JP2000331430A - Sync pattern detection method and information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce erroneous detection of a sync pattern (a synchronous pattern) at any other position than the true position of sync pattern by recording an auxiliary sync pattern in earlier position with the predetermined section than the sync pattern, detecting the auxiliary sync pattern at the time of reproducing, and limiting an extent to detect the sync pattern based on the detected auxiliary sync pattern. SOLUTION: An auxiliary sync pattern 202 is provided in earlier position with the predetermined section than a sync pattern 301. After elapse of a detection timing delay time td1 corresponding to the predetermined section from the point of the auxiliary sync pattern detection, detection of the sync pattern 301 is executed over a period of a sync pattern detection extent TS1 determined to correspond to a sync pattern length. Further as the sync pattern detection is executed continuously, when the timing detecting the sync pattern is within the sync pattern detection extent TS1, it would be judged that an effective sync pattern is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention restricts a range in which a sync pattern is detected at the time of reproduction based on a sync auxiliary pattern recorded a predetermined section before a sync pattern (synchronous pattern), thereby enabling an error in a sync pattern to be detected. The present invention relates to a sync pattern detection method and an information recording / reproducing apparatus for reducing detection.

[0002]

2. Description of the Related Art In an information recording / reproducing apparatus, a channel clock (a clock in data bits) is provided in a preamble portion.
And a sync pattern signal for reproducing a symbol clock (a clock of a symbol unit of data) or a block clock (a clock of a block unit of data) in a sync pattern portion. I have. During reproduction, a channel clock is generated based on the preamble signal, a symbol clock is generated based on the sync pattern signal, and data recorded in a predetermined recording format is read based on the channel clock and the symbol clock. I have.

[0003] In Japanese Patent Application Laid-Open No. H2-177062, a repetition pattern of a minimum inversion interval after modulation and a block synchronization pattern of a regular interval are recorded in a preamble section before a data section, so that the data is reproduced during reproduction. There is described a digital information signal recording apparatus in which a pull-in operation of a PLL is performed without any trouble, and a block synchronization signal can be interpolated from the beginning of a data section.

Japanese Patent Laid-Open No. 4-1278 / 1992 discloses that a signal (pre-sync signal) of a pattern which does not occur in data and is synchronized with a symbol clock is written in a preamble portion. A magnetic recording / reproducing apparatus is described in which a synchronization signal detection section (sync signal) immediately after a preamble section ensures symbol synchronization.

Japanese Patent Application Laid-Open No. Hei 4-26959 discloses a technique in which a plurality of synchronization patterns are provided as synchronization information for data or address information, and a pattern different from the synchronization pattern is provided between two adjacent synchronization patterns.
A synchronous information recording / reproducing apparatus is described which can reliably detect synchronous information even if a defect exists on a recording medium.

Japanese Patent Laid-Open No. 4-181559 discloses that at the end of a preamble portion, a signal (presync signal) of a pattern which does not occur in data and which is synchronized with a symbol clock is written. Describes a magnetic recording / reproducing apparatus in which a synchronization signal detection section (sync signal) immediately after a preamble section can ensure symbol synchronization.

[0007] Japanese Patent Application Laid-Open No. Hei 9-139021 discloses that a sync used for detecting data at a predetermined position is accurately detected, and a pseudo sync control signal is generated even if an error occurs in the sync. A sync detection and protection circuit and a method for accurately detecting data at a predetermined position are described. This sync detection and protection circuit and its method are configured as follows. The demodulated data is supplied to a learn-up pattern detection unit and a sync pattern detection unit. The learn-up pattern detector detects a pattern of each preamble area of the data, and supplies a detection result to the sync pattern detector. The sync pattern detection section detects the demodulated data, compares the demodulated data with a predetermined sync pattern, and outputs a sync detection signal. The ID separation unit compares the current ID with the previous ID and outputs an ID comparison signal. The pseudo sync control signal generation unit generates a sync signal based on the sync detection signal and the ID comparison signal, and generates a pseudo sync control signal when an error occurs in the sync signal.

[0008]

A conventional information recording / reproducing apparatus detects a sync pattern during reproduction over the entire range of reproduction data. Therefore, when the quality of the reproduced data is deteriorated or when there is an abnormality in the reproduced data, the sync pattern may be erroneously detected at a position where the sync pattern is not originally located. If a sync pattern is erroneously detected, a data burst error or the like may occur, and data may not be correctly reproduced.

The cause of the deterioration of the quality of the reproduced data or the occurrence of an abnormality in the reproduced data may be caused by an automatic gain amplifier (A
GC) lack of response, PLL pull-in operation is incomplete, filter optimization is insufficient, medium defect, thermal asperity, etc.

In the magnetic recording / reproducing apparatus described in JP-A-4-13278 and JP-A-4-181559, the preamble portion has a pattern which does not occur in the data and a symbol clock. By writing a signal of a pattern that can be synchronized (pre-sync signal), symbol synchronization can be reliably achieved in a synchronization signal detection section (sync signal) immediately after the preamble section. However, these conventional magnetic recording / reproducing apparatuses provide a pre-sync signal having substantially the same function as the sync signal in the preamble section, so that there is essentially no difference from preparing a plurality of sync patterns. For this reason, the user data area is reduced by an amount corresponding to the recording of the pre-sync signal.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem, and it is possible to reduce erroneous detection of a sync pattern at a position other than the original sync pattern position and improve the accuracy of detecting the sync pattern. It is an object to provide a detection method and an information recording / reproducing device. It is another object of the present invention to provide a sync pattern detection method and an information recording / reproducing apparatus that reduce erroneous detection of a sync pattern without significantly reducing a user data area.

[0012]

According to a first aspect of the present invention, there is provided a method for detecting a sync pattern, comprising the steps of: Record the pattern,
It is characterized in that the range in which a sync pattern is detected during playback is limited based on the sync assist pattern.

A sync pattern detection method and an information recording / reproducing apparatus according to the present invention detect a sync auxiliary pattern at the time of reproduction and limit a range in which the sync pattern is detected based on the detection time of the sync auxiliary pattern. This allows
The sync pattern is detected only in the section where the sync pattern exists. In a section where no sync pattern exists, such as a user data section, no sync pattern is detected. Therefore, the sync pattern is not erroneously detected in the section where the sync pattern does not exist.

According to a third aspect of the present invention, there is provided a sync pattern detecting method and an information recording / reproducing apparatus according to the eighth aspect, wherein the preamble section is provided with a sync auxiliary pattern having a cycle that is an integral multiple of the cycle of the preamble pattern for channel clock reproduction. In addition, a range in which a sync pattern is detected based on a sync auxiliary pattern during reproduction is limited.

According to a third aspect of the present invention, there is provided a method for detecting a sync pattern and an information recording / reproducing apparatus according to the eighth aspect, wherein a sync assist pattern is provided in the preamble portion, and a cycle of the sync assist pattern is set to an integral multiple of a cycle of the preamble pattern. Therefore, the insertion of the sync assist pattern in the preamble portion hardly affects the channel clock reproduction operation (PLL pull-in operation) based on the preamble pattern.

For example, the preamble pattern is a repetition of a signal having a period twice as long as the minimum magnetization reversal interval (T), and the sink assist pattern is a single-shot signal having a period four times the minimum magnetization reversal interval (T). An increase in the pattern length of the preamble portion due to the insertion of the sync assist pattern can be minimized. Thereby, it is possible to prevent the user data area from being significantly reduced.

The time when the time required to reproduce a predetermined section from the sync assist pattern has elapsed is defined as the sync pattern detection start timing. From the detection start timing, the detectable time set in advance corresponding to the sync pattern length has elapsed. By setting the time when the detection ends as the detection end timing,
The range in which the sync pattern is detected may be limited.

Thus, a sync pattern can be detected only in a section where the sync pattern exists. Therefore, a sync pattern is not erroneously detected in a section where no sync pattern exists.

Further, a sync pattern detection clock may be generated in synchronization with the sync auxiliary pattern, and the range in which the sync pattern is detected based on the generated sync pattern detection clock may be limited.

Thus, the sync pattern can be detected only in the section where the sync pattern exists. Therefore, a sync pattern is not erroneously detected in a section where no sync pattern exists.

[0021]

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

FIG. 1 is an explanatory diagram showing an example of a recording format used in a sync pattern detection method and an information recording / reproducing apparatus according to the present invention, and an example of a sync pattern detection range. In FIG. 1, 200 is a preamble part, 300 is a sync pattern part, and 400 is a user data part.

The preamble section 200 includes preamble patterns 201a and 201b and a sync assist pattern 2
02 is recorded. The preamble pattern 201a,
201b is for generating a channel clock at the time of reproduction. The sync assist pattern 202 is a reference pattern for setting a sync pattern detection range during reproduction. The sync auxiliary pattern 202 is recorded before a predetermined section set before the sync pattern unit 300.

In the sync pattern section 300, one or a plurality of sync patterns 301a and 301b are recorded.
FIG. 1 shows an example in which two sync patterns 301a and 301b are continuously recorded. Each of the sync patterns 301a and 301b is for synchronizing data symbols or data blocks at the time of reproduction. User data 401 is recorded in the user data section 400.

When the sync pattern detection method and the information recording / reproducing apparatus according to the present invention detect the sync auxiliary pattern 202 during reproduction, the range for detecting each of the sync patterns 301a, 301b is limited based on the sync auxiliary pattern detection time. I do.

More specifically, the sync pattern (1) 301a is detected in the section of the sync pattern (1) detection range TS1 from the time when the first detection timing delay time td1 has elapsed since the sync auxiliary pattern was detected. The first detection timing delay time td1 corresponds to the sync assist pattern 2
A time corresponding to the section from 02 to the sync pattern (1) 301a (time from when the sync auxiliary pattern is reproduced to when the sync pattern (1) is reproduced) is set to a time slightly shorter than the time. I have. The sync pattern (1) detection range TS1 is equal to the sync pattern (1) 30
It is set slightly longer than the time corresponding to the pattern length of 1a.

The sync pattern (2) 301b is detected in the section of the sync pattern (2) detection range TS2 from the time when the second detection timing delay time td2 has elapsed from the sync auxiliary pattern detection time. The second detection timing delay time td2 is a time corresponding to the section from the sync auxiliary pattern 202 to the sync pattern (2) 301b (the time from when the sync auxiliary pattern is reproduced until when the sync pattern (1) is reproduced). It is set to a time equal to or slightly shorter than. The sync pattern (1) detection range TS2 is set to be slightly longer than the time corresponding to the pattern length of the sync pattern (2) 301b.

Each detection timing delay time td1, td2
Each sync pattern detection range TS1, TS2 is
The time is measured based on the channel clock generated at the time of reproduction. Thus, even when the rotational speed of a disk-shaped recording medium such as a magnetic disk or an optical disk is deviated from a predetermined value, the sync pattern detection range can be set in accordance with the sync pattern position defined by the recording format. . Further, even when a tape-shaped recording medium is used and the tape traveling speed or the number of rotations of the rotary head deviates from a predetermined value, the sync pattern detection range can be set accurately.

Each sync pattern detection range TS1, TS2
, The sync pattern detection operation may be performed only when the sync pattern detection operation is continuously performed and the sync pattern detection timing matches the sync pattern detection ranges TS1 and TS2. It may be determined that a valid sync pattern has been detected.

Although the detection position is located at the rear end of the sync assist pattern 202 in FIG. 1, it is not limited to this.
The point at which detection is performed depends on the detection method of the sync assist pattern. In the case of level detection, the detection point is a point near the threshold value. Also, even in the case of level detection, if the detection timing is determined by a certain clock, even if the detection timing is exceeded, the detection is not performed until the next clock comes.

FIG. 2 is a block diagram of a data write system of the information recording / reproducing apparatus according to the present invention. The data write system includes a data I / O (input / output) control unit 1, a reproduction auxiliary pattern generation unit 2, a scrambler 3, and an encoder 4.
, A precoder 5, a recording timing compensating means 6, a synthesizer 7, and a control means 8.

The data I / O (input / output) control means 1 controls input / output of data to be recorded / reproduced. The reproduction auxiliary pattern generating means 2 includes a preamble pattern for obtaining a clock synchronized with data by a data synchronizer in a bit unit at the time of reproduction, and a sync pattern serving as a reference for performing synchronization detection of a decoding unit by each modulation method of the reproduction data at the time of reproduction. Then, a pattern other than user data for assisting in reproduction, such as a sync auxiliary pattern serving as a reference for limiting the detection range of the sync pattern during reproduction, is generated.

The scrambler 3 randomizes the data. The encoder 4 modulates data. The precoder 5 is used to prevent error propagation or during playback.
In order to limit the maximum value of the run length that is a continuous length of 0 ", code conversion before recording is performed.

The recording timing compensating means 6
For example, in the case of magnetic recording, the magnetic flux from the magnetic domain recorded immediately before interacts with the magnetic flux of the write head, and the position of the magnetization reversal shifts non-linearly.
The data recording timing is controlled to compensate for a problem that can be reduced by changing the recording timing, such as r Transition Shift (NLTS).

The synthesizer 7 generates a write clock serving as a reference for controlling the operation timing of each means during recording. The control unit 8 determines whether the data to be recorded is an area in which a reproduction assist pattern such as a preamble, a sync, or a sync assist pattern is to be recorded.
ON / OFF of the function of each means, based on an area signal 81 indicating whether the area is an area where user data should be recorded,
Control operation timing and the like.

FIG. 3 is a block diagram of a data read system of the information recording / reproducing apparatus according to the present invention. The data read system includes an AGC 10, a filter 11, various signal processing means 12, a sync detection means 13, a decoder 14, a data synchronizer 15, and a sync detection control means 16. The sync detection control unit 16 includes a sync auxiliary pattern detection unit 161 and a detection timing determination unit 162.

The reproduced data reproduced from the data storage medium or the reproduced data obtained by amplifying the reproduced data by a preamplifier or the like is input to the AGC 10. AGC10
Automatically amplifies the input reproduction data so as to have an arbitrary set amplitude. The data output from the AGC 10 is supplied to the filter 11. Filter 11
Performs a process of bringing the data output from the AGC 10 closer to the optimum waveform for each signal processing method.

The various signal processing means 12 performs various signal processing to extract data from the reproduced waveform. The sync detecting means 13 detects a sync pattern. Decoder 1
Reference numeral 4 demodulates data modulated by the encoder 4 shown in FIG. The data synchronizer 15 generates a read clock, which is a reference of timing when reproducing data synchronized with the reproduction waveform, from the reproduction data. The sync detection control means 16 controls a range in which a sync pattern start portion is detected. The sync assist pattern detection unit 161 detects a sync assist pattern. Detection timing determination unit 1
62 controls the timing of sync detection.

FIG. 4 is an explanatory diagram showing a method for determining the sync pattern detection timing. FIG. 4A shows the reproduced signal, and FIG. 4B shows the sync pattern detection timing based on the detection timing delay time.

Next, the operation of the data write system shown in FIG. 2 will be described with reference to FIG. When the information recording / reproducing apparatus according to the present invention is in the data recording state, the area signal 81 indicates at first that the area is where the reproduction assist pattern should be recorded. The control means 8 which has received the area signal 81 sets the reproduction auxiliary pattern generation means 2 to an operable state. The reproduction auxiliary pattern generation means 2 generates a reproduction auxiliary pattern in synchronization with a write clock generated by the synthesizer 7.

The reproduction assist pattern generated at this time is:
As shown in FIG. 4A, the preamble pattern 201
When a occurs first and occurs for an arbitrary set number, a sync assist pattern 202 occurs next, and then a preamble pattern 201b occurs for another arbitrary set number, and then a sync assist pattern 202b occurs. Pattern 301a, 3
01b occurs. FIG. 4 shows an example in which there are two sync patterns.

When a reproduction assist pattern is generated,
Whether the scrambler 3, the encoder 4, the precoder 5, and the recording timing compensating means 6 operate can be changed by setting. The means not operating at this time are automatically bypassed.

When the generation of the reproduction auxiliary pattern is completed, the area signal 81 changes to a signal indicating the user data portion, and the user data recorded from the data I / O control means 1 is sent to the next stage. At this time, the control means 8 keeps the reproduction auxiliary pattern generating means 2 inoperative. The user data to be recorded is randomized by the scrambler 3 and modulated by the encoder 4 according to each modulation method. Further, code conversion is performed by the precoder 5, the recording timing is shifted to an arbitrary set timing by the recording timing compensating means 6, and transmitted as write data to a write driver such as a preamplifier that actually performs recording.

Next, the operation of the data read system shown in FIG. 3 will be described with reference to FIG. The reproduced signal shown in FIG. 4A is input to the AGC 10 shown in FIG. 3, and is amplified to a given amplitude. The amplified reproduction signal is input to a filter 11 and shaped by the filter 11 so as to have a waveform suitable for each subsequent signal processing. Output data from the filter 11 is supplied to various signal processing means 12, a data synchronizer 15, and a sync detection control means 16, respectively.

The data synchronizer 15 generates a read clock synchronized with the data bit from the filter output data.

The sync auxiliary pattern detection section 161 in the sync detection control means 16 detects a sync auxiliary pattern from the filter output data and supplies a sync auxiliary pattern detection pulse shown in FIG. I do.

The detection timing determining section 162 determines that the sync detection means 13 is the same as that shown in FIG. 4 for only the sync pattern start position detectable time t1 after the first detection timing delay time td1 is delayed from the sync auxiliary pattern detection pulse.
Control is performed so that detection of the first sync pattern (1) 301a shown in (a) can be started. Further, the detection timing determination unit 162 determines that the sync detection means 13 is in the state shown in FIG. 4A from the time when the sync auxiliary pattern detection pulse is delayed by the second detection timing delay time td2 during the sync pattern start position detectable time t2. Control is performed so that detection of the second sync pattern (2) 301b shown can be started.

When the sync detecting means 13 detects a sync pattern, the decoder 14 starts decoding based on the detected sync pattern. If no sync pattern is detected, the time when the sync auxiliary pattern detection pulse is output (the time when the sync auxiliary pattern is detected)
The decoding may be forcibly started at the time point when the forced decoding start delay time td3 has elapsed.

FIG. 5 is an explanatory diagram showing another method of determining the sync pattern detection timing. FIG. 5A shows the reproduction signal, and FIG. 5B shows the detection timing of the sync pattern based on the detection timing clock.

The sync auxiliary pattern detector 1 shown in FIG.
When detecting the sync assist pattern 202, the 61 outputs a sync assist pattern detection signal. The detection timing determination unit 162 generates and outputs a detection timing clock shown in FIG. 5B based on the sync auxiliary pattern detection signal. This detection timing clock is supplied to the sync detection means 13.

The sync detecting means 13 determines that a valid sync pattern has been detected if the start of the detected sync pattern is within a predetermined range with respect to the detection timing clock upon detecting the sync pattern. For example, if the start portion of the sync pattern is within a predetermined allowable time with respect to the rising point of the detection timing clock, it is determined that the sync pattern is valid.

The cycle of the detection timing clock is set to a time corresponding to the pattern length of each of the sync patterns 301a and 301b. The pattern length of the preamble pattern 201b provided before the first sync pattern (1) 301a is equal to the length of each sync pattern 301a,
It is set to be the same as the pattern length of 301b.

When no sync pattern is detected, the user data 401 may be decoded based on the detection timing clock.

Next, the data write system shown in FIG. 2 and the data read system shown in FIG. 3 will be described in detail, assuming a magnetic recording type information recording / reproducing apparatus. In magnetic recording, data handled by the data I / O control means 1 is as follows.
An NRZ (Non Return to Zero) signal is common. Each unit such as the scrambler 3 and the precoder 5 for randomizing data may not be provided depending on the data storage method or the signal processing method. Scrambler 3
Is particularly effective when using a signal processing method that is resistant to random errors such as PRML.

Although there are various types of auxiliary reproduction patterns generated by the auxiliary reproduction pattern generating means 2, if the minimum magnetization reversal interval of recorded data is T, the waveform of the preamble portion is a waveform written at an interval of 2T. The most common. Normally, the data synchronizer 15 is tuned with the reproduced waveform of the preamble portion. A PLL (Phase Locke) is provided to the data synchronizer 15 for generating a read clock synchronized with the data at the time of reproduction and the synthesizer 7 for generating a write clock to be a reference at the time of recording.
d Loop) is generally used. PLL
Synchronizing the read clock output from the data synchronizer 15 with the data means synchronizing the phase of the read clock with the data (phase pull-in).

The preamble is the data synchronizer 1
It is necessary to set the length of the preamble so that tuning to the data of No. 5 can be sufficiently completed, but it is better to set the length shorter in consideration of the format efficiency which affects the storage capacity of the entire system. Therefore, the minimum length that allows sufficient tuning is the optimal preamble length.

It is desirable that the sync auxiliary pattern be a pattern that can be easily distinguished from the sync pattern. Further, a pattern that does not disturb the phase pull-in of the data synchronizer 15 synchronized with the reproduction data is desirable. By doing so, even when the sync assist pattern is placed at a position where the phase pull-in of the data synchronizer 15 is not sufficient, the data synchronizer 15 pulls in the phase sufficiently until the sync pattern is reproduced including the preamble portion following the sync assist pattern. Can be shortened.

FIGS. 4 and 5 show a case where a 4T waveform is used as the sync auxiliary pattern. Since 4T is a multiple of 2T, the phase pull-in of the data synchronizer 15 is hardly disturbed. Also, in resolution, which is the amplitude ratio between the highest frequency and the lowest frequency that is usually used for recording, the amplitude of the 4T waveform is larger than that of the 2T waveform, so this sync assist pattern is detected by level detection or the like. It becomes possible to do. Further, it is also possible to detect the value by sampling the reproduced waveform with the read clock.

Next, there are various types of sync patterns depending on the signal processing method and the allowable sync error. 4 and FIG.
This shows a case where there are two sync patterns. In this case, the sync pattern (1) or the sync pattern (2)
A plurality of detection methods can be selected, such as determining the starting reference of the decoding unit of each subsequent signal processing method only when the sync pattern is found or when both the sync patterns (1) and (2) are found. This is the same when there are three or more sync patterns.

When there is one sync pattern, a sync detection error basically occurs when the sync pattern cannot be found. When a signal other than a sync pattern, such as a training pattern for initial adjustment of a digital filter, is a decoding start reference, the signal corresponds to the sync pattern. Further, even when a decoding reference is made by detecting a part of the sync pattern, erroneous detection can be reduced by limiting the range for detecting the start part of the detection pattern which is a part of the sync pattern. .

The recording format shown in FIGS. 1, 4 and 5 assumes an ID-less sector format in which ID information such as a cylinder number, a sector number, and a head address is not recorded. In the case of a certain format, the sync pattern detection method according to the present invention can be similarly applied.

As the filter 11 shown in FIG. 3, an analog filter, a digital filter, or both filters can be used. It is desirable to employ a suitable filter configuration according to the signal processing method of the subsequent stage.

There are various signal processing methods for the various signal processing means 12. The main signal processing methods in magnetic recording include peak detection, PRML, and EPRM.
L and EEPRML are known. The various signal processing units 12 are configured using such a signal processing method.

Next, a method of determining the range of sync pattern detection from sync auxiliary pattern detection in the sync detection means 16 will be described. The sync detecting means 16
For example, as shown in FIG. 4B, the sync pattern (1) is detected only during the time t1 after a certain delay time td1 after the detection of the sync auxiliary pattern, and the delay time td
2 so that the sync pattern (2) is detected only during the time t2. This can reduce the possibility of erroneous sync detection. Also, by forcibly starting the decoding after the delay time td3 from the detection of the sync auxiliary pattern, it is possible to provide a possibility that the user data can be reproduced when the sync pattern cannot be detected.

As another method, as shown in FIG. 5B, based on the detection of a sync auxiliary pattern, a detection timing clock synchronized with a decoding unit is generated to limit the range of sync pattern detection. can do. In FIG. 5B, only the period of time t centered on the rise of the detection timing clock is set as the sync pattern start portion detection range.

FIGS. 6 and 7 are explanatory views showing a method of limiting the sync pattern start portion detection range when a plurality of sync auxiliary patterns are provided. FIG. 6A and FIG. 7A show a reproduced signal. FIG. 6B shows the detection timing of the sync pattern for the first sync auxiliary pattern, and FIG. 7B shows the detection timing of the sync pattern for the second sync auxiliary pattern.

When there are a plurality of sync assist patterns, as shown in FIG. 6B, the first (first) sync assist pattern starts from td11, td12, td13, td14,
A detectable time of t1 is provided with a delay time of td15, and as shown in FIG. 7B, td21, td22, and td2 are shifted from the second sync assist pattern.
3, with td24 and td25 delay times, respectively.
2, a detectable time is provided. Further, the delay time and the detectable time are similarly provided for the third and fourth sync auxiliary patterns.

As described above, by setting a plurality of sync pattern detection ranges corresponding to the respective sync auxiliary patterns, the possibility of erroneous detection of the sync pattern can be reduced. here,
Td11, td1 in the case of the first sync assist pattern
Although the sync pattern is not actually detected in the detectable range with the delay time of 2, td13, the sync pattern start portion detection range can be set even when some of the sync auxiliary patterns cannot be detected. Can be set incorrectly. This is because it is not possible to confirm the order of the detected sync auxiliary pattern.

In the case of using a method for determining the order of the detected sync assist pattern and the order of the sync assist patterns for distinguishing the order of the sync assist patterns, the respective sync assist patterns are used. The delay time at the time of detecting the auxiliary pattern and the sync pattern detectable time may be set by the number of sync patterns to be detected. Further, even when a part of the sync assist pattern cannot be detected, it is sufficient that at least one of the plurality of sync assist patterns can be detected.

FIG. 8 is an explanatory diagram showing another method of limiting the sync pattern start portion detection range when a plurality of sync auxiliary patterns are provided. FIG. 8A shows the reproduced signal, and FIG.
Indicates the sync pattern detection timing. FIG.
As shown in (b), by forming a detection timing clock from a plurality of sync auxiliary patterns, a sync pattern start portion detection range can be set.

The detection clock synchronized with the decode timing is generated for each of the plurality of sync auxiliary patterns in the same manner as the detection timing determination method for one sync auxiliary pattern shown in FIG. 5B. A pattern start part detection range can also be set.

FIG. 9 is an explanatory diagram showing the reduction of the erroneous detection of the sync pattern. FIG. 9 shows a case where the data decoding unit is 17 bits. By setting the sync pattern start part detection range and limiting the sync pattern detection range, when the data decoding unit is, for example, 17 bits, as shown in FIG. It is possible to reduce the possibility of detecting a pattern and causing a burst error in the data section.

Even when one or more sync assist patterns are recorded, if no sync assist pattern is detected, it is best to perform normal sync detection.

Next, another embodiment (second embodiment) of the information recording / reproducing apparatus according to the present invention will be described with reference to FIGS. FIG. 10 is a block diagram of a data write system of another information recording / reproducing apparatus according to the present invention. The data write system shown in FIG. 10 operates in a case where the area signal 81 indicates an area in which a reproduction auxiliary pattern is to be recorded, and operates when the area signal 81 indicates an area in which user data is to be recorded. The signal system is divided into two parts, namely, an operating scrambler 3, an encoder 4, and a precoder 5. Then, the selection means 9
Which of the three signal systems is supplied with data is selected based on the area signal 81. Further, the data write system includes a storage unit 17 capable of storing a plurality of combinations of generation patterns of the reproduction auxiliary pattern and a plurality of operation methods of each unit.

By dividing the signal flow into two systems by the selection means 9, it is possible to reduce the passage of the signal through the means that does not operate, so that the addition of extra noise to the signal can be reduced.

In FIG. 10, a clock signal is output from the synthesizer 7 to the reproduction auxiliary pattern generation means 2 and the control means 8, and a control signal is output from the control means 8 to the reproduction auxiliary pattern generation means 2.

