JPH05205402A - Recording and reproducing method - Google Patents

Abstract

PURPOSE:To provide the recording and reproducing method where data and synchronizing information do not interfere with each other at the time of inserting synchronizing information to data in the device which records data in series with RLL records. CONSTITUTION:Data to be recorded is divided section data 20 having a prescribed unit length, and synchronizing information 10 indicating the start is added to the head of section data 20, and plural resynchronizing information 11 different from synchronizing information are inserted to section data 20, and they are recorded on a discoid recording medium. Synchronizing information and resynchronizing information 11 are detected from the reproduced signal from the recording medium to obtain a synchronizing signal and a resynchronizing signal, and the compounding timing is controlled by the synchronizing signal and the resynchronizing signal to compound the reproduced signal. Section data is converted to code words by the (2, 7) modulation system and is recorded on the recording medium, and two terminal bits of resynchronizing information are recorded as pattern '00' on the recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording and detecting synchronization information in data in an apparatus for serially recording data such as an optical disk apparatus.

[0002]

2. Description of the Related Art FIG. 1 shows run length limited variable word length coding (Run-
A correspondence table of data words and code words in the Length-Limited Variable-Length Coding) method is shown. In the text below, the above code is abbreviated as RLL code. In particular, the code shown in FIG. 1 is called a (2,7) modulation method. The case where data is coded by this code (data words are converted into code words) and information is recorded one-dimensionally (that is, in series) with respect to time t is handled. In such a case, normally, for example, a well-known uneven pit is formed in the portion corresponding to the code word "1" shown in FIG. 1 to perform recording on the recording medium.

A publicly known example of a synchronizing signal is Japanese Patent Publication No.
There are JP-A-48607 and JP-A-55-129914.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to
When inserting synchronization information into data in an optical disc device or the like that records data serially by LL code,
It is intended to provide a recording / reproducing method in which data and synchronization information do not interfere with each other. Further, the present invention provides a recording / reproducing method capable of preventing an error from being propagated at the time of decoding and stably performing the correction.

[0005]

According to the present invention, data to be recorded is divided into section data having a length of a predetermined unit, synchronization information indicating the beginning is added to the beginning of the section data, and synchronization is performed in the middle of the section data. A plurality of resynchronization information different from the information is inserted and recorded on a disc-shaped recording medium, and the synchronization information and the resynchronization information are respectively detected from the reproduction signal from the recording medium to obtain the synchronization signal and the resynchronization signal. , The sync signal and the resync signal are combined to control the composite timing to composite the reproduced signal, and the section data is converted into a code word by the (2,7) modulation method and recorded on the recording medium. The last two bits are recorded on the recording medium as a pattern of "00".

Further, the data to be recorded is divided into section data of a predetermined unit length, synchronization information indicating the beginning is added to the beginning of the section data, and a plurality of resynchronizations different from the synchronization information are provided in the middle of the section data. Information is inserted and recorded on a disk-shaped recording medium, and a synchronization signal and a resynchronization signal are obtained by detecting synchronization information and resynchronization information from the reproduction signal from the recording medium,
It is characterized in that the reproduction signal is decoded by controlling the composite timing with the synchronization signal and the re-synchronization signal, and the error is corrected for each section data by the error correction function attached to the data.

[0007]

In FIG. 2, reference numeral 10 is a sync signal indicating the beginning of recorded data. Reference numeral 20 is a data area in which the code encoded by FIG. 1 is recorded. A delimiter signal 11 is located in the middle of the data section 20 and indicates a delimiter for each fixed unit of the data section. The delimiter signal is also coded according to the coding rule of the RLL code shown in FIG. Separation signal 11
Has a function of dividing the reproduction data and reproducing the code word that enters the decoder at the time of reproducing the data. That is, at the time of reproducing the information recorded in the form of FIG. 2, the decoding is started by the sync pulse 100 detected from the sync signal 10 indicating the start of the recording, and the re-sync pulse 110 detected from the halfway signal 11 is also the sync pulse 1.
00 as a backup.

That is, the error rate of an optical disk is considerably worse than that of a magnetic disk, for example. Sync pulse 10
If the decoder controlled by 0 causes a timing shift due to noise or some other cause in the middle, all data thereafter will be erroneously decoded. In order to prevent this, even if the timing shift occurs at a place, the timing of the decoder is restored to normal by the resynchronization pulse 110, so that the error due to the timing shift can be limited to only the specific section in which the error occurs. If the error is limited to a specific section, the error can be corrected by the error correction function attached to the code. A data recording / reproducing apparatus having this kind of error correction function is described in, for example, Japanese Utility Model Laid-Open No. 56-77018.

In order to obtain the above-mentioned function, it is necessary to divide the data area into several parts and insert the resynchronization pattern 11 into the divided part for recording. However, in this case, since the resynchronization pattern exists mixed with the data, it needs to be detected separately from the data. That is, the above (2,
7) The modulation method is coded so that the interval (the number of "0" s) of marks "1" recorded on the medium is 2 to 7 as shown in FIG. In this case, the minimum distance between marks is determined to be at least 2 from the viewpoint of reducing mutual influence of marks and enabling stable reproduction. Therefore, the last 2 bits of the resynchronization pattern need to be "00".
Otherwise, when the coded data following the resynchronization pattern starts with "1", "1" may be recorded closely and there is a possibility that the data cannot be decomposed. Further, it is desirable that the resynchronization pattern itself also follow the promise that "1" s are separated by 2 or more.

From the above point of view, if the data is divided and the resynchronization information is added and the code is collectively converted, the resynchronization information also follows the promise of the coding rule, which is convenient. By the way, in the RLL code shown in FIG. 1, when converting a data word to a code word, it is not fixed how many bits of data are converted for variable word length coding. That is, 2-bit, 3-bit, or 4-bit data is coded in units of the data pattern. Therefore, when data of a certain length is encoded, excess or deficiency occurs at the end of the code word due to the pattern of the data.

On the other hand, the resynchronization pattern is always the same regardless of the data pattern, and the correct sync pulse is generated in the shortest possible length, that is, even if noise or the like occurs in the reproduced signal, the position and phase of the resync pulse. It is necessary that the gap does not shift. Conventionally, a highly reliable resynchronization pattern for the variable word length code and its detection method have not been obtained.

It is an object of the present invention to obtain a resynchronization pattern which is inserted in the middle of data for a variable word length code, has a high detection reliability independently of the data, and a detection device therefor.

[0013]

The present invention will be described in detail with reference to the following examples.
The above-mentioned state of excess and deficiency of word divisions at the code word terminal portion can be classified into the following six cases. That is, when a code word is converted into a data word, there are cases where the code word end portion has too many code words, which are the following cases.

When there is no excess or deficiency: When the data ends with 0 when there is 1 bit left. When the data ends with 1 when there is 1 bit left. When the data ends with 00 when 2 bits remain, the data ends with 01 when 2 bits remain. Case When data ends with 001 when 3 bits are left over It is impossible to obtain all the same resynchronization patterns in the form of code words for all of the above cases, but it depends on each case. It is possible to make the part one minimum. Furthermore, the data pattern following the resynchronization pattern must always be a code word delimiter. Although there are 18 types of patterns that satisfy this condition, the inter-code distance between the normal timing and the pattern generated at the timing deviated from the normal timing must be large in order to improve the detection reliability. From the above conditions, when the length of the resynchronization part is 1 byte, the pattern in which the data word "10111010" is coded according to the rule of FIG. 1 is optimal.

FIG. 3 shows how the resynchronization pattern becomes for the cases (1) to (3). In FIG. 3, the symbol Δ indicates the place where the code word is separated. As is apparent from the figure, two types of converted recording patterns are generated by the previous data pattern. However, if this pattern is carefully considered, it is always the same pattern except that the part marked with X in the pattern of FIG. Furthermore, one of the two x portions is always 1. Therefore, as the standard or reference pattern, the code word read out from the pattern of FIG. 3C is collated with the above reference pattern, and if at least one of the X portions is "1", it is regarded as a match. Then, the comparison result when the timing is deviated in the positive and negative directions with respect to the normal timing position Δt = 0 is as shown in FIG.
In the figure, d in the vertical direction is the distance between both patterns (Hamming distance),
The horizontal axis indicates the timing deviation amount Δt. As is clear from the figure, the distances on both sides of the timing coincidence point are large, so that even if an error occurs in the read signal, the re-synchronization pulse can be obtained only at the correct position in FIG. However, a similar pattern may occur in the data, so in order to exclude this, the pattern shown in FIG.
A gate signal such as (b) is used. The gating signal originates from the previous sync or resync signal.

FIG. 5 is a diagram showing the configuration of the resynchronization pattern generation circuit, and FIG. 6 is a diagram showing an embodiment of the configuration of the detection circuit.

In FIG. 5, reference numeral 30 is write data, and 31 is the resynchronization pattern (data word). The write data is put together as a predetermined series of data words at 32, and a resynchronization pattern is added to this and sent to the encoder 40. Encoder 40
Then, it is coded according to the rule of FIG. The code word is given from 51 to the write driver 50 and becomes a recording signal 61 to the disc. At this time, a series of predetermined format information such as a sync signal is given from the format signal generator 53 prior to recording the data. As a result, it is recorded in the form as shown in FIG.

FIG. 6 is a block diagram of the reproducing apparatus. A read signal 61 from the head is converted into a signal 62 corresponding to the code word recorded by the read signal processing circuit 60. This signal is given to the timing recovery circuit 70, and the read clock 700 is obtained. The reproduction signal 62 is the synchronization signal detection circuit 7
Also given to 1,72. Reference numeral 71 is a sync signal detection circuit corresponding to 10 in FIG. 2, and 72 is a resync signal detection circuit corresponding to 11 in FIG. The reproduction signal 62 and the two sync signals are supplied to the decoder circuit 80 and converted into data words. The read clock 700 is used for the synchronization detection in the synchronization signal detection circuits 71 and 72, the decoder in the decoder circuit 80, and the processing in the read data reconstruction circuit 90. After being converted into a data word by the decoder circuit 80, the read data reconstruction circuit 90 removes the pattern for resynchronization and obtains the data 900 corresponding to the write data 30 of FIG.

FIG. 7 shows an embodiment of a specific configuration of the resynchronization signal detection circuit 72. 721 is a shift register, 723
Is a match detection circuit for collating patterns, 724 is a reference pattern source, 726 is an AND gate, 729 is an OR gate, 73
Reference numeral 0 is a timing generation circuit. The read signal 62 is taken into the shift register 721 at the clock 700, the pattern taken into the shift register and the reference pattern are collated by the coincidence detection circuit 723, and when they coincide, a coincidence signal 725 is obtained.
Occurs and outputs a resync pulse 720 through the gates of 726 and 729. Here, the synchronization signal 710 and the re-synchronization signal pass through the OR gate 729 and the timing generation circuit 73.
0 to generate a gate signal (Fig. 4 (b) 727.) Even if an error or the like occurs in the read signal and the resynchronization signal cannot be detected at a normal time, the timing generation circuit 730 outputs the previous signal. It generates a gate signal with the timing generated by the synchronization signal.

[0020]

As described above, according to the present invention, it is possible to always use the same synchronization pattern regardless of the data pattern while using the code of variable word length coding, and to easily generate and detect it. There is a feature that you can. Therefore, it is possible to minimize the influence of the timing deviation due to some cause and improve the reliability of data reproduction.
In carrying out the present invention, there is no limitation on the length of data, so that an arbitrary format configuration can be taken as necessary.

[Brief description of drawings]

FIG. 1 is a code diagram showing an example of a variable word length encoding system.

FIG. 2 is a conceptual diagram showing an example of a recording format of data recorded on an optical disc or the like.

FIG. 3 is a conceptual diagram showing classification of code word patterns created from data word patterns and resynchronization pattern portions.

FIG. 4 is a graph showing the ability of a resynchronization pattern according to an embodiment of the present invention.

FIG. 5 is a circuit configuration diagram showing an example of a synchronization pattern generation method.

FIG. 6 is a circuit configuration diagram showing an example of a synchronization detection method.

FIG. 7 is a block diagram showing an embodiment of a resynchronization signal detection circuit.

[Explanation of symbols]

 10 ... Sync signal, 11 ... Separation signal, 20 ... Data section

Claims (8)

[Claims] 1. Data to be recorded is divided into section data having a length of a predetermined unit, synchronization information indicating the beginning is added to the beginning of the section data, and a plurality of sections different from the synchronization information are provided in the middle of the section data. Re-synchronization information is inserted and recorded on a disk-shaped recording medium, the synchronization information and the re-synchronization signal are respectively detected from the reproduction signal from the recording medium to obtain the synchronization signal and the re-synchronization signal, The reproduction signal is decoded by controlling the composite timing with the sync signal and the resync signal, and the section data is converted into a code word by the (2,7) modulation method and recorded in the recording medium. The resynchronization information is recorded on the recording medium as a pattern in which the last two bits are "00". 2. The recording / reproducing method according to claim 1, wherein the data has an error correction function. 3. The resynchronization information is "10111010", and the last 2 bits are "0" according to the (2,7) modulation method.
The recording / reproducing method according to claim 1 or 2, wherein the code word is converted into a code word of 0 "and recorded on the recording medium. 4. The recording / reproducing method according to claim 1, wherein the resynchronization information is detected by using a gate formed from previous synchronization information or a resynchronization signal. 5. Data to be recorded is divided into section data having a length of a predetermined unit, synchronization information indicating the beginning of the section data is added, and a plurality of sections different from the synchronization information are provided in the middle of the section data. Re-synchronization information is inserted and recorded on a disk-shaped recording medium, the synchronization information and the re-synchronization signal are respectively detected from the reproduction signal from the recording medium to obtain the synchronization signal and the re-synchronization signal, A recording / reproducing method characterized in that the reproduction signal is decoded by controlling the composite timing with a synchronization signal and a re-synchronization signal, and an error is corrected for each section data by an error correction function attached to the data. .. 6. The recording / reproducing method according to claim 5, wherein the data is encoded by a (2,7) modulation method and recorded on the recording medium. 7. The resynchronization information is "10111010", and the last 2 bits are "0" by the (2,7) modulation method.
7. The recording / reproducing method according to claim 5, wherein the code word is converted into a code word of 0 ″ and recorded on the recording medium. 8. The recording / reproducing method according to claim 5, wherein the resynchronization information is detected by using a gate formed from previous synchronization information or a resynchronization signal.