JP3191763B2 - Information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts recorded information into a code string according to a run-length limited coding rule, and converts the code string into positions of a leading edge and a trailing edge of a recording mark formed in a data area of a recording medium. The present invention relates to an information recording medium for recording a pattern corresponding to.

[0002]

2. Description of the Related Art JP-A-3-113872 discloses 1-7.
"1000000010000001" and "100" are the resynchronization patterns for the run-length limited code.
Although it is described that a specific pattern of "0000100000001" is used, no consideration is given to reproducing information immediately before and after a resynchronization pattern.

Further, no consideration is given to making the length of a pit portion formed in each data area equal to the length of a non-pit portion.

[0004]

The conventional resynchronization pattern is characterized by using a code string which does not conform to the 1-7 run-length limited code rule, but the entire recording information recorded in each data area is used. Since no consideration is given to make the length of the pit portion equal to the length of the non-pit portion, the reproduced signal level fluctuates depending on the data pattern, and an original waveform detection method that is advantageous in terms of a signal-to-noise ratio is used. It is difficult.

The resynchronization pattern used in the present invention has the following functions.

[0006] 1. Recorded information immediately before and after the resynchronization pattern can be reproduced without considering the resynchronization pattern.

[0007] 2. A run length switching code for making the length of a recording mark portion and the length of a portion other than the recording mark portion the same in the entire recording information recorded in each data area is included.

[0008] 3. Includes code patterns that do not exist in the run-length limited coding rules.

4. The resynchronization pattern is composed of 24 code strings.

[0010]

In order to achieve the above object, according to the present invention, a resynchronization pattern includes a code pattern not included in the run-length limited coding rule, and a resynchronization pattern. A code for reproducing recorded information immediately before and immediately after the resynchronization pattern is included before and after the resynchronization pattern. Further, the resynchronization pattern includes a run length switching code for making the length of the recording mark portion and the length of the portion other than the recording mark portion the same in the entire recording information recorded in each data area. Features.

In the present invention, the resynchronization pattern inserted at predetermined intervals of recording information includes a code for reproducing the recording information immediately before and after the resynchronization pattern.
The information can be reproduced by the demodulation circuit without being aware of the resynchronization pattern.

In addition, during the resynchronization pattern, a run length switching code for making the length of the recording mark portion equal to the length of the non-recording mark portion in the entire recording information recorded in each data area is used. By including them, it becomes possible to keep the amplitude of the reproduction signal constant when reading information from the medium.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The following embodiments are examples applicable to pit-type, magneto-optical, and phase-change type optical recording media, particularly those using an optical disk. It can also be applied to the recording / reproduction of information using the recording medium.

Further, in the following embodiment, an example of a recording / reproducing apparatus capable of performing both recording and reproducing of information will be described. However, the apparatus may be separated into a recording apparatus and a reproducing apparatus.

FIG. 1 shows a schematic configuration of an example of an information recording / reproducing apparatus for implementing an information recording / reproducing method of the present invention using a novel resynchronization pattern according to the present invention.

The information recording / reproducing apparatus of this embodiment uses an optical disc 1 rotated at a constant angular velocity by a rotation-controlled spindle motor (not shown) to record / reproduce information.
Perform playback. The apparatus includes a head unit 2 for writing and reading data to and from the optical disk 1, and a control unit (not shown) for controlling the entire apparatus including the writing and reading head unit 2 and controlling the rotation of the optical disk 1 and the like. A recording unit 3 for converting information to be recorded into a signal to be written on the optical disk 1 by the write / read head unit 2 and a reproducing unit for reproducing information from a signal read from the optical disk 1 by the write / read head unit 2 4.

The same applies to the following embodiments. However, the configuration of this embodiment is divided in this way for the sake of convenience of explanation, and is not necessarily limited to such division. Similarly, such as a write / read head unit,
Each name is also for convenience, and does not limit the configuration of the information recording / reproducing apparatus of the present invention.

The optical disc 1 is provided with a number of tracks spirally or concentrically along the rotation direction, and a spindle motor (not shown) whose rotation is controlled.
Is rotating at a constant angular velocity. These tracks are
For example, a groove formed in advance in a spiral or concentric shape along the rotation direction and a land formed between adjacent grooves, and a land between the grooves while using the groove as a guide for tracking. Record / reproduce information on Each track is divided into a plurality of sectors, and information is recorded / reproduced in sector units.
Each sector is physically identified by an identification number called a sector address. A sector head portion is provided at the head of each sector. The sector head portion has a sector mark for recognizing that it is the head of a sector, and a sector mark.
Information such as a synchronizing signal for starting generation of a clock signal in the L circuit and a sector address is preformatted as necessary. The data area following the sector head section is an area where a recording mark (a state change portion such as a pit or a magnetization domain) is actually recorded at the time of recording by the recording / reproducing apparatus of FIG. For recording information in the data area in each sector, for example, a land (unrecorded area) is irradiated with an optical beam to form a state change portion (record mark) called a pit, and the length of the pit is This is performed by forming a state change pattern (pit pattern) indicating a corresponding state change. Similarly, in the case of a magneto-optical disk, information is recorded by forming a state change portion called a magnetization domain having a different magnetization direction in a land region. In this embodiment, the leading edge and the trailing edge of the state change portion (record mark such as a pit or a magnetization domain) correspond to the position of the code symbol “1” of the code pattern to be recorded on the medium. That is, information is recorded on the recording medium by associating the symbol “1” of the code pattern encoded by the run-length limited code with a state change inversion portion formed on the medium.

In the data area in the sector, first, P
A synchronization signal (SYNC) for locking the frequency of the clock signal generated by the LL circuit is recorded. Although a signal having the same function as this synchronization signal (SYNC) also exists in the sector head section, the synchronization signal of the sector head section is preformatted, and is actually recorded by the recording / reproducing apparatus of FIG. 1 during recording. Not recorded.
In the case where there is a difference between the clock signal generated from the synchronization signal of the sector head section and the clock signal at the time of recording in the data area, the clock information used at the time of recording in the data area is used as the synchronization signal (SYNC). Is recorded at the beginning of the data area, and using this synchronization signal (SYNC), the PLL
By finely adjusting the clock signal generated by the circuit, the clock signal is synchronized with the recording information recorded in the data area.

In the data area, the synchronization signal (SYN)
Subsequent to C), a signal obtained by transcoding the user information is recorded. The amount of information to be recorded in one sector is predetermined for each optical disc, and is usually 1 Kbyte or 512 bytes.
Bytes. After the predetermined amount of user information, when the user information is erroneously detected due to noise or the like during reproduction, an error correction code (E) for detecting and correcting the error is used.
Record CC). The recording information including the user information and the error correction code is provided with a predetermined amount (for example, 2 bytes) of a resynchronization signal (RESSYNC) inserted every predetermined amount (for example, 20 bytes or 30 bytes). Recorded together with the synchronization signal.

The resynchronization signal (RESSYNC) is a portion (defect portion) where recording marks cannot be continuously recorded due to a flaw in a recording medium or the like, and is generated by a PLL circuit while clock information cannot be detected from a reproduced signal during reproduction. It is provided to cope with a phenomenon in which a clock signal is shifted by an integer period and erroneous signal detection is performed thereafter. That is,
A resynchronization signal that can be identified even if the clock is shifted is recorded at regular intervals of recording information (user information and an error correction code), and a shift in the clock signal is detected based on the resynchronization signal during reproduction to reproduce the resynchronization signal. By performing the synchronization, the subsequent information detection is returned to the normal state again. The present invention
The present invention relates to improvement of the resynchronization signal (RESSYNC) pattern.

Note that, after the user information and the error correction code recorded together with the resynchronization signal, a buffer for adjusting the variation of one sector time caused by rotational jitter or the like follows, followed by the head of the next sector. .

The write / read head unit 2 includes a laser light source 5 for irradiating the optical disk 1 with an optical beam, a light receiving unit 6 for detecting the reflected light of the optical beam from the optical disk 1, and a light receiving unit 6. And a preamplifier 7 for amplifying the detected signal and outputting a detection signal used for reproducing information, and irradiating a pulsed light beam corresponding to the recorded information at the time of recording operation, and a light beam having a constant light amount at the time of reproduction. And a laser light source driving circuit 8 for driving the laser light source 5 so as to irradiate the laser beam. The preamplifier 7 has focusing control,
A control signal for controlling the irradiation position of the light beam, such as tracking control, is also output. However, since the control signal is not directly related to the present invention, the description is omitted here.

The write / read head unit 2 includes:
Necessary means and functions are added according to the information recording mode (pits, magnetization domains, phase changes) on the optical disc 1. For example, when recording information by forming a magnetization domain using a magneto-optical disk, in addition to the write / read head unit 2, a write magnetic head and a drive circuit therefor are provided.

The recording unit 3 records a recording block (for example, recording information in sector units) in which synchronization information is inserted for each predetermined amount of recording information by a recording data consisting of run-length limited codes by a predetermined 1-7 modulation method. 1-7 modulation circuit 9 for converting the data into a code (code pattern), and synchronizing information (especially, a resynchronization pattern) included in the output of 1-7 modulation circuit 9 in accordance with a 1-7 run-length limited code conversion rule. Irregular generating circuit 10 for changing the pattern to no pattern, buffer (BUFF) 11 for storing the output of irregular generating circuit 10, recording marks such as pits or magnetization domains from the output of irregular generating circuit 10 ) And a pit (run length) measuring circuit 13 for measuring the run length of the portion other than the state change portion (not the pit or the magnetization domain). Based on the result of the circuit 13, the pit length (run length) switching code for making the length of the state change portion (recording mark) of the entire recording block equal to the length of the non-state change portion is "1". And a pit length (run length) determination circuit 14 for determining whether or not to make it "0". The buffer 11 includes a pit length (run length) determination circuit 14
, The pit length (run length) included in the resynchronization signal pattern is changed so that the length of the pit (record mark) of the entire recording block and the length of the non-pit (record mark) become the same. It also has the function of changing the sign to “1” or “0”. The recording unit 3 further outputs the output of the buffer 11 to an NRZI (Non-Return-
NRZ to convert to to Zero Inverted)
An I circuit 12 and a timing generation circuit 15 for controlling the timing of the recording unit 3 are provided.

The irregular generation circuit 10 in the recording unit 3
The buffer (BUFF) 11, the pit (run length) measurement circuit 13, and the pit length (run length) determination circuit 14 constitute a resynchronization pattern generation unit.
The I exchange circuit 12 and a part of the read / write head unit 2 constitute information recording means for recording on a recording medium.

The reproducing section 4 includes a write / read head section 2
The detected reproduction signal is converted to a state change section (recording mark).
Is separated into a leading edge detection signal consisting of a pulse corresponding to the position of the leading edge and a trailing edge detection signal consisting of a pulse corresponding to the position of the trailing edge.
A clock synchronization circuit 16 for generating trailing edge data; a pattern detection circuit 18 for detecting a resynchronization pattern included in the output from the output of the clock synchronization circuit 16; By synthesizing the edge data and the trailing edge data,
1-7 demodulation circuit 17 for demodulating reproduced data, reproducing section 3
And a timing control circuit 19 for performing the above-mentioned timing control, and constitutes information reproducing means for reproducing data from a recording medium.

The 1-7 modulation circuit 9 operates according to the 1-7 run length limited code conversion rule shown in FIG. As shown in FIG. 2, the 1-7 code is generated in accordance with a combination of the 1-7 previous code, current data, and next data. The 1-7 run-length limited code converts a 2-bit data word into a 3-bit code word. A code string generated by conversion according to this coding conversion rule has code symbols "1" and "1". 1 "
Between 1 and 7 inclusive. A code string converted according to the 1-7 run-length limited code conversion rule has a polarity inversion that is a source of clock information in a reproduced signal at the time of decoding during reproduction. Clock information can be extracted from the signal itself.

As a code string that does not exist in the 1-7 run-length limited code conversion rule, for example, a run length "
There is a code consisting of six consecutive 0's.
By inserting a pattern "1000000010000001" in which six "0" s are consecutive after the seven consecutive "0s" in the pattern, a predetermined amount of recording information (user data, error correction code) is inserted. Thus, the resynchronization pattern recorded together with the record information can be easily detected by the pattern detection circuit 18 in distinction from the record information (user data, error correction code).

After the above seven “0” s are consecutive, “0” becomes 6
Individual continuous pattern "10000000100000"
1 ″ does not exist in the conversion rule in the 1-7 modulation circuit 9.
In order to generate a pattern that does not exist in such a conversion rule, when recording information is encoded, "0" is input to the 1-7 modulation circuit at predetermined intervals of the recording information as input data.
0 "," 11 "," 01 "," 10 "," 01 "," 0 "
When the synchronization information consisting of 1 "," 11 ", and" 01 "is input, the 1-7 modulation circuit 9 outputs a predetermined amount (for example, 30 bytes) of recording information patterns of 30 to 33 as shown in FIG. The pattern 3 is output.
The difference between 0 and 33 is caused by the code (“0” or “1”) of the recording information input to the 1-7 modulation circuit 9 immediately before and immediately after the synchronization information inserted at predetermined intervals. This 1-
7) Of the patterns 30 to 33 output from the modulating circuit 9, the tenth code 38 is changed from "1" to "0" by the irregular generating circuit 10, and any of the patterns 34 to 37 is changed. Generate a pattern. In the 1-7 run-length limited code conversion rule, as can be seen from FIG. 2, in order to perform demodulation, a code to be demodulated and codes before and after the code are affected. In this embodiment, as shown by patterns 34 to 37 in FIG. 3, before and after the pattern "1000000010000001" which does not exist in the 1-7 conversion rule, the code of the previous information ("0" or "1") is used. Previous information reproduction pattern consisting of either "010" or "000"
"00" depending on the sign of the subsequent information ("1" or "0").
A resynchronization pattern is formed by adding a post-information reproduction pattern consisting of either 1 "or" 000 ".

The resynchronization pattern used in this embodiment is, as shown by patterns 34 to 37 in FIG. 3, between the pattern "1000000010000001" and the post-information reproduction pattern "001" or "000". A pit length (run length) switching code 39 is included. The pit length (run length) switching code 39 is the length of a pit portion (recording mark portion) of the entire recording information (recording block) recorded in the data area of one sector and the length of a portion other than the pit portion (recording mark portion). In order to make them the same, it is switched to “0” or “1” according to the outputs of the pit length (run length) measuring circuit 13 and the pit length (run length) determining circuit 14. The pit length (run length) measuring circuit 13 includes an information information pattern recorded before and after the resynchronization pattern and a pre-information reproduction pattern and a post-information reproduction pattern included in the resynchronization pattern.
The pit length (run length) is measured.

FIG. 4 shows a state change pattern formed on the medium when the pit length (run length) switching code 39 is switched to "0" or "1". When recording is performed with a code pattern 40 including a resynchronization pattern in which the pit length (run length) switching code 39 is set to "0", it is formed on the medium like a state change pattern 41. On the other hand, the pit length (run length) switching code 39 of the code pattern 40 is changed to "
When recording is performed with the code pattern 42 including the resynchronization pattern set to "1", a state change pattern 43 is formed on the medium. Thus, the pit length (run length) included in the resynchronization pattern is switched. The code 39 is switched to “0” or “1” in accordance with the outputs of the pit length (run length) measurement circuit 13 and the pit length (run length) determination circuit 14, so that the pit portion (recording) of the entire recording block is changed. Adjustment is made so that the sum of the lengths of the mark portions) and the lengths of the portions other than the pit portions (recording mark portions) are the same.

According to the resynchronization pattern of this embodiment, since the resynchronization pattern includes the pattern for reproducing the previous information and the pattern for reproducing the post information, the resynchronization pattern includes the pattern for the re-synchronization pattern immediately before the resynchronization pattern. When reproducing the immediately following recording information pattern, the 1-7 demodulation circuit 17 of the reproducing unit 4 outputs a pattern "10000000100000" which does not exist in the 1-7 conversion rule included in the resynchronization pattern.
Reproduction is possible regardless of 1 ".

The resynchronization patterns 34 to 37 in FIG.
This is merely an example, and the pattern for reproducing the preceding information and the pattern for reproducing the subsequent information included in the resynchronization pattern may be patterns other than those of the present embodiment. The pit length (run length)
The switching code 39 may be added immediately after the previous information reproduction pattern.

[0036]

According to the present invention, a resynchronization pattern which is added at predetermined intervals of recording information and is recorded in the data area of each sector together with the recording information is provided before and after a pattern which does not exist in the encoding rule. The demodulation circuit is aware of the resynchronization pattern because it includes a pattern for reproducing the previous information determined according to the sign of the preceding information and a pattern for reproducing the information determined according to the sign of the following information. Thus, the recorded information patterns immediately before and immediately after the resynchronization pattern can be reproduced.

Also, by including a pit length (run length) switching code in the resynchronization pattern, the sum of the lengths of the pit portions (recording mark portions) of the entire recording block and the pit portions (recording mark portions) are eliminated. Adjustments can be made so that the sum of the lengths is the same, and even if an encoding rule that originally has no DC-free property is used, it is possible to suppress the level fluctuation of the reproduced signal while maintaining the self-clocking property. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an optical disk recording / reproducing apparatus for performing an information recording / reproducing method of the present invention.

FIG. 2 is an explanatory diagram showing a 1-7 run-length encoding rule used in the present invention.

FIG. 3 is a diagram showing an example of a resynchronization pattern used in the present invention.

FIG. 4 is a diagram illustrating the shape of a pit pattern formed on a recording medium for explaining the function of a pit length switching code.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Write / read head part, 3 ...
Recording section, 4 ... Reproduction section, 39 ... Pit length switching code

Claims (3)

(57) [Claims] (1)Corresponding to the edge of the area where the condition of the medium changes
Record information and run-length limited coding
Data area where information converted based on rules is recorded
And a code pattern not in the run-length limited coding rule.
Information recording medium in which resynchronization patterns
In the body, A code string of the data area immediately before the resynchronization pattern,
And the length of the portion where the state of the medium is changing and
The difference from the length of the part where the condition of the medium has not changed
Recording the different resynchronization patterns.
Information recording medium . 2. The information recording medium according to claim 1, wherein
The resynchronization pattern is the information immediately before the resynchronization pattern.
Information reproduction pattern for reproducing information and the resynchronization pattern.
For post-information reproduction to reproduce the information immediately after the turn
An information recording medium including a pattern. 3. The information recording medium according to claim 1, wherein
The run-length limited coding rule is a 1-7 modulation method.
Information recording medium.