FIG. 11 is a block diagram of a data read system of another information recording / reproducing apparatus according to the present invention. The data read system shown in FIG. 11 follows the data read system shown in FIG. 3 with storage means 17 capable of storing a plurality of detection timings and detection methods and the like, and reproduced data of the data synchronizer 15. A sensitivity adjusting means 18 capable of adjusting the sensitivity is added.

By providing the sensitivity adjusting means 18, the sensitivity of the data synchronizer 15 can be reduced before the arrival of the sync assist pattern. Thus, it is possible to reduce disturbance of the synchronization of the data synchronizer 15 due to the sync assist pattern and reduce disturbance of the output read clock.

In FIG. 11, a signal for reading and writing data is output from the detection timing section 162 to the storage means 17, and a signal for reading and writing data at the time of sensitivity adjustment is output from the sensitivity adjustment means 18 to the storage means 17. A signal for adjusting the sensitivity is output from the sensitivity adjuster 18 to the data synchronizer 15.

As still another embodiment, the storage means 17 may be added to the data write system shown in FIG. 2 and the storage means 17 may be added to the data read system shown in FIG. Also, an information recording / reproducing apparatus is configured by combining the data write system shown in FIG. 2 and the data read system shown in FIG. 11, or the data write system shown in FIG. 10 and the data read system shown in FIG. May be combined to form an information recording / reproducing apparatus.

Next, another embodiment (second embodiment) of the information recording / reproducing apparatus according to the present invention will be described in detail. The storage unit 17 shown in FIGS. 10 and 11 is configured using a semiconductor memory such as a read only memory (ROM), a random access memory (RAM), and a nonvolatile flash memory. Although there is a problem in terms of processing speed and reliability, the storage unit 17 may be configured using various recording media such as a magnetic disk device in terms of storage capacity and cost.

The storage means 17 stores a plurality of sets of data of a plurality of types of sync auxiliary patterns, combinations of preamble patterns and sync auxiliary patterns, their timings, and timings for controlling the respective means for each reproduction auxiliary pattern. can do. Further, the plurality of setting data can be selected or recorded by an external setting.

The sensitivity adjusting means 18 shown in FIG. 11 is for adjusting the sensitivity of the phase pull-in when generating a read clock synchronized with the data of the data synchronizer 15. For example, for the reproduction signal shown in FIG.
In the preamble portion up to a little before 2, the sensitivity of the data synchronizer phase pull-in is increased, and the sensitivity is lowered before the sync assist pattern 202, so that the phase pulled in based on the preamble pattern is changed by the sync assist pattern 202. Disturbance can be reduced. In this case, the sink assist pattern 20
It is necessary to optimize the length of the preamble so that the phase pull-in is almost completed by the time before 2.

In the case where a sync auxiliary pattern which has almost no influence on the synchronization with the data of the data synchronizer 15 without adjusting the sensitivity is used, a sufficient phase pull-in is performed in both the preamble and the sync auxiliary pattern. Can also be set to In other words, this means that even when a sync assist pattern is recorded, data synchronization is not disturbed by the sync assist pattern, so that it operates as a preamble including the sync assist pattern and the preamble portion. Thus, a sync assist pattern that functions as a part of the preamble is most preferable.

It should be noted that even if the information recording / reproducing apparatus is different from the block configuration exemplified in each embodiment, it is possible to limit the sync pattern detection range by providing means for recording / reproducing and detecting the sync auxiliary pattern. It is possible, and erroneous detection of the sync pattern can be reduced. Also,
Although the data read system shown in FIGS. 3 and 11 exemplifies a case where the reproduction signal (reproduction data) has a differential signal configuration, the reproduction signal (reproduction data) does not have to be differential. Further, in the present embodiment, the case where the number of sync patterns is two is exemplified, but the sync pattern detecting method and the information recording / reproducing apparatus according to the present invention can be applied even when the number of sync patterns is one or three or more. it can.

[0086]

As described above, the sync pattern detecting method and the information recording / reproducing apparatus according to the present invention record the sync auxiliary pattern a predetermined section before the sync pattern, and based on the sync auxiliary pattern during reproduction. Since the range of sync pattern detection is limited,
The sync pattern is detected only in the section where the sync pattern exists. Since a sync pattern is not detected in a section where a sync pattern does not exist, such as a user data section, a sync pattern is not erroneously detected in a section where no sync pattern exists.

Further, since the sync auxiliary pattern only needs to be detected, it can be a relatively short pattern. As a result, it is possible to reduce erroneous detection of the sync pattern without substantially lowering the format efficiency (without significantly reducing the user data area).

Further, by inserting a sync assist pattern into the preamble portion and setting the cycle of the sync assist pattern to an integral multiple of the cycle of the preamble pattern, a channel clock reproducing operation based on the preamble pattern (PLL pull-in operation). The sync assist pattern can be detected while minimizing the effect on the sync assist pattern.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a recording format used in a sync pattern detection method and an information recording / reproducing apparatus according to the present invention, and an example of a sync pattern detection range.

FIG. 2 is a block diagram of a data write system of the information recording / reproducing apparatus according to the present invention.

FIG. 3 is a block diagram of a data read system of the information recording / reproducing apparatus according to the present invention.

4A and 4B are explanatory diagrams showing a method of determining a sync pattern detection timing. FIG. 4A shows a reproduced signal, and FIG.
(B) shows the detection timing of the sync pattern.

5A and 5B are explanatory diagrams showing another method of determining a sync pattern detection timing. FIG. 5A shows a reproduction signal,
FIG. 5B shows the detection timing of the sync pattern.

6A and 6B are explanatory diagrams (part 1) illustrating a method of restricting a sync pattern start portion detection range when a plurality of sync auxiliary patterns are provided. FIG. 6A illustrates a reproduction signal, and FIG.
Indicates the sync pattern detection timing.

7A and 7B are explanatory diagrams (part 2) illustrating a method of limiting a sync pattern start portion detection range when a plurality of sync auxiliary patterns are provided. FIG. 7A illustrates a reproduced signal, and FIG.
Indicates the sync pattern detection timing.

8A and 8B are explanatory diagrams showing another method of limiting the sync pattern start portion detection range when a plurality of sync auxiliary patterns are provided. FIG. 8A shows a reproduced signal, and FIG. 8B shows a sync pattern. This shows the detection timing of.

FIG. 9 is an explanatory diagram showing erroneous detection of a sync pattern.

FIG. 10 is a block diagram of a data write system of another information recording / reproducing apparatus according to the present invention.

FIG. 11 is a block diagram of a data read system of another information recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Data I / O control means 2 Reproduction auxiliary pattern generation means 3 Scrambler 4 Encoder 5 Precoder 6 Recording timing compensation means 7 Synthesizer 8 Control means 9 Selection means 10 AGC 11 Filter 12 Various signal processing means 13 Sink detection means 14 Decoder 15 Data Synchronizer 16 Sync detection control unit 17 Storage unit 18 Sensitivity adjustment unit 81 Area signal 161 Sync auxiliary pattern detection unit 162 Detection timing determination unit 200 Preamble unit 201a, 201b Preamble pattern 202 Sync auxiliary pattern 300 Sync pattern unit 301a, 301b Sync pattern 400 User Data section 401 User data

Claims (10)

[Claims] 1. A sync pattern detecting method, wherein a range for detecting a sync pattern at the time of reproduction is limited. 2. A sync pattern detecting method, wherein a sync auxiliary pattern is recorded a predetermined section before a sync pattern, and a range in which the sync pattern is detected during reproduction is limited based on the sync auxiliary pattern. . 3. The method according to claim 1, wherein the auxiliary sync pattern is provided in a preamble portion before the sync pattern, and the sync auxiliary pattern is set to a cycle of an integral multiple of a cycle of a preamble pattern for reproducing a channel clock. The sync pattern detection method according to claim 2, wherein: 4. A timing at which a time required for reproducing the predetermined section from the sync assist pattern elapses is set as a detection start timing of the sync pattern, and a detection preset from the detection start timing corresponding to the sync pattern length is performed. 3. The sync pattern detection method according to claim 2, wherein a detection time of the sync pattern is limited by setting a time point at which the available time has elapsed as a detection end timing. 5. A sync pattern detecting clock is generated in synchronization with the sync auxiliary pattern, and a range in which a sync pattern is detected based on the generated sync pattern detecting clock is limited. Sync pattern detection method. 6. An information recording / reproducing apparatus comprising a sync pattern detection range limiting means for limiting a range in which a sync pattern is detected during reproduction. 7. A sync assist pattern recording means for recording a sync assist pattern a predetermined section before a sync pattern, and a sync pattern detection range limit for limiting a range for detecting the sync pattern based on the sync assist pattern during reproduction. And an information recording / reproducing apparatus. 8. The sync assist pattern is recorded in a preamble part before the sync pattern, and the sync assist pattern has a cycle that is an integral multiple of a cycle of a preamble pattern for reproducing a channel clock. The information recording / reproducing device according to claim 7, wherein the information is set. 9. The sync pattern detection range limiting means sets a time when a time required for reproducing the predetermined section from the sync auxiliary pattern elapses as a sync pattern detection start timing, and determines the sync pattern from the detection start timing. 8. The information recording / reproducing apparatus according to claim 7, wherein a range in which the sync pattern is detected is limited by setting a time point at which a detectable time set in advance corresponding to the length has elapsed as a detection end timing. 10. The sync pattern detection range limiting means generates a sync pattern detection clock in synchronization with the sync auxiliary pattern, and limits a range in which a sync pattern is detected based on the generated sync pattern detection clock. The information recording / reproducing apparatus according to claim 7, wherein: