When the C+ decoder 37 finishes performing simple error correction on the data stored in the dinterleave memory 32, the C+ decoder 37
2 decode address counter 36 generates an address for reading a data word in the C2 correction series and applies it to dinterleave memory 32 and C2 decoder 38 via address bus ADO.

As a result, the data read from the dinterleave memory 32 is applied to the 02 decoder 38 to perform the single error correction described above, and the corrected data word is returned to the dinterleave memory 32 and its The contents are rewritten and, like the 0-plate decoder 37, the correction flag EF2 is set every time a correction sequence is detected in which the syndromes SP and SQ are both non-zero and the error position is in the data section.
Output.

When one sector of data has been corrected in this way, the memory read address counter 34 sequentially reads out the data words from the dinterleave memory 32 in the order of the original data, and the data words are read out from the data bus DDB and the output register 39. The corrected data CD is then outputted to the optical disc control unit 181 via the corrected data CD.

Further, the correction flags EFI and EF2 output from the C+ decoder 37 and the C2 decoder 38 are output from the OR circuit 4.
0 to the correction flag counter 9 as the correction flag EF.
is output to.

FIG. 6 shows another example of the control section of the optical disc device. In this figure, the same parts and corresponding parts as in FIG. 4 are given the same reference numerals, and the explanation thereof will be omitted.

In this control section, when the over error flag OF is raised when reading data from the optical disc, the recorded data of that sector is rewritten to a spare alternative sector.

That is, in this case, the error decoding circuit 8a outputs l sectors worth of corrected data CD stored therein at the time when the data read signal RE is output from the optical disc control circuit 1, and the error decoding circuit 8a outputs the corrected data CD for l sectors stored therein. When the over error flag OF is raised, the control circuit 1 sets the sector address of the spare sector in the sector address detection circuit 6, and also sets the corrected data CD read from the error decoding circuit 8a as shown by the broken line in the figure. When the sector discovery signal SF is output, the recording data WD is read out from the error encoding circuit 2.

The vacant state of the spare sector is stored in optical disc management information such as a predetermined storage area of the optical disc, and the optical disc control circuit 1 takes in the management information when starting the apparatus or inserting the optical disc. Further, the relationship between the defective sector and the spare sector to be rewritten may be stored in the management information and further notified to the central processing unit.

In this way, the data in the bad sector is automatically rewritten to the spare sector, so the burden on the external device (host device) such as the central processing unit and the operator can be reduced.

By the way, in one or more of the embodiments described above, one data frame DF is composed of one set of recording data (ie, eight words of data W I-Wa and a parity word P+).

Ql, P2. Q2), but is limited to 1
It is also possible to include multiple sets of recording data in one data frame DF. In that case, CI correction series.

The C2 correction sequence can be realized by extracting and forming, for example, 256 recorded data in the same order in each data frame DF.

Further, the number of bits of a data word, the number of words in one recording data, and the number of data frames DF in sector SC are not limited to those described above. The format of the sector SC may also be changed to other formats.

Furthermore, in one or more embodiments, two sets of error correction sequences are set,
Although single error correction is performed in each correction series, the error correction method is not limited to this.

Further, as the error correction code, a well-known code other than the b-adjacent code (for example, a Reed-Solomon code) can be used.

[Effects] As explained above, according to the present invention, the number of data errors is counted for each sector and the degree of failure of that sector is determined, thereby alerting you to a defective sector.

Furthermore, since the recorded data in the defective sector is rewritten in the spare sector, there is an advantage that it is possible to prevent a situation in which data cannot be recovered due to aging or the like.

[Brief explanation of drawings]

FIG. 1 is a signal arrangement diagram showing the data recording format in an optical disk memory to which the present invention is applied, FIG. 2 is a signal arrangement diagram showing the arrangement of each correction series, and FIG. 3 is a schematic diagram illustrating the interleaving direction. FIG. 4 is a block diagram showing an example of a control section according to an embodiment of the present invention, FIG. 5 is a block diagram showing a specific example of an error decoding circuit, and FIG. 6 is a block diagram showing an example of a control section according to the present invention. This block shows another example. 1.1a... Optical disk control circuit, 2... Error encoding circuit, 3... Modulation circuit, 4... Read/write control circuit, 5... Optical disk drive circuit, 6... Sector address Detection circuit, 7... Demodulation circuit, 8, 8a...
error decoding circuit, 9...correction flag counter, 31.
...Input register, 32...Dinterleave memory, 33...Memory write address counter, 34...
・Memory read address counter, 35...C1 decode address counter, 36...C2 decode address counter, 37...C+ decoder, 38...C2
Decoder, 39...output register. 40...OR circuit, ADB...address bus,
DDB...data bus, EDB...external data bus. '・-Please include it outside of Figure 2- Figure 3 Figure 4

Claims (2)

[Claims] (1) In an optical disk device that stores recorded data by dividing it into sectors and corrects data errors by adding an error correction code that completes each sector, the frequency of data errors within the same sector is a predetermined value. An optical disk device characterized by comprising a bad sector determining means that outputs a warning when the number of sectors exceeds the number of sectors. (2) In an optical disk device that stores recorded data by dividing it into sectors and corrects data errors by adding an error correction code that completes each sector, the frequency of data errors within the same sector is a predetermined value. A defective sector determining means outputs an alarm when the defective sector determining means exceeds the limit, and a sector rewriting means adds an error correction code to the recorded data of the sector determined to be defective by the bad sector determining means and rewrites it to a predetermined spare sector. An optical disc device characterized by: